IS 875 ALL IN ONE

IS : 875 (Part 1) - 1987 ( Incorporating IS : 1911-1967 ) (Reaffirmed 1997) Edition 3.1 (1997-12)

Indian Standard

C O D E O F P R A C T IC E F O R D E S IG N L O A D S (O T H E R T H A N E A R T H Q U A K E ) F O R B U IL D IN G S A N D S T R U C T U R E S PART 1

DEAD LOADS — UNIT WEIGHTS OF BUILDING MATERIALS AND STORED MATERIALS

( Second Revision ) (Incorporating Amendment No. 1)

UDC 624.042 : 006.76

© BIS 2002

BUREAU

OF INDIAN

STANDARDS

MANAK BHAVAN , 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002

Price Group 12

IS : 875 (Part 1) - 1987 CONTENTS PAGE 0. FOREWORD

3

1. SCOPE

4

2. BUILDING MATERIALS

4

TABLE 1 UNIT WEIGHT OF BUILDING MATERIALS 1. Acoustical material 2. Aggregate, coarse 3. Aggregate, fine 4. Aggregate, organic 5. Asbestos 6. Asbestos cement building pipes 7. Asbestos cement gutters 8. Asbestos cement pressure pipes 9. Asbestos cement sheeting 10. Bitumen 11. Blocks 12. Boards 13. Bricks 14. Brick chips and broken bricks 15. Brick dust ( SURKHI ) 16. Cast iron, manhole covers 17. Cast iron, manhole frames 18. Cast iron pipes 19. Cement 20. Cement concrete, plain 21. Cement concrete, prestressed 22. Cement concrete, reinforced 23. Cement concrete pipes 24. Cement mortar 25. Cement plaster 26. Cork 27. Expanded metal 28. Felt, bituminous for waterproofing and damp-proofing 29. Foam slag, foundry pumice 30. Glass 31. Gutters, asbestos cement 32. Gypsum 33. Iron 34. Lime 35. Linoleum 36. Masonry brick 37. Masonry, stone 38. Mastic asphalt 39. Metal sheeting, protected 40. Mortar 41. Pipes 42. Plaster 43. Sheeting 44. Slagwool 1

4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 7 7 7 7 7 8 8 8 8 8 8 8 9 9 9 9 9 9 9 10 10 10 10 10 10 11 16 16 17

IS : 875 (Part 1) - 1987 PAGE 17 17 25 25 25 26 26 26 26 28 28

45. Soils and gravels 46. Steel sections 47. Stone 48. Tar, coal 49. Thermal insulation 50. Terra cotta 51. Terrazzo 52. Tiles 53. Timber 54. Water 55. Wood-wool building slabs 3. BUILDING PARTS AND COMPONENTS TABLE 2 UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS 1. Ceilings 2. Cement concrete, plain 3. Cement concrete, reinforced 4. Damp-proofing 5. Earth filling 6. Finishing 7. Flooring 8. Roofing 9. Walling

29 29 29 29 29 29 29 30 31

4. STORE AND MISCELLANEOUS MATERIALS

31

APPENDIX A UNIT WEIGHTS OF STORE AND MISCELLANEOUS MATERIALS 1. Agricultural and food products 2. Chemicals and allied materials 3. Fuels 4. Manures 5. Metals and alloys 6. Miscellaneous materials 7. Ores 8. Textiles, paper and allied materials

32 33 33 34 34 36 37 37

2

IS : 875 (Part 1) - 1987

Indian Standard C O D E O F P R A C T IC E F O R D E S IG N L O A D S (O T H E R T H A N E A R T H Q U A K E ) F O R B U IL D IN G S A N D S TR U C T U R E S PART 1

DEAD LOADS — UNIT WEIGHTS OF BUILDING MATERIALS AND STORED MATERIALS

( Second Revision ) 0.

FOREWORD

0.1 This Indian Standard (Part 1) (Second Revision) was adopted by the Bureau of Indian Standards on 30 October 1987, after the draft finalized by the Structural Safety Sectional Committee had been approved by the Civil Engineering Division Council.

w eights and m easurem ents w as adopted. 0.3.1 With the increased adoption of the code, a number of comments were received on provisions on live load values adopted for different occupancies. Simultaneously, live load surveys have been carried out in America and Canada to arrive at realistic live loads based on actual determination of loading (movable and immovable) in different occupancies. Keeping this in view and other developments in the field of wind engineering, the Sectional Committee responsible for the preparation of the standard has decided to prepare the second revision in the following five parts: Part 1 Dead loads Part 2 Imposed loads Part 3 Wind loads Part 4 Snow loads Part 5 Special loads and loads combinations Earthquake load is covered in a separate standard, namely IS : 1893-1984* which should be considered along with the above loads. 0.4 This standard deals with dead loads to be assumed in the design of buildings and same is given in the form of unit weight of materials. The unit weight of other materials that are likely to be stored in a building are also included for the purpose of load calculations due to stored materials. 0.4.1 This standard incorporates IS : 1911† published in 1967. The unit weight of materials incorporated in this standard are based on information available through published Indian Standards and various other publications. 0.4.2 This edition 3.1 incorporates Amendment No. 1 (December 1997). Side bar indicates modification of the text as the result of incorporation of the amendment. 0.4.3 T he values given in this standard have been rounded off in accordance w ith IS : 2 - 1960‡.

0.2 A building has to perform m any functions satisfactorily. A m ongst these functions are the utility of the building for the intended use and occupancy, structural safety, fire safety; and com pliance w ith hygienic, sanitation, ventilation and daylight standards. T he design of the building is dependent upon the m inim um requirem ents prescribed for each of the above functions. T he m inim um requirem ents pertaining to the structural safety of buildings are being covered in this code by w ay of laying dow n m inim um design loads w hich have to be assum ed for dead loads, im posed loads, snow loads and other external loads, the structure w ould be required to bear. S trict conform ity to loading standards recom m ended in this code, it is hoped, w ill not only ensure the structural safety of the buildings w hich are being designed and constructed in the country and thereby reduce the hazards to life and property caused by unsafe structures, but also elim inate the w astage caused by assum ing unnecessarily heavy loadings. 0.3 T his Indian S tandard code of practice w as first published in 1957 for the guidance of civil engineers, designers and architects associated w ith planning and design of buildings. It included the provisions for the basic design loads (dead loads, live loads, w ind loads and seism ic loads) to be assum ed in the design of buildings. In its first revision in 1964, the w ind pressure provisions w ere m odified on the basis of studies of w ind phenom enon and its effect on structures, undertaken by the special com m ittee in consultation w ith the Indian M eteorological D epartm ent. In addition to this, new clauses on w ind loads for butterfly type structures w ere included; w ind pressure coefficients for sheeted roofs both curved and sloping, w ere m odified; seism ic load provisions w ere deleted (separate code having been prepared) and m etric system of

*Criteria for earthquake resistanT design of structures ( third revision ). †Schedule of unit weights of building materials ( first revision ). ‡Rules for rounding off numerical values ( revised ).

3

IS : 875 (Part 1) - 1987 1. SCOPE

NOTE 1 — Table 1 gives the unit weight mass of individual building materials in alphabetical order; Table 2 covers the unit weight mass of parts or components of a building; and Appendix A gives unit weight mass of stored materials.

1.1 This code (Part 1) covers unit weight/mass of materials, and parts or components in a building that apply to the determination of dead loads in the design of buildings. 1.1.1 The unit weight/mass of materials that are likely to be stored in a building are also specified for the purpose of load calculations along with angles of internal friction as appropriate.

MATERIAL

(1)

2.1 The unit weight/mass of materials used in building construction are specified in Table 1.

UNIT WEIGHT OF BUILDING MATERIALS NOMINAL SIZE OR THICKNESS

WEIGHT/MASS                         

TABLE 1

2. BUILDING MATERIALS

mm

kN

kg

per

(2)

(3)

(4)

(5)

10 10 10 10 — —

5.70 × 10–3 to 7.65 × 10–3 3.80 × 10–3 19.10 × 10–3 13.45 × 10–3 2.65 2.35

0.58 to 0.78 0.39 1.95 1.37 270 240

m2 ,, ,, ,, m3 ,,

1. Acoustical Material Eelgrass Glass fibre Hair Mineral wool Slag wool Cork 2. Aggregate, Coarse Broken stone ballast: Dry, well-shaken Perfectly wet Shingles, 3 to 38 mm

— — —

15.70 to 18.35 18.85 to 21.95 14.35

1 600 to 1 870 1 920 to 2 240 1 460

,, ,, ,,

— — — —

14.20 9.90 6.85 7.85

1 450 1 010 700 800

,, ,, ,, ,,

— — — —

15.10 to 15.70 18.05 17.25 to 19.60 9.90

1 540 to 1 600 1 840 1 760 to 2 000 1 010

,, ,, ,, ,,

Broken bricks: Fine Coarse Foam slag (foundry pumice) Cinder* 3. Aggregate, Fine Sand: Dry, clean River Wet Brick dust ( SURKHI ) 4. Aggregate, Organic Saw dust, loose

—

1.55

160

,,

Peat: Dry Sandy, compact Wet, compact

— — —

5.50 to 6.30 7.85 13.35

560 to 640 800 1 360

,, ,, ,,

5. Asbestos Felt

10

0.145

15

m2

— 10

9.40 0.02

960 2

m3 m2

Fibres: Pressed Sprayed Natural Raw

— —

29.80 5.90 to 8.85

3 040 600 to 900

m3 ,,

6. Asbestos Cement Building Pipes ( see under 41 ‘Pipes’ in this table ) *Also used for filling purposes. ( Continued )

4

IS : 875 (Part 1) - 1987 UNIT WEIGHT OF BUILDING MATERIALS — Contd

MATERIAL

NOMINAL SIZE OR THICKNESS

(1)

WEIGHT/MASS                     

TABLE 1

mm

kN

kg

per

(2)

(3)

(4)

(5)

7. Asbestos Cement Gutters [ see IS : 1626 (Part 2)-1980* ] Boundry wall gutters: 400 × 150 × 250 mm 450 × 150 × 300 mm 300 × 150 × 225 mm 275 × 125 × 175 mm

12.5 12.5 12.5 10.0

0.16 0.16 0.13 0.085

16.0 16.0 13.0 8.5

m ,, ,, ,,

12.5 12.5 12.5 12.5

0.245 0.160 0.145 0.130

24.8 16.1 14.6 13.2

,, ,, ,, ,,

9.5 9.5 9.5

0.043 0.079 0.087

4.4 8.1 8.9

,, ,, ,,

6 6 5

0.118 to 0.130 0.118 to 0.127 0.09

12.0 to 13.3 12.0 to 13.0 9.16

m2 ,, ,,

—

0.102

10.40

m3

—

8.65 to 12.55

880 to 1 280

,,

—

1.41

144

,,

—

1.41 to 0.94

144 to 96

,,

—

1.41 to 0.94

144 to 96

,,

Valley gutters: 900 × 200 × 225 mm 600 × 150 × 225 mm 450 × 125 × 150 mm 400 × 125 × 250 mm Half round gutters: 150 mm 250 mm 300 mm 8. Asbestos Cement Pressure Pipes ( see under 41 ‘Pipes’ in this table ) 9. Asbestos Cement Sheeting ( See IS : 459-1970† ) Corrugated (pitch = 146 mm) Semi-corrugated (pitch = 340 mm) Plain 10. Bitumen 11. Blocks Lime-based solid blocks ( see IS : 3115-1978‡ ) Hollow (open and closed cavity concrete blocks) [ see IS : 2185 (Part 1)-1979§ ] Grade A (load bearing) Grade B (load bearing) Grade C (non-load bearing) Solid concrete blocks

—

17.65

1 800

10 10

0.04 0.02

4 2

6 8 10 12

0.028 to 0.047 0.038 to 0.063 0.047 to 0.078 0.056 to 0.095

2.88 to 4.80 3.84 to 6.40 4.80 to 8.00 5.76 to 9.60

,,

12. Boards Cork boards: Compressed Ordinary Fibre building boards ( see IS : 1658-1977|| ) Medium hardboard

    

m2 ,,

,, ,, ,, ,,

*Specification for asbestos cement building pipes and pipe fittings, gutters and gutter fittings and roofing fittings: Part 2 Gutters and gutter fittings ( first revision ). †Specification for unreinforced corrugated and semi-corrugated asbestos cement sheets ( second revision ). ‡Specification for lime based block ( first revision ). §Specification for concrete masonry units: Part 1 Hollow and solid concrete blocks ( second revision ). ||Specification for fibre hardboards ( second revision ). ( Continued )

5


MATERIAL

NOMINAL SIZE OR THICKNESS mm

(1) Standard hardboard Tempered hardboard Fire insulation board ( see IS : 3348-1965* ) Fibre insulation board, ordinary or flame-retardant type, bitumen-bounded fibre insulation board Gypsum plaster boards ( see IS : 2095-1982† ) Insulating board (fibre) Laminated board (fibre)

WEIGHT/MASS                       

TABLE 1

kN

(2)

kg

(3)

per

(4)

(5)

0.024 to 0.035 0.031 to 0.047 0.039 to 0.059

2.40 to 3.60 3.20 to 4.80 4.00 to 6.00

m3 ,, ,,

0.047 to 0.071 0.071 to 0.106 0.035 0.047 0.071 0.098

4.80 to 7.20 7.20 to 10.80 3.6 4.8 7.2 10.0

,, ,, ,, ,, ,, ,,

12 6

0.069 to 0.098 0.093 to 0.147 0.110 to 0.154 0.034 0.034

7.0 to 10.0 9.5 to 15.0 11.25 to 15.75 3.5 3.5

,, ,, ,, ,, ,,

— — — — —

4.90 to 8.85 4.90 to 8.85 4.90 to 8.85 4.90 to 8.85 3.90

— — — —

0.117 0.088 0.117 0.088

 3  4  5  6  9  9 12 18 25  9.5  12.5  15

Wood particle boards ( see IS : 3087-1985‡ ) Designation: FPSI FPTH XPSO XPTU Wood particle boards for insulation purposes ( see IS : 3129-1985§ )

500 to 900 500 to 900 500 to 900 500 to 900 400

m3 ,, ,, ,, ,,

High density wood particle boards ( see IS : 3478-1966|| ) Type 1, Grade A Type 1, Grade B Type 2, Grade A Type 2, Grade B

12 9 12 9

m2 ,, ,, ,,

NOTE 1 — Density of medium hardboard varies from 350 to 800 kg/m3. NOTE 2 — Density of normal hardboard varies from 800 to 1 200 kg/m3. NOTE 3 — Density of tempered hardboard varies according to treatment. The actual value may be had from the manufacturers. NOTE 4 — All the three types of hardboards are manufactured to width of 1.2 m. 13. Bricks Common burnt clay bricks ( see IS : 1077-1987¶ ) Engineering bricks Heavy duty bricks ( see IS : 2180-1985** ) Pressed bricks Refractory bricks Sand cement bricks Sand lime bricks

m3

—

15.70 to 18.85

1 600 to 1 920

— —

21.20 24.50

2 160 2 500

,, ,,

— — — —

17.25 to 18.05 17.25 to 19.60 18.05 20.40

1 760 to 1 840 1 760 to 2 000 1 840 2 080

,, ,, ,, ,,

1 010

,,

14. Brick Chips and Broken Bricks ( see under 2 ‘Broken bricks’ in this table ) 15. Brick Dust ( SURKHI )

—

9.90

*Specification for fibre insulation boards. †Specification for gypsum plaster boards ( first revision ). ‡Specification for wood particle boards (medium density) for general purposes ( first revision ). §Specification for low density particle boards ( first revision ). ||Specification for high density wood particle boards. ¶Specification for common burnt clay building bricks ( fourth revision ). **Specification for heavy-duty burnt clay building bricks ( second revision ). ( Continued )

6


MATERIAL

(1)

NOMINAL SIZE OR THICKNESS mm (2)

WEIGHT/MASS                     

TABLE 1

kN

kg

per

(3)

(4)

(5)

16. Cast Iron, Manhole Covers ( see IS : 1726* ) Double triangular (HD) Circular (HD) Circular (MD) Rectangular (MD) Rectangular (LD) : Single seal (Pattern 1) (Pattern 2) Double seal Square (LD) : Single seal Double seal

500 560 500 560 500 560 —

1.16 1.37 1.16 1.37 0.57 0.63 0.78

118 140 118 140 58 64 80

Cover ,, ,, ,, ,, ,, ,,

— — —

0.23 0.15 0.28

23 15 29

,, ,, ,,

455 610 455 610

0.13 0.25 0.23 0.36

13 26 23 37

,, ,, ,, ,,

500 600 500 560 500 560 —

1.09 1.13 0.83 1.06 0.57 0.63 0.63

111 115 85 108 58 64 64

Frame ,, ,, ,, ,, ,, ,,

— — —

0.15 0.10 0.23

15 10 23

,, ,, ,,

455 610 455 610

0.07 0.13 0.15 0.18

7 13 15 18

,, ,, ,, ,,

— —

14.10 12.55

1 440 1 280

— — — — — — — —

7.45 15.70 to 18.80 8.65 to 12.55 17.25 to 21.20 9.40 to 16.50 12.55 to 17.25 5.50 to 11.00 22.00 to 23.50

760 1 600 to 1 920 880 to 1 280 1 760 to 2 160 960 to 1 680 1 280 to 1 760 560 to 1 120 2 240 to 2 400

,, ,, ,, ,, ,, ,, ,, ,,

— —

6.30 to 16.50 9.40 to 18.05

640 to 1 680 960 to 1 840

,, ,,

17. Cast Iron, Manhole Frames ( see IS : 1726* ) Double triangular (HD) Circular (HD) Circular (MD) Rectangular (MD) Rectangular (LD) : Single seal (Pattern 1) (Pattern 2) Double seal Square (LD) : Single seal Double seal 18. Cast Iron Pipes ( see under 41 ‘Pipes’ in this table ) 19. Cement ( see IS : 269-1976† ) Ordinary and aluminous Rapid-hardening

m3 ,,

20. Cement Concrete, Plain Aerated No-fines, with heavy aggregate No-fines, with light aggregate With burnt clay aggregate With expanded clay aggregate With clinker aggregate With pumice aggregate With sand and gravel or crushed natural stone aggregate With saw dust With foamed slag aggregate

*Specification for cast iron manhole covers and frames. †Specification for ordinary and low heat Portland cement ( third revision ). (Continued)

7


MATERIAL


(1)

(2)

21. Cement Concrete, Prestressed (conforming to IS : 1343-1980* )

—

WEIGHT/MASS                       

TABLE 1

kN

kg

per

(3)

(4)

(5) m3

23.50

2 400

22.75 to 24.20 23.25 to 24.80 24.80 to 26.50

2 310 to 2 470 2 370 to 2 530 2 530 to 2 700

,, ,, ,,

22. Cement Concrete, Reinforced With sand and gravel or crushed natural stone aggregate: With 1 percent steel With 2 percent steel With 5 percent steel

— — —

23. Cement Concrete Pipes ( see under 41 ‘Pipes’ in this table ) 24. Cement Mortar

—

20.40

2 080

,,

25. Cement Plaster

—

20.40

2 080

,,

26. Cork

—

2.35

240

,,

27. Expanded Metal (conforming to IS : 412-1975† ) Size of Mesh, Nominal

            

Reference No.

1 2 3 4 5 6 7 8 9 10

SWM mm 100 100 100 75 75 75 40 40 40 40

LWM mm 250 250 250 200 200 200 115 115 75 75

0.030 0.024 0.016 0.042 0.032 0.021 0.080 0.060 0.060 0.028

3.08 2.47 1.60 4.28 3.29 2.14 8.02 6.17 6.17 2.85

m2 ,, ,, ,, ,, ,, ,, ,, ,, ,,

115 75 115 75 75 75 75 75 60 50

0.039 0.039 0.020 0.020 0.054 0.038 0.028 0.021 0.070 0.070

4.01 4.01 2.04 2.04 5.53 3.93 2.81 2.19 7.15 7.15

,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

11 12 13 14 15 16 17 18 19 20

40 40 40 40 25 25 25 25 20 20

21 22 23 24 25 26 27 28 29 30

20 20 20 20 20 20 12.5 12.5 12.5 12.5

60 50 60 50 60 50 50 40 50 50

0.050 0.050 0.036 0.036 0.021 0.021 0.050 0.050 0.040 0.030

5.09 5.09 3.63 3.63 2.18 2.18 5.04 5.04 4.00 3.13

,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

31 32 33 34 35 36

12.5 12.5 12.5 10 10 10

40 50 40 40 40 40

0.030 0.025 0.025 0.050 0.035 0.028

3.13 2.50 2.50 5.98 3.59 2.87

,, ,, ,, ,, ,, ,,

*Code of practice for prestressed concrete ( first revision ). †Specification for expanded metal steel sheets for general purposes ( second revision ). ( Continued )

8


MATERIAL


(1)

kN

kg

per

(3)

(4)

(5)

(2) Size of Mesh, Nominal

              

Reference No.

WEIGHT/MASS                       

TABLE 1

37 38 39 40

SWM mm 9.5 9.5 9.5 6

41 42 43 44

LWM mm 28.5 28.5 28.5 25

0.050 0.028 0.020 0.074

5.19 2.81 2.09 7.55

25 25 20 15

0.048 0.038 0.050 0.041

4.88 3.90 5.01 4.28

m2 ,, ,, ,, ,, ,, ,, ,,

—

8.34 × 10– 3

0.85

,,

— —

21.48 × 10– 3 30.21 × 10– 3

2.19 3.08

,, ,,

— —

21.87 × 10– 3 35.70 × 10–3

2.23 3.64

,, ,,

6 6 5 3

28. Felt, Bituminous for Waterproofing and Damp-proofing ( see IS : 1322-1982* ) Fibre base: Type 1 (Underlay) Type 2 (Self-finished felt): Grade 1 Grade 2 Hessian base: Type 3 (Self finished felt): Grade 1 Grade 2

NOTE 1 — The weight of untreated based shall be taken as in the dry condition. NOTE 2 — The weights given above are indicative of the total weight of ingredients used in the manufacture of felt and not of the ingredients determined from a physical analysis of the finished material. 29. Foam Slag, Foundry Pumice

—

6.85

700

m3

30. Glass ( see IS : 2835-1977† )

Sheet

        

2.0 2.5 3.0 4.0 5.0 5.5 6.5

0.049 0.062 0.074 0.098 0.123 0.134 0.167

5.0 6.3 7.5 10.0 12.5 13.7 17.0

,, ,, ,, ,, ,, ,, ,,

31. Gutters, Asbestos Cement ( see under 7 ‘Asbestos cement gutter’ in this table ) 32. Gypsum Gypsum mortar Gypsum powder

— —

11.75 13.89 to 17.25

1 200 1 410 to 1 760

m3 ,,

— — — —

70.60 68.95 to 69.90 74.30 to 75.70 75.50

7 200 7 030 to 7 130 7 580 to 7 720 7 700

,, ,, ,, ,,

—

18.80

1 920

,,

33. Iron Pig Gray, cast White, cast Wrought 34. Lime Lime concrete with burnt clay aggregate

*Specification for bitumen felts for waterproofing and damp-proofing ( third revision ). †Specification for flat transparent sheet glass ( second revision ). ( Continued)

9


MATERIAL


(1)

WEIGHT/MASS                       

TABLE 1

kN

kg

per

(3)

(4)

(5)

(2)

Lime mortar Lime plaster Lime stone in lumps, uncalcined Lime, unslaked, freshly burnt in pieces Lime slaked, fresh Lime slaked, after 10 days Lime, unslaked ( KANKAR ) Lime, slaked ( KANKAR )

— — — — — — — —

15.70 to 18.05 17.25 12.55 to 14.10 8.60 to 10.20 5.70 to 6.30 7.85 11.55 10.00

1 600 to 1 840 1 760 1 280 to 1 440 880 to 1 040 580 to 640 800 1 180 1 020

m3 ,, ,, ,, ,, ,, ,, ,,

35. Linoleum ( see IS : 653-1980* )

Sheets and tiles

    

4.4 3.2 2.0 1.6

0.056 9 0.040 2 0.026 5 0.021 5

5.8 4.1 1.7 2.2

m2 ,, ,, ,,

36. Masonry, Brick Common burnt clay bricks Engineering bricks Glazed bricks Pressed bricks

— — — —

18.85 23.55 20.40 22.00

1 920 2 400 2 080 2 240

m3 ,, ,, ,,

— — — — — — —

22.55 20.40 25.90 23.55 25.10 26.50 22.00

2 300 2 080 2 640 2 400 2 560 2 700 2 240

,, ,, ,, ,, ,, ,, ,,

37. Masonry, Stone Cast Dry rubble Granite ashlar Granite rubble Lime stone ashlar Marble dressed Sand stone 38. Mastic Asphalt

10

0.215

22

m2

39. Metal sheeting, Protected Galvanized Steel Sheets and Plain ( see IS : 277-1985† )

Class 1

    

1.60 1.26 1.00 0.80 0.63

0.131 0.104 0.084 0.069 0.056

13.31 10.56 8.60 7.03 5.70

,, ,, ,, ,, ,,

Class 2

    

1.60 1.25 1.00 0.80 0.63

0.129 0.102 0.083 0.067 0.054

13.16 10.41 8.45 6.88 5.55

,, ,, ,, ,, ,,

Class 3

    

1.60 1.25 1.00 0.80 0.63

0.128 0.101 0.081 0.066 0.053

13.01 10.26 8.30 6.73 5.40

,, ,, ,, ,, ,,

Class 4

    

1.60 1.25 1.00 0.80 0.63

0.127 0.100 0.081 0.065 0.052

12.94 10.19 8.22 6.66 5.32

,, ,, ,, ,, ,,

40. Mortar Cement Gypsum Lime

— — —

20.40 11.80 15.70 to 18.05

2 080 1 200 1 600 to 1 840

m3 ,, ,,

*Specification for linoleum sheets and tiles ( second revision ). †Specification for galvanized steel sheets (plain and corrugated) ( fourth revision ). ( Continued )

10


MATERIAL

(1)


WEIGHT/MASS                     

TABLE 1

kN (3)

kg (4)

per (5)

41. Pipes  50  60   80  90  100   125  150  50  80  100  125  150   200  250  300

0.032 to 0.034 0.032 to 0.043 0.051 to 0.054 0.052 to 0.060 0.058 to 0.065 0.072 to 0.086 0.086 to 0.108 0.056 0.067 0.090 0.139 0.175 0.264 0.380 0.539

3.3 to 3.5 3.3 to 4.4 5.2 to 5.5 5.3 to 6.1 5.9 to 6.6 7.3 to 8.8 8.8 to 11.0 5.7 6.8 9.2 14.2 17.8 26.9 38.8 55

Standard overall length 1.8 m with socket

    

Standard overall length 1.5 m with socket

    

550 75 100 125 150 50 75 100 125 150

0.073 0.108 0.137 0.196 0.255 0.064 0.093 0.123 0.172 0.230

7.5 11.0 14.0 20.0 26.0 6.5 9.5 12.5 17.5 23.5

pipe ,, ,, ,, ,, ,, ,, ,, ,, ,,

80 100 125 150 200 250 300 350 400 450 500 600 700 750 80 100 125 150 200 250 300 350 400 450 500

1.144 0.182 0.237 0.295 0.432 0.582 0.750 0.944 1.146 1.383 1.620 2.156 2.778 3.111 0.157 0.201 0.259 0.326 0.472 0.637 0.824 1.030 1.262 1.530 1.775

14.7 18.6 24.2 30.1 44.0 59.3 76.5 96.3 116.9 141.0 165.2 219.8 283.2 317.2 16.0 20.5 26.4 33.2 48.1 65.0 84.0 105.0 128.7 156.0 181.0

m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Asbestos cement pipes [ see IS : 1626 (Part) 1-1980* ]

Asbestos cement pressure pipes ( see IS : 1592-1980† )

m3 ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Cast iron Pipes: Rainwater pipes ( see IS : 1230-1979‡ )

Pressure pipes for water, gas and sewage: a) Centrifugally cast ( see IS : 1536-1976§ ) i) Socket and spigot pipes: Barrel:

Class LA

                

Class A

          

*Specification for asbestos cement buildings pipes and pipe fittings, gutters and gutter fittings and roofing fittings: Part 1 Pipes and pipe fittings ( first revision ). †Specification for asbestos cement pressure pipes ( second revision ). ‡Specification for cast iron rainwater pipes and fittings ( second revision ). §Specification for centrifugally cast (spun) iron pressure pipes for water, gas and sewage ( second revision ). ( Continued )

11


(1)


Class A

 600  700  750

Class B

                

Sockets for Class LA, Class A and Class B barrels

                

ii) Flanged pipe with screwed flanges: Barrel: Class A Class B

80 to 300

        

Class A

Class B

                     

80 100 125 150 200 250 300

80 to 750 800 900 1 000 1 100 1 200 1 500 80 to 750 800 900 1 000 1 100 1 200 1 500

kN (3)

kg (4)

per (5)

2.367 3.056 3.422 0.172 0.216 0.281 0.352 0.511 0.692 0.896 1.122 1.368 1.657 1.929 2.578 3.317 3.733 0.054 0.069 0.090 0.113 0.165 0.225 0.292 0.368 0.454 0.549 0.647 0.876 1.145 1.292

241.4 311.6 348.9 17.3 22.0 28.7 35.9 52.1 70.6 91.4 114.5 139.5 169.0 196.7 262.9 338.2 380.6 5.5 7.1 9.2 11.5 16.8 22.9 29.8 37.5 46.3 56.0 66.0 89.3 116.8 131.7

m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, Socket ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Same as for centrifugally cast socket and spigot pipes, Class A Same as for centrifugally cast socket and spigot pipes, Class B 0.042 4.3 Flange 0.049 5.0 ,, 0.065 6.6 ,, 0.080 8.2 ,, 0.112 11.4 ,, 0.144 14.7 ,, 0.182 18.6 ,,

80 to 300

Flanges for Class A and Class B barrels

b) Vertically cast socket and spigot pipes ( see IS : 1537-1976* ) Barrel:

80 100 125 150 200 250 300 350 400 450 500 600 700 750 80 100 125 150 200 250 300 350 400 450 500 600 700 750

WEIGHT/MASS

                        

TABLE 1 MATERIAL

  

Same as for centrifugally cast socket and spigot pipes, Class A 3.82 389 m 4.65 474 ,, 5.59 570 ,, 6.59 672 ,, 7.67 783 ,, 11.98 1 222 ,,

  

Same as for centrifugally cast socket and spigot pipes, Class B 4.15 423 m 5.07 516 ,, 6.07 619 ,, 7.23 739 ,, 8.35 851 ,, 13.07 1 333 ,,

*Specification for vertically cast iron pressure pipes for water, gas and sewage ( first revision ). ( Continued )

12


MATERIAL (1)

Socket for Class A and Class B barrels

NOMINAL SIZE OR THICKNESS mm (2)           

80  to  750  800 900 1 000 1 100 1 200 1 500

WEIGHT/MASS

                        

TABLE 1

kN (3)

kg (4)

per (5)

Same as for centrifugally cast socket and spigot pipes, Class A and Class B 1.45 1.79 2.18 2.60 3.07 4.91

147 182 222 265 313 501

Socket ,, ,, ,, ,, ,,

c) Sand cast (flanged pipes): Barrel:

Class A

Class B

Flanges for Class A and Class B Barrels

80   to    750   800   to    1 500  80   to    750    800  to    1 500  80   100  125  150   200  250  300  350   400  450  500   600  700  750   800  900  1 000   1 100  1 200  1 500

Same as for centrifugally cast socket and spigot pipes, Class A Same as for vertically cast socket and spigot pipes, Class A Same as for centrifugally cast socket and spigot pipes, Class B Same as for vertically cast socket and spigot pipes, Class B 0.036 0.041 0.052 0.066 0.091 0.117 0.145 0.186 0.229 0.250 0.315 0.431 0.587 0.685 0.792 0.928 1.18 1.38 1.70 2.71

3.7 4.2 5.3 6.7 9.3 12.0 14.8 19.4 23.4 26.5 32.1 44.0 59.9 69.8 80.8 94.6 120.0 139.0 173.0 276.2

Flange ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Concrete pipes ( see IS : 458-1971* )

Class NP1 (unreinforced non-pressure pipes)

        

Class NP2 (reinforced concrete, light duty, non-pressure pipes)

            

80 100 150 250 300 350 400 450 80 100 150 250 300 350 400 450 500 600 700 800 900

0.19 0.22 0.30 0.40 0.69 0.84 0.95 1.17 0.196 0.235 0.324 0.510 0.736 0.902 1.02 1.26 1.38 1.89 2.19 2.81 3.51

19 22 31 41 70 86 97 119 20 24 33 52 75 92 104 128 141 193 223 287 358

m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

*Specification for concrete pipes (with and without reinforcement) ( second revision ). ( Continued )

13


MATERIAL


WEIGHT/MASS                       

TABLE 1

kN

kg

per

(2)

(3)

(4)

(5)

Class NP2 (reinforced concrete, light duty, non-pressure pipes)

      

1 000 1 100 1 200 1 400 1 600 1 800

4.30 5.15 6.09 8.18 9.93 12.58

438 525 620 834 1 013 1 283

m ,, ,, ,, ,, ,,

Class NP3 (reinforced concrete, heavy duty, non-pressure pipes)

          

350 400 450 500 600 700 800 900 1 000 1 100 1 200

2.35 2.63 2.91 3.19 4.02 4.61 5.92 7.39 8.13 10.34 11.18

240 269 297 325 410 470 604 754 829 1 054 1 140

,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

(1)

80   100  150  250  300   350  400 Class P1 (reinforced concrete pressure  450 pipes safe for 20 MPa pressure  500  tests)  600  700  800  900   1 000  1 100  1 200

0.196 0.235 0.324 0.510 0.736 0.902 1.02 1.26 1.38 1.89 2.19 2.81 3.51 4.30 5.15 6.09

20 24 33 52 75 92 104 128 141 193 223 287 358 437 525 620

,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Class P2 (reinforced concrete pressure pipes safe for 40 MPa pressure tests)

          

80 100 150 250 300 350 400 450 500 600

0.196 0.235 0.324 0.608 1.01 1.31 1.67 1.84 1.56 3.20

20 24 33 63 103 134 170 188 261 326

,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Class P3 (reinforced concrete pressure pipes safe for 60 MPa pressure tests)

      

80 100 150 250 300 350 400

0.196 0.235 0.324 0.736 1.15 1.65 2.04

20 24 33 75 117 168 204

,, ,, ,, ,, ,, ,, ,,

Lead pipes [ see IS : 404 (Part 1)-1977* ] (service and distribution pipes to be laid underground):

For working pressure 40 MPa

      

10 15 20 25 32 40 50

0.018 0.031 0.042 0.060 0.074 0.091 0.142

1.87 3.13 4.24 6.11 7.50 9.28 14.45

,, ,, ,, ,, ,, ,, ,,

*Specification for lead pipes: Part 1 For other than chemical purposes ( second revision ). ( Continued )

14


MATERIAL


(1)

WEIGHT/MASS                       

TABLE 1

kN

kg

per

(3)

(4)

(5)

0.022 0.038 0.050 0.069 0.126 0.175

2.26 3.83 5.11 7.03 12.80 17.82

m ,, ,, ,, ,, ,,

0.029 0.048 0.067

2.96 4.88 6.86

,, ,, ,,

0.105

10.75

,,

10 15 20 25 32 40 50

0.014 0.021 0.027 0.036 0.059 0.091 0.142

1.45 2.15 2.74 3.67 6.00 9.28 14.45

,, ,, ,, ,, ,, ,, ,,

10

0.018 0.024 0.030 0.069 0.126 0.175

1.81 2.47 3.11 7.03 12.80 17.82

,, ,, ,, ,, ,, ,,

0.029 0.048 0.067

2.96 4.88 6.86

,, ,, ,,

0.105

10.75

,,

(2) 10



 15  20  25  32  40 10 15 20 ( see Note below ) 25 ( see Note below )

Service pipes to be fixed or laid above ground:


      


 15  20  25  32  40


10 15 20 ( see Note below ) 25 ( see Note below )

Cold water distribution pipes to be fixed or laid above ground:


      

10 15 20 25 32 40 50

0.014 0.021 0.027 0.036 0.048 0.067 0.084

1.45 2.15 2.74 3.67 4.85 6.79 8.53

,, ,, ,, ,, ,, ,, ,,


      

10 15 20 25 32 40 50

0.014 0.021 0.027 0.036 0.059 0.091 0.142

1.45 2.15 2.74 3.67 6.00 9.29 14.45

,, ,, ,, ,, ,, ,, ,,

      

10 15 20 25 32 40 50

0.015 0.023 0.031 0.041 0.062 0.082 0.142

1.50 2.34 3.13 4.13 6.30 8.38 14.45

,, ,, ,, ,, ,, ,, ,,

Hot water distribution pipes to be fixed or laid above ground:


NOTE — The maximum working pressure for these sizes is 90 MPa. ( Continued )

15

IS : 875 (Part 1) - 1987 UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE OR THICKNESS mm

(1)

(2)

WEIGHT/MASS                       

TABLE 1 MATERIAL

kN

kg

per

(3)

(4)

(5)

10 15 20 25 32

0.015 0.027 0.045 0.085 0.132

1.50 2.34 4.56 8.69 13.51

m ,, ,, ,, ,,

 75  100  150

50

0.050 0.073 0.097 0.160

5.07 7.48 9.88 16.36

,, ,, ,, ,,

    

20 25 32 40 50

0.020 0.025 0.032 0.039 0.049

2.09 2.56 3.28 3.95 5.07

,, ,, ,, ,, ,,

Heavy weight gas pipes

      

10 15 20 25 32 40 50

0.008 0.017 0.025 0.034 0.045 0.061 0.071

0.81 1.70 2.60 3.44 4.57 6.27 7.20

,, ,, ,, ,, ,, ,, ,,

Light weight gas pipes

      

10 15 20 25 32 40 50

0.008 0.012 0.020 0.029 0.037 0.047 0.058

0.81 1.21 2.09 2.99 3.74 4.76 5.87

,, ,, ,, ,, ,, ,, ,,

    


Soil, waste, and soil and waste ventilation pipes

Flushing and warning pipes

Gas pipes:

Stoneware, salt-glazed pipes ( see IS : 651-1980* )

          

100 150 200 230 ( see Note below ) 250 300 350 400 450 500 600

0.137 0.216 0.324 0.412

14 22 33 42

,, ,, ,, ,,

0.510 0.775 0.980 1.26 1.44 1.77 2.35

52 79 100 128 147 180 240

,, ,, ,, ,, ,, ,, ,,

— — 10 10 10 10 10

20.40 17.25 0.078 0.206 0.284 0.088 0.186

2 080 1 760 8 21 29 9 19

1

0.007

42. Plaster ( see also 6 ‘Finishing’ in Table 2 ) Cement Lime Acoustic Anhydrite Barium sulphate Fibrous Gypsum

m3 ,, m2 ,, ,, ,, ,,

43. Sheeting Asbestos ( see under 9 ‘Asbestos cement sheeting’ in this table ) Galvanized iron ( see under 39 ‘Metal sheeting, protected’ in this table ) Glass ( see under 30 ‘Glass’ in this table ) Plywood

0.7

,,

NOTE — This is non-preferred size and its manufacture is permitted for a limited period. *Specification for salt-glazed stoneware pipes and fittings ( fourth revision ). ( Continued )

16


MATERIAL


(1)

(2)

44. Slagwool

WEIGHT/MASS                       

TABLE 1

kN

kg

(3)

(4)

per (5) m3

—

2.65

270

—

15.69

1 600

,,

— —

15.70 to 18.35 18.85 to 21.95

1 600 to 1 870 1 920 to 2 240

,, ,,

—

15.70 to 18.85

1 600 to 1 920

,,

—

21.95

2 240

,,

— — — — — —

10.20 14.10 17.25 20.40 18.85 20.40

1 040 1 440 1 760 2 080 1 920 2 080

,, ,, ,, ,, ,, ,,

— —

13.85 to 18.05 15.70 to 19.60

1 410 to 1 840 1 600 to 2 000

,, ,,

Loose Rammed

— —

15.70 18.85 to 21.20

1 600 1 920 to 2 160

,, ,,

Kaolin, compact

—

25.50

2 600

,,

— — — — — —

11.75 15.70 18.85 14.10 17.25 to 18.85 17.25 to 18.85

1 200 1 600 1 920 1 440 1 760 to 1 920 1 760 to 1 920

,, ,, ,, ,, ,, ,,

— — — —

5.50 to 6.30 7.85 13.35 12.55 to 14.10

560 to 640 800 1 360 1 280 to 1 440

,, ,, ,, ,,

— — —

15.10 to 15.70 18.05 17.25 to 19.60

1 540 to 1 600 1 840 1 760 to 2 000

,, ,, ,,

—

13.75

1 400

,,

— —

15.70 20.40

1 600 2 080

,, ,,

—

17.25 to 18.85

1 760 to 1 920

,,

45. Soils and Gravels Aluvial ground, undisturbed Broken stone ballast: Dry, well-shaken Perfectly wet Chalk Clay: China, compact Clay fills: Dry, lumps Dry, compact Damp, compact Wet, compact Undisturbed Undisturbed, gravelly Earth: Dry Moist Gravel:

Loam: Dry, loose Dry, compact Wet, compact Loess, dry Marl, compact Mud, river, wet Peat: Dry Sandy, compact Wet, compact Rip-rap Sand: Dry, clean River Wet Shingles: Aggregate 3 to 38 mm Fine sand: Dry Saturated Silt, wet 46. Steel Sections Hot rolled [ see IS : 808 (Part 1)-1978* ] Beams — Designation MB 100 MB 125 MB 150 MB 175 MB 200 MB 225

— — — — — —

0.113 0.131 0.147 0.191 0.249 0.306

11.5 13.4 15.0 19.5 25.4 31.2

m ,, ,, ,, ,, ,,

*Dimensions for hot-rolled steel sections: Part 1 MB series (beams) ( second revision ). ( Continued )

17


(1) Beams — Designation MB 250 MB 300 MB 350 MB 400 MB 450 MB 500 MB 550 MB 600 Columns — Designation [ see IS : 808 (Part 2)-1978* ] SC 100 SC 120 SC 140 SC 160 SC 180 SC 200 SC 220 SC 250 Channels — Designation [ see IS : 808 (Part 3)-1979† ] Medium weight channel sections with sloping flanges MC 75 MC 100 MC 125 MC 150 MC 175 MC 200 MC 225 MC 250 MC 300 MC 350 MC 400 Medium weight channel sections with parallel flanges ( see Note below ) MCP 75 MCP 100 MCP 125 MCP 150 MCP 175 MCP 200 MCP 225 MCP 250 MCP 300 MCP 350 MCP 400


WEIGHT/MASS                       

TABLE 1 MATERIAL

kN (3)

kg (4)

per (5)

— — — — — — — —

0.365 0.452 0.514 0.604 0.710 0.852 1.00 1.21

37.3 46.1 52.4 61.6 72.4 86.9 104 123

m ,, ,, ,, ,, ,, ,, ,,

— — — — — — — —

0.196 0.257 0.327 0.411 0.495 0.591 0.690 0.839

20.0 26.2 33.3 41.9 50.5 60.3 70.4 85.6

,, ,, ,, ,, ,, ,, ,, ,,

— — — — — — — — — — —

0.070 0.098 0.165 0.192 0.219 0.256 0.300 0.356 0.419 0.491

7.14 10.0 16.8 19.6 22.3 26.1 30.6 36.3 42.7 50.1

,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

— — — — — — — — — — —

0.070 0.094 0.128 0.165 0.192 0.219 0.256 0.300 0.356 0.419 0.491

7.14 9.56 13.1 16.8 19.6 22.3 26.1 30.6 36.3 42.7 50.1

,,

 3.0   4.0

0.009 0.011 0.011 0.014 0.018 0.014 0.018 0.022

0.9 1.1 1.1 1.4 1.8 1.4 1.8 2.2

m ,, ,, ,, ,, ,, ,, ,,

,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Equal leg angles — Size [ see IS : 808 (Part 5)-1976‡ ] ISA 2020 ISA 2525

ISA 3030

     

3.0 4.0 5.0 3.0 4.0 5.0

NOTE — These sections are steel in the developmental stage and may be available subject to agreement with the manufacturer. *Dimensions for hot-rolled steel sections: Part 2 Columns — SC series ( second revision ). †Dimensions for hot-rolled steel sections: Part 3 Channels, MC and MPC series ( second revision ). ‡Dimensions for hot-rolled steel sections: Part 5 Equal leg angles ( second revision ). ( Continued )

18

IS : 875 (Part 1) - 1987

(1) ISA 3535

ISA 4050

ISA 4545

ISA 5050

ISA 5555

ISA 6060

ISA 6565

ISA 7070

ISA 7575

ISA 8080

ISA 9090

ISA 100100

ISA 110110

ISA 130130

ISA 150150

ISA 200200

UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE OR THICKNESS mm (2)  3.0  4.0  5.0   6.0  3.0  4.0   5.0  6.0  3.0  4.0   5.0  6.0  3.0  4.0   5.0  6.0  5.0  6.0   8.0  10.0  5.0  6.0   8.0  10.0  5.0  6.0   8.0  10.0  5.0  6.0   8.0  10.0  5.0  6.0   8.0  10.0  6.0  8.0   10.0  12.0  6.0  8.0   10.0  12.0  6.0  8.0   10.0  12.0  8.0  10.0   12.0  16.0  8.0  10.0   12.0  16.0  10.0  12.0   16.0  20.0  12.0  16.0   20.0  25.0

19

WEIGHT/MASS

                      

TABLE 1 MATERIAL

kN (3) 0.016 0.021 0.026 0.029 0.018 0.024 0.029 0.034 0.021 0.027 0.033 0.039 0.023 0.029 0.037 0.044 0.040 0.048 0.063 0.077 0.044 0.053 0.069 0.084 0.048 0.057 0.076 0.092 0.052 0.062 0.081 0.100 0.056 0.067 0.087 0.108 0.072 0.094 0.116 0.137 0.080 0.106 0.131 0.155 0.090 0.119 0.146 0.174 0.131 0.163 0.193 0.252 0.156 0.193 0.230 0.301 0.225 0.268 0.351 0.432 0.362 0.476 0.588 0.725

kg (4) 1.6 2.1 2.6 3.0 1.8 2.4 3.0 3.5 2.1 2.7 3.4 4.0 2.3 3.0 3.8 4.5 4.1 4.9 6.4 7.9 4.5 5.4 7.0 8.6 4.9 5.8 7.7 9.4 5.3 6.3 8.3 10.2 5.7 6.8 8.9 11.0 7.3 9.6 11.8 14.0 8.2 10.8 13.4 15.8 9.2 12.1 14.9 17.7 13.4 16.6 19.7 25.7 15.9 19.7 23.5 30.7 22.9 27.3 35.8 44.1 36.9 48.5 60.0 73.9

per (5) m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ( Continued )

IS : 875 (Part 1) - 1987

(1) Unequal leg angles — Size [ see IS : 808 (Part 6)-1976* ] ISA 3020

ISA 4025

ISA 4530

ISA 5030

ISA 6040

ISA 6545

ISA 7045

ISA 7550

ISA 8050

ISA 9060

ISA 10065

ISA 10075

ISA 12571

ISA 12595

ISA 15075

ISA 150115

ISA 200100

UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE OR THICKNESS mm (2)

 3.0  4.0  5.0 3.0 4.0 5.0 6.0  3.0  4.0   5.0  6.0  3.0  4.0   5.0  6.0  5.0  6.0  8.0  5.0  6.0  8.0  5.0  6.0   8.0  10.0  5.0  6.0   8.0  10.0  5.0  6.0   8.0  10.0  6.0  8.0   10.0  12.0  6.0  8.0  10.0  6.0  8.0   10.0  12.0  6.0  8.0  10.0  6.0  8.0   10.0  12.0  8.0  10.0  12.0  8.0  10.0   12.0  16.0  10.0  12.0  16.0     

WEIGHT/MASS

                      

TABLE 1 MATERIAL

kN (3)

kg (4)

per (5)

0.011 0.014 0.018 0.015 0.019 0.024 0.027 0.017 0.022 0.027 0.032 0.018 0.024 0.029 0.034 0.036 0.043 0.057 0.040 0.048 0.063 0.042 0.051 0.066 0.081 0.046 0.055 0.073 0.088 0.048 0.058 0.076 0.092 0.067 0.087 0.108 0.128 0.074 0.087 0.120 0.078 0.103 0.127 0.151 0.090 0.119 0.146 0.099 0.131 0.162 0.193 0.134 0.167 0.198 0.160 0.197 0.235 0.308 0.225 0.268 0.351

1.1 1.4 1.8 1.5 1.9 2.4 2.8 1.7 2.2 2.8 3.3 1.8 1.8 3.0 3.5 3.7 4.4 5.8 4.1 4.9 6.4 4.3 5.2 6.7 8.3 4.7 5.6 7.4 9.0 4.9 5.9 7.7 9.4 6.8 8.9 11.0 13.0 7.5 9.9 12.2 8.0 10.5 13.0 15.4 9.2 12.1 14.9 10.1 13.4 16.5 19.7 13.7 17.2 20.2 16.3 20.1 24.0 31.4 22.9 27.3 35.8

m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

*Dimensions of hot-rolled steel sections: Part 6 Unequal leg angles ( second revision ). ( Continued )

20

IS : 875 (Part 1) - 1987 TABLE 1

UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE OR THICKNESS mm

kN

kg

per

(1)

(2)

(3)

(4)

(5)

10.0 12.0 16.0 20.0

0.264 0.315 0.414 0.510

26.9 32.1 42.2 52.0

m ,, ,, ,,

100 × 100

 3.15   4.0

0.047 0.060

4.81 6.07

,, ,,

80 × 80

 2.5  3.15  4.0

0.030 0.037 0.047

3.05 3.82 4.82

,, ,, ,,

60 × 60

    

2.0 2.5 3.15 4.0

0.018 0.022 0.028 0.035

1.82 2.26 2.83 3.56

,, ,, ,, ,,

50 × 50

    

1.6 2.0 2.5 3.15 4.0

0.012 0.015 0.018 0.023 0.029

1.21 1.51 1.87 2.34 2.93

,, ,, ,, ,, ,,

40 × 40

    

1.2 1.6 2.0 2.5 3.15

0.007 0.009 0.012 0.014 0.018

0.75 0.96 1.19 1.48 1.84

,, ,, ,, ,, ,,

30 × 30

    

1.2 1.6 2.0 2.5

0.005 0.007 0.009 0.010

0.56 0.71 0.88 1.08

,, ,, ,, ,,

20 × 20

 1.2  1.6  2.0

0.004 0.005 0.006

0.36 0.46 0.56

,, ,, ,,

100 × 100

 3.15   4.0

0.070 0.088

7.15 9.01

,, ,,

80 × 80

 2.5  3.15  4.0

0.044 0.056 0.070

4.52 5.66 7.12

,, ,, ,,

60 × 60

    

2.0 2.5 3.15 4.0

0.026 0.033 0.041 0.051

2.69 3.35 4.18 5.24

,, ,, ,, ,,

50 × 50

    

1.6 2.0 2.5 3.15 4.0

0.018 0.022 0.027 0.034 0.042

1.79 2.23 2.76 3.44 4.30

,, ,, ,, ,, ,,

40 × 40

    

1.25 1.6 2.0 2.5 3.15

0.011 0.014 0.017 0.021 0.026

1.12 1.42 1.75 2.17 2.70

,, ,, ,, ,, ,,

30 × 30

    

1.21 1.6 2.0 2.5

0.008 0.010 0.013 0.015

0.82 1.04 1.28 1.58

,, ,, ,, ,,

ISA 200150

    

WEIGHT/MASS                       

MATERIAL

Cold formed light gauge structural steel sections ( see IS : 811-1965* ) : Light gauge sections — angles Size:

Channels without lips Size:

*Specification for cold formed light gauge structural steel sections ( revised ). ( Continued )

21

IS : 875 (Part 1) - 1987 TABLE 1

UNIT WEIGHT OF BUILDING MATERIALS — Contd

MATERIAL


kN

kg

per

(1)

(2)

(3)

(4)

(5)

 1.25  1.6  2.0

0.005 0.007 0.008

0.53 0.66 0.81

m ,, ,,

200 × 50

    

2.00 2.50 3.15 4.00

0.045 0.056 0.070 0.088

4.58 5.70 7.14 9.01

,, ,, ,, ,,

180 × 50

    

2.00 2.50 3.15 4.00

0.042 0.052 0.065 0.082

4.27 5.31 6.65 8.38

,, ,, ,, ,,

160 × 50

 2.00  2.50  3.15

0.039 0.048 0.060

3.95 4.92 6.16

,, ,, ,,

140 × 40

    

1.60 2.00 2.50 3.15

0.026 0.033 0.041 0.051

2.67 3.33 4.13 5.17

,, ,, ,, ,,

120 × 40

 1.60  2.00  2.50

0.024 0.030 0.037

2.42 3.01 3.74

,, ,, ,,

100 × 40

    

1.25 1.60 2.00 2.50

0.017 0.021 0.026 0.033

1.70 2.17 2.70 3.35

,, ,, ,, ,,

80 × 30

    

1.25 1.60 2.00 2.50

0.013 0.016 0.020 0.025

1.31 1.67 2.07 2.56

,, ,, ,, ,,

60 × 30

 1.25  1.60  2.00

0.011 0.014 0.017

1.12 1.42 1.75

,, ,, ,,

50 × 30

 1.25  1.60  2.00

0.010 0.013 0.016

1.02 1.29 1.60

,, ,, ,,

100 × 100

    

2.00 2.50 3.15 4.00

0.051 0.063 0.082 0.103

5.24 6.50 8.36 10.48

,, ,, ,, ,,

80 × 80

    

1.60 2.00 2.50 3.15

0.033 0.041 0.052 0.065

3.33 4.14 5.32 6.62

,, ,, ,, ,,

60 × 60

    

1.25 1.60 2.00 2.50

0.019 0.024 0.031 0.039

1.94 2.45 3.20 3.95

,, ,, ,, ,,

50 × 50

 1.25  1.60  2.00

0.016 0.020 0.025

1.64 2.08 2.57

,, ,, ,,

40 × 40

 1.25  1.60  2.00

0.013 0.017 0.020

1.35 1.70 2.09

,, ,, ,,

30 × 30

 1.25   1.60

0.009 0.012

0.95 1.20

,, ,,

                      

WEIGHT/MASS

Channels without lips Size: 20 × 20

Channels with lips Size:

( Continued )

22

IS : 875 (Part 1) - 1987

(1) Channels with lips Size:

UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE OR THICKNESS mm (2)

200 × 80

    

180 × 80

    

160 × 80

    

140 × 70

    

120 × 60

    

100 × 50

    

80 × 40 60 × 30 50 × 30

        

WEIGHT/MASS

                      

TABLE 1 MATERIAL

kN (3)

kg (4)

per (5)

1.60 2.00 2.50 3.15 4.00 1.60 2.00 2.50 3.15 4.00 1.60 2.00 2.50 3.15 4.00 1.60 2.00 2.50 3.15 4.00 1.25 1.60 2.00 2.50 3.15 1.25 1.60 2.00 2.50 1.25 1.60 2.00 1.25 1.60 1.25 1.60

0.047 0.059 0.075 0.094 0.118 0.045 0.056 0.071 0.089 0.112 0.043 0.053 0.068 0.084 0.106 0.038 0.047 0.058 0.075 0.094 0.025 0.031 0.041 0.050 0.063 0.021 0.027 0.033 0.043 0.017 0.022 0.027 0.012 0.015 0.011 0.014

4.84 6.02 7.67 9.59 12.05 4.59 5.71 7.28 9.10 11.42 4.34 5.39 6.89 8.60 10.79 3.84 4.76 5.91 7.61 9.54 2.52 3.21 4.14 5.12 6.38 2.13 2.71 3.35 4.34 1.74 2.20 2.72 1.25 1.57 1.15 1.45

m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

2.50 3.15 4.00 2.00 2.50 3.15 1.60 2.00 2.50 1.60 2.00 1.25 1.60 1.60 2.00 2.50 1.25 1.60 2.00 1.25 1.60 1.25 3.15 4.00

0.068 0.089 0.115 0.043 0.056 0.072 0.026 0.034 0.043 0.022 0.028 0.013 0.018 0.034 0.044 0.054 0.021 0.028 0.034 0.016 0.020 0.013 0.101 0.134

6.89 9.05 11.73 4.39 5.71 7.36 2.63 3.45 4.34 2.25 2.88 1.36 1.83 3.51 4.45 5.51 2.15 2.83 3.51 1.64 2.08 1.35 10.28 13.68

,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

Hat sections Size: 100 × 100

80 × 80

60 × 60 50 × 50 40 × 40 100 × 50

80 × 40 60 × 30

        

     

     

  

50 × 25 100 × 150

  

( Continued )

23


(1) Hat sections Size: 80 × 120 60 × 90

50 × 75

40 × 60


WEIGHT/MASS

                      

TABLE 1 MATERIAL

 3.15   4.00

kN (3)

kg (4)

per (5)

        

2.50 3.15 4.00 2.00 2.50 3.15 1.60 2.00 2.50

0.089 0.113 0.050 0.067 0.084 0.033 0.043 0.055 0.021 0.028 0.035

9.08 11.48 5.12 6.82 8.59 3.37 4.44 5.64 2.14 2.82 3.55

m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

                          

1.60 2.00 1.60 2.00 1.60 2.00 1.60 2.00 1.60 2.00 1.25 1.60 1.25 1.60 1.25 1.60 1.25 1.60

0.072 0.090 0.065 0.081 0.057 0.071 0.050 0.062 0.043 0.053 0.028 0.035 0.022 0.028 0.016 0.020 0.014 0.018

7.35 9.16 6.60 8.22 5.85 7.28 5.09 6.34 4.34 5.39 2.82 3.58 2.23 2.83 1.64 2.08 1.44 1.83

,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

                          

1.60 2.00 1.60 2.00 1.60 2.00 1.60 2.00 1.60 2.00 1.25 1.60 1.25 1.60 1.25 1.60 1.25 1.60

0.097 0.121 0.087 0.108 0.764 0.096 0.067 0.084 0.057 0.071 0.037 0.047 0.030 0.038 0.022 0.028 0.018 0.023

9.86 12.30 8.86 11.04 77.85 9.79 6.85 8.53 5.85 7.28 3.80 4.84 3.01 3.84 2.23 2.83 1.84 2.33

,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

0.009 0.014 0.034 0.044 0.053 0.094 0.147 0.223

0.9 1.4 3.5 4.5 5.4 9.6 15.0 22.8

,, ,, ,, ,, ,, ,, ,, ,,

Rectangular box sections Size: 200 × 100 180 × 90 160 × 80 140 × 70 120 × 60 100 × 50 80 × 40 60 × 30 50 × 30 Square box section Size: 200 × 200 180 × 180 160 × 160 140 × 140 120 × 120 100 × 100 80 × 80 60 × 60 50 × 50 Rolled steel tee bars ( see IS : 1173-1978* ) Designation ISNT 20 ISNT 30 ISNT 40 ISNT 50 ISNT 60 ISNT 80 ISNT 100 ISNT 150

— — — — — — — —

*Specification for hot-rolled and slit steel tee bars ( second revision ). ( Continued )

24


(1) Designation ISHT 75 ISHT 100 ISHT 125 ISHT 150 ISST 100 ISST 150 ISST 200 ISST 250 ISLT 50 ISLT 75 ISLT 100 ISJT 75 ISJT 87.5 ISJT 100 ISJT 112.5 Steel sheet piling sections ( see IS : 2314-1963* ) Designation ISPS 1 021 Z ISPS 1 625 U ISPS 2 222 U ISPS 100 F 47. Stone Agate Aggregate Basalt Cast Chalk Dolomite Emery Flint Gneiss Granite Gravel: Loose Moderately rammed, dry Green stone Gypsum Laterite Lime stone Marble Pumice Quartz rock Sand stone Slate Soap stone 48. Tar, Coal Crude ( see IS : 212-1983† ) Naphtha, light ( see IS : 213-1968‡ ) Naphtha, heavy Road tar ( see IS : 215-1961§ ) Pitch ( see IS : 216-1961|| ) 49. Thermal Insulation Unbonded glass wool Unbonded glass rock and slag wool Expanded polystyrene Cellular concrete Grade A Grade B Grade C Performed calcium silicate insulation (for temperature up to 650°C)


WEIGHT/MASS                         

TABLE 1 MATERIAL

kN

kg

per

(3)

(4)

(5)

— — — — — — — — — — — — — — —

0.150 0.196 0.269 0.288 0.079 0.154 0.279 0.368 0.040 0.070 0.125 0.034 0.039 0.049 0.063

15.3 20.0 27.4 29.4 8.1 15.7 28.4 37.5 4.0 7.1 12.7 3.5 4.0 5.0 6.4

m ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

— — — — —

0.483 0.641 0.811 0.541

49.25 65.37 82.70 55.20

,, ,, ,, ,,

— — — — — — — — — —

25.50 15.70 to 18.85 27.95 to 29.05 21.95 21.50 28.25 39.25 25.40 23.55 to 26.40 25.90 to 27.45

2 600 1 600 to 1 920 2 850 to 2 960 2 240 2 190 2 880 4 000 2 590 2 400 to 2 690 2 640 to 2 800

m3 ,, ,, ,, ,, ,, ,, ,, ,, ,,

— — — — — — — — — — — —

15.70 18.85 28.25 21.95 to 23.55 20.40 to 23.55 23.55 to 25.90 26.70 7.85 to 11.00 25.90 21.95 to 23.54 27.45 26.45

1 600 1 920 2 880 2 240 to 2 400 2 080 to 2 400 2 400 to 2 640 2 720 800 to 1 120 2 640 2 240 to 2 400 2 800 2 700

,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

— — — — —

9.90 9.90 9.90 9.90 9.90

1 010 1 010 1 010 1 010 1 010

,, ,, ,, ,, ,,

— — —

12.75 to 23.55 11.30 to 19.60 1.45 to 2.95

1 300 to 2 400 1 150 to 2 000 150 to 300

,, ,, ,,

— — — —

Up to 29.40 29.50 to 39.20 39.30 to 49.00 19.60 to 34.30

Up to 3 000 3 010 to 4 000 4 010 to 5 000 2 000 to 3 500

,, ,, ,, ,,

*Specification for steel sheet piling sections. †Specification for crude coal tar for general use ( second revision ). ‡Specification for coal-based naphtha ( first revision ). §Specification for road tar ( revised ). ||Specification for coal tar pitch ( revised ). ( Continued )

25

IS : 875 (Part 1) - 1987

(1) 50. Terra Cotta 51. Terrazzo Paving Cast partitions 52. Tiles Mangalore pattern ( see IS : 654-1972* ) Polystyrene wall tiles ( see IS : 3463-1966† ) 53. Timber Typical Indian timbers ( see IS : 399-1963‡ ) Aglaia Aini Alder Amari Amla Amra Anjan Arjun Ash Axlewood Babul Baen Bahera Bakota Balasu Ballagi Banati Benteak Ber Bhendi Bijasal Birch Black chuglam Black locust Blue gum Blue pine Bola Bonsum Bullet wood Casuarina Cettis Champ Chaplash Chatian Chikrassy Chilauni Chilla Chir Chuglam: Black White (silver grey-wood) Cinnamon Cypress Debdaru Deodar Devdam Dhaman: Grewia tiliofolia Grewia vestita Dhup Dilenia

UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE OR THICKNESS mm (2) —

WEIGHT/MASS

                        

TABLE 1 MATERIAL

kN (3) 18.35 to 23.25

kg (4) 1 870 to 2 370

(5) m3 m2 ,,

10 40

0.24 0.93

—

0.02 to 0.03

2 to 3

Tile

0.013 0.013

1.35 1.35

m2 ,,

99 × 99 148.5 × 148.5

24 95

per

m3 ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

8.34 5.83 3.63 6.13 7.85 4.41 8.33 7.99 7.06 8.82 7.70 7.70 7.99 4.21 7.55 11.13 4.41 6.62 6.91 7.55 7.85 6.13 7.85 8.34 8.34 5.05 6.42 5.20 8.78 8.34 6.42 4.85 5.05 4.07 6.62 6.42 7.85 5.64

850 595 370 625 800 450 850 815 720 900 785 785 815 430 770 1 135 450 675 705 770 800 625 800 850 850 515 655 530 895 850 655 495 515 415 675 655 800 575

— — — — — — —

7.85 6.91 6.42 5.05 6.28 5.35 7.06

800 705 655 515 640 545 720

,, ,, ,, ,, ,, ,, ,,

— — — —

7.70 7.40 6.42 6.13

785 755 655 625

,, ,, ,, ,,

*Specification for clay roofing tiles, Mangalore pattern ( second revision ). †Specification for polystyrene wall tiles. ‡Classification of commercial timbers and their zonal distribution ( revised ). ( Continued )

26

IS : 875 (Part 1) - 1987

(1) Dudhi Ebony Elm Eucalyptus Figs Fir Frash Gamari Gardenia Garuga Geon Gluta Gokul Grewia sp. Gurjan Gutel Haldu Hathipaila Hiwar Hollock Hollong Hoom Horse chestnut Imli Indian Chestnut Indian Hemlock Indian Oak Indian Olive Irul Jack Jaman Jarul Jathikai Jhingan Jutili Kadam Kail Kaim Kambli Kanchan Kanjuj Karada Karal Karani Karar Kardahi Karimgotta Kasi Kasum Kathal Keora Khair Khasipine Kindal Kokko Kongoo Kuchla Kumbi Kurchi Kurung Kusum Kuthan Lakooch Lambapatti Lampati Laurel Lendi Machilus: Gamblei Macrantha Maharukh

UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE OR THICKNESS mm (2) — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —

27

WEIGHT/MASS

                        

TABLE 1 MATERIAL

kN (3) 5.49 8.19 5.20 8.33 4.56 4.14 6.62 5.05 7.40 5.98 4.07 7.06 4.07 7.55 7.70 4.41 6.62 5.84 7.70 5.98 7.21 7.21 5.05 8.97 6.28 3.92 8.48 10.35 8.33 5.83 7.70 6.13 5.05 5.63 7.85 4.85 5.05 6.42 4.07 6.62 5.84 8.34 7.99 6.28 5.34 9.27 3.92 5.83 10.84 5.85 6.13 9.90 5.05 7.55 6.28 9.76 8.63 7.70 5.20 9.76 11.28 4.71 6.28 5.34 5.05 8.33 7.40

kg (4) 560 835 530 850 465 450 675 515 755 610 415 720 415 770 785 450 675 595 785 610 735 735 515 915 640 400 865 1 065 850 595 785 625 515 575 800 495 515 655 415 675 595 850 815 640 545 945 400 595 1 105 595 625 1 010 515 770 640 995 880 785 530 995 1 150 480 640 545 515 850 755

5.05 5.20 4.07

515 530 415

per (5) m3 ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ,, ( Continued )

IS : 875 (Part 1) - 1987 UNIT WEIGHT OF BUILDING MATERIALS — Contd NOMINAL SIZE WEIGHT/MASS OR THICKNESS mm kN kg per (1) (2) (3) (4) (5) Mahogany — 6.62 675 m3 ,, Mahua — 8.97 915 ,, Maina — 5.64 575 ,, Makai — 3.14 320 ,, Malabar neem — 4.41 450 ,, Mango — 6.77 690 ,, Maniawga — 7.40 755 ,, Maple — 5.64 575 ,, Mesua — 9.76 995 ,, Milla — 9.12 930 ,, Mokha — 7.99 815 ,, Mulberry — 6.62 675 ,, Mullilam — 7.21 735 ,, Mundani — 6.77 690 ,, Murtenga — 7.70 785 ,, Myrabolan — 9.27 945 ,, Narikel — 5.49 560 ,, Nedunar — 5.05 515 ,, Oak — 8.48 865 ,, Padauk — 7.06 720 ,, Padri — 7.06 720 ,, Palang — 5.98 610 ,, Pali — 6.28 640 ,, Papita — 3.28 335 ,, Parrotia — 8.48 865 ,, Persian lilac — 5.84 595 ,, Piney — 6.13 625 ,, Ping — 8.97 915 ,, Pinus insignis — 6.13 625 ,, Pipli — 5.83 595 ,, Pitraj — 6.77 690 ,, Poon — 6.42 655 ,, Poplar — 4.41 450 ,, Pula — 3.78 385 ,, Pyinma — 5.98 610 ,, Rajbrikh — 8.48 865 ,, Red sanders — 10.84 1 105 ,, Rohini — 11.33 1 155 ,, Rosewood (black wood) — 8.19 835 ,, Rudrak — 4.71 480 ,, Sal — 8.48 865 ,, Salai — 5.64 575 ,, Sandal wood — 8.97 915 ,, Sandan — 8.34 850 ,, Satin wood — 9.41 960 ,, Saykaranji — 7.40 755 ,, Seleng — 4.85 495 ,, Semul — 3.78 385 ,, Silver oak — 6.28 640 ,, Siris — 3.92 400 ,, Kala-siris — 7.21 735 ,, Safed-siris — 6.28 640 ,, Sisso — 7.70 785 ,, Spruce — 4.71 480 ,, Suji — 2.65 270 ,, Sundri — 9.41 960 ,, Talauma — 5.64 575 ,, Tanaku — 2.99 305 ,, Teak — 6.28 640 ,, Toon — 5.05 515 ,, Udal — 2.50 255 ,, Upas — 3.14 320 ,, Uriam — 7.40 755 ,, Vakai — 9.41 960 ,, Vellapine — 5.83 595 ,, Walnut — 5.64 575 ,, White bombwe — 5.98 610 ,, White cedar — 7.06 720 ,, White chuglam (silver grey-wood) — 6.91 705 ,, White dhup — 4.22 430 ,, Yon — 8.33 850 NOTE — The unit of timbers correspond to average unit weight of typical Indian timbers at 12 percent moisture content. 54. Water — 9.81 1 000 m3 Fresh ,, — 10.05 1 025 Salt 55. Wood-Wool Building Slabs 10 0.059 6 ,, TABLE 1

                      

MATERIAL

28

IS : 875 (Part 1) - 1987 3. BUILDING PARTS AND COMPONENTS 3.1 The unit weights of building parts or components are specified in Table 2. UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS

MATERIAL


WEIGHT/MASS                       

TABLE 2

mm

kN

kg

per

Plaster on tile or concrete Plaster on wood lath Suspended metal lath and cement plaster

1.3 cm 2.5 cm 2.5 cm

0.25 0.39 0.74

25 40 75

m2 ,, ,,

Suspended metal lath and gypsum plaster

2.5 cm

0.49

50

,,

1. Ceilings

2. Cement Concrete, Plain ( see 20 ‘Cement concentrate, plain’ in Table 1 ) 3. Cement Concrete, Reinforced ( see 21 ‘Cement concrete, reinforced’ in Table 1 ) 4. Damp-Proofing ( see 28 ‘Felt bituminous for waterproofing and damp proofing’ in Table 1 ) 5. Earth Filling ( see 45 ‘Soils and gravels’ in Table 1 ) 6. Finishing ( see also ‘Floor finishes’ given under 7 ‘Flooring’ and 8 ‘Roofing’ in Table 1 ) Negligible

—

Aluminium foil Plaster: Acoustic Anhydrite Barium sulphate Fibrous Gypsum or lime Hydraulic lime or cement Plaster ceiling on wire netting NOTE — When wood or metal lathing is used, add

10 10 10 10 10 10 10 —

0.08 0.21 0.28 0.09 0.19 0.23 0.26 0.06

8 21 29 9 19 23 27 6

m2 ,, ,, ,, ,, ,, ,, ,,

10 10 10

0.22 0.26 0.04

22 27 4

,, ,, ,,

    

100 125 150 175 200

1.47 1.67 1.86 2.16 2.55

150 170 190 220 260

,, ,, ,, ,, ,,

        

100 115 125 140 150 175 200

1.18 1.27 1.37 1.47 1.57 1.76 1.96

120 130 140 150 160 180 200

,, ,, ,, ,, ,, ,, ,,

7. Flooring Asphalt flooring NOTE — For macadam finish, add Compressed cork Floors, structural: Hollow clay blocks including reinforcement and mortar jointing between blocks, but excluding any concrete topping NOTE — Add extra for concrete topping Hollow clay blocks including reinforcement and concrete ribs between blocks, but excluding any concrete topping

NOTE — Add extra for concrete topping. ( Continued )

29

IS : 875 (Part 1) - 1987 UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS — Contd

Hollow concrete units including any concrete topping necessary for constructional purposes

NOMINAL SIZE OR THICKNESS mm  100  125  150   175  200  230

WEIGHT/MASS           

MATERIAL

           

TABLE 2

kN 1.67 1.96 2.16 2.35 2.65 3.14

kg 170 200 220 240 270 320

per m2 ,, ,, ,, ,, ,,

Floors, wood: Hard wood

     

22 28 22 28 —

0.16 0.20 0.11 0.13 0.015

Soft wood Weight of mastic used in laying wood block flooring NOTE — All thicknesses are ‘finished thicknesses’. Floor finishes: 12.5 to Clay floor tiles ( see IS : 1478-1969* ) 25.4 NOTE — This weight is ‘as laid’ but excludes screeding. Magnesium oxychloride: Normal type (saw dust filler) 10 Heavy duty type (mineral filler) 10 Parquet flooring — Rubber ( see IS : 809-1970† )  3.2  4.8  6.4 Terra cotta, filled ‘as laid’ — Terrazzo paving ‘as laid’ 10 8. Roofing

0.10

0.142 0.216 0.08 0.048 0.070 0.093 5.54 0.23

to 0.2

to 0.12 to 0.062 to 0.09 to 0.130 to 7.06

16 20.5 11 13.5 1.5

,, ,, ,, ,, ,,

10 to 20

,,

14.5 22 8 to 12 4.9 to 6.3 7.1 to 9.5 9.5 to 13.2 570 to 720 24

,, ,, ,, ,, ,, ,, m3 m2

Asbestos cement sheeting ( see ‘Asbestos cement sheeting’ in Table 1 ). ,, Allahabad tiles (single) including battens 85 0.83 — ( see Note below ) ,, Allahabad tiles (double) including 170 1.67 — battens ( see Note below ) ,, 70 Country tiles (single) with battens 0.69 — ( see Note below ) ,, 120 Country tiles (double) with battens 1.18 — ( see Note below ) ,, 65 0.64 Mangalore tiles with battens — ( see Note below ) ,, 110 1.08 Mangalore tiles bedded in mortar over — flat tiles ( see Note below ) ,, 80 0.78 — Mangalore tiles with flat tiles ( see Note below )  0.56 Copper sheet roofing including laps and 0.08 8 ,,  rolls 0.10 10 ,,  0.72 Flat Roofs: Clay tiles hollow ( see 7 ‘Flooring’ in this table ) Concrete hollow precast ( see 7 ‘Flooring’ in this table ) Galvanized iron sheeting ( see 39 ‘Metal sheeting, protected’ in Table 1 ) Glazed Roofing: Glazing with aluminium alloy bars for 6.4 0.19 19.5 ,, spans up to 3 m Glazing with lead-covered steel bars 6.4 0.25 to 0.28 26 to 29 ,, at 0.6 m centres States on battens — 0.34 to 0.49 35 to 50 ,, Thatch with battens — 0.34 to 0.49 35 to 50 ,, NOTE — Weights acting vertically on horizontal projection to be multiplied by cosine of roof angle to obtain weights normal to the roof surface. *Specification for clay flooring tiles ( first revision ). †Specification for rubber flooring materials for general purposes ( first revision ). ( Continued )

30

IS : 875 (Part 1) - 1987 UNIT WEIGHTS OF BUILDING PARTS OR COMPONENTS — Contd

MATERIAL


Roof finishes: Bitumen mecadam Felt roofing ( see 28 ‘Felt, bituminous for water-proofing and damp-proofing’ in Table 1 ) Glass silk, quilted Lead sheet Mortar screeding

WEIGHT/MASS                         

TABLE 2

mm

kN

kg

per

10 10

0.22 0.008

22 0.8

m2 ,,

0.5 0.8 10

0.05 0.07 0.21

5 7 21

,, ,, ,,

9. Walling (IS : 6072-1971*) Autoclaved reinforced cellular concrete wall slabs Class A Class B Class C Class D Class E Brick masonry ( see 36 ‘Masonry, brick’ in Table 1 ) Concrete blocks ( see 11 ‘Block’ in Table 1 ) Stone masonry ( see 37 ‘Masonry, stone’ in Table 1 ) Partitions: Brick wall Cinder concrete Galvanized iron sheet Hollow glass block (bricks) Hollow blocks per 200 mm of thickness: Ballast or stone concrete Clay Clinker concrete Coke breeze concrete Diatomaceous earth Gypsum Pumice concrete Slag concrete, air-cooled Slag concrete, foamed Lath and plaster Solid blocks per 20 mm of thickness: Ballast or stone Clinker concrete Coke breeze concrete Pumice concrete Slag concrete, foamed Terrazzo cast partitions Timber studding plastered

— — — — —

8.35 to 9.80 7.35 to 8.35 6.35 to 7.35 5.40 to 6.35 4.40 to 5.40

850 to 1 000 750 to 850 650 to 750 550 to 650 450 to 550

m3 ,, ,, ,, ,,

m2 ,, ,, ,,

100 75 — 100

1.91 1.13 0.15 0.88

20 20 20 20 20 20 20 20 20 —

0.201 0.201 0.220 9.176 0.093 0.137 0.177 0.196 0.186 0.392

20.5 20.5 22.5 18 9.5 14 18 20 19 40

,, ,, ,, ,, ,, ,, ,, ,, ,, ,,

20 20 20 20 20 40 —

0.451 0.300 0.221 0.221 0.250 0.932 9.981

46 30.5 22.5 22.5 25.5 95 100

,, ,, ,, ,, ,, ,, ,,

195 115 15 90

NOTE — For unit weight of fixtures and fittings required to buildings including builder’s hardware, reference may be made to appropriate Indian Standards. *Specification for autoclaved reinforced cellular concrete wall slabs.

4. STORE AND MISCELLANEOUS MATERIALS

materials intended for dead load calculations and other general purposes are given in Appendix A.

4.1 Units weights of store and miscellaneous

31

IS : 875 (Part 1) - 1987 APPENDIX A [ Clauses 1.1.1 ( Note ) and 4.1 ] UNIT WEIGHTS OF STORE AND MISCELLANEOUS MATERIALS WEIGHT/MASS 3

ANGLE OF FRICTION, DEGREES

8.45 5.50 7.35 2.95 5.80 4.90 2.20 to 5.90 1.25 3.45

860 560 750 300 590 500 225 to 600 125 350

— — — — — 45 — — —

6.75 7.55 7.35 5.30 6.55 7.35 8.15 6.85 0.98 1.45 3.45

690 770 750 540 670 750 830 700 100 150 350

27 27 30 30 33 30 28 30 30 30 —

1.65 0.69 14.10

170 70 1 440

— — —

1.65 4.60 2.85

170 470 290

— — —

3.90 1.85

400 190

20 —

                

MATERIAL kN/m

3

kg/m

1. Agricultural and Food Products Butter Coffee in bags Drinks in bottles, in boxes Eggs, packed Eats, oil Fish meal Flour in sacks up to 1 m height Forage (bales) Fruits Grains: Barley Corn, shelled Flax seed Oats Rice Soyabeans Wheat Wheat flour Grain sheaves up to 4 m stack height Grain sheaves over 4 m stack height Grass and clover Hay: Compressed Loose up to about 3 m stack height Honey Hops: In sacks In cylindrical hop bins Sewn up or compressed in cylindrical shape in hop cloth Malt: Crushed Germinated Meat and meat products Milk Molasses Onion in bags Oil cakes, crushed Potatoes Preserves (tins in cases)

7.05 10.05 4.40 5.40 5.80 7.05 4.90 to 7.85

720 1 025 450 550 590 720 500 to 800

— — — 0 0 30 —

Salt: Bags Bulk

7.05 9.40

720 960

— 30

4.90 to 7.85 3.90 to 6.85

500 to 800 400 to 700

25 —

0.45 1.65

45 170

— —

7.35 7.85 7.85 3.45 10.40

750 800 800 350 1 080

30 — — — —

Seeds: Heaps Sacks Straw and chaff: Loose up to about 3 m stack height Compressed Sugar: Crystal Cube sugar in boxes Sugar beet, pressed out Tobacco bundles Vinegar

32

IS : 875 (Part 1) - 1987 WEIGHT/MASS

                

MATERIAL kN/m3

kg/m3


2. Chemicals and Allied Materials Acid, hydrochloric Acid, nitric 91% Acid, sulphuric 87% Alcohol Alum, pearl, in barrel Ammonia, liquid Ammonium chloride, crystalline Ammonium nitrate Ammonium sulphate Beeswax Benzole Benzene hexachloride Bicarbonate of soda Bone Borax Calcite Camphor Carbon disulphide Casein Caustic soda Creosole Dicalcium phosphate Disodium phosphate Iodine Oils in bottles or barrels

11.75 14.80 17.55 7.65 5.20 8.85 8.15 7.05 to 9.80 7.05 to 9.00 9.40 8.90 8.75 6.40 18.65 17.15 26.50 9.70 12.75 13.25 13.85 10.50 6.65 3.90 to 4.80 48.55 5.70 to 8.90

1 200 1 510 1 790 780 530 900 830 720 to 1 000 720 to 920 960 910 890 650 1 900 1 750 2 700 990 1 300 1 350 1 410 1 070 6.80 400 to 490 4 950 580 to 910

5.70 7.05 8.50 9.40 7.85 to 9.40 9.90 17.85

580 720 865 960 800 to 960 1 010 1 820

— — — — — — —

12.25 to 13.35 13.25 to 15.70 11.60 12.55 10.40 11.75 to 13.25 12.85 to 13.55 13.25 to 13.55 14.40 8.65 9.90 20.70 87.30 6.75

1 250 to 1 360 1 350 to 1 600 1 185 1 280 1 060 1 200 to 1 350 1 310 to 1 380 1 350 to 1 380 1 470 880 1 010 2 110 8 900 690

— — — — — — — — — — — — — —

8.90 to 9.40 8.90 to 9.10 9.91 8.35 20.10 27.45 9.40 7.05

910 to 960 910 to 930 1 010 850 2 050 2 800 960 720

— — — — — — — —

— — — — — — 30-40 25 32-45 — — 45 30 — — — — — — — — 45 30-45 — —

Oil, linseed: In barrels In drums Oil, turpentine Paints Paraffin wax Petroleum Phosphorus Plastics: Cellulose acetate Cellulose nitrate Methyl methacrylate Phenol formaldehyde Polystryrene Polyvinyl chloride (Perspex) Resin bonded sheet Urea formaldehyde Potash Potassium Potassium nitrate Red lead, dry Red lead, paste Rosin in barrels Rubber: Raw Vulcanized Saltpetre Sodium silicate in barrels Sulphur Talc Varnishes Vitriol, blue, in barrels 3. Fuels Brown coal Brown coal briquettes heaped

6.85 7.85

33

700 800

— 35


                

MATERIAL kN/m3

Brown coal briquettes, stacked Charcoal

kg/m3


12.75 2.95

1 300 300

— —

9.80 11.75 6.85 8.35

1 000 1 200 700 850

35 0 25 35

4.90 9.80 8.35 9.80 9.40 3.90 6.75 1.95 1.45 2.45

500 1 000 850 1 000 960 400 690 200 150 250

35 35 35 35 0 45 0 45 35 35

11.75 17.65 11.75

1 200 1 800 1 200

45 45 24.30

25.30 to 26.60 25.90 to 27.45 0.028

2 580 to 2 710 2 640 to 2 800 2.8

— — —

60.90 65.70

6 210 6 700

— —

Coal: Untreated, mine-moist In washeries Dust All other sorts Coke: Furnace or gas Brown coal, low-temperature Hard, raw coal Hard, raw coal, mine-damp Diesel oil Firewood, chopped Petrol Wood in chips Wood shavings, loose Wood shavings, shaken down 4. Manures Animal manures: Loosely heaped Stacked dung, up to about 2.5 m stack height Artificial manures 5. Metals and Alloys Aluminium Cast Wrought Sheet per mm of thickness per m2 Antimony, pure: Amorphous Solid Bismuth: Liquid Solid

98.07 95.02 to 97.09

10 000 9 690 to 9 900

— —

83.75 to 84.05 85.03 15.60 63.95 to 66.00

8 540 to 8 570 8 670 1 590 6 520 to 6 730

— — — —

83.25 to 85.10 88.45

8 490 to 8 680 9 020

— —

86.20 to 87.65 86.70 to 87.65 0.09

8 790 to 8 940 8 840 to 8 940 8.7

— — —

188.75 to 189.55 189.55

19 250 to 19 330 19 330

— —

70.60 68.95 to 69.90 74.35 to 75.70 75.50

7 200 7 030 to 7 130 7 580 to 7 720 7 700

— — — —

Cadmium: Cast Wrought Calcium Chromium Cobalt: Cast Wrought Copper: Cast Wrought Sheet per mm of thickness Gold: Cast Wrought Iron: Pig Grey, cast White, cast Wrought

34


                

MATERIAL kN/m3

kg/m3


Lead: Cast Liquid Wrought Sheet per mm of thickness Magnesium Manganese Mercury Nickel Platinum

111.20 105.00 111.40 0.11 16.45 to 17.15 72.55 133.35 81.20 to 87.20 210.25

11 340 10 710 11 360 11 1 680 to 1 750 7 400 13 600 8 280 to 8 890 21 440

— — — — — — — — —

102.0 to 102.85 93.15 103.35 to 103.55

10 400 to 10 490 9 500 10 540 to 10 560

— — —

Silver: Cast Liquid Wrought Sodium: Liquid Solid

9.10 9.30

930 950

— —

Tungsten Uranium

188.30 180.45

19 200 18 400

— —

Zinc: Cast Wrought Sheet per mm of thickness

68.95 to 70.20 70.50 0.07

7 030 to 7 160 7 190 7

— — —

75.40 82.00 85.10 27.45 71.70 95.00

7 690 8 360 8 680 2 800 7 310 9 690

— — — — — —

80.60 84.25 80.30

8 220 8 590 8 190

— — —

82.75 85.10 83.85

8 440 8 680 8 550

— — —

85.60 86.10 75.40

8 730 8 780 7 690

— — —

82.75 81.70 81.40

8 440 8 330 8 300

— — —

184.75 168.20

18 840 17 150

— —

Alloys: Aluminium and copper Aluminium 10%, copper 90% Aluminium 5%, copper 95% Aluminium 3%, copper 97% Aluminium 91%, zinc 9% Babbit metal (tin 90%, lead 5%, copper 5%) Wood’s metal (bismuth 50%, lead 25%, cadmium 12.5%, tin 12.5%) Brasses: Muntz metal (copper 60%, zinc 40%) Red (copper 90%, zinc 10%) White (copper 50%, zinc 50%) Yellow (copper 70%, zinc 30%): Cast Drawn Rolled Bronzes: Bell metal (copper 80%, tin 20%) Gun metal (copper 90%, tin 10%) Cadmium and tin German Silver: Copper 52%, zinc 26%, nickel 22% Copper 59%, zinc 30%, nickel 11% Copper 63%, zinc 30%, nickel 7% Gold and Copper: Gold 98%, copper 2% Gold 90%, copper 10%

35


                

MATERIAL kN/m3

kg/m3


Lead and Tin: Lead 87.5%, tin 12.5% Lead 30.5%, tin 69.5% Monel metal, cast (nickel 70%, copper 30%)

103.85 81.10 87.00

10 590 8 270 8 870

— — —

77.00 76.80 0.08

7 850 7 830 8

— — —

10.80 to 15.70 5.50 to 6.30 5.50 to 6.30 7.05 to 7.85 7.05 to 7.85 7.05 3.55 to 8.35 18.65 8.35 9.80 11.75 21.95 10.80 7.85 7.85 to 8.50 7.05 to 9.30 5.90

1 100 to 1 600 560 to 645 560 to 645 720 to 800 720 to 800 720 360 to 850 1 900 851 1 000 1 200 2 240 1 100 800 800 to 865 720 to 950 600

30 40 38 52 50 30-45 27 — — 28 30 — — 30 29 34 —

Steel: Cast Wrought mild Black plate per mm of thickness Steel sections ( see 46 ‘Steel sections’ in Table 1 ) 6. Miscellaneous Materials Aggregate, coarse Ashes, coal, dry, 12 mm and under Ashes, coal, dry, 75 mm and under Ashes, coal, wet, 12 mm and under Ashes, coal, wet, 75 mm and under Asphalt, crushed, 12 mm and under Ammonium nitrate, prills Bone Books and files, stacked Calcium ammonium nitrate Copper sulphate, ground Chalk Chinaware, earthenware, stacked (including cavities) Clinker, furnace, clean Diammonium phosphate Double salt (ammonium sulphate nitrate) Filling cabinets and cupboards with contents, in records offices, libraries, archives Flue dust, boiler house, dry Fly ash, pulverised

5.50 to 7.05 5.50 to 7.05

720 720

≥ 30 —

2 400 to 2 720 16 to 120 2 600 1 280 889 to 960 960 to 1 280 1 440 to 1 600

— — — — 40 45 30-45

560 to 560 to

Glass: Glass, solid Wool In sheets Glue Gypsum, calcined, 12 mm and under Gypsum, calcined, powdered Gypsum, raw, 25 mm and under

23.50 to 26.70 0.16 to 1.18 25.50 12.55 8.60 to 9.40 9.40 to 12.55 14.10 to 15.70

Hides Dry Salted

  

Only green

8.65

Ice Leather put in rows Lime, ground, 3 mm and under Lime, hydrated, 3 mm and under Lime, hydrated, pulverized Lime pebble Limestone, agricultural, 3 mm and under Limestone, crushed Limestone dust Magnesite, caustic, in powder form Magnesite, sinter and magnesite, granular Phosphate, rock, pulverized Phosphate rock Phosphate sand Potassium carbonate Potassium chloride, pellets Potassium nitrate Potassium sulphate Pyrites, pellets

8.90 7.85 9.40 6.30 5.00 to 6.30 8.25 to 8.75 10.60 13.30 to 14.10 8.65 to 14.90 7.85 19.60 9.40 11.75 to 13.35 14.10 to 15.70 7.95 18.85 to 20.40 4.85 6.55 to 7.45 18.85 to 20.40

36

880 910 800 960 640 510 to 640 840 to 890 1 080 1 355 to 1 440 880 to 1 520 800 2 000 960 1 200 to 1 360 1 440 to 1 600 810 1 920 to 2 080 495 670 to 760 1 920 to 2 080

— — — ≥ 45 30-45 30-45 ≥ 45 30-45 30-45 38-45 — — 40-52 30-45 30-45 30-45 30-45 ≥ 30 45 30-45


                

MATERIAL kN/m3

Pumice Rubbish:

5.80 to 9.90

Building General Salt, common, dry, coarse Salt, common, dry, fine Salt cake, dry, coarse Salt cake, dry, pulverized Sand, bank, damp Sand, bank, dry Sand, silica, dry Saw dust, loose Silica gel Soda ash, heavy Soda ash, light Sodium nitrate, granular Sulphur, crushed, 12 mm and under Sulphur, 76 mm and under Sulphur, powdered Single superphosphate (S.S.P.), granulated Slag, furnace, crushed

kg/m3


590 to 1 010

—

13.80 6.30 6.30 to 10.00 11.00 to 12.55 13.35 11.20 to 13.35 17.25 to 20.40 14.10 to 17.25 14.10 to 15.70 1.57 4.40 8.65 to 10.20 4.70 to 6.00 11.00 to 12.55 7.85 to 8.25 8.65 to 13.35 7.85 to 9.40 7.65 to 8.25 14.90

1 410 645 640 to 1 020 1 120 to 1 280 1 360 1 140 to 1 360 1 760 to 2 080 1 440 to 1 760 1 440 to 1 600 160 450 880 to 1 040 480 to 610 1 120 to 1 280 800 to 840 880 to 1 360 800 to 960 780 to 840 1 520

— — 30-45 30-45 30 35 45 30 30-35 30 30-45 35 37 24 35-45 32 30-45 37 35

13.80 44.00 9.40 7.85 to 8.65 2.85 to 5.70 6.40

1 410 4 490 960 800 to 880 2 910 to 5 810 650

— — 30-45 30-45 — 23-26

29.80 26.50 13.85

3 040 2 700 1 400

— — —

29.80 19.60

3 040 2 000

— —

7.35 12.75 2.95 8.90 6.85

750 1 300 300 910 700

— — — — —

6.85 3.90 10.80 4.90 12.75

700 400 1 100 500 1 300

— — — — —

Steel goods: Cylinders, usually stored for carbonic acid, etc Sheets, railway rails, etc, usually stored Trisodium phosphate Triple superphosphate Turf Urea, prills 7. Ores Antimony Ferrous sulphide Ferrous sulphide ore waste after roasting Iron ore, compact storing Magnesium ore 8. Textiles, Paper and Allied Materials Cellulose in bundles Cotton, compressed Flax, piled and compressed in bales Furs Jute in bundles Paper: In bundles and rolls Newspapers in bundles Put in rows Thread in bundles Wood, compressed

37

Bureau of Indian Standards BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country. Copyright BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publications), BIS. Review of Indian Standards Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Catalogue’ and ‘Standards : Monthly Additions’. This Indian Standard has been developed by Technical Committee : CED 37 Amendments Issued Since Publication Amend No.

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IS : 875 ( Part 2 ) - 1987 (Reaffirmed 1997)

Indian Standard CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURES PART 2 IMPOSED LOADS

(Second Revision) ~Sixtll Reprint JUNE 1998

UDC 624~042.3 : 006.76

@ Copyright 1989

BUREAU

OF

INDIAN

STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 Gr 8

March 1989

IS : 875 ( Part 2 ) - 1987

.I

Indian Standard

CODEOFPRACTICEFOR DESIGNLOADS(OTHERTHANEARTHQUAKE) FORBUILDINGSANDSTRUCTURES PART 2 IMPOSED LOADS

(Second Rev’sion) Structural Safety Sectional Committee, BDC 37 Chairman BRIG

L. V.

R AMAKRISHNA

Representing

Engineer-in-Chief’s Branch, Army Headquarters, New Delhi

Members D R K. G. BHATIA S HRI M. S. BHATIA SHRT N. K. BHATTACHARYA SHRI S. K. MA L H O T R A (Alternate ) C HAKRABARTI SHKI A. D A T T A ( AIIernare ) C HIEF E NGINEER ( NDZ ) II S U P E R I N T E N D I N G S URVEYOR OF W O R K S ( NDZ ) II ( Alternate ) D R P. DA Y A R A T N A M D R A. S. R. SAI ( Alternate ) D E P U T Y M U N I C I P A L COMMISSIOKER ( EN G G ) C ITY E NGINEER ( Alternate ) D IRECTOR ( CMDD-I ) D EPUTY D IRECTOR ( CMDD-I ) ( Alternate ) M A J- GEN A. M. GOGLEKAR P ROF D. N. T RIKHA ( Alternate ) SHRI A. C. GUPTA SHRI P. SEN G U P T A S HRI M. M. GHOSH ( Alternate ) SHRI G. B. J A H A G I R D A R

DR

S. C.

J OINT D IRECTOR S T A N D A R D S ( B & S ), CB S HRI S. P. JOSHI S HRI A. P. M ULL ( Alternate ) S HRI S. R. KUI.KARNI S HRI S. N. PAL ( Alternate ) S HRI H. N. MI S H R A

SHRI R. K. PUNHANI ( Alternate )

S HRI T. K. D. MU N S H I D R 6. RA J K U M A R

D R M. N. KESHWA RA O S HRI S. GO M A T H I N A Y A G A M ( Alternate ) D R T. N. S UBBA R A O DR S. V. L O N K A R ( AIfernafe ) S HRI P. K. RA Y S HRI P. K. M UKHERJEE ( Alternate ) SHRI S. SE E T H A R A M A N S HRI S. P. C HAKRABORTY ( Alternate )

Bharat Heavy Electricals Ltd ( Corporate, Research & Development Division ), Hyderabad In pe;rs;;l) capacity ( A-2136, Sa/darjmg Enclave, New Engineer-in-Chief’s Branch, Army Headquarters, New De Ihi Central Building Research Institute ( CSIR ), Roorkee Central Public Works Department, New Delhi Indian Institute of Technology, Kanpur Municipal Corporation of Greater Bombay, Bombay Central Water Commission, New Delhi Institution of Engineers ( India ), Calcutta National Thermal Power Corporation Ltd, New Delhi Stewarts and Lloyds of India Ltd, Calcutta National Industrial Development Corporation Ltd, New Delhi Ministry of Railways Tata Consulting Engineers, New Delhi M. N. Dastur & Co, Calcutta Forest Research institute and Colleges, Dehra Dun Engineers India Ltd. New Delhi National Council for Cement and Building Materials, New Delhi Structural Engineering Research Centre ( CSIR ), Madras Gammon India Ltd, Bombay Indian Engineering Association, Calcutta Ministry of Surface Transport ( Roads Wing ), New Delhi ( Continued on page 2 )

0 Copyright 1989 BUREAU OF INDIAN STANDARDS This publication is protected under the Indian Cop.vright Act ( XIV of 1957) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.

IS : 875 ( Part 2 ) - 1987 ( Continuedfrom page 1 ) Representing

Members SHRI SHRI

S HRI

India Meteorological Department, New Delhi National Buildings Organization, New Delhi

M. C. SHARMA K. S. SRINIVASAN SHRI A. K. LAL ( Alternate ) SUSHJL KLIMAR

National Building Construction Corporation, Limited, New Delhi Director General, BIS ( Ex-officio Member )

SHRI G. RAMAN, Director ( Civ Engg )

Secretary S HRI

B. R. NARAYANAPPA Deputy Director ( Civ Engg ), BIS

Panel on Loads ( Other than Wind Loads ), BDC 37 : P3 Convener

D R T. N. SUBBA RA O D R S. V. LONKAR ( Alternate )

Gammon India Limited, Bombay

Members

D R T. V. S. R. APPA RA O D R M. N. KESHAVA R AO ( Alternate ) S. R. KULKARNI SHRI M. L. MLHTA SHRI

SHRI S. K. DATTA ( Alternate ) D R C. N. SRINIVASAN SUPERINTENDING E NGINEER ( D ) DR

E XECUTIVE E NGINEER ( D ) VII ( Alternate ) V ISVESVARAYA

H. C.

Structural Engineering Research Centre, CSIR Campus, Madras M. N. Dastur & Co Ltd, Calcutta Metallurgical & Engineering Consultants ( India ) Ltd. Ranchi M/s C. R. Narayana Rao, Madras Central Public Works Department ( Central Designs Organization ), New Delhi National Council for Cement and Building Materials, New Delhi

IS : 875 ( Part 2 ) - 1987 CONTENTS Page 0.

FOREWORD

...

*..

...

...

...

4

1.

SCOPE

...

...

...

...

...

5

...

...

...

...

...

...

...

..,

...

...

...

5 6 6 12 12

...

...

...

...

...

...

...

...

.,.

12 13 13

...

...

...

13

...

...

...

13

...

...

...

13 13

TERMINOLOGY ... ... ... 2. 3. IMPOSED LOADS ON FLOORS D UE TO USE AND O CCUPANCY 3.1 Imposed Loads ... ... 3.1.1 Load Application ... ... 3.1.2 Loads Due to Partitions

...

4.1

Reduction in Imposed Loads on Floors Posting of Floor Capacities ... IMPOSED LOADS ON ROOFS ... Imposed Loads on Various Types of Roofs

4.2

Concentrated Load on Roof Coverings

4.3

Loads Due to Rain

4.4 4.5 5.

... Dust Load Loads on Members Supporting Roof Coverings IMPOSED HORIZONTAL LOADS ON PARAPETS AND BALUSTRADES

...

...

...

.,.

...

...

6.

LOADING EFFECTS DUE TO IMPACT AND VIBRATION

...

...

3.2 3.3 4.

... ...

Impact Allowance for Lifts, Hoists and Machinery ... 6.1 Concentrated Imposed Loads with Impact and Vibration .,* 6.2 Impact Allowances for Crane Girders ... ... 6.3 ... Crane Load Combinations ... 6.4 ... 7. OTHER LOADS ... f.. ... ... APPENDIX A ILLUSTRATIVE EXAMPLE SHOWING REDUCTION OF UNIFORMLY DISTRIBUTED IMPOSED F LOOR L OADS IN M U L T I- STOREYED B UILDINGS FOR D ESIGN OF C OLUMNS

.I

. . .

. . .

. . .

. . .

13 13 14 14 15 15 16 16 17

IS : 875 ( Part 2 ) - 1987

Indian Standard

CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STtiUCTURES PART 2 IMPOSED LOADS

(Second Revision) 0.

FOR E W O R D

0.1 This Indian Standard ( Part 2 ) ( Second Revision ) was adopted by the Bureau of Indian Standards on 31 August 1987. after the draft finalized by the Structural Safety Sectional Committee had been approved by the Buildmg Division Council. 0.2 A building has to perform many functions satisfactorily. Amongst these functions are the utility of the building for the intended use and occupancy, structural safety, fire safety; and compliance with hygienic, sanitation, ventilation and day light standards. The design of the building is dependent upon the minimum requirements prescribed for each of the above functions. The minimum requirements pertaining to the structural safety of buildings are being covered in this Code by way of laying down minimum design loads which have to be assumed for dead loads, imposed loads, snow loads and other external loads, the structure would be required to bear. Strict conformity to loading standards recommended in this Code, it is hoped, will not only ensure the structural safety of the buildings which are being designed and constructed in the country and thereby reduce the hazards to life and property caused by unsafe structures, but also eliminate the wastage caused by assuming unnecessarily heavy loadings. 0.3 This Code was first published in 1957 for the guidance of civil engineers, designers and architects associated with the planning and design of buildings. It included the provisions for the basic design loads ( dead loads, live loads, wind loads and seismic loads ) to be assumed in the design of buildings. In its firs! revision in 1964, the wind pressure provisions were modified on the basis of studies of wind phenomenon and its effects on structures, undertaken by the special committee in consultation with the Indian Meteorological Department. In addition to this, new clauses on wind loads for butterfly type structures were included; wind ,pressure coefficients for sheeted roofs, both curved and sloping, were modified; seismic load provisions were deleted ( separate code having been prepared ) and metric system of weights and measurements was adopted.

0.3.1 With the increased adoption of the Code, a number of comments were received on the provisions on live load values adopted for different occupancies. Simultaneously live load surveys have been carried out in America and Canada to arrive at realistic live loads based on actual determination of loading ( movable and immovable ) in different occupancies. Keeping this in view and other developments in the field of wind engineering, the Sectional Committee responsible for the preparation of the Code has decided to prepare the second revision of IS : 875 in the following five parts : Part 1 Dead loads Part 2 Imposed loads Part 3 Wind loads Part 4 Snow loads Part 5 Special loads and load combinations Earthquake load is covered in a separate standard, namely IS : 1893-1984* which should be considered along with above loads. 0.3.2 This Code ( Part 2 ) deals with imposed loads on buildings produced by the intended occupancy or use. In this revision, the following importalit changes have been made: a) The use of the term ‘live load’ has been modified to ‘imposed load’ to cover not only the physical contribution due to persons but also due to nature of occupancy, the furniture and other equipments which are a part of the character of the occupancy. b) The imposed loads on floors and roofs have been rationalized based on the codified data available in large number of latest foreign national standards, and other literature. Further, these values have been spelt out for the major occupancies as classified in the National Building Code of India as well as the various service areas appended to the major occupancies. *Criteria for earthquake resistant design of structures (fourth revision ).

4

IS : 875 ( Part 2 ) - 1987

C) 4

e) f> g>

the prevailing practices in regard to loading standards followed in this country by the various municipal authorities and has also taken note of the developments in a number of countries abroad. In the preparation of this Code, the following national standards have been examined :

The reduction of imposed loads for design of vertical supporting members in multi-storeyed b u i l d i n g s h a s b e e n further increased from 40 to 50 percent. Provision has been included for sign posting of loads on floors in view of the different loadings specified. for different occupancies and to avoid possible misuse in view of conversion of occupancies. The value of loads on parapets and balustrades have been revised with its effect taken both in the horizontal and vertical directions. In the design of dwelling units planned with executed in accordance and IS : 8888-1979*, an imposed load of 1.5 kN/m* is allowed. SI Units have been used in the Code.

a) BS 6399 : Part 1 : 1984 Design Loading for Buildings Part I: Code of Practice for Dead and Imposed Loads. British Standards Institution. b) AS : 1170, Part 1-1983 - SAA Loading Code, Part I Dead and Live Loads. Australian Standards Institution. c) NZS 4203-1976 New Zealand Standard General Structural Design and Design Loading for Building. Standards Association of New Zealand. d) ANSI. A 58.1 - 1982American Standard Building Code Requirements for Minimum Design Loads in Buildings and Other Structures.

0.3.3 The buildings and structural systems shall provide such structural integrity that the hazards associated with progressive collapse such as that due to local failure caused by severe overloads or abnormal loads not specifically covered therein are reduced to a level consistent with good engineering practice.

e) National Building Code of Canada ( 1977 ) Supplement No. 4. Canadian Structural Design Manual.

f ) DIN 1055 Sheet 3 - 1971 Design Loads

0.3.4 Whenever buildings are designed for future additions of floor at a later date, the number of storeys for which columns/walls, foundations, etc, have been structurally designed may be posted in a conspicuous place similar to posting of floor capacities and both could be placed together. 0.4 The Sectional Committee responsible for the preparation of this Code has taken into account - *Guide for requirements of low income housing.

for Buildings - Live Load ( West German Loading Standards ).

!?I IS0 2103-1986 Loads due to use and

occupancy in residential and public buildings.

h)

IS0 2633-1974 Determination of Imposed Floor Loads in Production Buildings and Warehouses. lnternational Organization for Standardization.

2.1 Imposed Load - The load assumed to be produced by the intended use or occupancy of a building, mcluding the weight of movable partitions, distributed, concentrated loads, load due to impact and vibration, and dust load but excluding wind, seismic, snow and other loads due to temperature changes, creep, shrinkage, differential settlement, etc. 2.2 Occupancy or Use Group - The principal occupancy for which a building or part of a building is used or intended to be used; for the purpose of classification of a building according to occupancy, an occupancy shall be deemed to include subsidiary occupancies which are contingent upon it. The occupancy classification is given from 2.2.1 to 2.2.8. 2.2.1 Assembly Buildings - These shall include any building or part of a building where groups of people congregate or gather for amusement, recreation, social, religious, patriotic, Civil, travel and similar purposes, for example, theatres, motion picture houses, assembly halls, city halls,

1. SCOPE

1.1 This standard ( Part 2) covers imposed loads* ( live loads ) to be assumed in the design of buildings. The imposed !oads, specified herein, are minimum loads which should be taken into consideration for the purpose of structural safety of buildings. 1.2 This Code does not cover detailed provisions for loads incidental to construction and special cases of vibration, such as moving machinery, heavy acceleration from cranes, hoists and the like. Such loads shall be dealt with individually in each case. 2. TERMINOLOGY 2.0 For the purpose of this Code, the following definitions shall apply. *The word ‘imposed load’ is used through out instead of ‘live load’ which is synonymous. 5

IS : 875 ( Part 2 ) - 1987 marriage halls, town halls, auditoria, exhibition halls, museums, skating rinks, gymnasiums, restaurants ( also used as assembly halls ), places of worship, dance halls, club rooms, passenger stations and terminals of air, surface and other public transportation services, recreation piers and stadia, etc.

provided for normal residential purposes with or without cooking or dining or both facilities ( except buildings under 2.2.5). It includes one multi-family dwellings, apartment houses phats ), lodging or rooming houses, restaurants, hostels, dormitories and residential hotels. 2.2.7.1 Dwellings - These shall include any building or. p;i:t occupied by members of single/ multi-family units with independent cooking These shall also include apartment facilities. houses ( flats ).

2.2.2 Business Buildings - These shall include any building or part of a building, which is used for transaction of business ( other than that covered by 2.2.6 ); for the keeping of accounts and records for similar purposes; offices, banks, professional establishments, court houses, and libraries shall be classified in this group so far as principal function of these is transaction of public business and the keeping of books and records.

2.2.8 Storage Buildings - These shall include any building or part of a building used primarily for the storage or sheltering of goods, wares or merchandize, like warehouses, cold storages, freight depots, transity sheds, store houses, garages, hangers, truck terminals, grain elevators, barns and stables.

2.2.2.1 Ofice buildings - The buildings primarily to be used as an office or for office purposes; ‘office purposes’ include the purpose of administration, clerical work, handling money, telephone and telegraph operating and operating computers, calculating machines; ‘clerical work’ includes writing, book-keeping, sorting papers, typing, filing, duplicating, punching cards or tapes, drawing of matter for publication and the editorial preparation of matter for publication.

3. IMPOSED LOADS ON FLOORS DUE TO USE AND OCCUPANCY 3.1 Imposed Loads - The imposed loads to be assumed in the design of buildings shall be the greatest loads that probably will be produced by the intended use or occupancy, but shall not be less than the equivalent minimum loads specified in Table 1 subject to any reductions permitted by 3.2.

2.2.3 Educational Buildings - These shall include any building used for school, college or day-care purposes involving assembly for instruction, education or recreation and which is not covered by 2.2.1.

Floors shall be investigated for both the uniformly distributed load ( UDL ) and the corresponding concentrated load specified in Table 1 and designed For the most adverse effects but they shall not be considered to act simultaneously. The concentrated loads specified in Table 1 may be assumed to act over an area of 0.3 x 0.3 m. However, the concentrated loads need not be considered where the floors are capable of effective lateral distribution of this load.

2.2.4 Industrial Buildings - These shall include any building or a part of a building or structure in which products or materials of various kinds and properties are fabricated, assembled or processed like assembly plants, power plants, refineries, gas p!ants, mills, dairies, factories, workshops, etc. 2.2.5 Institutional Buildings - These shall include any building or a part thereof, which isused for purposes, such as medical or other treatment in case of persons suffering from physical and mental illness, disease or infirmity; care of infants, convalescents of aged persons and for penal or correctional detention in which the liberty of the inmates is restricted. Institutional buildings ordinarily provide’ sleeping accommodation for the occupants. It includes hospitals, sanitoria, custodial institutions or penal institutions like jails, prisons and reformatories.

All other structural elements shall be investigated for the effects of uniformly distributed loads on the floors specified in Table 1. N OTE 1 - Where in Table 1, no values are given for concentrated load, it may be assumed that the tabulated distributed load is adequate for design purposes. N OTE 2 - The loads specified in Table I are equivalent uniformly distributed loads on the plan area and provide for normal effect of impact and acceleration. They do not take into consideration special concentrated loads and other loads. N OTE 3 - Where the use of an area or floor is not provided in Table 1, the imposed load due to the use and occupancy of such an area shall be determined from the analysis of loads resulting from:

2.2.6 Mercantile Buildings -These shall include any building or a part of a building which is used as shops, stores, market for display and sale of merchandise either wholesale or retail. Office, storage and service facilities incidental to the sale of merchandise and located in the same building shall be included under this group.

a! weight of the probable assembly of persons; b) weight of the probable accumulation of equipment and furnishing;

4 weight of the probable storage materials; and 4 impact factor, if any.

2.2.7 Residential Buildings - These shall include any building in which sleeping accommodation is 6

IS : 875 ( Part 2 ) - 1987 TABLE 1 IMPOSED FLOOR LOADS FOR DlFFERENT OCCUPANCIES (Clauses 3.1, 3.1.1 and4.1.1 )

SL No.

OCCYJPANCY

CLASSIFICATION

U NIFORMLY DISTRIBUTED L OAD ( UDL )

C ONCENTRATED LOAD

(3) kNlma

(4) kN

(2)

(1)

i ) RESIDENTIAL BUILDINS a) Dwelling houses: 1) All rooms and kitchens

2’0

1’8

2) Toilet and bath rooms

2’0

-

3) Corridors, passages, staircases including tire escapes and store rooms

3.0

4.5

b)

trated at the outer edge

kitchens,

I.5

1’4

2) Corridors, passages and staircases including fire escapes

1.5

1’4

3) Balconies

3.0

Habitable rooms, toilet and bathrqoms

1.5 per metre run concentrated at the outer edge

Hotels, hostels, boarding houses, dormitories, lodging houses, residential clubs: Living rooms, bed rooms and dormitories Kitchens and laundries

2’0

1.8

3.0

4.5

3)

Billiards room and public loungcs

3.0

2.7

4)

5.0

4.5

5)

Store rooms Dining rooms, cafeterias and restaurants

4.0

2.7

6)

Oflice rooms

2.5

2.7

7)

Rooms for indoor games

3.0

1.8

8)

Baths Lind toilets

2’0

-

9)

Corridors, passages, staircases including fire escapes, lobbies -- as per the floor serviced ( excluding stores and the like ) but not less than

3’0

4.5

1)

2)

10)

d)

1’5 per metre run concen-

Dwelling units planned and executcd in accordance with IS : 888S1979* only: 1)

C)

3.0

Balconies

4)

Balconies

Same as rooms to which they give access but with a minimum of 4’0

Boiler rooms and plant rooms - to be calcuiated but not less than

5’0

1.5 per metre run concentrated at the outer edge 6.7 ( Continued )

7

IS : 875 ( Part 2 ) - 1987 TABLE 1 IMPbED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Conrd O CCUPANCY C LASSIFICATION

SL No.

UNSFORMLY DISTRIBUTED L OAD ( UDL )

CONCENTRATED LOAD

(3) kN/ms

(4) kN

Garage floors ( including parking area and repair workshops ) for passenger cars and vehicles not exceeding 2’5 tonnes gross weight, including access ways and ramps - to be calculated but not less than

2.5

9.0

Garage floors for vehicles not exceeding 4.0 tonnes gross weight ( including access ways and ramps ) - to be calculated but not less than

5’0

9.0

(2)

(1) e) Garages:

ii) EDUCATIONAL BUILDINGS

a) Class rooms and lecture rooms

( not used for assembly purposes )

b) Dining rooms,

cafeterias

restaurants

and

4 Offices, lounges and staff rooms d) Dormitories e) f1 Lx) h) 3

3’0

2.1

3.0t

2.7

2.5

2.7

2.0

2.7 -

Projection rooms

5’0

Kitchens

3.0

Toilets and bathrooms

2.0

4.5 -

Store rooms

5.0

45

Libraries and archives: 1) Stack room/stack area

6’0 kN/ms for a minimum height of 2’2 m + 2’0 kN/m* per metre height beyond 2.2 m

4’5

2) Reading rooms ( without separate storage )

4’0

4.5

3) Reading rooms ( with separate storage

3.0

4.5

k) Boiler rooms and plant rooms - to

4.0

45

be calculated but not less than

ml

40

Corridors, passages, lobbies, staircases including fire escapes - as per the floor serviced ( without accounting for storage and projection rooms ) but not less than

n) Balconies

Same as rooms to which they give access but with a minimum of 4.0

4.5

15 per metre run concentrated at the outer edge

iii) INSTITUTIONAL BUILDlNGS a) Bed rooms, wards, dressing rooms, dormitories and lounges

2’0

1.8

b) Kitchens, laundries and laboratories

3.0

45 ( Continued )

8

IS : 875 ( Part 2 ) - 1987 TABLE 1 IMPOSED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Cod

SL No.

O CCUPANCY C LASSIFICATION

(1)

(2)

UNIFORMLY DISTRIB UTED L OAD ( UDL )

C ONCENTRATED LOAD

(3) kN/m’

(4) kN

3.0t

2.7

d) Toilets and bathrooms

2.0

-

e) X-ray rooms, operating rooms, general storage areas -to be calculated but not less than

3’0

4’5

f)

2’5

2’7

4’0

45

5’0

4.5

c) Dining rooms, restaurants

cafeterias

and

Office rooms and OPD rooms

g) Corridors, passages, lobbies and staircases including fire escapes as per the floor serviced but not less than h) Boiler rooms and plant rooms - to be calculated but not less than j) Balconies

Same as the rooms to which they give access but with a minimum of 4.0

1’5 per metre run concentrated at the outer edge

iv) ASSEMBLY BUILDINGS a) Assembly areas: 1) with fixed seatsz

4’0

2) without fixed seats

-

5’0

3.6

b) Restaurants ( subject to assembly ), museums and art galleries and gymnasia

4.0

4.5

c) Projection rooms

5'0

-

d) Stages

5’0

4.5

e) Office rooms, kitchens and laundries

3’0

4.5

f) Dressing rooms

2’0

1’8

g) Lounges and billiards rooms

2.0

2.7

h) Toilets and bathrooms j) Corridors, passages, including fire escapes k) Balconies

2.0

-

staircases

4’0 Same as rooms to which they give access but with a mintmum of 4.0

4.5 1.5 per metre run concentrated at the outer edge

m) Boiler rooms and plant rooms including weight of machinery

7’5

4’5

n)- Corridors, passages subject to loads greater than from crowds, such as wheeled vehicles, trolleys and the like. Corridors, staircases and passages in grandstands

5’0

4.5

v) BUSINESS AND OFFICE BUILDINGS ( see ulso 3.1.2 ) a) Rooms for general use with separate storage

2’5

2’7

b) Rooms &thout separate storage

4.0

4.5

I Continued ) 9

IS : 875 ( Part 2 ) - 1987 TABLE 1

IMPOSED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Contd


SL No.

UNTFORMLY D ISTRIBUTED L OAD ( UDL )

(2)

(1)

CONCENTRATED LOAD

(3) kN/m’ 3’0

(4) kNe 2.7

d) Business computing machine rooms ( with fixed computers or similar equipment )

3’5

4.5

and

5’0

4.5

f) Vaults and strong room - to be calculated but not less than

5’0

4.5

g) Cafeterias and dining rooms

3.0t

2.7

h) Kitchens

3.0

2.7

j) Corridors, passages, lobbies and staircases including fire escapes - as per the floor serviced (excluding stores ) but not less than

4.0

4.5

k) Bath and toilet rooms

2.0

.-.

c) Banking halls

e) Records/files storage space

store

rooms

m) Balconies


n) Stationary stores

4’0 for each metre of storage height

p)

Boiler rooms and plant rooms - to be calculated but not less than

q) Libraries

I.5 per metre run concentrated at the outer edge

5’0 see

Sl No. ( ii )

vi) MERCANTILE BUILDINGS a) Retail shops

4.0

3.6

b) Wholesale shops - to be calculated but not less than

6’0

4.5

c) Office rooms

2’5

2’7

d) Dining rooms, restaurants and cafeterias

3’0t

2.7

e) Toilets

2.0

-

f) Kitchens and laundries

3’0

4’5

g) Boiler roooms and plant rooms to be calculated but not less than

5’0

6.7

h) Corridors, staircases passages, including fire escapes and lobbies

4.0

4.5

j) Corridors, passages, staircases subject to loads greater than from crowds, such as wheeled vehicles, trolleys and the like

5.0

4.5

k) Balconies


10

1.5 per metre run concentrated at the outer edge

IS : 875 ( Part 2 ) - 1987 TABLE 1 IMPOSED FLOOR LOADS FOR DIFFERENT OCCUPANCIES - Contd


SL No.

(1)

U NIFORMLY DrsTRleUTED LOAD ( UDL )

C ONCENTRATED LOAD

(3)

(4)

kN/ma

kN

(2)

vii) INDUSTRIAL BUILDTNGS

a) Work areas without machinery/ equipment

2.5

4.5

5’0

b) Work areas with machinery/equipments

1) Light duty 1 To be calcula2) Medium duty > ted but not 3) Heavy duty J less than

7.0 10.0

4.5 4.5 4.5

d Boiler rooms and plant rooms - to

5.0

6.7

4 Cafeterias and dining rooms

3.0t

2.7

e) Corridors, passages and staircases

4.0

4.5

5.0

4.5

3.0 2’0

4.5

be calculated but not less than

including fire escapes

f)

Corridors, passages, staircases subject to machine loads, wheeled vehicles - lo be calculated but not less than

9) Kitchens h) Toilets and bathrooms viii) STORAGE BUILDINGS /I Storage rooms ( other than cold storage ) warehouses - to be calculated based on the bulk density of materials stored but not less than

2.4 kN/m* per each metre of storage height with a minimum of 7.5 kN/ma

7.0

b) Cold storage -- to be calculated

per each kN/m2 5.0 metre of storage height w i t h a minimum of 15 kN/m*

9.0

but not less than

Corridors, passages and staircases including fire escapes --~ as per the floor serviced but not less than

4.0

4.5

d) Corridors, passages subject to loads

5.0

4.5

e) Boiler rooms and plant rooms

7.5

4.5

cl

greater than from crowds, such as wheeled vehicles, trolleys and the like

*Guide for requirements of low income housing. tWhere unrestricted assembly of persons is anticipated, the value of UDL should be increased to 4.0 kN/m*. $‘With fixed seats’ implies that the removal of the seating and the use of the space for other purposes is improbable. The maximum likely load in this case is, therefore, closely controlled. §The loading in industrial buildings ( workshops and factories ) varies considerably and SO three loadings under the terms ‘light’, ‘medium’ and ‘heavy’ are introduced in order to allow for more economical designs but the terms have no special meaning in themselves other than the imposed load for which the relevant floor is designed. It is, however, important particularly in the case of heavy weight loads, to assess the actual loads to ensure that they are not in excess of 10 kN/m*; in case where they are in excess, the design shall be based on the actual loadings. i/For various mechanical handling equipment which are used to transport goods, as in warehouses, workshops, store rooms, etc, the actual load coming from the use of such equipment shall be as-ertained and design should cater to such loads.

11

IS : 875 ( Part 2 ) - 1Yar N OTE 4 - While selecting a particular loading, the possible change in use or occupancy of the building should be kept in view. Designers should not necessarily select in every case the lower loading appropriate to the first occupancy. In doing this, they might introduce considerable restrictions in the use of the build-

ing at a later date and thereby reduce its utility.

N OTE 5 - The loads specified herein which are based on estimations, may be considered as the characteristic loads for the purpose of limit state method of design till such time statistical data are established based on load surveys to be conducted in the country. N OTE 6 - When an existing building is altered by an extension in height or area, all existing structural parts affected by the addition shall be strengthened, where necessary, and all new structural parts shall be designed to meet the requirements for building thereafter erected. N OTE 7 - The loads specified in the Code does not

include loads incidental to construction. Therefore, close supervision during construction is essential to

eusure that overloading of the building due to loads by way of stacking of building materials or use of equipment ( for example, cranes and trucks ) during construction or loads which may be induced by floor to floor propping in multi-storeyed construction. does not occur. However: if construction loads were of short duration, permissible increase in stresses in the case of working stress method or permissible decrease in load factors in limit state method, as applicable to relevant design codes, may be allowed for. N OTE 8 - The loads in Table 1 are grouped together as applicable to buildings having separate principal occupancy or use. For a building with multiple occupancies, the loads appropriate to the occupancy with comparable use shall be chosen from other occupancies. N OTE 9 -- Regarding loading on machine rooms inc!uding storage space used for repairing lift machines, designers should go by the recommendations of lift manufacturers for the present. Regarding the loading due to false ceiling the same should be considered as an imposed load on the roof/floor to which it is fixed.

3.1.1 Load Application - The uniformly distributed loads specified in Table 1 shall be applied as static loads over the entire floor area under consideration or a portion of the floor area whichever arrangement produces critical effects on the structural elements as provided in respective design codes.

weight per metre run of finished partitions, subject to a minimum of 1 kN/m2, provided total weight of partition walls per square metre of the wall area does not exceed 1.5 kN/m2 and the total weight per metre length is not greater than 4.0 kN. 3.2 Reduction in Imposed Loads on Floors 3.2.1 For Floor Supporting Structuraal Members Except as provided for in 3.2.1.1, the following reductions in assumed total imposed loads on floors may be made in designing columns, load bearing walls, piers, their supports and foundations. Number of Floors ( In&d- Reduction in Total ing the Roof) to be Carried Distributed Imposed by Member under Load on all Floors to Consideration be Carried by the Member under Consideration ( Percent ) 1 2 3 4 5 to 10 Over 10

0 10 20 30 40 50

3.2.1.1 NO reduction shall be made for any plant or machinery which is specifically allowed for, or in buildings for storage purposes, warehouses and garages. However, for other buildings where the floor is designed for an imposed floor load of 5.0 kN/m” or more, the reductions shown in 3.2.1 may be taken, provided that the loading assumed is not less than it would have been if all the floors had been designed for 5.0 kNjmZ with no reductions. N OTE -In case if the reduced load in the lower floor is lesser than the reduced load in the upper floor, then the reduced load of the upper floor will be adopted.

In the design of floors, the concentrated loads are considered to be applied in the positions which produce the maximum stresses and where deflection is the main criterion, in the positions which produce the maximum deflections Concentrated load, when used for the calculation of bending and shear are assumed to act at a point. When used for the calculation of local effects, such as crushing or punching, they are assumed to act over an actual area of application of 0.3 x 0.3 m.

3.2.1.2 An example is given in Appendix A illustrating the reduction of imposed loads in a multi-storeyed building in the design of column members. 3.2.2 For Reams in Each Floor Level - Where a single span of beam, girder or truss supports not less than 50 m2 of floor at one general level, the imposed floor load may be reduced in the design of the beams, girders or trusses by 5 percent for each 50 ma area supported subject to a maximum reduction of 25 percent. However, no reduction shall be made in any of the following types of loads:

3.1.2 Loads Due to Light Partitions - In office and other buildings where actual loads due to light partitions cannot be assessed at the time of planning, the floors and the supporting structural members shall be designed to carry, in addition to other loads, a uniformly distributed load per square metre of not less than 339 percent of

a) Any superimposed moving load, 12

IS : 875 ( Part 2 ) - 1987

b)

where it is ensured that the roof coverings would not be transversed without suitable aids. In any case, the roof coverings shall be capable of carrying the loads in accordance with 4.1,4.3, 4.4 and snow load/wind load.

Any actual load due to machinery or similar concentrated loads,

c) The additional load in respect of partition walls, and

4

Any impact or vibration.

4.3 Loads Doe to Rain - On surfaces whose positioning, shape and drainage systems are such as to make accumulation of rain water possible! loads due to such accumulation of water and the Imposed loads for the roof as given in Table 2 shall be considered separately and the more critical of the two shall be adopted in the design.

N OTE - The above reduction does not apply to beams, girders or trusses supporting roof loads. 3.3 Posting of Floor Capacities - Where a floor or part of a floor of a building has been designed to sustain a uniformly distributed load exceeding 3.0 kN/m2 and in assembly, business, mercantile, industrial or storage buildmgs, a permanent notice in the form as shown in the label, indicating the actual uniformly distributed and/or concentrated loadings for which the floor has been structurally designed shall be posted in a conspicuous place in a position adjacent to such floor or on such part of a floor.

4.4 Dust Load - Jn areas prone to settlement of dust on roofs ( example, steel plants, cement plants ), provision for dust load equivalent to probable thickness of accumulation of dust may be made. 4.5 Loads on Members Supporting Roof Coverings - Every m e m b e r o f t h e supporting structure which is directly supporting the roof covering(s) shall be designed to carry the more severe of the following loads except as provided in 4.5.1 :

DESIGNED IMPOSED FLOOR LOADING DISTRIBUTED. . . . . . . . . . . ..kN/mZ CONCENTRATED, . . . . kN

a) The load transmitted to the members from the roof covering(s) in accordance with 4.1, 4.3 and 4.4; and

L-ABEL INDICATING D ESIGNED I MPOSED F L O O R LOADING

b) An incidental concentrated load of 0.90 kN concentrated over a length of 12.5 cm placed at the most unfavourable positions on the member.

N OTE 1 - The lettering of such notice shall be embossed or cast suitably on a tablet whose least dimension shall be not less than 0’25 m and located not less than 1.5 m above floor level with lettering of a minimum size of 25 mm. N OTE 2 - If a concentrated load or a bulk load has

N OTE - Where it is ensured that the roofs would be traversed only with the aid of planks and ladders capable of distributing the loads on them to Iwo or more supporting members, the intensity of concentrated load indicated in (b) may be reduced to 0.5 kN with the approval of the Engineer-in-Charge.

to occupy a definite position on the floor, the same could also be indicated in the label above.

4.5.1 In case of sloping roofs with slope greater t h a n lo”, members supporting the roof purlins, such as trusses, beams, girders, etc, may be designed for two-thirds of the imposed load on purlins or roofing sheets.

4. IMPOSED LOADS ON ROOFS 4.1 Imposed Loads on Various Types of Roofs On flat roofs, sloping roofs and curved roofs, the imposed loads due to use or occupancy of the buildings and the geometry of the types of roofs shall be as given in Table 2.

5. IMPOSED HORIZONTAL LOADS ON PARAPETS AND BALUSTRADES 5.1 Parapets, Parapet Walls and Balustrades Parapets, parapet walls and balustrades together with the members which give them structural support shall be designed for the minimum loads given in Table 3. These are expressed as horizontal forces acting at handrail or coping level. These loads shall be considered to act vertically also but net simultaneously with the horizontal forces. The values given in Table 3 are minimum values and where values for actual loadings are available, they shall be used instead.

4.1.1 Roofs of buildings used for promenade or ir.cidental to assembly purposes shall be designed for the appropriate imposed floor loads given ih Table 1 for the occupancy. 4.2 Concentrated Load on Roof Coverings - To provide for loads Incidental to maintenance, unless otherwise, specified by the Engineer-in-Charge, all roof coverings ( other than glass or transparent sheets made of fibre glass ) shall be capable of carrying an incidental load of 0.90 kN concentrated on an area of 12.5 cm* so placed as to fireduce maximum stresses in the covering, The intensity of the concentrated load may be reduced with the approval of the Engineer-in-Charge,

5.2 Grandstands and the Like-Grandstands, stadia, assembly platforms, reviewing stands and the like shall be designed to resist a horizontal force applied to seats of 0.35 kN per linear metre 13

.

IS : 875 ( Part 2 ) - 1987 along the line of seats and O-15 kN per linear metre perpendicular to the line of the seats. These loadings need not be applied simultaneously. Platforms without seats shall be designed to resist a minimum horizontal force of O-25 kN/m’ of plan area.

factors, lateral and longitudinal braking forces acting across and along the crane rails respectively.

6. LOADING EFFECTS DUE TO IMPACT AND VIBRATION 6.0 The crane loads to be considered under imposed loads shall include the vertical loads, eccentricity effects induced by vertical loads, impact

6.1 Impact Allowance for Lifts, Hoists and Machinery - The imposed loads specified in 3.1 shall be assumed to include adequate allowance for ordinary impact conditions. However, for structures carrying loads which induce impact or vibration, as far as possible, calculations shall be made for increase in the imposed load, due to impact or vibration. In the absence of sufficient data for

TABLE 2 IMPOSED LOADS ON VARIOUS TYPES OF ROOFS ( Clause 4.1 )

T YPE OF R OOF

U NIFORMLY D ISTRIBUTED IMPOSED LOAD M EASUKED ON P LAN AREA

(2) i) Flat, sloping or curved roof with slopes up to and including 10 degrees

(3)

SL No. (1)

a) Access provided

1’5 kN/m’

b) Access not provided except for maintenance

0.75 kN/m2

M INIMUM IMPOSED L OAD M EASURED ON P LAN (4)

3.75 kN uniformly distributed over any span of one metre width of the roof slab and 9 kN uniformly distributed over the span of any beam or truss or wall 1.9 kN uniformly distributed over any span of one metre width of the roof slab and 4.5 kN uniformly distributed over ths span of any beam or truss or wall

ii) Sloping roof with slope greater than 10 degrees

For roof membrane sheets or purlins-0.75 kN/mZ l e s s 0.02 kN/m’ for every degree increase in slope over 10 degrees

Subject to 0.4 kN,W

a minimum of

iii) Curved roof with slope of line obtained by joining springing point to the crown with the horizontal, greater than 10 degrees

( O;le; 0.52 ya ) kN/m”

Subject to 0.4 kN/m*

a

minimum of

N OTE 1 - The loads given above do not include loads due to snow, rain, dust collection, etc. be designed for imposed loads given above or for snow/rain load, whichever is greater.

The roof shall

y = h/l h = the height of the highest

point of the structure measured from its springing; and I = ;hord width of the roof singly curved and shorter of the two sides if doubly curved

Alternatively, where structural analysis can be carried out for curved roofs of all slopes in a simple manner applying the laws of statistics, the curved roof shall be divided into minimum 6 equal segments and for each segment imposed load shall be calculated appropriate to the slope of the chord of each segment as given in ( i ) rind ( ii ) above

N OTE 2 - For special types of roofs with highly permeable and absorbent material, the contingency of roof material increasing in weight due to absorption of moisture shall be provided for.

14

IS : 875 ( Part 2 ) - 1987 TABLE 3 HORIZONTAL LOADS ON PARAPETS, PARAPET WALLS AND BALUSTRADES ( Cfause 5.1 ) U SAGE A R E A

SL No.

INTENSITY OF HORIZONTAL LOAD, kN/m RUN

(2)

(3)

Light access stairs-gangways and the like not

0.25

ii)

Light access stairs. gangways and the like, more than 600 mm wide: stairways, landings, balconies and parapet walls ( private and part of dwellings )

0.35

iii)

All other stairways, landings and balconies, and all parapets and handrails to roofs except those subject to overcrowding covered under ( iv )

0.75

iv)

Parapets and balustrades in place of assembly, such as theatres, cinemas, churches, schools, places of entertainment. sports, buildings likely to be overcrowded

2’25

more than 600

mm

wide

NOTE - In the case of guard parapets on a floor of multi-storeyed car park or crash barriers provided in certain buildings for fire escape, the value of imposed horizontal load ( together with impact load ) may be determined.

6.2 Concentrated Imoosed Loads with Imuact and Vibration - Concentrated imposed loads with impact and vibration which may be due to installed machinery shall be considered and provided for in the design. The impact factor shall not be less than 20 percent which is the amount allowable for light machinery.

such calculation, the increase in the imposed loads shall be as follows: Structures

For frames supporting lifts

and hoists For foundations, footings and piers supporting lifts and hoisting apparatus For supporting structures and foundations for light machinery, shaft or motor units For supporting structures and foundations for reciprocating machinery or power units

Impact Allowance Min 100 percen 40 percent

6.2.1 Provision shall also be made for carrying any concentrated equipment loads whiIe the equipment is being installed or moved for servicmg and repairing.

20 percent

50 percent

6.3 Impact Allowances for Crane Girders - For crane gantry girders and supporting columns, the following allowances shall be deemed to cover all forces set up by vibration, shock from slipping or slings, kinetic action of acceleration, and retardation and impact of wheel loads :

Type of Load

Additional Load

a) Vertical loads for electric overhead cranes

25 percent of maximum static loads for crane girders for all classes of cranes 25 percent for columns supporting Class IJI and Class IV cranes 10 percent for columns supporting Class I and Class II cranes No additional load for design of foundations 10 percent of maximum wheel loads for crane girders only

b) Vertical loads for hand operated cranes

(Continued) 15

IS : 813 ( rart L ) - 1Y17 c) Horizontal forces transverse to rails:

1) For electric overhead cranes with trolley having rigid mast for suspension of lifted weight ( such as soaker crane, stripper crane, etc )

-10 percent of weight of crab and the weight lifted by the cranes, acting on any one crane track rail. acting in either direction and equally distributed amongst all the wheels on one side of rail track For frame analysis this force shall be applied on one side of the frame at a time in either direction -5 percent of weight of crab and the weight

2) For all other electric overhead cranes and hand operated cranes

lifted by the cranes, acting on anyone crane track rail, acting in either direction and equally distributed amongst the wheels on one side of rail track For the frame analysis, this force shall be applied on one side of the frame at a time in either direction -5 percent of all static wheel loads

d) Horizontal traction forces along the rails for overhead cranes, either electrically operated or hand operated

accommodated on the span but without taking into account overloading according to 6.3( a ) to give the maximum effect.

Forces specified in ( c ) and ( d ) shall be considered as acting at the rail level and being appropriately transmitted to the supporting system. Gantry girders and their vertical supports shall be designed on the assumption that either of the horizontal forces in ( c ) and ( d ) may act at the same time as the vertical load.

6.4.2 Lateral Surge - For design of columns and foundations, supporting crane girders, the following crane combinations shall be considered:

NOTE-&e IS : 807-l!%+ for classification ( ClaSSeS 1 to 4 ) of cranes. 6.3.1 Overloading Factors in Crane Supporting Sttu twes - For all ladle cranes and charging

cranes, where there is possibility of overloading from production considerations, an overloading factor of 10 percent of the maximum wheel loading shall be taken. 6.4 Crane Load Combinations - In the absence of any specific indications, the load combinations shall be as indicated in the following sub-clauses.

b)

For single-bay frames - Effect of one crane in the bay giving the worst effect shall be considered for calculation of surge force, and

b)

For multi-bay frames - Effect of two cranes working one each in any of two bays in the cross-section to give the worst effect shall be considered I‘or calculation of surge force.

6.4.3 Tractive Force 6.4.3.1 Where one crane is in operation with no provision for future crane, tractive force from only one crane shall be taken

6.4.1 Vertical Loads - In an aisle, where more than one crane is in operation or has provision for more than one crane in future, the following load combinations shall be taken for vertical loading:

a)

a)

6.4.3.2 Where more than one crane is in operation or there is provision for future crane, tractive force from two cranes giving maximum effect shall be considered.

Two adjacent cranes working in tandem w i t h f u l l l o a d a n d w i t h overloadmg according to 6.3( a ); and

N OTE - Lateral surge force and longitudinal tractive force actingacross and along the crane rail respectively, shall not be assumed to act simultaneously. However, if there is only one crane in the bay, the lateral and longitudinal forces may act together simultaneously with vertical loads.

For long span gantries, where more than one crane can come in the span, the girder shall be designed for or.e crane fully loaded with overloading according to 6.3(a) plus as many loaded cranes as can be

7. OTHER LOADS

-

7.1 Dead Load - Dead load includes the weight of all permanent components of a building including walls,partitions, columns, floors, roofs, finishes

*Code of practice for design, manufacture, erection and testing ( structural portion ) of cranes and hoists (first revision ).

16

IS:875(Part2)-1987 and fixed permanent equipment and fittings that are an integral part of the structure. Unit weight of building materials shall be in accordance with IS : 875 ( Part 1 )-1988:

7.4 Snow Load - Snow loading on buildings shall be in accordance with IS : 875 ( Part 4 )-I 988.

7.2 Wind Load -- The wind load on buildings/ structures shall be in accordance with IS : S75 ( Part 3 )-1988.

7.1 Special Loads and Load CombinationsSpecial loads and load combinations shall be i n accordance with 1s : 875 ( Part 5 )-1988.

7.3 Seismic I;;;;t dfeismic load on buildings/ , in structures accordance with

( fc;ur/h revision ).

IS : 1893-1984*.

*Criteria for eartnquake resistant design of structures

APPENDIX

A

( Clause 3.2.1.2 ) ILLUSTRATIVE EXAMPLE SMOWING REDUCTION OF UNIFORMLY DISTRIBUTED IMPOSED FLOOR LOADS IN MULTI-STOREYED BUII,DINGS FOR DESIGN OF COLUMNS A-l. ‘I he total imposed loads from different floor levels ( including the roof) coming on the central column of a multi-storeved building ( with mixed occupancy ) is shown in Fig. I. Calculate the reduced imposed load for the design of column members at different floor levels as given in 3.2.1.

Floor loads do.not exceed 5-O kN/m’. A-l.1 Applying reduction coefficients in accordance with 3.2.1, total reduced floor loads on the column at different levels is indicated along with Fig. 1.

17

IS:875(Part2)-1987 Floor No. from Top ;zfd;ng

Actual Floor Load Coming on Columns at Different Floors, kN Loads for which Columns are to be Designed, kN

( 30 + 40 t- 50 ) (1 - 0.2 ) = 96

(30$4O$50$50)(1-Oo’3)=119

( 3F2Z- 4O + 50 + 50 t 40 ) ( 1 - 0 4 ) =

(3~~50+50+50+40+45)(1-o~4)

( 30 + 40 + 50 + 50 c 40 + 45 + 50 ) ( l - 0 . 4 ) = 183 ( 30 + 40 + 50 + 50 + 40 f 45 + 50 t so) ( i -- 0.4) = 213 ( 30 + 40 $- 50 + 50 + 40 + 45 + 50 + 50 + 40 ) ( 1 - 0.4 ) = 237 ( 30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 + 40 -+ 40 ) ( 1 - 0.4:) = 261 (30+40+5O+50+40+45+50+50 +40+40+40)(1-O.5)=237’5< 261 :. adopt 261 for design (30+40+50+50+40+45+50+50 -t40+40+40+55) ( l - 0 5 ) = 2 6 5 ( 30 + 40 + 50 + 50 + 40 + 45 + 50 + 50 H02-y0+40+55+55)(1-O~5) ( 30 + 40 + 50 t 50 + 40 + 45 I- 50 t 50 -I- 40 + 40 + 40 + 55 + 55 + 70 ) ( 1 -05 ) = 327.5 ( 30 + 40 + 50 t 50 + 40 + 45 + 50 + 50 +40+40-t-40+55+55+70+80) ( 1 - 0.5 ) - 367’5

F:G. 1 LOADING D E T A I L S 18

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Printograpb, New Delhi, Ph

: 5726837

IS:875

(Part

3) - 1987

( Renfficd

1997 )

Indian Standard

CODEOFPRACTICEFORDESIGNLOADS (OTHERTHANEARTHQUAKE) FORBUILDINGSANDSTRUCTURES PART 3

WIND COADS

( Second Revision / Sixth Reprint NOVEMBER 1998 UDC

624-042-41

@J Copyright 1989

BUREAU MANAK

Gr I4

OF BHAVAN,

INDIAN

STANDARDS

9 BAHADUR SHAH NEW DELHI 110002

ZAFAR

MARG

Febfuafy 1989

IS : 875 ( Part

CONTENTS Page 0.

1.

FOREWORD SCOPE

... ...

.. . ...

... ...

2.

NOTATIONS

.. .

.. .

.. .

5

3 5

3.

TERMINOLOGY

...

6

4.

GENERAL

...

.. .

7

5.

WIND SPEEDAND PRESSURE

.. .

.. .

7

5.1

Nature of Wind in Atmosphere

.. .

...

7

5.2

Basic Wind Speed

...

. ..

5.3

Design Wind Speed ( V, )

...

.. .

...

8

...

...

8

5.3.1

Risk Coefficient ( kr Factor )

.. .

...

8

53.2

Terrain, Height and Structure Size Factor ( kt Factor )

...

8

5.3.3 Topography

( kS Factor )

...

Design Wind Pressure

.. .

5.5

Off-Shore Wind Velocity

.. .

6.

WIND PRESSURES ANDFORCESON BUILDXNCSISTRUCTURES

6.1

General

6.2 Pressure Coefficients 6.2.1 Wind Load on Individual 6.2.2

Members

External Pressure Coefficients

6.2.3 Internal Pressure Coefficients 6.3 Force Coefficients 6.3.1 Frictional Drag 6.3.2 Force Coefficients for Clad Buildings 6.3.3 Force Coefficients for Unclad Buildings 7.

DYNAMICEP~ECTS

7.1 7.2

General Motion Due to Vortex Shedding

7.2.1

4.

12

. . .

12

. . .

13

1..

13

.. . ,..

... ...

. ..

.. .

.. .. .

. . ...

.. . ._. __.

... .. . .. .

... 1..

.. . .. . .. .

.

.

.

13

.

.

.

13

.

.

.

13

.

.

.

13

.

.

.

.

.

.

.

.

.

Application Hourly Mean Wind Variation

.. .

.. .

Along Wind Load

...

...

37

. .

38

.

.

47

. .

.

.

.

.

... .. . of Hourly Me‘an Wind Speed with Height

27 36 37

,..

.

.

... . . Gust Factor ( GF ) or Gust Effectiveness Factor ( GEF] Method . . .

8.2 8.3

...

Slender Structures

8.1 8.2.1

.-.

...

...

.m.

. ..

5.4

.

.

47 48 48 49 49

... ... ...

49 49

..

49

l

APPENDIK A BASICWIND SPEEDAT 10 m HEIGHTFOR SOME IMPORTANT .. . ... ... .. . ... Crrrxs/TowNs . .. .. . APPENDIX B CHANGESIN TERRAIN CATEGORIES i..

53 54

APPENDIX C EFFECT OF A CLIFF OR ESCARPMENTON EQUIVALENT 55 ... ... HEIGHT ABOVE GROUND( k3 FACTOR) APPENDIX D WIND FORCEON CIRCULARSECTIONS. . .

.. .

. ..

57

3 ) - 1987

As in the Original Standard, this Page is Intentionally Left Blank

IS t 875 ( Part 3 ) - 1987

Indian Standard

CODEOFPRACTICEFORDESIGNLOADS (OTHERTHANEARTHQUAKE) FORBUILDINGSANDSTRUCTURES PART

(

3

WIND

LOADS

Second Revision) 6). FOREWORD

0.1 This Indian Standard ( Part 3 ) ( Second Revision ) was adopted by the Bureau of Indian Standards on 13 November 1987, after the draft finalized by the Structural Safety Sectional Committee had been approved by the Civil Engineering Division Council.

sheeted modified; ( separate system of

roofs, both curved and seismic load provisions code having been prepared weights and measurements

sloping were were deleted ) and metric was adopted.

0.3.1 With the increased adoption of this Code, a number of comments were received on provisions on live load values adopted for. different occupancies. Simultaneously, live load surveys have been carried out in America and Canada to arrive at realistic live loads based on actual determination of loading ( movable and immovable ) in different occupancies. Keeping this in view and other developments in the field of wind engineering, the Structural Safety Sectional Committee decided to prepare the second revision of IS : 875 in the following five parts:

0.2 A building has to perform many functions satisfactorily. Amongst these functions are the utility of the building for the intended use and occupancy, structural safety, fire safety and compliance with hygienic, sanitation, ventilation and daylight standards. The design of the building is dependent upon the minimum requirements prescribed for each of the above functions. The minimum requirements pertaining to the structural safety of buildings are being covered in loading codes by way of laying down minimum design loads which have to be assumed for dead loads, imposed loads, wind loads and other external loads, the structure would be required to bear. Strict conformity to loading standards, it is. hoped, will not only ensure the structural safety of the buildings and structures which are being designed and constructed in the country and thereby reduce the hazards to life and property caused by unsafe structures, but also eliminate the wastage caused by assuming unnecessarily heavy loadings without proper assessment.

Part 1 Dead loads Part 2 Imposed loads Part 3 Wind loads Part 4 Snow loads Part 5 Special loads and load combinations Earthquake load is covered in a separate standard, namely, IS : 1893-1984* which should be considered along with the above loads.

0.3 This standard was first published in 1957 for the guidance of civil engineers, designers and architects associated with the planning and design of buildings. It included the provisions for the basic design loads ( dead loads, live loads, wind loads and seismic loads ) to be assumed in the design of the buildings. In its first revision in 1964, the wind pressure provisions were modified on the basis of studies of wind phenomenon and its effect on structures, undertaken by the special committee in consultation with the Indian Meteorological Department. In addition to this, new clauses on wind loads for butterfly type structures were included; wind pressure coefficients for

0.3.2 This Part ( Part 3 ) deals with wind loads to be considered when designing buildings, structures and components thereof. In this revision, the following important modifications have been made from those covered in the 1964 version of IS : 875: a) The earlier wind pressure maps ( one giving winds of shorter duration and another excluding winds of shorter duration ) *Criteria for earthquake (fourlh recision ).

3

resistant

design of structures

IS : 875 ( Part 3 ) - 1987 have been replaced by a single wind map giving basic maximum wind speed in m/s ( peak gust velocity averaged over a short time interval of about 3 seconds duration ). The wind speeds have been worked out for 50 years return period based on the upto-date wind data of 43 dines pressure tube ( DPT ) anemograph stations and study of other related works available on the subject since 1964. The map and related recommendations have been provided in the code with the active cooperation of Indian Meteorological Department ( IMD ). Isotachs ( lines of equal velocity ) have not been given as in the opinion of the committee, there is still not enough extensive meteorological data at close enough stations in the country to justify drawing of isotachs.

b)

Modification factors to modify the basic wind velocity to take into account the effects of terrain, local topography, size of structure, etc, are included.

4

Terrain is now classified into four categories based on characteristics of the ground surface irregularities.

d)

Force and pressure coefficients have been included for a large range of clad and unclad buildings and for individual structural elements.

4

meteorological wind data and response of structures to wind, felt the paucity of data on which to base wind maps for Indian conditions on statistical analysis. The Committee, therefore, recommall individuals and organizations ends to responsible for putting-up of tall structures to ,provide instrumentation in. their existing and new structures ( transmission towers, chimneys, cooling towers, buildings, etc ) at different elevations ( at least at two levels ) to continuously measure and monitor wind data. The instruments are required to collect data on wind direction, wind speed and structural response of the structure due to wind ( with the help of accelerometer, strain gauges, etc ). It is also the opinion of the committee that such instrumentation in tall structures will not in any way affect or alter the functional behaviour of such structures. The data so collected will be very valuable in evolving more accurate wind loading of structures. 0.4 The Sectional Committee responsible for the preparation of this standard has taken into account the prevailing practice in regard to loading standards followed in this country by the various authorities and has also taken note of the developments in a number of other countries. In the preparation of this code, the following overseas standards have also been examined: a) BSCP 3 : 1973 Code of basic data for design of buildings: Chapter V Loading, Part 2 Wind loads.

Force coefficients ( drag coefficients ) are given for frames, lattice towers, walls and hoardings.

b) AS 1170, Part 2-1983 SAA Part 2 - Wind forces.

f 1 The calculation of force on circular sections is included incorporating the effects of Reynolds number and surface roughness. g)

Pressure coefficients are given for combined roofs, roofs with sky light, circular siIos, cylindrical elevated structures, grandstands, etc.

3

Some requirements regarding study of dynamic effects in flexible slender structures are included.

for for

d) ANSI A58.1-1972 American Standard Building code requirements for minimum design loads in buildings and other structures. e) Wind resistant design regulations, A World List. Association for Science Documents Information, Tokyo. 0.5 For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS : 2-1960*. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard.

W Use

of gust energy method to arrive at the design wind load on the whole structure is now permitted.

0.3.3 The Committee responsible revision of wind maps while reviewing

code

c) NZS 4203-1976 Code of practice general structural design loading buildings.

The external and internal pressure coefficients for gable roofs, lean-to roofs, curved roofs, canopy roofs ( butterfly type structures ) and multi-span roofs have been rationalised.

h)

Loading

for the available

*Rules for roundingoff numerical values ( rcoiscd). 4

IS : 875 ( Part 3 ) - 1987 1. SCOPE

IS : 802 ( Part 1 )-I977 Code of practice for use of structural steel in overhead transmission line towers: Part 1 Loads and permissible stresses ( smmd revision )

1.1 This standard gives wind forces and their effects ( static and dynamic ) that should he taken into account when designing buildings, structures and components thereof. 1.1.1 It is believed that ultimately wind load estimation will be made by taking into account the random variation of wind speed with time but available theoretical methods have not matured sufficiently at present for use in the code. For this season, static wind method of load estimation which implies a steady wind speed, which has proved to be satisfactory for normal, short and heavy structures, is given in 5 and 6. However, a beginning has been made to take account of the random nature of the wind speed by requiring that the along-wind or drag load on structures which are prone to wind induced oscillations, be also determined by the gust factor method ( see 8 ) and the more severe of the two estimates be taken for design.

IS : 11504-1985 Criteria for structural design of reinforced concrete natural draught cooling towers NOTE 1 - This standard does not apply to buildings or structures with unconventional shapes, unusual locations, and abnormal environmental conditions that have not been covered in this code. Special investigations are necessary in such cases to establish wind loads and their effects. Wind tunnel studies may aiso be required in such situations.

NOTE2 - In the case of tall structures unsymmetrical geometry, the designs may have checked for torsional effects due to wind pressure.

2. NOTATIONS 2.1 The following notations shall unless otherwise specified in relevant

A large majority of structures met with in practice do not however, suffer wind induced oscillations and generally do not require to be examined for the dynamic effects of wind, including use of gust factor method, Nevertheless, there are various types of structures or their components such as some tall buildings, chimneys, latticed towers, cooling towers, transmission towers, guyed masts, communication towers, long span bridges, partially or completely solid faced antenna dish, etc, which require investigation of wind induced oscillations. The use of 7 shall be made for i.dentifying and analysing such structures.

A= Ae

-

b =

=

force coefficient/drag

= -

normal force coefficient; transverse force coefficient;

c’f

-

frictional

=

CPl = d-

D

F Fa

1.1.3 In the design of special structures, such as chimneys, overhead transmission line towers, etc, specific requirements as specified in the respective codes shall be adopted in conjunction with the provisions of this code as far as they are applicable. Some of the Indian Standards available for the design of special structurers are:

h,

pressure

coefficient;

external pressure coefficient; internal pressure coefficient; depth of a structure or structural member parallel to wind stream; diameter

1

force normal

X

=

IS : 4998 ( Part 1 )-1975 Criteria for design of reinforced concrete chimneys: Part 1 Design criteria ( jirst revision ) and

coefficient;

drag coefficient;

=

Ft F' = h

IS : 5613 ( Part l/Set 1 )-I970 Code of practice for design, installation and maintenance of overhead power lines: Part 1 Lines up to and including 11 kV, Section 1 Design

breadth of a structure or structural member normal to the wind stream in the horizontal plane;

Cl

c, =

or part of

effective frontal area; an area at height z;

Cl, tit

C PB

be followed clauses:

surface area of a structure a Structure;

Ar, =

1.1.2 This code also applies to buildings or other structures during erection/construction and the same shall be considered carefully during various stages of erection/construction. In locations where the strongest winds and icing may occur simultaneously, loads on structural members, cables and ropes shall be calculated by assuming an ice covering based on climatic and local experience.

IS : 6533-1971 Code of practice for design construction of steel chimneys

with to be

normal

of cylinder;

transverse frictional height ground

to the surface;

force; force; force; of structure level;

above

height of development of a velocity profile at a distance x down wind from a change in terrain category; multiplication

factors;

multiplication

factor;

length of the member or greater zontal dimension of a building; Pd 5

mean

design wind pressure;

hori-

’

IS : 875 ( Part 3 ) - 1987

pz =

design wind pressure at height <;

Pe -

external pressure;

Pi -

internal pressure;

R,

=

reynolds

w

strouhal number;

s vb

-

regional basic wind speed; design wind velocity at height 2;

rz =

hourly mean wind speed at height c;

3

w’

-

e

s

a

-

B = +t= c-

lesser horizontal dimension of building, or a structural member;

3.1.7 Force Coeficient A non-dimensional coefficient such that the total wind force on a bbdy is the product of the force coefficient, the dynamic pressure of the incident design wind speed and the reference area over which the force is required.

a

bay width in multi-bay buildings;

NOTE - When the force is in the direction of the incident wind, the non-dimensional coefficient will be called as ‘drag coefficient’. When the force is perpendicular to the d&ection of incident wind, the ndn-dimensional coefficient will be called as ‘lift coeficient’.

distance down wind from a change in terrain category;

X=

9”

3.1.6 Element of Surface Area - The area of surface over which the pressure coefficient is taken to be constant.

number;

v, = W

3.1.5 l$+ffective Frontal Area - The projected area of the structure normal to the direction of the wind.

wind angle from a given axis; inclination of the roof to the horizontal; effective solidity ratio;

3.1.8 Ground Roughness - The nature of the earth’s surface as influenced by small scale obstructions such as trees and buildings ( as distinct from topography ) is called ground roughness.

shielding factor or shedding frequency; solidity ratio; a height or distance above the ground; and average height of the surface roughness.

3.1.9 Gust - A positive or negative departure of wind speed from its mean value, lasting for not more than, say, 2 minutes over a specified interval of time.

Peak Gust - Peak gust or peak gust speed is the wind speed associated with the maximum amplitude.

3. TERMINOLOGY 3.1 For the purpose of this code, definitions shall apply. 3.1.1 Angle of Attack -Angle tion of wind and a reference ture,

Fetch Length Fetch length is the distance measured along the wind from a boundary at which a change in the type of terrain occurs. When the changes in terrain types are encountered ( such as, the boundary of a town or city, forest, etc ), the wind profile changes in character but such changes are gradual and start at ground level, spreading or penetrating upwards with increasing fetch length.

the following

between the direcaxis of the struc-

Breadth means horizontal 3.1.2 Breudth dimension of the building measured normal to the direction of wind.

Gradient HeightGradient height is the height above the mean ground level at which the gradient wind blows as a result of balance among pressure gradient force, coriolis force and centrifugal force. For the purpose of this code, the gradient height is taken as the height above the mean ground level, above which the variation of wind speed with height need not be considered.

NOTE - Breadth and depth are dimensions measured in relation to the direction of the wind, whereas length and width are dimensions related to the plan.

3.1.3 Depth - Depth means the horizontal dimension of the building measured in the direction of the wind.

Mean Ground Level - The mean ground level is the average horizontal plane of the area enclosed by the boundaries of the structure.

3.1.4 Developed Height - Developed height is the height of upward penetration of the velocity profile in a new terrain. At large fetch lengths, such penetration reaches the gradient height, above which the wind speed may be taken to be constant. At lesser fetch lengths, a velocitv profile of a smaller height but similar to that of the fully developed profile of that terrain category has to be taken, with the additional provision that the velocity at the top of this shorter profile equals that of the unpenetrated earlier velocity profile at that height.

Pressure Coeficient - Pressure coefficient is the ratio of the difference between the pressure acting at a point on a surface and the static pressure of the incident wind to the design wind pressure, where the static and design wind pressures are determined at the height of the point considered after taking into account the geographical location, terrain conditions and shielding effect. The pressure coeSicient is also equal to [ 1 - ( VD/Pz)2], where Vv is the actual wind speed at any point

6

-..,,

._.., ___+. .__.

IS : 875 ( Part 3 ) - 1987 thunderstorms, dust storms or vigorous monsoons. A feature of the. cyclonic storms over the Indian area is that they rapidly weaken after crossing the coasts and move as depressions/lows inland. The influence of a severe storm after striking the coast does not, in general exceed about 60 kilometres, though sometimes, it may extend even up to 120 kilometres. Very short duration hurricanes of very high wind speeds called Kal Baisaki or Norwesters occur fairly frequently during summer months over North East India.

on the structure at a height corresponding to that of vz. coefficient NOTE - Positive sign of the pressure indicates pressure acting towards the surface and negative sign indicates pressure acting away from the surface.

Return Period - Return period is the number of years, ‘the reciprocal of which gives the probability of e.xtreme wind exceeding a given wind speed in any one year. Shielding E$ect - Shielding effect or shielding refers to the condition where wind has to pass along some structure(s) or structural element(s) located on the upstream wind side, before meeting the structure or structural element under consideration. A factor called ‘shielding factor’ is used to account for such effects in estimating the force on the’ shielded structures.

4.3 The wind speeds recorded at any locality are extremely variable and in addition to steady wind at any time, there are effects of gusts which may last for a few seconds. These gusts cause increase in air pressure but their effect on stability ofthe building may not be so important; often, gusts affect only part of the building and the increased local pressures may be more than balanced by a momentary reduction in the pressure elsewhere. Because of the inertia of the building, short period gusts may not cause any appreciable increase in stress in main components of the building although the walls, roof sheeting and individual cladding units ( glass panels ) and their supporting members such as purlins, sheeting rails and glazing bars may be mqre seriously affected. Gusts can also be extremely important for design of structures with high slenderness ratios.

Suction - Suction means pressure less than the atmospheric ( static ) pressure and is taken to act away from the surface. Solidity Ratio - Solidity ratio is equal to the effective area ( projected area of all the individual elements ) of a frame normal to the wind direction divided by the area enclosed by the boundary of the frame normal to the wind direction. NOTE - Solidity ratio is to be calculated vidual frames.

for indi-

4.4 The liability of a building to high wind pressures depends not only upon the geographical location and proximity of other obstructions to air flow but also upon the characteristics of the structure itself.

Y?-eerrain Category - Terrain category means the characteristics of the surface irregularities of an area which arise from natural or constructed features. The categories are numbered in increasing order of roughness.

4.5 The effect of wind on the structure as a whole is determined by the combined action of external and internal pressures acting upon it. In all cases, the calculated wind loads act normal to the surface to which they apply.

The variation of the horizontal component of the atmospheric wind speed at different heights above the mean ground level is termed as velocity profile. Velocity Profile -

4.6 The stability calculations as a whole shall be done considering the combined effect, as well as separate effects of imposed loads and wind loads on vertical surfaces, roofs and other part of the building above general roof level.

The nature of the earth’s Tokography surface as influenced the hill and valley configurations. 4. GENERAL 4.1 Wind is air in motion relative

to the surface of the earth. The primary cause of wind is traced to earth’s rotation and differences in terrestrial The radiation effects are primarily radiation. responsible for convection either upwards or downwards. The wind generally blows horizontal to the ground at high wind speeds. Since vertical components of atmospheric motion are relatively small, the term ‘wind’ denotes almost exclusively the horizontal wind, vertical winds are always identified as such. The wind speeds are assessed with the aid of anemometers or anemographs which are installed at meteorological observatories at heights generally varying from 10 to 30 metres above ground.

4.7 Buildings shall also be designed with due attention to the effects of wind on the comfort of people inside and outside the buildings. 5. WIND SPEED

AND PRESSURE

5.1 Nature of Wind in Atmosphere - In general, wind speed in the atmospheric boundary layer increases with height from zero at ground level to a maximum at a height called the gradient height. There is usually a slight change in direction ( Ekman effect ) but this is ignored in the code. The variation with height depends primarily on the terrain conditions. However, the wind speed at any height never remains constant and it has been found convenient to resolve its instantaneous magnitude into an average or mean value and a fluctuating component around this

Very strong winds ( greater than 80 km/h ) are generally associated with cyclonic storms,

4.2

7

IS : 875 ( Part 3 ) - 1987

The average value depends on average vaiue. the averaging time employed in analysing the meteorological data and this averaging time varies from a few seconds to several minutes. The magnitude of fluctuating component of the wind speed which is called gust, depends on the averaging time. In general, smaller the averaging interval, greater is the magnitude of the gust speed. 5.2 Basic Wind Speed - Figure 1 gives basic wind speed map of India, as applicable to 10 m height above mean ground level for different zones of the country. Basic wind speed is based on peak gust velocity averaged over a short time interval of about 3 seconds and corresponds to mean heights above ground level in an open terrain ( Category 2 ). Basic wind speeds presented in Fig. 1 have been worked out for a 50 year return period. Basic wind speed for some important cities/towns is also given in Appendix A., 5.3 Design Wind Speed ( V, ) - The basic wind speed ( V, ) for any site shall be obtained from Fig. 1 and shall be modified to include the following effects to get design wind velocity at any height ( V, j for the chosen structure: a) Risk level; b) Terrain roughness, height and size of structure; and c) Local topography. It can be mathematically v, =

expressed as follows:

vb kl k~ ks

where V, =

design wind speed at any height z in m/s;

probability factor ( risk coeffi. cient ) ( see 5.3.1 ); ks = terrain, height and structure size factor ( see 5.3.2 ); and

kl

=

ks = topography factor ( see 5.3.3 ). NOTE - Design wind speep up to IO m height from mean ground level shall be considered constant.

5.3.1 Risk Coej’icient ( kI Factor ) - Figure 1 gives basic wind speeds for terrain Category 2 as applicable at 10 m above ground level based on 50 years mean return period. The suggested life period to be assumed in design and the corresponding kl factors for different class of structures for the purpose of design is given in Table 1. In the design of all buildings and structures, a regional basic wind speed having a mean return period of 50 years shall be used except as specified in the note of Table 1.

5.3.2 Terrain, ( k, Factor )

Height

and

Structure

Size

Factor

5.3.2.1 Terrain - Selection of terrain categories shall be made with due regard to the effect

8

of obstructions which constitute the ground surface roughness. The terrain category used in the design of a structure may vary depending on the direction of wind under consideration. Wherever sufficient meteorological information is available about the nature of wind direction, the orientation of any building or structure may be suitably planned. Terrain in which a specific structure stands shall be assessed as being one of the following terrain categories:

4

1 - Exposed open terrain with few or no obstructions and in which the average height of any object surrounding the structure is less than 1.5 m.

Category

NOTE - This category and flat treeless plains.

b)

includes open sea-coasts

Open terrain with well scattered obstructions having heights generally between I.5 to 10 m. Category 2 -

for measureNOTE - This is the criterion ment of regional basic wind speeds and includes airfields, open parklands and undeveloped sparsely built-up outskirts of towns and suburbs. Open land adjacent to sea coast may also be classified as Category 2 due to roughness of large sea waves at high winds.

3 - Terrain with numerous closely spaced obstructions having the size of building-structures up to 10 m in height with or without a few isolated tall structures.

Cl CategoTy

NOTE 1 - This category includes well wooded areas, and shrubs, towns and industrial areas full or partially developed. NOTE 2 - It is likely that the next higher category than this will not exist in most design situations and that selection of a more severe category will be deliberate. NOTE 3 - Particular attention must be given to performance of obstructions in areas affected by fully developed tropical cyclones.Vegetation which is likely to be blown down or defoliated cannot be relied upon to maintain Category 3 conditions. Where such situation may exist, either an intermediate category with velocity multipliers midway between the values for Category 2 and 3 given in Table 2, or Category 2 should be selected having due regard to local conditions.

d) Category 4 - Terrain with numerous large high closely spaced obstructions. NOTE - This category includes large city centres, generally with obstructions above 25 m and well developed industrial complexes.

5.3.2.2 Variation of wind speed with height for di@erent sizes of structures in different terrains ( k, factor ) - Table 2 gives multiplying factors ( lir )

by which the basic wind speed given in Fig. 1 shall be multiplied to obtain the wind speed at different heights, in each terrain category for different sizes of buildings/structures.

As in the Original Standard, this Page is Intentionally Left Blank

IS : 875 ( Part 3 ) - 1387 The buildings/structures are classified into the following three different classes depending upon their size:

ponents such as claddinp, glazing, roofing, etc, having maximum dimension’ ( greatest horizontal or vertical dimension ) between 20 and 50 m.

Class A - Structures and/or their components such as cladding, glaxing, roofing, etc, having maximum dimension ( greatest horizontal or vertical dimension ) less than 20 m.

Class B -

Structures

TABLE

CLASS

OF

1

and/or

RISK

their

COEF’FICIENTS.FOR DIFFERENT

c1a.U C - Structures and/or their components such as cladding, glazing, roofing, etc, having maximum dimension ( greatest horizontal or vertical dimension ) greater than 50 m.

com-

DIFFERENT WIND SPEED ( Clause 5.3.1 )

PROBABLE DESIGN LIFE OF STRUCTURE IN YEARS

STRUCTWZE

CLASSES ZONES

OF STRUCTURES

IN

FACTOR BOB BASIC WIND SPEED (m/s ) 0~ ---_--__7 r-------33 39 44 47 50 55

MEAN

k,

All general buildings and structures

50

1’0

1.0

1’0

1.0

1’0

Temporary sheds, structures such as those used during construction operations ( for example, formwork and falsework ), structures during construction stages and boundary walls

5

0.82

0.76

0.73

0’71

0.70

0’67

25

0.94

0.92

0.91

0.90

0’90

0’89

100

1’05

I ‘06

1’0’:

1’07

I ‘08

1.08

Buildings and structures a low degree of hazard property in the event such as isolated towers areas, farm buildings residential buildings

presenting to life and of failure, in wooded other than

Important buildings and structures such as hospitals communication buildings / towers, power plant structures

-1.0

NOTE The factor kt is based on statistical concepts which take account of the degree of reliability required and period of time in years during which these will be exposure to wind, that is, life of the structure. Whatever wind speed is adopted for design purposes, there is always a probability ( however small ) that it may be exceeded in a storm of exceptional violence; the greater the period of years over which these will be exposure to the wind, the greater is the probability. Higher return periods ranging from 100 to 1 000 years ( implying lower risk level ) in association with greater periods of exposure may have to be selected for exceptionally important structures, such Equation given below may be used in such cases as, nuclear power reactors and satellite communication towers. to estimate k, factors for different periods of exposure and chosen probability of exceedance ( risk level ). The probability level of 0’63 is normally considered sufficient for design of buildings and structures against wind effects and the values of k, corresponding to this risk level are given above.

XN,

kl =

P

x5O, 0.63

*-L+*{-+ql-P$J z----

A + 4B

where N = mean probable design life of structure in years; PN -

risk level in N consecutive years ( probability N successive years ), nominal value = 0’63;

that the design wind speed

X N,P = extreme wind speed for given values of Nand x5O, 0’63

=

is exceeded

PN; and

extreme wind speed for N = 50 years and PN = 0’63.

A and B are coefficients having the following

values for different basic wind speed zones:

Zone

A

33 m/s

83’2

9’2

39 m/s

84’0

14’0

44 m/s 47 m/s

88,O

18’0

88.0

20’5

50 m/s

88’8

22’8

55 m/s

90.8

27.3

11

B

at least once in

LL.

._ ._

_

_

.-. .-

IS : 875 ( Part 3 ) - 1987 WITH HEIGHT TABLE 2 k, FACTORS TO OBTAIN DESIGN WIND SPEED VARIATION DIFFERENT TERRAINS FOR DIFFERENT CLASSES OF BUILDINGS/STRUCTURES

IN

( ClaUJC 5.3.2.2 ) HEIGHT m

TEBRAIN CATEQORY 1 CLASS I---_*--1 A B c

TERRAIN CATEC+ORY 2 CLbSS r---_h-_--~ c A B

(5) 1’03 1’07 1.10 1’13 1’18

(4) 0.99 1’03 1’06 1’09 1’14

(5) 1’00 1’05 1.07 1’12 1’17

(6) 0.98 1’02 1’05 1’10 1’15

(7) 0.93 0.97

:o” 30 50

(2) 1’05 1.09 1’12 1’15 1-20

100 150 200 250 300

1’26 1’30 1’32 1’34 1’35

1’24 1.28 1’30 1’32 1’34

1’20 1’24 1’26 1’28 1’30

1’24 1’28 1’30 1’32 1.34

1’22 1.25 1’28 1’31 1 32

1.17 1.21 1’24 1’26 1.28

350 400 459 500

1’37 1’38 1’39 1’40

1’35 1’36 1’37 1.38

1’31 1.32 1’33 1’34

1’36 1’37 1’38 1’39

1’34 1’35 1’36 1’37

1’29 1’30 1’31 1’32

(1) IO

NOTE 1 -

::z 1’10

TEP.BAIN CATECJORP 4 CLASS t-_-*---~ c B A

TEERAIN CATEQO~Y 3 CLASS c--_-~--_-~ A c B

(11) 0.80 0.80 0.80 O’Y7 1’10

(12)

:%* 1’09

(10) 0’82 0’87 0’91 0’96 1.02

0.76 0’76 0’76 0’93 1’05

(131 0’67 0.67 0’67 0’83 0’95

x

1’17 1’21 1.24 1’26 1.28

1’10 1’15 1’18 1’20 1’22

1’20 1’24 1’27 1’28 1’30

1’15 1’20 1’22 1.24 1’26

1’05 1.10 1’13 1’16 I.17

1’32 1’34 1’35 1~36

1’30 1’31 1’32 1’33

1’24 1.25 1’26 1.28

1.31 1.32 1.33 1’34

1.27 1.28 1’29 1.30

1’19 1’20 1’21 1’22

(8) 0’91 0’97 1’01 1’06 1’12

(9) 0’88 0%

1’20 1’24 1’27

Se6 5.3.2.2 for definitions of Class A, Class B and Class C structures.

NOTE 2 - Intermediate values may be obtained by linear interpolation, if desired, It is permissible to assume constant wind speed between 2 heights for simplicity.

5.3.2.3 Terrain categories in relation to the direccategory used in the tion of wind - The terrain design of a structure may vary depending on the direction of wind under consideration. Where sufficient meteorological information is available, the basic wind speed may be varied for specific wind direcion.

TABLE

(1) 0’2

a) Fetch and develobed height relationship - The relation between the developed height (h,) and the fetch (x) for wind-flow over each of the four terrain categories may be taken as given in Table 3. b) For structures of heights greater than the developed height (h,) in Table 3, the may be determined in velocity profile accordance with the following: i) The

les3 or least rough

ii) The method

described

terrain,

HEIGHT

(2) 12

(3) 20

(4) 35

(5) 60

0’5

20

30

35

9.5

1

25

45

80

130

2

35

65

110

190

5

60

100

170

300

10

80

140

25C

450

20

120

200

350

500

50

180

300

400

500

5.3.3.1 The effect of topography will be significzt at a site when the upwind slope (6) is greater than about 3”, and below that, the value of ks may be taken to be equal to 1-O. The value of ks is confined in the range of 1-O to 1.36 for slopes greater than 3”. A method of evaluating the value of ks for values greater than 1.0 is given in Appendix C. It may be noted that the value of ks varies with height above ground level, at a maximum near the ground, and reducing to 1.0 at higher levels.

or

in Appendix

FETCH AND DEVELOPED RELATIONSHIP ( C1UUS6 5.3.2.4 )

DEVELOPEDHEIGHT, hx IN METRES (x) ,--__--h_ ----y Terrain Terrain Terrain Terrain Category 1 Category 2 Category 3 Category 4

FE?:

5.3.2.4 Changes in terrain categories - The velocity profile for a given terrain category does not develop to full height immediately with the commencement of that terrain category but develop gradually to height ( h, ) which increases with the fetch or upwind distance (x).

3

B.

5.3.3 Tojography ( ks Factor ) - The basic wind speed Vb given in Fig. 1 takes account of the general level of site above sea level. This does not allow for local topographic features such as hills, valleys, cliffs, escarpments, or ridges which can significantly affect wind speed in their vicinity. The effect of topography is to accelerate wind near the summits of hills or crests‘of cliffs, escarpments or ridges and decelerate the wind in valleys or near the foot of cli%, steep escarpments, or ridges.

5.4 Design Wind Pressure - The design wind pressure at any height above mean ground level shall be obtained by the following relationship between wind pressure and wind velocity: pz = 0.6 12

r-i

IS : 875 ( Part 3 ) - 1987 where

NOTE 1 - The coefficients given ’ different tables have k!ey?%tained mainly from me; gurements on models in wind- tunnels, ahd the great majority C.of data available has been obtained in conditions of ielatively smooth flow. Where sufficient field data exists as in the case of rectangular buildings, values have been obtained to allow for turbulent flow.

pz = design wind pressure in N/ms at height z, and v, -

design wind velocity height 2.

in m/s at

NOTE 2 - In recent years, wall glazing and cladding design has been a source of major concern. Although of less consequence than the collapse of main structures. damage to glass can be hazardous and cause considerable financial losses.

NOTE - The coefficient 0’6 (in SI units ) in the above formula depends on a number of factors aod mainly on the atmospheric pressure and air temperature. The value chosen corresponds to the average appropriate Indian atmospheric conditions.

NOTE 3 - For pressure coefficients for structures not covered here, reference may be made to specialist literature on the subject or advise may be sought from specialists in the subject.

5.5 Off Shore Wind Velocity - Cyclonic storms form far away from the sea coast and gradually reduce in speed as they approach the sea coast. Cyclonic storms generally extend up to about 60 kilometres inland after striking the coast. Their effect on land is already reflected in basic wind speeds specified in Fig. 1. The influence of wind speed off the coast up to a distance of about 200 kilometres may be taken as 1.15 times the value on the nearest coast in the absence of any definite wind data. 6. WIND PRESSURES AND BUILDINGS/STRUCTURES 6.1 General - The wind shall be calculated for:

FORCES

load on

6.2.1 Wind Load on Individual Members - When calculating the wind load on individual strcutural elements such as roofs and walls, and individual cladding units and their fittings, it is essential to take account of the pressure difference between opposite faces of such elements or units. For clad structures, it is, therefore, necessary to know the internal pressure as well as the external pressure. Then the wind load, F, acting in a direction normal to the individual structural element or cladding unit is:

ON

a building

F=(G~---C~~)AP~ where

a) The building as a whole,

c De = external pressure coefficient, c Di = internal pressure- coefficient, A = surface area of structural or cladding unit, and

b) Individual structural elements as roofs and walls, and c) Individual cladding units including glazing and their fixings.

element

Pd = design wind pressure.

pressure 6.2 Pressure Coefficients - The coefficients are always given for a particular surface or part of the surface of a building. The wind load acting normal to a surface is obtained by multiplying the area of that surface or its appropriate portion by the pressure coefficient (C,) and the design wind pressure at the height of the surface from the ground. The average values of these pressure coefficients for some building shapes are given in 6.2.2 and 6.2.3.

NOTE 1 - If the surface design pressure varies with height, the surface areas of the structural element may be sub-divided so that the specified pressures are taken over appropriate areas. NOTE 2 - Positive wind acting towards the structural away from it.

6.2.2

load indicates the force element and negative

External Pressure Coeficients

6.2.2.1 Walls - The average external pressure coefficient for the walls of clad buildings of rectangular plan shall be as given in Table 4. In addition, local pressure concentration coefficients are also given.

Average values of pressure coefficients are given for critical wind directions in one or more quadrants. In order to determine the maximum wind load on the building, the total load should be calculated for each of the critical directions shown from all quadrants. Where considerable variation of pressure occurs over a surface, it has been subdivided atid mean pressure coefficients given for each of its several parts.

6.2.2.2 Pitched rbofs of rectangular clad buildThe average external pressure coefficients and pressure concentration coeecients for pitched roofs of rectangular clad building shall be as given in Table 5. Where no pressure concentration coefficients are given, the average coefficients shall apply. The pressure coefficients on the under side of any overhanging roof shall be taken in accordance with 6.2.2.7. ings -

areas of high local suction In addition, ( negative pressure concentration ) frequently occurring near the edges of walls and roofs are separately shown. Coefficients for the local effects should only be used for calculation of forces on these local areas affecting roof sheeting, glass panels, individual cladding units including their fixtures. They should not be used for calculating force on entire structural elements such as roof, walls or structure as a whole.

NOTE 1 - The pressure concentration shall be assumed to act outward ( suction pressure ) at the ridges, eaves, cornices and 90 degree corners of roofs ( see 6.2.2.7 ). NOTE 2 - The pressure concentration shall not be included with the net external pressure when computing overall loads.

13

km.“_._.

_____.__...

_...~._

IS : 875 ( Part 3 ) - 1987 TABLE

4

EXTERNAL

PRESSURE

COEFFICIENTS ( Cpe ) FOR WALLS CLAD BUILDINGS

OF RECTANGULAR

( clause 6.2.2.1 )

-

BUILDING PLAN RATIO

BUILDINU HEIGHT RATIO

ELEVATION

WIND ANGLE 0

PLAN

_-

-

-

+<+

c

7 81 -i

0

+0.7

30

-0.5

D

1 I

-.El

e&5 A

0

I<‘<; w

-iI_Cl ‘/ I

w2

-0’5

-0’5

-0’5

I

i-0.7

-0’2

,’

c -0’8

I

cl?-*

0

-

+0.7

-0.25

-0.6

-06

1

30

-0’5

-0.5

+0.7

-0’1

:

--

--

--

-i_

+0.7

-0’2

-0’6

-0.6

90

-0’6

-0’6

+0*7

-0’2 5j

_j.

u

-1.0

.-

0

I!

-0.2

0

0

--

Cpe

I

-I-

.C

3 g<;<4

.-

--

--

a

/ LOCAL

D

B

A

--

degrees

A

’

Cpe FOR SURFACE

-

I3

I

I

-l > -1'1

J

--

C

$.<.$<4

0

ec?&

0

90

D

+0*7

- 0.3

-0’5

-0.5

-0’7

-0.7

+0.7

-0.1

-_

--

_-

-I } -1’1 J

-_

C

l<;C+

b -

A

Cl 0

0

90

+ 0.8

--02

-0.8

-0%

-0’8

-0.8

+0’8

-02

7 15

> - 1’2

J

D

3 z_< h<6 w

.-

-C

p,+

ti*

1 e

0

l-o.7

-0’4

-0’7

-0’7

-I

90

-0’5

-0’5

+0’8

-0’1

J

} - 1.2

0

( Continued )

14

l!3:875(Part3)-1987 TABLE

4

I -aw

COEFFICIENTS ( Cpe ) FOR WALLS CLAD BUILDINGS - Contd PLAN

ELEVATION

BUILDING PLAN RATIO

BUILDING HEIGHT RATIO

PRESSURE

EXTERNAL

WIND ANGLE 8

0

3 2

90

OF RECTANGULAR

LOCAL cpe

Cpe FOR SUX~FACE

I C

D

-1’85

-0’9

-0’9

-I ) -1’25

-0’8

-0’8

+0’9

-0’85

J

+0’95

-1.25.

-0.7

A

B

+0’951

pggg?z

C

0 I3

A

h is the height to caves or parapet, dimension of a building.

NOTE -

horizontal

1 is the greater

6.2.2.3 Monoslope roofs of rectangular clad buildThe average pressure coefficient and pressure concentration coefficient for monoslope ( lean-to ) roofs of rectangular clad buildings shall be as given in Table 6. ings -

6.2.2.4 I<

&<3

Canoby roofs with

>

-

The

1

and

pressure coefficients

are

(

$4:

Q

given in Tables 7 and 8 separately for monopitch and double pitch canopy roofs such as open-air parking garages, shelter areas, outdoor areas, railway platforms, stadiums and theatres. The coefficients take account of the combined effect of the wind exerted on and under the roof for all wind directions; the resultant is to be taken normal to the canopy. Where the local coefficients overlap, the greater of the two given values should be taken. However, the effect of partial closures of one side and or both sides, such as those due to trains, buses and stored materials shall be foreseen and taken into account.

90

horizontal

dimension

of a building

and w IS the

lesser

to the wind direction. 4 = 0 represents a canopy with no obstructions underneath. $ - 1 represents the canopy fully blocked with contents to the downwind eaves. Values of C, for intermediate solidities may be linearly interpolated between these two extremes, and apply upwind of the position of maximum blockage only. Downwind of the position of maximum blockage the coefficients for 4 = 0 may be used. In addition to the pressure forces normal to the canopy, there will be horizontal loads on the canopy due to the wind pressure on any fascia and to friction over the surface of the canopy. For any wind direction, only the greater of these two forces need be taken into account. Fascia loads should be calculated on the area of the surface facing the wind, using a force coefficient of l-3. Frictional drag should be calculated using the coefficients given in 6.3.1. NOYE -

Tables

9 to 14 may be

used

to get internal

and external pressure coefficients for pitches and troughed free roofs for some specific cases for which aspect ratios and roof slopes have been specified. However,

The solidity ratio 4 is equal to the area of obstructions under the canopy divided by the gross area under the canopy, both areas normal

while using Tables 9 to 14 any significant departure from it should be investigated carefully. No increase shall be made for local effects except as indicated.

15

TABLE

5

EXTERNAL

PRESSURE

COEFFICIENTS

( cp, ) FOR PITCHED

ROOFS

OF RECTANGULAR

CLAD

BUILDINGS

( Clause 6.2.2.2 )

ik;Il>lD1N0 HEIGHT RATIO

RlX!F AKaLE CL

WIND

EF

I

nk---W

ANGLE 8 0”

WIND

GH

EG

ANQLE O 900

FH

- 0’8 -0’9 -1’2 -0‘4 0 +0*3 +0*7

-0’4 -0’4 -0.4 -0’4 -0.4 -0.5 -0.6

-0’8 - 0’8 -0’8 -0’7 -0.7 -0’7 -0’7

-0.4 -0’4 -0’6 -0’6 -0.6 -0’6 -0.6

-2’0 - 1’4 -1’4 - 1’0 -0’8

-0‘8

-0’6

-1’0

-0’6

-2’0

-1’1 -09 -0’7 -0’2 +o 2 +0’6

-0.6 -0’5 -0.6 -0.5 -0’5 -0’5

-0’8 -0’8 -0.9 -0’8 -0.8 -0’8

-0’6 -0’6 -06 -0.a -0’8 -0’8

-2’0 --2’0 1’5

0

I

30 _

I

I

0 10 5

I

I

IL

I -.0.7 -0.7 -0’8 - 1’0

-0’6 -0% -0’6 -0.6 -0.5

I

-

--

,.

-1’0 -1’2 - 1’2 - 1’1 -1’1 - 1’1

-_1

I

_.3 , h r‘5;;<0

LOCAL COEFFICIENTS

-0.9 -0’8 -0’8 -0’8 --oi -0’8 -0’8

-0.7 -0’8 -0’8 -0.7 -0.7 -0’7 -0.7

-I’0

-2.0 - 1’5 -2’0

l_pp___m

/

-1’5 -1’5

-

-_

/

-1’2 -I.0 - 1’0 -1’0

.-

-9.n Ii.! - 1’5

-1.5

-;.;

-9.n

-3.n

1 I _~

l$;; -7’fl -1.5 __

/ I_.

-;.;

_:vJ

-1.5

-1’2 -1’2

__i. 5

18:875(Part3)-1987 TABLE 6

EXTERNAL

PRESSURE COEFFICIENTS ( C,, ) FOR MONOSLOPE ROOFS FOR

RECTANGULAR

CLAD BUIILDINGS WITH $

< 2

( Clause 6.2.2.3 )

y = h or 0’15 W, whichever is the lesser.

NOTE -

area L refer to the whole quadrant.

LOCAL Cpe

WIND ANQLE 13

ROOF AIGQLE OL

Degree

Area Hand

45O

0”

H

L

H

135O

90”

L

H&LH&L

180”

H

L

H

L

Hi

Hs

Lz

Ls

He

Le

-0.9

-1.0

-0’5

-1’0

-2.0

__1’5

-2’0

-1’5

-2’0

-2’0

-1.5

-2’0

-2.0

em* 3% %g

-0.5

-1.0

5

-1’0

10

-1’0

-0.5

-1.0

-0.8

-1.0

15

-o-,9

-0.5

-1’0

-0’7

20

-0.8

-0.5

-1.0

25

-0’7

-0.5

-1’0

30

-0’5

-0’5

-1’0

-0.9

%$

.I& o, .L .5! a -z E; a%* <:93 4: -1’0 -0’5

-0.6

-1.0

-0.4

-1.0

-2’0

v-1.5

-2.0

- 1.0 1 -0’5

-0.6

-1.0

-0’3

- 1’0

- 1’8

-0’9

-1’8

- 1.4

-2’0

-2’0

-0.6

-0.9

‘-0.5

-0.5

-1.0

-0’2

-1.0

-1.8

-0’8

-1’8

-1.4

-2.0

-2’0

-0.6

-0

8. -0.5

-0.3

-0.9

-0.1

-0.9

-1’8

-0.7

-0.9

-0.9

-2.0

-2’0

-0.6

-0

8

-0.1

-0’6

0

-0’6

-1’8

-0-j

-0.5

-0.5

-2.0

-2.0

-0

-0’5

5

J NOTE 2 h is the height to eaves at lower side, I is the greater horizontal lesser horizontal dimension of a building.

18

dimension

of a building

and UJ is the

IS : 875 ( Part 3 ) - 1987 TABLE 7

PRESSURE COEFFICIENTS FOR MDNOSLOPE FREE RQOFS ( Clause 6.2.2.4 )

h

1 SOLIDITY RATIO

Rooy ANGLE ( DECUUUES)

MAXINUY

( LARQEST + VE ) AKD

MINIMTJIU( LARGEST COEFFICIENTS

Overall Coefficients

VE ) PRESSURE

Local Coefficients

1

BzzzB

-

N

0

+0-z

+0*5

+1*8

5

+0*4

+0’8

+2-l

+I’3

10

+0*5

+1*2

+2’4

+I’6

All values of d

+1-l

+0*7

+ 1’4

+2’7

+1’8

-l-O’8

+1*7

+2*9

+2*1

25

+1-o

+2-o

+3*1

+2’3

30

+1-z

f2’2

+3’2

+2’4

d=O

-0’5

-0’6

-1’3

- 1’4

4-l

-1’0

-1’2

- 1’8

-1’9

4-O

-0.7

- 1.1

- 1’7

- 1.8

4-l

-1’1

-1.6

-2.2

-2’3

15 20

0

5

10

15

20 25

30

NOTE -

-

-.

4=0

-0.9

-1’5

-2.0

-2.1

4=1

-1’3

-21

-2.6

-2.7

4-o

-1.1

-1’8

-2’4

-2’5

4-I

-1’4

-2’3

-2.9

-3’0

b-0

-1.3

-2’2

-2’8

-2’9

4-l

-1.5

-2’6

-3’1

-3’2

4-o

-1.6

-2’6

-62

-3’2

4-l

-1’7

-2’8

-3.5

-3’5

4-o 4=1

-1’8

-3.0

-3.8

-3’6

- 1’8

-3’0

-3’8

-3.6

For monopitch

canopies the centre of pressure should

edge.

19

be taken

to

act at 0’3 UJ from the windward

KS : 875 ( Part 3 ) - 1987 TABLE

PRESSURE

8

COEFFICIENTS

FOR FBEE STANDING

DOUBLE

SLOPED

ROOFS

( Clause 6.2.2.4 ) -c,

-CP

.-Cn

F

I

10

h -‘I

1 1

ROOF

ANGLE

-

I

Roos Xsa~n : DEc;lIEZ% )

+ve

ROCF ANGLE

-ve

MAXIMOX

SOLIDITY RATIO

1

! !

( LAB~EST+VE )

Overall Coefficients

-15 - 10 -5 7-5 f 10 +15 i20 3’ :3;

+0*7 +0.5 $-O-4 +0’3 +0.3 +0.4 +0*4 +0’6

-20

j Ail values of !

I

9

! / I

+=1

I$=0

-0.7 -0’9 -06 -0.8

I

*

-0’6 -0.8

1

!

-0.5 -0’8

/

o-0 4-l

-10

I

“,y_ $10

-5

:

/ I +5

+ 10

+ 15

K:,

i30

-

-

; /

f=i=

= f=Y

_ ;

$I:,

1 I

$w&

$1;

I 1

liz%@zl / +0’6 + 0’7 +0’8 i-0.8 +1*3 +1*4 +1’4 +1*5 f1’6 +1’6

+1*7 +I’4 +I’1 +0’8 +0’4 +0*4 +0*4 +0.4 -!-0’5 +0*7

:x’,’ . +0*7 +0.9 +1*1 +I’2 +I’3

+I’6 +1.5 +I’4 +1*5 + 1’8 +I’8 +1.9 +1*9 +1*9 +1*9

-0.9 - 1’2

-1’3 -1’7

-1’6 -1’9

-0’6 -_1’2

-0’8

-1’3 -1’7

-1’6 -1’9

-0’6 - 1’2

-1.5 -1’9

-0.6 -1:3

-1.6 -1’9

-0.6 -1’4

-1’4 -1.8

-1’1 -2’1

-1’5 -2’0

Al.4 -1.8

-1.4 -2’4

-1.1

-0.7

/ / /

i20 i-25

-0’6 -0’9

/ -i-O% +06 +0’6

:x:;

--:5

VE ) Pn~aacnn

Local Coefficients

I

--“Cl

MINI~X ( LARGEST CO~FFI~~~NTS

AYD

-08 -1’1

j_

-1.3 -1’7

-0’7 -1’5

-1’3 -1’7

-0.6 -1’3

-1.4 -1’8

-0’7 -1.4

1

/

’

1

-l’l

1

-0’8 -1’2

j

-0.9 - 1’5

- 1’7 -2’2

-1’4 -1.9

-1’8 -2%

-0’9 -1’3

/

-1’ -1.7

-1’8 -2’3

- 1.4 -1.9

-2’0 -3’0

-1’9 -2’4

- 1’4 -2’1

-2’0 -3’0

-1’4 -2’2

-2’0 -3.0

-1.0 -1’4 -1’0 - 1’4

-1.4 1 I_L___-!‘9

i -_ ;

-1-4 -2’1

1

I::?

_b

---.-_

Each slope of a duopitch canopy should he able to withstand forces using both the maximum and the mmimurn oefficients, and the whole canopy should be able to support forces using one slope at the maximum coefficient with the Ither slope at the minimum coeffictent. For duopitch canopies the cenrre of pressure should be taken to act at the centre ‘Peach slope.

20

YS : 875 ( Pars

TABLE

9

PRESSURE

COEFFICIENTS

( TOP

AND BOTTOM

) FOR

PXTCHED

ROOFS,

3 ) - Y987

a +e 3tP

( &uw 6.2.2.4 )

-T

1

i

1

I G

_____:

Roof sIope a 0 30’ e - 0’ - 450, D, D’, E, E’ :x1: length 9 = 90”, D, D’, E, E’ prr !engzh b’, thereafter Cp = 0

z J

c

I

--

1

E

i

L;----

I__

T

7

9 D

0

9o”

j_

_-A45” 90” I-

I

!

-1’0

0.1

;

-0.3

-0’3

j

E’

j

-05

/

-0.3

/ j

-0’6

/ 1

-0.3

-0.3

-C’4

-7

) I

I 0’6

End Surfaces

1

E

D

I

-I

45O

1

----I

,

1

c

i I1

-0.4

j

-0*3

/ / :

I

I

Forj

I

Tangentially

: Cp top =

-i’O;

acting

Cp bottom

friction:

21

=

-0.2

ROOo ip 0’05 pdbd

c’

/

c;

I 1 ! I 0.8

/ I

I

-

0’3

.j_

G’

IS I 875 ( Part 3 ) - 1387

TABLE

10 PRESSURE

COEFFICIENTS ( TOP AND BOTTOM ) FOR PITCHED a = 300 WITH EFFECTS OF TRAIN OR STORED MA’I’BRIALS

FREE ROOFS,

( Clause 6.2.2.4 )

Roof slope LY= 300 Efftctz of trains or stored materials: 0 a 0” -45”, or 135” -180”, D, D’. E, F’ full lqngth 6 - ;;,.$, D , E, E part thereafter b’, & = 0

-

! ,

b:5C I

E

I I !

L

- --_ .I-. _G__ I

c

&d

--I

PRESSURE COEFFICIENTS,cp

cl

“/ D

End Surfaces E’

E

D’

c 0”

0’1

0’8

-0’7

0’9

0’5

-0’8

0’5

45O

-0’1

90”

-0’4

-0’5

180”

-0’3

-0’6

-0’4

-0’5

0’4

-0’6

i : Cp top = - 1’5; C, bottom

45”

Forj

go0

Tangentially

acting friction:

&a”

Q 0’5 = 0’05 pdbd

.-

22

-0’3

c

G

0’8

0’3

G’

-0’4

-a.-%“---_-_-_“_...

_.

_

IS I 875 ( Part 3 ) - 1987

TABLE 11 PRESSURE

COEFFICIENTS (TOPANDBOTTOM)FORPlTCHEDF~~

BOOFS,am

10"

( Clause 6.2.2.4)

f b’=d

1

b=Sd

Roof slope (L = IO” 8 = 0” - 45”, D, D’, E, E’ full length 0 = 90°, D, D’, E, E’ par1 length b’, thereafter Cp = 0

PRESSURECOEFFICIENTS, CD

End Surfaces

e D

D’

E’

E

c -~.

-00

45" 90”

-1.0

03

-0'3 -0.3

0.1

0

-0.5 -0'3 -0.3

0.2

0” -

90°

Forf:

Cp top = -11’0; Cp bottom

Tangentially

acting friction,

C

G

1

G

,

0’1

0

0"

I

= 0’4

RIO’ = O”1 pdbd

23

-0'4

0.8

09

-0.6

TABU

I2

PRESSURE COEFFICIFiNTS (*OP AND BOTTOM ) FOR PITCRBD FBE ir - 10” WITH EFFECTS OF TRAIN OR STORED MATJZItIAL8 ( CIaw

6.2.2.4

ROOFS

)

-T

h’=O$th

_A_

i i

!

Roof slope m - IO0 EAacts of trains or stored materials: e-o.=45’,or 135’ - 180°, D, D’, E, E’ full length 0 = 90*, D, D’, E, E’ part length b’, thereafter CD = 0

G

G’

i !

1 I /

-0’4

1

! I

0.8

-0%

0’3

i I

I

0” 0” -

’ I!$”

ForJ: I;, top = -15;

/ Tangentially

Cp bottom

acting friction:

= 0.9

R,o” .= 0.1 p&j

i

24

1sr875(Part3)-1987

TABLE

13 EXTERNAL

PRESSURE COEFTZCXENTS

FOR

( Clause 6.2.2.4

TROUGHED

FRER

ROOPS,

a = IO”

)

Roof slope a - 10” 9 = 0” -45”, D. D’, E. E’ full iength A = 90*, D,_ D’, E, E’ Fatt length b’, thereafter Cp I 9

P&EssUnE

cOEFFICIEK?K3,

cp

I

0”

0” 0” -90

D’

0’3

-0’7

Forf

I

acting friction

25

0’1 -0’1

: CD top = 0’4; Cp bottom =

Tangentially

0’2

, /

0.1

-0’1

E

1 ,

-0’2

0

4Y 90”

D

- i-1

Rgo” = G’i &bi

/ I / ! I j I

E’ -0’9 -0’3 0‘1

ISr875(

Part3)-1987

TAtWE 14 PRESSURE COEFFICIENTS ( TOP AND BOTTOM ) FOR TROUGHED FREE ROOFS, a = IO” WITH EFFECTS OF TRAINS OR STORED MATERIALS ( Clause 6.2.2.4 )

E

b= 5d

f Lm

Roof slope (I = 10” Effects of trains or stored materials: 13= 0” - 450, or 135” - 180”, D, D’, E, E’ full length 13= go”, D, D’, E, E’, part length b’ thereafter Cp = 0

T

i------i

PRESSURE COEFFICIENTS, Cp e D

E

D’

E’

00

-0’7

0’8

-0’6

0’6

45O

-0’4

0’3

-0’2

0’2

90°

-0.1

0’1

-0’1

0’1

180”

-0’4

-0.6

- 0’3

0” O”- 180’

-0.2

Forf:

Cp top =

Tangentially

26

- 1’1; CD bottom

acting

friction:

= 0’9

&,o’ = 0’1 pabd

IS : 875 ( Part 3 ) - 1987

6.2.2.5 Curved roofs - For curved roofs, the external pressure coefficients shall be as given in Table 15. Allowance for local effects shall be -made in accordance with Table 5.

The total resultant load (P) acting on the roof of the structure is given by the following formula:

6.2.2.6 Pitched and saw-tooth roofs of multiFor pitched and saw-tooth span buildings roofs of multi-span buildings, the external average pressure coefficients and pressure concentration coefficients shall be. as given in Tables 16 and 17 respectively. provided that all spans shall be equal and the height to the eaves shall not exceed the span.

The resultant of Pfor roofs lies at 0.1 D from the centre of the roof on the windword side.

Evidence on multi-span buildings is NOTEfragmentary; any departure given in Tables 16 and 17 should be investigated separately.

6.2.2.7 Pressure coeficients on overhangs from roofs - The pressure coefficients on the top overhanging portion of the roofs shall be taken to be the same as that of the nearest top portion of the non-overhanging portion of the roofs. The pressure coefficients for the underside surface of the overhanging portions shall be taken as follows and shall be taken as positive if the overhanging portion is on the windward side: a)

1.25 if the overhanging

b)

1.00 if the overhanging

c) 0.75 if the overhanging

slopes, isShorizontal,

and

slopes upwards.

For overhanging portions on sides other than the windward side, the average pressure coefficients on adjoining walls may be used. 6.2.2.8 Cylindrical structures - For the purpose of calculating the wind pressure distribution around a cylindrical structure of circular crosssection, the value of external pressure coefficients given in Table 18 may be used provided that the Reynolds number is greater than 10 000. They may be used for wind blowing normal to the axis of cylinders having axis normal to the ground plane ( that is, chimneys and silos ) and cylinders having their axis parallel to the ground plane ( that is, horizontal tanks ) provided that the clearance between the tank and the ground is not less than the diameter of the cylinder. h is height of a vertical cylinder or length of a horizontal cylinder. Where there is a free flow of air around both ends, h is to be taken as half the length when calculating h/D ratio. In the calculation of the resultant load on the periphery of the cylinder, the value of C,t shall be taken into account. For open ended cylinders, C,i shall be taken as follows: a) 0.8 where h/D is not less than 0.3, and b) 0.5 where h/D is less than

0.3.

6.2.2.9 Roofs and bottoms of cylindrical elevated structures - The external pressure coefficients for roofs and bottoms of cylindrical elevated structures shall be as given in Table 19 ( see also Fig. 2 ).

P =

0.785

D’ ( _!q -

C,, pa)

6.2.2.10 Combined roofs and roofs with a sky light - The average external pressure coefficients for combined roofs and roofs with a sky light is shown in Table 20. 6.2.2.11 Grandstands - The pressure coefficients on the roof ( top and bottom ) and rear wall of a typical grandstand roof which is open on three sides is given in Table 21. The pressure coefficients are valid for a particular ratio of dimensions as specified in Table 21 but may be used for deviations up to 20 percent. In general, the maximum wind load occurs when the wind is blowing into the open front of the stand, causing positive pressure under the roof and negative pressure on the roof. of round silos and 6.2.2.12 Upper surface tanks - The pressure coefficients on the upper surface of round silos and tanks standing on ground shall be as given in Fig. 2. 6.2.2.13 Spheres coefficients for spheres Table 22.

The. shall

external be as

pressure given in

6.2.3 Internal Pressure Coejicients - Internal air pressure in a building depends upon the degree of permeability of cladding to the flow of air. The internal air pressure may be positive or negative depending on the direction of flow of air in relation to openings in the buildings. 6.2.3.1 In the case of buildings where the claddings permit the flow of air with openings not more than about 5 percent of the wall area but where there are no large openings, it is necessary to consider the possibility of the internal pressure being positive or negative. Two design conditions shall be examined, one with an internal pressure coefficient of +0.2 and another with an internal pressure coefficient of -0.2. The internal pressure coefficient is algebraically added to the external pressure coefficient and the analysis which indicates greater distress of the member shall be adopted. In most situations a simple inspection of the sign of external pressure will at once indicate the proper sign of the internal pressure coefficient to be taken for design. NOTE - The term normal permeability relates t* the flow of air commonly aft‘orded by claddings not only through open windows and doors, but also through the slits round the closed winc’ows 2nd doors and through chimneys, ventilators and through the joints between roof coverings, the total open area being less than 5 percent of area of the walls having the openings.

TABLE

15

EXTERNAL

PRESSURE

COEFFICIENTS

( Clause 6.2.2.5

FOR

l------~-----l a) Roof springing

from ground

CURVED

ROOFS

)

Values

of C, Cl and C2

level c2 -CL_

0'1 0.2 03 p_-0’4 -0.5

-0.6

b) Roof on elevated

-0’8 _-0’9 ___-1.0 -~

+0*3

c) Doubly --7

curved

0 0.6

roofs

-0.7 -0.3

jp

-1’1

+06

+0*4

-1’2

+0.7

i-o.7

NOTE - fihen the wind is blowing normal to gable ends, Cpe may be taken as equal to -0.7 for the full width of the roof.over a length of l/2 from the gable ends and -0.5 for the remaining portion.

HALF

(Cl GUARTE R 4 i

fiGkIfCiN OF ROOF EEL THIS LINE TO BE TREAIED AS AN EXTENSION of VERTICAL SUPPORTS

.~

+0*4

structure

rCENTRAL

-0’8

+0*1

..___I.__

ISr875(Part3)-19a7

TABLE 16

EXTERNAL PRESSURE COEFFICIENTS ( C b i’OR PlTCHED ROeFS MULTISPAN BUILDINGS (ALL SPANS EQ&lp, WITH h > w’

OP

( Ckusc 6.2.2.6 )

I

w’

w’

J_

I-

J_

w’

_1_

w’

_I_

I

w’

w*

1

I-

-l-

ROOF

y=h or 0-1~ WHICHEVER IS LESS h,= h,=h

PLAN

i

I

SECTION

ROOF

WIND

ANR LE

ANQLE

a

e

FIRST

FIRST SPAN

INT~YIcDIATE SPAN

--74

OTHER INT~R~~EDIATE SPAN

-- C

d

-- m

n

END SPAN c----t

x

2

LOCAL

~RFPIOUNT

degrees degrees -0’9

-0.6

-0’4

-0’3

-0’3

-0’3

-0.3

-0’3

10

-1’1

-0.6

-0’4

-0’3

-0’3

-0.3

-0’3

-0’4

I

20

-0’7

-0’6

-0’4

-0’3

-0’3

-0’3

-0.3

-0.3

\

30

-0.2

-0’6

-0.4

-0’3

-0.2

-0’3

-0’2

-0’5

)

45

+0*3

-0.6

-0.6

-0’4

-0’2

-0.4

-0’2

-0.5

J

5

0

--

r---Roof Angle d;reea

Wind Angle 8 degrees

up to 45

90

Distance h-P---hx

-0’8

I

-2’0

-1’5

__ha

h3

-0’6

-0’2

Frictional drag: When wind angle 0 - O’, horizontal forces due to frictional drag are allowed for in the aboye values; and when wind angle 0 = 90°, allow for frictional drag in accordance with 6.3.1. NOTE - Evidence on these buildings investigated reparately.

is fragmentary

29

and any departure

from

the casu

given should ba

L_

.._

.

._.-

IS : 875 ( Part 3 ) - 1987 TABLE

17

EXTERNAL

PRESSURE

COEFFICIENTS

C,e FOR

SAW-TOOTH

SPAN BUILDINGS (‘ALL SPANS EQUAL ) WITH h > w’ ( Clause 6.2.2.6 )

ROOF

ROOFS

PLAN

OF MULTI-

0’1 UI whichY =hor ever is the less hl=hB = h

SECTION

WIND ANC+LE e

FIRST SPAN c----Y a

b

FIRST INTER~~~EDIATE SPAN r--hw-y d c

OTHER INTERMEDIATE SPANS r---h_-~ R m

LOCAL COEFFICIENT

END SPANS C--h--7 x

t

degrees 0

+0’6

-0.7

-0’7

-0.4

-0.3

-0’2

-0.1

-0’3

1

180

-0’5

-0.3

-0.3

-0.3

-0.4

-0.6

-0’6

-0’1

J

c-----------WIND ANGLE 0 degrees 90

DISTANCE -+.L----_-----~ h

ha

ha

-0.8

-0%

-0’2

Similarly,

210 Frictional

but handed

drag: When wind angle 0 = O’, horizontal values; and when wind angle 8 I

NOTE separately.

-1’5

-2’0

Evidence on these buildings

forces

90”, allow for frictional is fragmentary

due to

frictional

drag in accordance

and any departures

30

drag

are allowed

for

in the above

with 6.3.1.

from the cases given should

be investigated

18:875(P8rt3)-1987

TABLE I8

EXTERNAL

PRESSURE DISTRIBUTION COEFPICIENTS AROuN6 sTRucTURm3 ’ ( CIaucs6.2.2.8 )

CTLiNDkWWL

PRESSUI~E COEFFICIENT,Cm

POSITION OF PEBIPHERY, 0 IX DEQREEB

h/D = 7

h/D = 25

I

h/D = 1

0

1’0

1.0

1’0

15

O-8

0’8

0’8

30

0.1

0’1

0’1

45

-0’9

-0’8

-0’7

60

-1’9

-1’7

-1;2

75

-2’5

-2.2

- 1.6

90

-2’6

-2’2

-1’7

105

- 1.9

-1’7

-1.2

120

-0’9

-0’8

-0.7

135

-0.7

-0.6

-0.5

150

-0’6

-0.5

-0’4

165

-06

-0’5

-0’4

180

-0.6

-0.5

-0’4 --

31

I

IS -I 875 ( Part 3 ) - 1987

T-LB

19

=TBRNAL

PRESSURE COE@FICIENTS FOR ROOFS AND BOTTOMS CYLINDRICAL BUILDINGS ( Clause6.2.2.9 )

P

OIREC?TION Of WIN0

(bl

(cl

COS~FICIE~

OF EXTERXAL PREBSURE, Cps

STRUCTURE ACCOBDIITGTO SEAPE

a,budc

d

HID

Roof

0’5

-0.65

130

-1’00

Roof

Bottom

1’00

-0’75

-0’8

1’25

-0’75

(z/H)

-1

-0.7

_ 2.00

- 1’00

1’50

-0’75

I Total force acting The resultant

-0.6

on the roof of the structure,

of P lier ecceotricdly,

P 1 0’785 Da ( pi -

# a O’ID

32

CpePd )

OF

IS:875(Part5)-1987 TABLE 28

EXTERNAL

PRESSURE COEFFICIENTS, Cw FOR COMBINED ROOFS AND ROOF’S WITH

A SKY LIGHT

( Clause 6.2.2.10

a) Combined

)

Roofs

-0.8

VALUE0

POETION

a

cpe DIRECTION 2

DIRECTION 1

From the Diagram

Cpe = -0’5,

-

Cpe = -0’7,

_!!!_ > I.5 he

b

I

OP

candd

hr

<

1’5

-0’4

See Table 5

see 6.2.2.7 ( Confinurd)

33

IS : 875 ( Part

TABLE 20

3 ) - 1987

EXTERNAL

PRESSURE

COEFFICIENTS, -Cpe FOR COMBINED WITH A SKY LIGHT - Contd

ROOFS AND ROOFS

b) .Roofs with a Sky Light

WIN0

b; ; b, PORTION

0

bl < bs a and b

b

--Ge

-0.6

$0’7

See Table for combined

I

34

roofs

IS t 875 ( Part 3 ) - 1987 TABLE

21

PRESSURE

COEFFICIENTS AT TOP AND BOTTOM ROOF OF GRAND OPEN THREE SIDES ( ROOF ANGLE UP TO 5” )

STANDS

( Clause 6.2.2.11 ) ( A : b : I=

0.8

: 1 : 2’2 ) FRONT AND BACK OF WALL

-8

x

L

M

-0.5

+0.9

-0.5

+0.8

-0’6

+0*4

-0’4

- 1’1

+0’6

- 1.0

+0*4

-0.3

co.9

-0’3

3 ---

0*

-l-O’9

45”

KM

135O

777

-_ 180~

+0.9 -

7

60”

‘Mw’ - CpofK=

60”

‘Mw’ - c, Of.3 = + 1’0

-1’0

Mw

1 I

G 0H

i-----b4 ( Shaded area to

scale ) TOP AND BOTTOM OF ROOF

1

B

0

c

0”

+0*9

E

D -.-

--1.0

+0.9

-0.7

* 45O

$0’7

-0’7

-CO’4

135”

-1.1

-0’7

-1’0

-0.5

180” i

-0.6

45O

-0’3

-0.6

-0.3

-0.9

-0’6

‘MR’ - cp ( top ) = -2.0 ‘MB’ - Cp ( bottom ) = + 1’0

35

-0’5

f0’3

-0.9

-1’0

-0’6

-0’3

--.-

45”

f0’9 --

+0’8

N_

/

CO’7

+0’9 ~-

T-

I8 : 875 ( Part 3 ) - 1987

1.5

a 0.5

j.0

h

tand c 0.2

0.20

<30

/I I,,,

, ,,

, , ,,

_, , ,,.,

0

SECTION

._.

AA

, ,,,

, ,

---I

PLAN (

For Force Coefficient

Corresponding

to Shell Portion,

see Table 23 ).

EXTERNAL PRESSURE COEFFICIENT ON THE UPPER ROOF SURFACEOF SINQULAR ChtCr;t~~ STANDINGON ‘1:HE GROUND

FIQ. 2 6.2.3.2

Buildings

with

medium

and

6.3 Force Coefficients - The value of force coefficients apply to a building or structure as a whole, and when multiplied by the effective. frontal area A, of the building or structure and by design wind pressure, pd gives the total wind load on that particular building or structure.

large

with medium and large Buildings openings may also exhibit either positive or negative internal pressure depending upon the direction of wind. Buildings with medium openings between about 5 to 20 percent of wall area shall be examined for an internal pressure coeffiFient of +0*5 and later with an internal presand the analysis which sure coefficient of -0.5, produces greater distress of the members shall be adopted. Buildings with large openings, that is, openings larger than 20 percent of the wall area shall be examined once with an internal pressure coefficient of $-O-7 and again with an internal pressure coefficient of -0.7, and the analysis which produces greater distress on the members shall be adopted. ojenings -

F -

Ci A, ~a

where F is the force acting in a direction specified in the respective tables and Ci is the force coeficient for the building. RiOTE 1 The value of the force coefficient differs for the wind acting on different faces of a building or structure. In order to determine the critical load, the total wind load should be calculated for each wind

direction.

Buildings with one open side or opening exceeding 20 percent of wall area may be assumed to be subjected to internal positive pressure or suciion similar to those for buildings with large openings. A few examples of buildings with one sided openings are shown in Fig. 3 indicating values of internal pressure coefficients with respect to the direction of wind. 6.2.3.3 In buildings with roofs but no walls, the roofs be subjected to pressure from both inside and outside and the recommendations shall be as given in 6.2.2.

NOTE 2 - If surface design pressure varies with height, the surface area of the building/structure mav be sub-divided so that specified pressures are taken over appropriate areas. NOTE3 - In‘tapered buildinq/structures, the force coefficients shall be applied aiier sub-dividing the building/structure into suitable number of strips and the load on each strip calculated individually, taking the area of each strip as Ae.

wiil

NOTE 4 - For force coefficients for structures not. covered above, reference may be made to specialist literature on the subject or advise may be sought from specialists in the subject.

36

iS I 875 ( Part 3 ) - 1987

TARLE !Z2 =TRRNAL

PRESSURE DISTRIRUTION COEFFICIENTS SPHERICAL STRUCTURES ( Chse 6.2.2.13 )

-

1-

REMAIIKS

0

4-1'0

15

+0.9

30

-to*5

45

-0’1

60

-0.7

75

--I’1

90

- 1.2

105

- 1’0

120

-0.6

135

-0.2

150

+0*1

165

+0*3

180

+0*4

Ct = 0.5 for Dl;d < 7 = 0.2 for DVa > 7

C,’ -

6.3.1 Frictional Drag - In certain buildings of special shape, a force due to .frictional drag shall be taken into account in addition to those loads specified in 6.2. For rectangular clad buildings, this addition is necessary only where the ratio d d or F is greater than 4. The frictional drag h force, F’, in the direction of the wind is given by the following formulae:

0.02 for surfaces with corrugations across the wind direction, and

Cf’ = 0.04 for surfaces with ribs across the wind direction. For other buildings, the frictional drag has been indicated, where necessary, in the tables of pressure coefficients and force coefficients.

Ifh<

b,F’=C,‘(d-4h)b@, s Cr’ ( d - 4h ) 2 hi&, and if A > b, F’ - “;‘&-j 4b ) bjd - 4b ) 2 h&. The first term in each case gives the drag on the roof and the second on the walls. The value of Cr’ has the following values: C,‘ -

AROdND

6.3.2

Force Corficients for Ciad Buildings

6.3.2.1 Clad buildings of uniform section The overall force coefficients for rectangular clad b ur‘ld’mgs of uniform section with Aat roofs in uniform flow shall be as given in Fig. 4 and for other clad buildings of uniform section ( without projections, except-where otherwise sho& ) shall be as given in Table 23.

0.01 for smooth surfaces without corrugations or ribs across the wind direction, 37

IS : 875 ( Part 3 ) - 1987

(C)

For F

Arrows

= I,

indicate

use average direction

FIG. 3

values

of wind.

LARGE OPENINQ IN-BUILDINGS( VALUES OF COEFFICIENTSOF INTERNAL PRESXJRE ) WITM TOP CLOSED surface varying linearly from a maximum of l-7’ 6.3.2.2 Buildings of circular shajcs - Force cross-section Cr at the up wind edge to 044 Ci at the down coefficients for buildings circular wind edge. shapes shall be as given in Table 23. However, more precise estimation of force coefficients for The wind load on appurtenances and supports circular shapes of infinite length can be obtained for hoardings shall be accounted for separately by from Fig. 5 taking into account the average using the appropriate net pressure coefficients. height of surface roughness E. When the length Allowance shall be made for shielding effects of is finite, the values obtained from Fig, 5 shall be one element or another. reduced by the multiplication factor K ( see also 6.3.2.4 Solid circular shajes mounted on a Table 25 and Appendix D ). surface - The force coefficients for solid circular walls and hoardings - Force 6.3.2.3 Lox shapes mounted on a surface shall be as given in coefficients for low walls and hoardings less than Fig. 6. 15 m high shall be as given in Table ‘21 provided 6.3.3 Force Coejicients for Unclad Buildings the height shall be measured from the ground to the top of the walls or hoarding, and provided 6.3.3.1 General - This section applies to. that for walls’ or hoardings above ground the permanently unclad buildings and to frameworks clearance between the wall or hoarding and the of buildings while temporarily unclad. In the case ground shall be not less than 0.25 times the vertiof buildings whose surfaces are well rounded, such cal dimension of the wall or hoarding. as those with elliptic, circular or ovoid crosssections, the total force can be more at wind To allow for oblique winds, the design shall speeds much less than the maximum due to also be checked for net pressure normal to the 38

IS : 875 ( Part ztransition in the nature of boundary layer OII them. Although this phenomenon is well known in the case of circular cylinders, the same phenomenon exists in the case of many other well-rounded :structures, and this possibility must be checked. 6.3.3.2

obstructed, the ratio l/b shall be taken as infinity for the purpose of determining K_ coefficients’ for b) Flat-sided members - Force wind normal to the longitudinal axis of flat-sided structural members shall be as given in Table 26.

Individual members

The force coeficients are given for two mutually perpendicular directions relative to a reference axis on the structural member. They are designated as CI, and Cft, give the forces normal and transverse, respectively to the relerence plane as shown in Table 26.

a) The coefficients refer to the members of infinite length. For members of finite length, the coefficients should be multiplied by a factor K that depends on the ratio I/b where 1 is the length of the member and 5 is the width across the direction or wind. Table 25 gives the required values of K. The foliowing special cases must be noted while estimating K.

i)

Normal

both

ends of

a

member

are

force,

Transverse

Where any member abuts onto a plate or wall in such a way that free flow of air around that end of the member is prevented, then the ratio of l/b shall be doubled fat the purpose of determining K; and

ii) When

c)

701

F,

force,

=

C,, pd A’1 b

Ft =

Cft pa K 1 b

Circular sections - Force coefficients for members of circular section shall be as given in Table 23 ( seealso Appendix D ).

d) Force coefficients for wires and cables shall be as given in Table 27 according to the diamater (D), the design wind speed ( f’ti) and the surface roughness.

so

h -_=a b \\I

3 ) - 1987

a

i

I

I

t

cf

a/b 4A

4B ‘FI~J. 4

Values of Cr versus -I

Values

of Cc versus -:

for

for -a

$

2 1

< 1

FORCE COEFFICIENTBFOR RECTANGULAR CLAC BUILDINGSIN UNIPBRM FLO~V 39

d

_-_

. ..-.

--

-.-.

‘IS:873(Part3)-1987 TABLE

23

FORCE

COEFFICIENTS Cf FOR CLAD BUILDINGS OF UNIFORM ( ACTING IN THE DIRECTION OF WIND ) [ Clauses 6.3.2.1,6.3.2.2

and 6.3.3.2(c)

-

1 ,!

3pro1/2j

<6

Snzooth

See aim Apppendix c

0'7

,

--- 1, >

!

10

f

-

20

I

I

0’5

I

0.5

0’5

_j -I

_

0.8

I

I 0’5

!

I’

.I. !

0’5

I

I

_I.

c-5

j

0.6

i

I

0.6

-I-0’2

/

b/d = 1 r/b i= l/3

/

0’8

o-9

1’0

u-8

0’9

1’0

1-l

0’6

’

0’6

0’6

I

1’1

0.8

0’7

--_ 0.4

0’4

1’7

1.3

1’5

0’8

-_ 0’5

0:8

0.7

0’8

0.9

1‘0

0.5

0’5

0’5

0.5

0’6

1’3

--i Ia0 / 0%

0’3

I

0.3

@3

0.3

0’3

i

G.6

0.3

--

0’4 I

0.2

>s

)_ -1.

-<3

0.5

--

-10

)

O-5

0’4

--

>

i.3

-0.4

< 10

’ i

--_/___

(4

b/d = 1 r\e - lJ6

0.2

-!

0’8

34

-0

0'7 --

-1

j- O-2

I--r

0’6

r !

_-

>8

1’2

I

.j
oa

I

0’9

0’8

0’7

Ij-

10

Ellipse b/d - 2

T - 1. I

, o-5

- i,

< 10

5

-,-

I 0-i

I j. 1

>6

I

2

I

1 >6

1

i--

_-; Rough or with projections

]

Cr POX HEIOET/BEEADTH RATJO

-i-

All surfaces

SECTION

i ,

0.2

0.2

0.2

0’5

0’5

0.5

o-9

1.0

-b/d = l/2 r/b = l/6

All values

0’5

0.6

0’6

0’7

._

-]-

d

t i d

-n

I!

b/d - 2 rib = l/12

All values

0.9

;

1’1

I

--

( Chlintrcd

40

)

IS t 875 ( Part 3 ) - 1987 TABLE 23

P~ax

FORCE COEFFICIENTS Ci FOR CLAD BUILDINGS OF UNIFORM ( ACTING IN THE DIRECTION OF WIND’) - Contd

SRAPE

SECTION

Cf FOR HEIGHT/BREADTH RATIO

Vdb

m2;s

p to 1;2

1

5

2

10

20

. I- _/--.-J-_-____ , I

I / 0.7

<6 b/d = 2 r/b - l/4

-

-

0’5

>6

-/-

-0 -~

va

0

u

_

0.5

All values

0.9

1’0

0.5

1’2

O-6

1

1’6

j

0’6

1

I

-I-

1’1

_-

0.5

0’9

1’3

1’5

0'6

0’6

1’3

1’6

:‘3

1’6

-i-

0’5

1’2

1.1

.-

-

_

0.9

I !

,0.9

_- --

I

0.5

.I-

0’9

1

1’0

.I_

. _--

l/12

0.5

/

I

0.5

_-

0.8

ICC

__...+__/-I

710

r/a =

0.9

0’5

0.5

0’8

(10 r/a=113

0.8

_-

.I-

/--“I

r’

0’8

-_

!

--I

0’9

0.9

1’2

1.1

I

_0’7

(11 r/b

=

l/4

O-7

0.8

_-

~

0.4

0’4

--

0’8

_

0.8

0’8

0.7

0.7

0’8

--

-

0.7

0.4

-I

-I

12

1.4

0’9

1.0

1’1

1.3

0.9

1’0

I.1

1’3

_

-

--

--

0.7

- -

0.5

1’1

1’0

_-

-_

0.5

_ _--

--

1’2 ---

O-5

0’4

__/_

1’0

0’9 _-

0’4

711

-_

I

0.8

-.__

-/- _I-------

I-

0’4

0’4

0.4

1

0’5

0.5

0.5

IS : 875 ( Part 3 ) - R987

TABLE 23

P&AN

FORCE COEFFICIENTS cf FOB CLAD BUILDINGS OF UNIFORM SECTION ( ACTING IN THE DIRECTION OF WIND ) - Contd

Cr FOR HEI~ET/BREADTH RATIO

Vd

SHAPE

up to l/2 msls

D

-

-cl -0

All values

1’4:z~

I

2

5

10

_-----

1.2

20 I---’

I

1.2

1.2

1’4

1’6

0.7

0’8

0’9

1’0

cc

--

12-sided

PO1 ygon

<12

0’7

_-

1.1

512

0’7

0’7

0.7

0-Y

0.8

)__-

0’9

L----d----J

All values

1.0

1’0

1’1

1’2

I

1.3

1’2

1’4

~

-0

Hexagan

All values

1’0

1’1

l-2

1.3

1’4

1’1

I

-l-

Octagon

1.3

I

--

1’4

(

1’5

Structures that, because of their size and design wind velocity, are in the supercritical flow regime may need further calculation to ensure that the greatest loads do not occur at some wind speed below the maximum when the flow will be subcritical, The coefficients

are for buildings

without projections,

In this table Vdb is used as an indication

except where otherwise shown.

of the airflow regime.

42

---

~.____..

18:875(Part3)-1987

@6

0

Fro. 5

TABLE

3

2

14l6

L

VARIATION

24

FORCE

5 6

8 106-

Cf

OF

COEFFICIENTS

3

-2

L

R, ( >3

WITH

FOR LOW

5 6

8

107

x 10’ ) FOR CIRCULAR

WALLS

OR HOARDINGS

3

2

L56

SECTIONS

( < 15m HIGH )

( Clause 6.3.2.3 )

t--bl I

I

GROUND

ABOVE

ONE

h’>,O-25h’

Wind normal to face WIDTH

Wall

EDGE

GRUUND

-

1

TO HEIGHT RATIO, b/h

ON

DRAG COEFFICIENT, Cf

Wall on Ground

Above Ground

From

From 0’5 to 6

1 to 12

l-2

10

20

1’3

16

32

1’4

20

40

l-5

40

80

1.75

60

120

1’8

160 or more

2’0

80 or more

-

43

81’

IS : 875 ( Part 3 ) - 1987

SIOE

ELEVATION

DESCRIPTION

OF

CIRCULAR

OISC

SHAPE

HEMISPHERICAL BOWL

HEMISPHERICAL BOWL

HEMISPHERICAL SOLID

SPHERICAL

06

FOR

V,,O<7

O-2

FOR

‘IdO’/

SOLID

FIG.6

FORCE COEFFICIENTSFOR SOLID SHAPES-MOUNTED ON A SURFACE

TABLE 25 REDUCTION FACTOR K FOR INDIVIDUAL [ Clauses 6.3.2.2md 6.3.3.2(a) 20

40

50

0’68

0.74

0.82

0.87

0’98

1’00

0.80

0.82

O-90

0.98

0’99

1’00

1’00

0’66

0.69

0.81

0.87

0’90

o-95

1’00

2

5

10

0’58

0’62

Circular cylinder, supercritical flow ( DVd 9 6ma/s )

0.80

Flat plate perpendiwind cular to ( DV,j 2 6m2/s )

0.62

I/b or l/D Circular subcritical

cylinder, Row

MEMBERS

]

100

C-a

D I 875 ( Part 3 ) - 1987 cf sub a

TABLE 27 FORCE COEFFICIENTS FOR WIRES AND CABLES ( I/D = 100 ) [ Clause 6.3.3.2(d)

]

(2)

(1) DVa < 0’6 me/s

-

(3) -

(4) 1.2

-

-

0’9

1’1

Dvd < 0.6 ml/s

1’2

1’2

-

-

Dvd 2 cj m’js

0.5

0.7

-

-

6.3.3.3 Singleframes - Force coefficients a single frame having either: b) all circular members in which all members of the frame have either:

for

the

i) D va less than 6 ms/s, or ii) DVa greater than 6 ml/s. shall be as given in Table 28 according to the type of the member, the diameter (D), the design wind speed (v,J) and the solidity ratio (+).

SOLIDITY

RATIO Q

FORCE COEFFICIENTS SINGLE FRAMES

(2)

0’1

1.9

(3) 1’2

TABLE

(1) 0

(4) 0.7

and

=

29

SHIELDING FACTOR MULTIPLE FRAMES

q FOR

(2) 1.0

(3) 1’0

(4) 1’0

__‘_ >a.0

(5) 1’0

(6) 1’0 1’0

0.1

0’9

1.0

1.0

1.0

0.2

0.8

0.9

1’0

1’0

1’0

0’3 0’4

0’7

0.8

1’0

1’0

1’0

0.6

0’7

1’0

1.0

1’0

0’5 0.3

0.6

0’9

1’0

1’0

0.6

0.8

o-9

10

0’3

0’6

0’6

0.8

1‘0

0.2

1’0

1.2

0.8

1’7

1’2

0.8

0’4

I.7

1.1

0.8

0’5 0.7

0’5

i.6

1-l

0.8

1.0

0’75

I.6

I.5

1’4

1’00

2.0

2’0

2.0

Linear interpolation

between values is permitted.

between the values is permitted.

Force coefficients for a single frame not complying with the above requirements shall be calculated as follows:

+ (1 - Y) + where

Amty

EFFECTIVE FRAME SPACIXGRATIO SorJnrTY c_--_______*-_-.40RATIO, fl ~0’5 1’0 2’0 *

0.3

Linear interpolation

Bub +

Area of the frame in a supercritical flow > Ae

buildings - This 6.3.3.4 Mu&h frame section applies to structures having two or more. parallel frames where the windward frames may have a shielding effect upon the~frames to leeward side. The windward frame and any unshield parts of other frames shall be calculated in accordance with 6.3.3.3, but the wind load on the parts of frames that are sheltered should be multiplied by a shielding factor which is dependent upon the solidity ratio of the windward frame, the types of the members comprising the frame and the spacing ratio of the frames. The values of the shielding factors are given in Table 29.

FOR

FORCE COEFFICIENTS, Q, FOR r-___-_--*--_____-~ Circular Sections Fiat-sided Members ~--_--~~---~-~ SubcriSupertical flow critical flow (DVdC6 ms/s) (Dv&% ma/s)

(1)

&rc

Y

a) all flat sided members, or

28

A

+ub=

(5) 1.3

QVa 2 0’6 ma/s

TABLE

force coefficient for the flat sided members as given in Table 28, A clrc sub - effective area of subcritical circular members, area of flat-side& ht = effective members, c t iilbt =

FORCE COEFFICIENT, Cr FOR ~_--_-~-~--_---~ Fine Thick ModerSmooth Stranded Stranded ately Surface Smooth Cables Cables Wire (Galvanized or Painted)

FLOW REW.IE

force coefficient for subcritica) circular members as given in. Table 28 or Appendix D,

sub

Where there are more than two frames of similar geometry and spacing, the wind load on the third and subsequent frames should be taken as equal to that on the second frame. The loads. on the various frames shall be added to obtain total load on the structure. a) The frame spacing ratio is equal to the distance, centre to centre of the frames, beams or girders divided by the least overall dimension of the frame, beam or girder measured at right angles to the direction of the wind. For triangular framed structures or rectangular framed structures diagonal to the wind, the spacing ratio

crflat

C f super = force coefficient for the supercritical circular members as given in Table 28 or Appendix D, 46

IS t 875 ( Part 3 ) - 1987

should be calculated from the mean distance between the frames in the direction of the wind.

Force coefficients for lattice towers of equilateral-triangle s’ection with circular members all in the same flow ragime may be as given in Table 32.

Effective solidity ratio, p:

b)

p = CJ for flat-sided members. @ is to be obtained from Fig. members of circular cross-sections.

7

for

TABLE

31 OVERALL FORCE COEFFICIENT SQUARE TOWERS COMPOSED OF ROUNDED MEMBERS [ Clause 6.3.3.5(d)

SOLIDITY RATIO OF

FRONT FACE

r-----------

r-__*_-_y

Onto face

(2) 2’4

(3) 2.5

2’2 1’9 1’7 1’6 1’4

2’3 2.1

(4) 1’1 1’2 1’3

1’S

[ Clause 6.3.3.5(e)

6.3.3.5 Lattice

towers

SOLIDITY RATIO

a) Force coefficient for lattice towers of square or equilateral triangle section with flatsided members for wind blowing against any face shall be as given in Table 30. TABLE 30 OVERALL TOWERS COMPOSED

b)

4

4

1’4 1.4 1’4

1’9 1’9

Onto corner ,(5) 1’2 1’3 1’6 1’6 1.6 1’6

TABLE’ 32 OVERALL FORCE COEFFICIENT EQUILATERAL-TRIANGULAR TOWERS COMPOSED OF ROUNDED MEMBERS

FOR ROUND SECTION MEMBERS

4

--7

RATIO.9

EFFECTIVE SOLIDITY RATIO, p

SOLIDITY RATIO

r---h

Onto corner

0.1 O-2 0.3 04 05 06 0 7 0 8 SOLIDITY

FIG..~

--~

Supercritical Flow ( DVd 2 6 d/s 1

Onto face

0’4 0.5 0

]

FORCE COEFFICIENT FOR h-_____

Subcritical Flow (Dvd < 6 mr/s)

(1) 0’05 0’1 0’2 0’3

FOR

(1)

FORCE COEFFICIENT FOR OF FLAT-SIDED MEMBERS

0’05

FORGE COEEFICIENT BOR cm-_-_-.“-s-s-7

Square Towers

Equilateral Triangular Towers

(1) 0.1

(2) 3’8

(3) 3.1

0’2

3.3

2’7

0.3

2.8

2.3

0.4

2’3

1’9

0’5

2’1

1’5

OF FRONT FACE s+

FOR

]

FORCE COEFFICIENT FOB --_-_--_-~ I-------Subcritical Flow Supercritcial Flow (Dvd < 6 m*/s) (Dvd < 6 ms/s) c__-*-‘_~ r-__A-__y All wind All wind directions directions

!2)

1’8

(3) 0.8

0’1

l-7

0.8

0.2

1’6

1’1

0’3

1’5

1’1

0’4

1.5

1’1

0’5

1’4

1’2

6.3.3.6 Tower a@rtenanccs The wind loading on tower appurtenances, such as ladders, conduits, lights, elevators, etc, shall be calculated using appropriate net pressure coefficients for these elements. Allowance may be made for shielding effect from other elements.

For square lattice towers with flat-sided members the maximum load, which occurs when the wind blows into a corner shall be taken as 1.2 times the load for the wind blowing against a face. For equilateral-triangle lattice towers with flat-sided members, the load may be assum ed to be constant for any inclination of wind to a face. Force coefficients for lattice towers of square section with circular members, all in the same flow regime, may be as given in Table 31. 47

7. DYNAMIC

EFFECTS

7.1 General - Flexible slender structures and structural elements shall be investigated to ascertain the importance of wind induized oscillations or excitations along and across the direction of wind. In general, the following guidelines may be ‘used for examining the problems of wind induced oscillations: a) Buildings and closed structures with a height to minimum lateral dimension ratio of more than about 5.0. and

IS : 875 ( Part 3 ) - 1987 tions with a type of motion which is a combination of the individual modes of motion. Such energy transfer takes place when the natural frequencies of modes, taken individually, are close to each other ( ratio. being typically less than 2’0 ). Flutter can set in at wind speeds much less than those required for exciting the individual modes of motion. Long span suspension bridge decks or any member of a structure with large values of d/t ( where d is the depth of a structure or structural member parallel to wind stream and t is the least lateral dimension of a member ) are prone to low speed flutter. Wind tunnel testing is required to. determine critical flutter speeds and the likely structural response. Other types of flutter are single degree of freedom stall flutter, torsional flutter, etc.

b) Buildings and closed structures whose natural frequency in the first mode -is less than 1-O Hz. Any building or structure which does not satisfy either of the above two criteria shall be examined for dynamic effects of wind. may NOTE 1 - The fundamental time period (I) either be established by experimental observations on similar buildings or calculated by any rational method of analysis. In the absence of such data, T may be determined as follows for multi-storeyed buildings:

4

For moment .resisting frames without bracing shear walls for resisting the lateral loads z-=0*1 where n = number of storeys reys; and

or

n including

basement

sto-

Ovafiing- This walled structures with open ends at one or both ends such as oil storage tanks, and natural draught cooling towers in which the ratio of the diameter of minimum lateral dimension to the wall thickness is of the order of !OO or more, are prone to ovalling oscillations. These oscillations are characterized by periodic radial deformation of the hollow structure.

Cl

b) For all others ==

0’09 H

d/d

where

H - total height

of the main building in metres, and

structure

of the

NATE 7 -Buildings and structures that may be subjected to serious wind excited oscillations require careful investigation. It is to be noted that wind induced oscillations may occur at wind speeds lower than the static design wind speed for the location.

d = maximum base dimension of building in metrcs in a direction parallel to the applied wind force. studies indicate that NOTE 2 - If preliminary wind-induced oscillations are likely to be rignificant, investigations should be persuade with the aid of analytical methods or, if necessary, by means oi wind tunnel tests on models.

NOTE8 - Analytical methods for the response of dynamic structures to wind loading can be found in the following publications: i) Engineering Science Data, Wind Engineering Sub-Series ( 4 volumes ), London, ESDU International. ii) ‘Wind Engineering in the Eighties’, Construction Industry Research and Information Association, 1981, London. iii) ‘Wind Effects on Structures’ by E. Simiu and R.H. Scanlan, New York, John Wiley and Sons, 1978.

NOTE3 - CrossLwind motions may by due to lateral gustiness of the wind, unsteady wake flow (for shedding ), negative aerodynamic example, vortex damping or to a combination of these effects. These cross-wind motions, can become critical in the design of tall buildings/structures. NOTE 4 - Motions in the direction of wind (known also as buffeting) are caused by fluctuating wind force associated with gusts. The excitations depend on gust energy available at the resonant frequency.

iv) Supplement to the National Building Code of Canada. 1980. NRCC, No. 17724, Ottawa, National Research Council of Canada, 1980.

NOTE 5 - The wake shed from an upstream body may intensify motions in the direction of the wind, and may also affect crosswind motions.

v) Wind forces on structures gamon press.

designer must be aware of the NOTE6 -The following three forms of wind induced motion which are characterized by increasing amplitude of oscillation with the increase of wind speed.

Sachs. Per-

vi) Flow induced vibration by Robert D. Clevins, Van Nostrand Reinfold Co. vii) Appropriate Indian Standards ( see 1.1.3 ). NOTE 9 - In assessing wind loads due to such dynamic phenomenon as galloping, flutter and ovalling, if the required information is not available either in the references of Note 8 or other literature, specialist advise shall be sought, including experiments on models in wind tunnels.

a) Galloping - Galloping is transverse oscillations of some structures due to the development of aerodynamic forces which are in phase with the motion. It is characterized by the progressively increasing amplitude of transverse vibration with increase of wind speed. The cross-section which are particularly prone to this type of excitation include the following: i) All structures with non-circular cross-sections, such as triangular, square, polygons, as well as angles, crosses, and T-sections, ii) Twisted cables and cables with ice encrustations.

by Peter

7.2 Motion 7.2.1

Due to Vortex

Shedding

For a structure, the shedding frequency, 3 shall be determined by the following formula:

b) Flutter - Flutter is unstable oscillatory motion of a structure due to coupling between aerodynamic force and elastic deformation of the structure. Perhaps the’ most common form is oscillatory motion due to combined bending and torsion. Although oscillatory motions in each degree of frebdom may be damped, instability can set in due to energy transfer from one mode of oscillation to another, and the structure is seen to execute sustained or divergent oscilla-

Slender Structures -

where S = Strouhal number, v#j = design wind velocity, and b = breadth of a structure or structural members in the horizontal plane normal to the wind direction. 48

IS : 875 ( Part 3 ) - 1987 a)

Circular Structures -

For structures

circular

in cross-section: S = 0.20 for bV’, not greater than 7, and = 0.25 for bV, greater than 7. b) Rectangular Structures - For rectangular cross-section:

8.2.1 Variation of Hourb Mean Wind Speed with The variation of hourly mean wind speed with height shall cbe calculated as follows: Height -

structures

Vz =

of

P, = hourly mean wind speed in m/s, at height e;

S = O-15 for all values of b V,.

vb = regional basic wind speed in m/s (see Fig. 1 ); kl = probability factor ( see 5.3.1 );

NOTE 1 - Significant cross wind motions may be produced by vortex shedding if the natural frequency of the structure or structural element is equal to the frequency of the vortex shedding within the range of expected wind velocities. In such cases, further analysis should be carried out on the basis of references given in Note 8 of 7.1. welded steel chimney stacks NOTE 2 - Unlined and similar structures are prone to excitation by vortex shedding. NOTE 3 - Intensification of the effects of periodic vortex shedding has been reported in cases where two or more similar structures are located in close proximity. for example, at less than 20 b apart, where b is the dimension of the structure normal to the wind. NOTE 4 - The formulae given in 7.2.1(a) and (b) are valid for infinitely long cylindrical structures. The value of Sdecreases slowly as the ratio of length to maximum transverse width decreases; the reduction being up to about half the value, if the structure is only three times higher than its width. Vortex shedding need not be considered if the ratio of length to maximum transverse width is less than 2’0.

Vb h ha ks

where

& = terrain and height Table 33 ); and A-sTABLE

factor

( see

topography factor ( see 5.3.3 ).

33 HOURLY MEAN WIND SPEED FACTOR Xs IN DIFFERENT TERRAINS FOR DIFFERENT HEIGHTS ( Cluuses 8.2 and 8.2.1 )

HEIQ~T m

r--------Category

T~RRA.IN - ----1 Category 2 Category

3

---7 Category 4

(1)

(4

up to 10

0’78

(3) 0’67

(4) 0’50

(5) 0’24 0.24

15

0.82

O-72

0’55

20

0’85

0’75

0’59

0’24

30 50

0’88 0.93

0’79 0’85

0’64

0’34

0’70

0’45

8. GUST FACTOR ( GF ) OR GUST EFFECTIVENESS FACTOR ( GEF ) METHOD

100

0’99

0.92

0.79

0.57

150

1’03

0’96

0.81

0’64

8.1 Application - Only the method of calculating load along wind or drag load by using gust factor method is given in the code since methods for calculating load across-wind or other components are not fully matured for all types of structures. However, it is permissible for a designer to use gust factor method to calculate all components of load on a structure using any available theory. However, such a theory must take into account the random nature of atmospheric wind speed.

200

1.06

1’00

0.88

0.68

250

l-08

1.02

0.91

0.72

300

1’09

1.04

0’93

o-74

NOTE - It may be noted that investigations for various types of wind induced oscillations outlined in 7 are in no way related to tRe use of gust factor method given in 8 although the study of 7 is needed for using gust factor method.

Hourly Mean Wind - Use of the existing theories of gust factor method require a knowledge of maximum wind speeds averaged over one hour at a particular location. Hourly mean wind speeds at different heights in different terrains is given in Table 33.

350

1’11

1’06

0’95

0’77

400

1’12

1.07

0’97

0’79

450

1.13

1’08

0.98

081

500

1’14

1’09

o-99

0.82

8.3 Along Wind Load - Along wind load on a structure on a strip area ( A, ) at any height (2) is given by: F z- - Ci A, j& G where F,

8.2

NOTE - It must also be recognized that the ratio of hourly mean wind [ HMW ) to peak speed given in Table 33 may not be obtainable in India since extreme wind occurs mainly due to cyclones and thunderstorms, unlike in UK and Canada where the mechanism is fully developed pressure system. However Table 33 may be followed at present for the estimation of the hourly mean wind speed till more reliable values become available.

49

= along

wind load on the structure at any height z corresponding to strip area &

Ct = force coefficient for the building, A e = effective frontal area considered for the structure at height c, design pressure at height z due to hourly Pz = mean wind obtained as 0.6 vzs ( N/ma ), G

,

and

given by: G=

1 +gfr

B (l+b)”

+ ‘$1

is

IS : 875 ( Part 3 ) - 1987

.

where &

S = size reduction =

peak factor defined as the ratio of the expected peak value to the root mean value of afluctuating load, and

Y = roughness factor which is dependent the size of the structure in relation the ground roughness.

on to

/3=

factor indicating a measure of slowly varying component of fluctuating wind load and is obtained from Fig. 9,

measure

of the resonant

fluctuating

component

damping coefficient ( as a fraction of critical damping ) of the structure ( see Table 34 ), and grr 04

d=

wind load,

Fro

8

and

is to

be accounted

HEIGHT,m

VALUES

OF&r

AND

L (h)

0.8 0.6

0.01

-02

-04

.06

.l

.2

.3

.L

.5

.f!

1

CZh/L(h)

F1o.9

only

for buildings less than 75 m high in terrain Category 4 and for buildings .less than 25 m high in terrain Cateiory 3, and is to be taken as zero in all other cases.

of the

BUILDING

10 ),

of available energy in the wind stream at the natural frequency of the structure ( see Fig. 11 ),

B = background

SE P

( see Fig.

E = measure

The, value of (gfr’ is given in Fig. 8,

-e

factor

BACKGROUND

50

FACTOR

B

2

6

810

IS t 875 ( Part

W $ 0 c LI Q lL

3 ) - 1987

0.2 0.15 0 .!

“,

0.05 O.OL

=

0.03

‘;

0.02

gJ

2 0.01

fo L(h:/vh

Fro. 11 GUST ENERGYFACTOR, E In figures 8 to 11,

TABLE

34

SUGGESTED VALUES COEFFICIENT

OF DAMPING

( Clause 8.3 )

where c,

N ATUBE 0~

= lateral correlation constant which may be taken as 10 in the absence of more precise load data,

Ca = longitudinal correlation constant which may be taken as 12 in the absence of more precise load data, b = breadth of a structure wind stream,

normal to the

h = height of a structure, .pb = v, = hourly mean wind speed at height t, f,, = natural frequency of the structure, and

Lul) = a measure of turbulence ( see Fig. 9 ).

length scale

DAMPING COEFFICIENT, @

STRIJCTURE

(2)

(1) Welded

steel structures

0’010

Bolted steel structures

0’020

Reinforced

0’016

concrete structures

8.3.1 The peak acceleration along the wind direction at the top of the structure is given by the following formula:

where z== mean

deflection

at

where the acceleration

the

position

is required.

Other notations are same as given in 8.3.

52

IS t 875 ( Part 3 ) - 1987

APPENDIX

A

( Clause 5.2 ) BASIC WIND SPEED City/Town

AT 10 m HEIGHT

FOR SOME IMPORTANT

Basic Wind S’eed ( m/s )

City/Town

CITIES/TOWNS Basic Wind Speed ( m/s )

Agra

47

Jhansi

47

Ahmadabad

39

Jodhpur

47

Ajmer

47

Kanpur

47

Almora

47

Kohima

Amritsar

47

Kurnool

44 39 39

Asansol

47

Lakshadweep

Aurangabad

39

Lucknow

47

Bahraich

47

Ludhiana

47

Bangalore

33

Madras

50

Barauni

47

Madurai

39

Bareilly

47

Mandi

39

Bhatinda

47 39

Mangalore

39 47

Bhopal Bhubaneshwar

39

Mysore

33

50

Nagpur

44

Bhuj

50

Bikaner

47

Nainital Nasik

47 39

Bokaro Bombay

47 44

Nellore Panjim

50 39

Calcutta Calicut Chandigarh

50 39 47

Pondicherry

50

Coimbatore

39

Port Blair

44

Cuttack Darbhanga Darjeeling

50 55

Pune Raipur

39 39

Rajkot

39

Ranchi Roorkee R ourkela Simla Srinagar Surat

39 39 39 39 39 44 47 39 47 44 47 50 50

Bhilai

47

Dehra Dun

47

Delhi

47

Durgapur

47

Gangtok Gauhati

47

Gaya Gorakhpur

39 47

Hyderabad

50

Moradabad

Patiala

47

Patna

47

Imphal

44 47

Jabalpur

47

Jaipur Ja.mshedpur

47

Tiruchchirrappalli Trivandrum Udaipur Vadodara Varanasi Vi jaywada

47

Visakhapatnam

53

IS a 875 ( Part 3 ) - 1987

APPENDIX B [ Clau.se5.3.2.4(b)(ii) ] CHANGES IN TERRAIN B-1. LOW TO HfGH

CATEGORIES

NUMBER

determined in accordance with the rougher ( more distant ) terrain; and

B-l.1 In cases of transition from a low category number ( corresponding to a low terrain roughness ) to a higher category number ( corresponding to a rougher terrain ), the velocity profile over the rougher terrain shall be determined as follows:

b) Below

height h,, the velocity shall be taken as the lesser of the following: i) that determined in accordance less rough terrain, and

ii) the velocity at height h, as determined. in relation to the rougher terrain.

a) Below height h,, the velocities shall be determined in relation to the rougher terrain; and

NOTE - Examples of determination of velocity profiles in the vicinity of a change in terrain category are shown in Fig. 12A and 12B.

b) Above height h,, the velocities shall be determined in relation to the less rough ( more distant ) terrain. B-2.

HIGH

B-3. MORE THAN

TO LOW NUMBER

x,=FETCH,h,

= HEIGHT

e PROFILE

FOR

O&E CATEGORY

B-3.1 Terrain changes involving more than one category shall be treated in similar fashion to that described in B-1 and B-2.

B-2.1 In cases of transition from a more rough to a less rough terrain, the velocity profile shall be determined as follows: a) Above height h,, the velocities shall be

-..,.

with the

NOTE’- Examplesinvolvingthree terrain categoriesare shownin Fig. 12C. CATEGORY

4

FOR CATEGORY6

-----.

PROFILE

FOR

-

DESIGN

PROFILE

CATEGORY

2

AT A

WIND DIRECTION

CATEGORY

12A

Determination

2

of Velocity Profile Near a Change in Terrain Category

x2=FETCH,

h2=HEIGHT

..--..PROFILE - ---

PROFILE

-DESIGN

FOR

CATEGORY

FOR

CATEGORY

.4

FOR

CATEGORY

2

PROFILE

AT

( less rough to more rough )

2

A

I

L I I I

WIND DIRECTION /

CATEGORY

128

Determination

Fro. 12

of Velocity

L

/

I--

A x2 -*

CATEGdRY

2

PioRle Near a Change in Terrain Category (more rough to less rough)

VELOCITY PROFILEIN THE VICIIVITYOF A CHANGE IN TERRAIN CATEGORY

54

-

Co&

ISt875(Part3)-1387 q,=FETCH, x,=FETCH,

h&-HEIGHT

FOR

h,=HEIGHT

4 1

. . . .. . . . VELOCITY

PROFILE

FOR

CATEGORY

---__

VELOCITY

PROFILE

FOR

CATEGORY

3

VELOCITY

PROFILE

FOR

CATEGORY

1

_._.

-

-

DESIGN

Determination of Design

Profile

L

PROFILE

VELOCITY

VELOCITY

VELOCITY 12C

CATEGORY

FOR CATEGORY

Involving

More

Than

One Change in Terrain Category

FIG. 12 VELOCITYPROFILEIN THE VICINITYOF A CHANGE IN TERRAIN CATEGORY

APPENDIX C ( Clause5.3.3.1 ) EFFECT

OF A CLIFF OR ESCARPMENT ON EQUIVALENT ABOVE GROUND ( kJ FACTOR )

HEIGHT

< - effective height of the feature, and The influence of the topographic feature is considered to extend l-5 L, upwind add 2.5 Le 6 = upwind slope in the wind direction. downwind of the summit of crest of the feature If the zone downwind from the crest of the where L, is the effective horizontal length of the feature is relatively flat ( 8 < 3” ) for a distance hill depending on slope as indicated below ( SCG exceeding L,, then the feature should be treated Fig. 13 ): as an escarpment. If not, then the feature should be treated as a hill or ridge. Examples of typical features are given in Fig. 13. NOTE 1 - No difference is made, in evaluating k,

C-l.

between a three ridge.

hill and two dimensional

undulating terrain, it is often not NOTE 2 -In possible to decide whether the local topography to the site is significant in therms of wind flow. In such cases, the average value of the terrain upwind of the site for a distance of 5 km should be taken as the base level from wind to assess the height, z, and the upwind slope 8, of the feature.

where L = actual length of the upwind the wind direction,

dimensional

slope in

55

C-2. TOPOGRAPHY The topography following: ks -

FACTOR,

ks

kB is given by the

factor I+

C-2.1 The factor, s, should be determined from:

es

a) Figure 14 for cliffs and escarpments, and

where C has the following values: Slope 3” < 8 (

C 17O

> 170

level and the distance, X, from the summit or crest rektive to the effective length, LB.

1.2

b) Figure 15 for hills and ridges.

( z >

0.36

and s is a factor derived in accordance with C-2.1 appropriate to the height, H above mean ground

13A

General

NOTE- Where the downwind alope of a hill or ridge is greater than 3’, there will be large regions of reduced acceleratioos or even shelter and it is not posrible to give general design rules to cater for these circumstances. Values of s from Fig. 15 may be used as upper bound values.

Notations

CREST

WIND

DOWNWIND

136

SLOPE

Cliff and Escarpment

WIND

CREST

13C

FIG. 13

Hill and Ridge

TOPOGRAPHICAL DIMENSIONS

,3’

Is : 875 ( Part 3 ) - 1987 CREST

UPWIND

CREST

__

DOWNWIND

x Le

Fro.14

FACTOR JFOR CLIFF AND ESCARPMENT

CREST

CREST

0.5 UPWIND

21 Le

x LI

FIG. 15

1.0

1.5

DOWNWIND

2.0

2.5’

2 LC

FACTOR JFOR RIDGE AND HILL

APPENDIX D [ Clauses6.3.2.2, 6.3.3.2(c) and 6.3.3 3(b) ] WIND FORCE

ON CIRCULAR

SECTIONS

wind speeds likely to be encountered. However, for objects of circular cross-section, it varies considerably.

D-1. The wind force on any object is given by:

F = Ct &AI where ci e force coefficient, A, P effective area of the object normal to the wind direction, and Pa p: design pressure of the wind.

For a circular section, the force coefficient depends upon the way in which the wind flows around it and’is dependent upon the velocity and kinematic’viscosity of the wind and diameter of the section. The force coefficient is usually quoted against a non-dimensional parameter, called the Reynolds number, which takes account of the

For most shapes, the force coefficient remains approximately constant over the whole range of 57

IS I 875 ( Part 3 ) - 1987 veloci:y and viscosity of the flowing medium ( in this case the wind ), and the member diameter. DVa Reynolds number, R, = ‘I where

D = diameter of the member, Vd y -

FIG. 17

design wind speed, and kinematic viscosity of the air which is 146 X lO_sms s at 15°C and standard atmospheric pressure.

As a drop at followed increased

Since in most natural environments likely to be found in India, the kinematic viscosity of the it is convenient to use air is fairly constant, D Vd as the parameter instead of Reynolds numbers and this has been done in this code.

WAKE IN SURERCRITICALFLOW

result, the force coefficient shows a rapid a critical value of Reynolds number, by a gradual rise as Reynolds number is still further.

The variation of Cr with parameter DVd is shown in Fig. 5 for infinitely long circular cylinders having various values of relative surface roughness ( t/D ) when subjected to wind having an intensity and scale of turbulence typical of built-up urban areas. The curve for a smooth cylinder ( t/D ) = 1 x 10-s in a steady airstream, as found in a low-turbulence wind tunnel, is shown for comparison.

The dependence of a circular section’s force coefficient or Reynolds number is due to the change in the wake developed behind the body. At a low Reynolds number, the wake is as shown in Fig. 16 and the force coefficient is typically 1.2. As Reynolds number is increased, the wake gradually changes to that shown in Fig. 17, that is, the wake width d, decreases and the separation point, S, moves from front to the back of tbe body.

It can be seen that the main effect of freestream turbulence is to decrease the critical value of the parameter D V a. For subcritical flows, turbulence can produce a considerable reduction in Cr below the steady air-stream values. For supercritical flows, this effect becomes significantly smaller. If the surface of the cylinder is deliberately roughened such as by incorporating flutes, rivetted construction, etc. then the data given in Fig. 5 for appropriate value of t/D > 0 shall be used.

FIG. 16

WAKE IN SUBCRITICAL

NOTE - In case of uncertainty regarding the value of c to be used for small roughnesses, c/D shall be ta4en a5 0’001.

FLOW

58

.,

Bureau of Indian Standards BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote harmonious development of the activities of standardization, marking-and quality certification of goods and attending to.connected matters in the country. Copyright BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publication), BIS. Review of Indian Standards Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards Monthly Additions’

Amendments Amend No.

Issued Since Publication

Date of Issue

Text Affected

BUREAU OF INDIAN STANDARDS Headquarters: Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002 Telephones: 323 0131,323 33 75,323 94 02


Regional Offices: Central

Telephone

: Manak Bhavan, 9 Bahadur Shah Zafar Marg

3237617,3233841

NEW DELHI 110002 Eastern

: l/14 C.I.T. Scheme VII M, V.I.P. Road, Maniktola

CALCUITA Northern

{ 337 84 86 99,337 85 9120 61 26,337

700054

: SC0 335-336, Sector 34-A, CHANDIGARH

160022 { 60 38 20 43 25

Southern

: C.I.T. Campus, IV Cross Road, CHENNAI 600113

{ 235 02 15 19,235 16,235 04 23 42 15 Western

: Manakalaya, E9 MIDC, Marol, Andheri (East)

832 92 95,832 78 58 832 78 91,832 78 92

MUMBAI 400093 Branches

: AI-IMADABAD.

BANGALORE. BHOPAL. BHUBANESHWAR. COIMBATORE. FARIDABAD. GHAZIABAD: GUWAHATI. HYDERABAD. JAIPUR. KANPUR. LUCKNOW. NAGPUR. PATNA. PUNE. THIRUVANANTHAPURAM. Printed at Dee Kay Printers, New Delhi, India

IS I 875 ( Part 3 ) - 1987

CONTENTS Page j

3 5 5 6

AMENDMENT

NO. 1 DECEMBER 1997 TO IS 875 ( Part 3 ) : 1987 CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURES PART 3

7 7 7 8

WIND LOADS

8 8

( Second Revision ) ( Page 15, Tabk 4, first column ) -

8 Substitute

12

‘h ‘It - 26’ for - P CD’

12 13

( Page 40, Tablz 23, first rfolumn, first row ) Appendix D’ for ‘See alsoAppendix C’. (

Page 47, Table 32, coZ2 ) -

Substitute

‘See also

13 13

Substitute

13

‘DVd 2 6 m2/s7 for ‘Dvd 4 6 ~1~1s’.

13 13 27 36

(CED37)

37 37 38 47 47 48 48 49 49 49 19 *9

Printed at Dee Kay Printers, New Delhi-110015,

India.

53 54 j5 57

AMENDMENT

NO. 2 MARCH 2002 TO IS S75 ( PART 3 ) :1987 CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURES PART

3

WIND LOADS

(Second Revision ) Substitute ‘VZ’ for’ Vd’ at all places. ( Tables 5,6,7

and 8 ) — Insert the following Note at the end of each table

‘NOTE — W and L are overall length and width including overhangs, w and / are dimensionsbetween the walls excluding overhangs.’

( Tables 9, 10, 11, 12, 13 and 14, first column) — Substitute the following matter in the Iast row for the specific values of 6 given therein:

‘for all values of (3‘ [ Page 27, clause 6.2.2.7(a)] — Insert at the end ‘downwards’. [ Page 27, clause 6.2.2.8(a)] — Substitute ‘-O.8’~or ‘0.8’.

[ Page 27, clause 6.2.2.8(b)] — Substitute ‘-O.5’~or ‘0.5’. ( Page 27, clause 6.2.2.9) — Substitute ‘P= 0.785 D2 (Cpi - CpC)pd’ for the existing formula. ( Page 32, Table 19) — Substitute ‘P= 0.785 D2 (WI - C@pd for the existing

formula. ( Page 46, Table 27, third row) — Substitute CDVd <6 ( Page 46, Table 28,CO12, second row) — Substitute

m2Ls’ fQrthe ‘1.8’

existing.

for ‘1.0’.

( Page 46, clause 6.3.3.3, formula, last line) — Substitute

( Area.of the frame in a supercritical flow ) Y =

for the existing. Ae

[ Page 47, clause 7.l(a), third line] — Substitute ‘or’ for ‘and’. 1

...

Amend No. 2 to 1S 875 ( Part 3 ) :1987 [ Page 48, clause 7.l(b),first line ] — Delete ‘clcxs4’; ‘ ( Page 48, clause 7.1, fourth and fifih line ) — not satisfy’.

Substitute

‘ ‘satisfies’

for ‘does

( Page 55, clause C-1, second line) — Substitute ‘and’ for ‘add’. ( Page 56, clause C-2, last line) — Insert ‘~,between ‘crest’ and ‘relative’. ( Page 56, Fig. 13A) — Substitute the following figure for the existing: —

WIND

5— .,+$) A

2 r

&

‘f’/

,->

—x

L

5km

w -W LWW IND 13A

+ w DOWNWIND

GeneralNotetlons

( Page 56, Fig. 13B ) — Substitute ‘Hill and Ridge’ — for ‘Cliff and Escarpment’. ( Page 56, Fig. 13C ) — Substitute ‘Cliff and Escarpment’,for ‘Hill and ‘Ridge’. ( Page 58, clause D-1, eighth line) — Substitute ‘m2/s’~or ‘m2s’

( CED 57 ) ReprographyUnir, BIS, New Delhi, India

2

Indian Standard

IS : 875 ( Part 4 ) - 1987 ( Reaffirmed 1997 )

CODE OF PRACTICE,FOR DESIGN LOADS ( OTHER THAN EARTHQUAKE ) FOR BUILDINGS AND STRUCTURES PART 4 SNOW LOADS

(Second Revision) . Fourtll Rcprjnt OCTOBER 1997

UDC 624.042-42 : 006.7

@ Copyright 1988

BUREAU

OF

INDIAN

STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002

Gr 4

October 1988

IS:875(Bart4)-1987

fndian Standard

CODEOFPRACTICE FOR DESIGNLOADS(OTHERTHANEARTHQUAKE) FORBUILDINGSAND STRUCTURES r. PART 4 SNOW LOADS (Second Revision) 0. F O R E W O R D 0.1 This Indian Standard ( Part4 ) ( Second Revision ) was adopted by the Bureau of Indian Standards on 9 November 1987, after the draft finalized by the Structural Safety Sectional Committee had been approved by the Civil Engineering Division Council.

committee in consultation with the Indian Meteorological Department. In addition to this, new clauses on wind loads for butterfly type structures were included; wind pressure coefficients for sheeted roofs, both curved and sloping, were modified; seismic load provisions were deleted ( separate code having been prepared ) and metric system of weights and measurements was adopted.

0.2 A building has to perform many functions satisfactorily. Amongst these functions are the utility of the building for the intended use and occupancy. structural safety, fire safety; and compliance with hygienic, sanitation, ventilation and daylight standards. The design of the building is dependent upon the minimum requirements prescribed for each of the above functions. The minimum requirements pertaining to the structural safety of buildings are being covered in this Code by way of laying down minimum design loads which have to be assumed for dead loads, imposed loads, wind loads, snow loads and other external loads, the structure would be required to bear. Strict conformity to loading standards recommended in this Code, it is hoped, will not only ensure the structural safety of the buildings which are being designed and constructed in the country and thereby reduce the hazards to life and property caused by unsafe structures, but also eliminate the wastage caused by assuming unnecessarily heavy loadings. Notwithstanding what is stated regarding the structural safety of buildings, the application of the provisions should be carried out by competent and responsible structural designer who would satisfy himself that the structure designed in accordance with this code meets the desired performance requirements when the same is carried out according to specifications.

0.3.1 With the increased adoption of the Code, a number of comments were received on the provisions on live load values adopted for different occupancies. Simultaneously live loads surveys have been carried out in America, Canada and other countries to arrive at realistic live loads based on actual determination of loading( movable and immovable ) in different occupancies. Keeping this in view and other developments in the field of wind engineering, the Sectional Committee responsible for the preparation of this standard has decided to prepare the second revision in the following five parts: Part 1 Dead Loads Part 2 Imposed Loads Part 3 Wind Loads Part 4 Snow Loads Part 5 Special Loads and Load Combinations Earthquake load is covered in IS : 1893-1984* which should be considered along with the above loads. 0.3.2 This part ( Part 4 ) deals with snow loads on roofs of buildings. The committee responsible for the preparation of the code while reviewing the available snow-fall data, felt the paucity of data on which to make specific recommendations on the depth of ground snow load for different regions effected by snow-fall, In due course the characteristic

0.3 This Code was first published in 1957 for the guidance of civil engineers, designers and architects associated with the planning and design of buildings. It included the provisions for the basic design loads ( dead loads, live loads, wind loads and seismic loads ) to be assumed in the design of buildings. In its first revision in 1964, the wind pressure provisions were modified on the basis of studies of wind phenomenon and its effects on structures undertaken by the special

*Criteria for earthquake resistant designing of struetrues (fourth revision ). 1

IS:875(Part4)-1987 ‘Basis for design of structures - Determination of snow loads on roofs’, issued by the International Organization for Standardization.

snow load on ground for different regions will be included based on studies. 0.4 This part is based on IS0 4355-198 1 ( E )

where

1. SCOPE

s = design snow load in Pa on plan area of roof, p = shape coefficient ( see 4), and

1.1 This standard (Part 4) deals with snow loads on roofs of buildings. Roofs should be designed for the actual load due to snow or for the &posed loads specified in Part 2 Imposed loads, whichever is more severe.

so = ground snow load in Pa ( 1 Pa = lN/ma ). NOTE - Ground snow load at any place depends on the critical combinati.m of the maximum depth of un-

NOTB - Mountainous regions in northern parts of India are subjected to snow-fall. In India, parts of Jammu and Kashmir ( Baramulah District, Srinagar District, Anantnag District and Ladakh District ); Punjab, Himachal Pradesh ( Chamba, Kulu, Kinnaur District, Mahasu District, Mandi District, Sirmur District and Simla District ); and Uttar Pradesh ( Dehra Dun District, Tehri Garhwal District, Almora District and Nainital District ) experience snow-fall of varying depths two to three times in

disturbed aggregate cumulative snow-fall and its average density. In due course the characteristic snow load on ground for different regions will be included based on studies. Till such time the users of this standard are advised to contanct either Snow and Avalanches Study Establishment ( Defence Research and Development Organization ) Manali ( HP) or Indian Meteorological Department ( IMD ), Pune in the absence of any specific information for any location.

a year.

2. NOTATIONS

4. SHAPE COEFFICIENTS

p ( Dimensionless) - Nominal values of the shape coefficients, taking into account snow drifts, sliding snow, etc, with subscripts, if necessary. Ij ( in metres )

- Horizontal dimensions with numerical subscripts, if necessary.

hj ( in metres )

- Vertical dimensions with numerical subscripts, if necessary.

. fii (in degrees)

- Roof slope.

so (in pascals )

- Snow load on ground.

SI

- Snow load on roofs.

( in pascals )

4.1 General Principles In perfectly calm weather, falling snow would cover roofs and the ground with a uniform blanket of snow and the design snow load could be considerd as .a uniformly distributed load. Truly uniform loading conditions, however, are rare and have usually only been observed in areas that are sheltered on all sides by high trees, buildings, etc. In such a case, the shape coefficient would be equal to untiy. In most regions, snow falls are accompanied or followed by winds. The winds will redistribute the snow and on some roofs, especially multilevel roofs, the accumulated drift load may reach a multiple of the ground load. Roofs which are sheltered by other buildings, vegetation, etc, may collect more snow load than the ground level. The phenomenon is of the same nature as that illustrated for multilevel roofs in 4.2.4. So far sufficient data are not available to determine the shape coefficient in a statistical basis. Therefore, a nominal value is given. A representative sample of rcof is shown in 4.2. However, in special cases such as strip loading, cleaning of the roof periodically by deliberate heating of the roof, etc, have to be treated separately.

3. SNOW LOAD IN ROOF (S) 3.1 The minimum design snow load on a roof area or any other area above ground which is subjected to snow accumulation is obtained by multiplying the snow load on ground, s, by the shape coefficient CL, as applicable to the particular roof area considered.

The distribution of snow in the direction parallel to the eaves is assumed to be uniform.

S=c(S0

2

4.2 Shape Coefficients for Selected Types of Roofs Simple Pitched Roofs (Positive Roof Slope)*

Simple Flat and Monopitch Roofs

4.2.1

t+.= p, =O.% t'2~=0.8+04(~)

p, = 0.8

jL, =0*8

Simple or Multiple Pitched Roofs (Negative Roof Slope)

4.2.2

E

Two-Span or Multispan Roofs

o*
Pl**

3&#<6 49>60*

l

pp1-6 m-0

For.asymmetrical simple Pitched roofs, each side of the roof shall be treated as me half of corresponding

symmetwal roofs.

3

Is:875(Partl)-1987 4.2.3 Simple Curved Roofs

The following cases 1 and 2 must be examined:

CASE 2 Restriction: h60’

4

Is:875(Part4)-1987 4.2.4 Multilevel Roofs*

91 = 0’8

Bs = Ps + Pa

where A - due to sliding pw - due to wind = 1, 2ht but is restricted as follows: SmCls
with the restriction 0.8 < pw ( 4’0 where is in metres is in kilopascals ( kilonewtons per square metre ) so k =2kN/m8 h

p > 19” : ps is determined from an additional load amounting to SO percent of the maximum total load on the adjacent slope of the upper roofs, and is distributed linearly as shown on the figure. B < 15” : ps = 0 *A more extensive formula for pw is described in Appendix A. tlf 1~ < I,. the coe5cient p is determined by interpolation between JJ, and ps. SThe load on the upper roof is calculated according to 4.2.1 or 4.2.2.

5

4.25 Complex Multilevel Roofs

c

1, - 2h1: h - 2h,: p1 - 0’8 Restriction:

Sm< I,< Urn; Sm
6

I.S:875(Part4)-1987 4.2.6 Roofs with Local Projections and Obstructions

where /I is in metres sO is in kilopascals (kilonewtons per square metre) k I= 2 kN/ma /I1 = 0.8 1=2/l Kestrictions: 0’8 < /Ia < 2-O Sm41615m

4.3 Shape Coefficients in Areas Exposed to Wind

a) Winter calm valleys in the mountains where some-

The shape coefficients given in 4.2 and Appendix A may be reduced by 25 percent provided the designer has demonstrated that the following conditions are fulfilled: 4 The building is located in an exposed location such as open level terrain with only scattered buildings, trees or other obstructions so that the roof is exposed to the winds on all sides and is ndt likely to become shielded in the future by obstructions higher than the roof within a distance from the building equal to ten times the height of the obstruction above the roof level; b) The roof does not have any significant projections such as parapet walls which may prevent snow from being blown off the roof. NOTE - In some areas, winter climate may not be of such a nature as to produce a significant reduction of roof loads from the snow load on the ground. These areas are:

7

times layer after layer of snow accumulates on roofs without any appreciable removal of snow by wind; and b) Areas (that is, high temperature) where the maximum snow load may be the result of single snowstorm, occasionally without appreciable wind removal. In such areas, the determination of the shape coefficients shall be based on local experience with due regard to the likelihood of wind drifting and sliding.

5. ICE LOAD ON WIRES 5.1 Ice loads are required to be taken into account in the design of overhead electrical-transmission and communication lines, over-head contact lines for electric traction, aerial masts and similar structures in zones subjected to ice formation. The thickness of ice deposit alround may be taken to be between 3 and 10 mm depending upon the location of the structure. The mass density of ice may be assumed to be equal to O-9 g/cm”. While considering the wind force on wires and cables, the increase in diameter due to ice formation shall be taken into consideration.

IS:875(Part4)-1987

APPENDIX

A

( Clauses 42.4 and 4.3 ) SHAPE COEFFICIENTS FOR MULTILEVEL ROOFS A more comprehensive formula for the shape coefficient for multilevel roofs than that given in 4.2.4 is as follows: -OIRECTIONS WIN0

c

Pr

-1+ + ( ml iI + mI 1, )( 1, - 2 h )

Cl = 0’8 i,=hh fh and I being in metres) Restriction :

where so is in kilopascals (kilonewtons per square metre) k is in newtons per cubic metre I,< ISm Values of m, ( mr ) for the higher ( lower ) roof depend on its profile and are taken as equal to: 0.5 for plane roofs with slopes @ < 20’ and vaulted roofs with f< +0’3 for plane roofs with slopes p > 20” and vaulted roofs with f >$ The coefficients m, and ma may be adjusted to take into account conditions for transfer of snow on the roof surface ( that is, wind, temperature, etc. ). NOTE - The other condition of loading also shall be tried.

Bureau of Indian Standards BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country. Copyright BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary detaik, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publication), BIS. Review of Indian Standards Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards Monthly Additions’.

Amendments Issued Since Publication Amend No.

Date of Issue

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IS : 875( Part 5 ) - 1997 ( Reeed 1997 )

Indian Standard

CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURES PART 5 SPECIAL LOADS AND COMBINATIONS

( Second Revision ) Fourth Reprint NOVEMBER 1997

UDC

BURRAU MANAK

624'042:006'76

IS : 875 ( Part 5 ) - 1987

Igdian Standard CODE OF PRACTICE F6R DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURES PART 5 SPECIAL LOADS AND LOAD COMBINATIONS ( Structural

Second Revision ) Safety Sectional

Committee,

BDC

37

R~prcssnting

Chqirman BBIQ DE L. V. RAYAKRI~~NA

Engineer-in-Chief’s New Delhi

Branch,

Army Headquarters,

MNl?lbrrt Bharat Heavy Electricals Limited, Corporate Research & Development Division, Hyderabad SHBI M. S. BHATIA In perronal capacity ( A-2136, Safdarjang Enclave, New Delhi ) SHEI N. K. BEATTACEABYA Engineer-in-Chief’s Branch, Army Headquarters, New Delhi SHBI S. K. MALHOTI~A [ Allsraals 1 DE S. C. CHAKRABARTI den;tr~rk~t$lding Research Institute ( CSIR ),

DR K. G. BHATIA

SHBI A. DAT~A ( Alfernate ) CHIEF ENQINEEB ( ND2 ) II Central Public Works Department, New Delhi STJPERINTBNDINQSURVEYOR OF WOBKE ( NDZ ) II ( Altsrnats 1 DE P. DAYABATNAM Indian Institute of Technology, Kanpur DB A. S. R. SAI ( Altarnats ) Bombay, D~UTY MUNICIPAL COYMISSI- Municipal Corporation of Greater ONpa ( ENQo ) Bombay CITY ENQINEI~R ( Altern& ) DIBEOTOR ( CMDD-I ) Central Water Commission, New Delhi DEPUTY DIBEC~O~ ( CMDD-I ) ( Altcmats ) MAJ-Gm A. M. GOQLEKAB Institution of Engineers ( India ), Calcutta PBO~ D. N. TBIKHA ( Altmnatr j ( Continurd on page 2 ) 0 BUREAU

coplright 1988

OF INDIAN

STANDARDS

This publication is protected under the Zndian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.

IS : 875 ( Part 5 ) - 1987 ( Continasdfrom @gc 1 ) Members S~nr

Rep.wnting

A. C. GWPTA

Nati;:

Snap P. SEN GUPTA Soar M. M. Grtosn ( Aft~r~k SHBI G. B. JAHAQIRDAR J o I N T DIRECTOR STANDARDS (B&S ), CB Sxsr S. P. JO~HI SHRI A. P. MULL ( Alternate ) SHBI S. R. KTJLKARNI Saal S. N. PAL ( Alternate ) SEW H. N. MISHBA

DzIymal

Power

StewaFts and Lloyda )

National Industrial Ltd, New Delhi Ministry of Railways

Corporation

of India Ltd, Calcutta Development

Tata Consulting

Engineers,

M. N. Dastur

& Co, Calcutta

Forest Research Dun

Ltd,

Institute

Corporation

New Delhi

and

Colleges,

SHBI R. K. PUNEANI ( Alternate ) Engineers India Ltd, New Delhi SHRI T. K. D. MUNSHI National Council for Cement & DR C. RAJKU~A~ Materials, New Delhi Da M. N. KESHWA RAO Struc;;;iaxrgineering Research Centre

Debra

Building

( CSIR 1.

SHBI M. V. DHABAIVEEPATEY ( Altcrnafu ) SHRI T. N. SUBBA RAO Gammon India Ltd, Bombay DR S. V. LONEAR ( Alkrnafr ) SBEI P. K. RAY Indian Engineering Association, Calcutta SHRI P. K. MUKHERJEE ( Altcrnofe ) SHRI S. SEETEAR~MAN Ministry of Surface Transport ( Roads Wing ), New Delhi SHRI S. P. CEAKRABORTY \ Alternate ) Srrnr M. C. SHARMA Indian Meteorological Department, New Delhi SHRI K. S. SRINIVAYAN National Buildings Organization, New Delhi SHLU A. K. LAL ( Altcrnafc) SHRI SUSHIL Knri~ National Building Construction Corporation Ltd, New Delhi Snnr G. RAMAN. Director General, BIS ( Ex-o&io Mmbcr ) Director ( Civ’Engg ) SHRI B. R. NARAYANAPPA Deputy Director ( Civ Engg ), BIS

( Conlinud on page 18 )

2

IS t 875( Part 5 ) - 1987

Indian Standard CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURES PART 5

SPECIAL LOADS AND LOAD COMBINATIONS

( Second Revision ) 0.

FOREWORD

0.1 This Indian Standard ( Part 5 ) ( Second Revision ) was adopted by the Bureau of Indian Standards on 3 1 August 1987, after the draft finalized by the Structural Safety Sectional Committee had been approved by the Civil Engineering Division Council. 0.2 A building has to perform many functions satisfac orily. Amongst these functions are the utility of the building for the intended use and with hygienic, occupancy, structural safety, fire safety; and compliance ganitation, ventilation and day light standards. The design of the building is dependent upon the minimum requirements prescribed for each of the above functions. The minimum requirements pertaining to the structural safety of buildings are being covered in this code by way of laying down minimum design loads which have to be assumed for dead loads, imposed loads, snow loads and other external loads, the structure would be required to bear. Strict conformity to loading standards recommended in this will not only ensure the structural safety of the buildings code, ‘It is hoped, which are being designed and constructed in the country and thereby reduce the hazards to life and property caused by unsafe structures, but also eliminate the wastage caused by assuming unnecessarily heavy loadings. Notwithstanding what is stated regarding the structural safety of buildings, the application of the provisions should be carried out by competent and responsible structural designer who would satisfy himself that the structure designed in accordance with this code meets the desired performance requirements when the same is carried out according to specifications. 0.3 This standard code of practice was first published in 1957 for the guidance of civil engineers, designers and architects associated with planning and design of buildings. It included the provisions for basic design 3

IS t 875 ( Part 5 ) - 1987 loads ( dead loads, live loads, wind loads and seismicloads ) to be assumed in the design of buildings. In its first revision in 1964, the wind pressure provisions were modified on the basis of studies of wind phenomenon and its effects on structures, undertaken by the special committee in consultation with the Indian Meteorological Department. In addition to this, new clauses on wind loads for butterfly type structures were included; wind pressure coefficients for sheeted roofs both curved and sloping were modified; seismic load provisions were deleted ( separate code having been prepared ) and metric system of weights and measurements was adopted. 0.3.1 With the increased adoption of the code, a number of comments were received on the provisions on live load values adopted for different occupancies. Simultaneously live load surveys have been carried out in America, Canada and other countries to arrive at realistic live loads based on actual determination of loading ( movable and immovable ) in different occupancies. Keeping this in view and other developments in the field of wind engineering, the committee responsible for the preparation of the standard decided to prepare second revision in the following five parts: Part 1 Dead loads Part 2 Imposed loads Part 3 Wind loads Part 4 Snow loads Part 5 Special loads and load combinations. Earthquake load is covered in a separate standard, namely IS : 1893 1984* which should be considered along with the above loads. 0.3.2 This code ( Part 5 ) deals with loads and load effects ( other than those covered in Parts 1 to 4, and seismic loads ) due to temperature changes, internally generating stresses ( due to creep, shrinkage, differential settlement, etc ) in the building and its components, soil and hydrostatic pressure, accidental loads, etc. This part also includes guidance on load combinations. 0.4 The code has taken into account the prevailing practices in regard to loading standards followed in this country by the various municipal authorities and has also taken note of the developments in a number of countries abroad. In the preparation of this code, the following national standards have been examined: a) National Building Code of Canada ( 1977 ) Supplement Canadian Structural Design Manual. *Criteria for earthquakeresistantdesignof structures( thirdrenision ). 4

No. 4.

I& : 835 ( Part 5 ) - 1987

4

DS 410-1983 Code of practice for loads for the design of structures. Danish Standards Institution. NZS 4203-1976 New Zealand Standard General structural design and design loading for building. Standards Association of New Zealand.

4

ANSI A 58.1-1982 American Standard Building code requirements for minimum design loads in buildings and other structures.

b)

i. SCOPE 1.1 This code ( Part 5 ) deals with loads and load effects due to temperature changes, soil and hydrostatic pressures, internally generating stresses ( due to creep, shrinkage, differential settlement, etc ), accidental loads etc, to be considered in the design of buildings as appropriate. This part also includes guidance on load combinations. The nature of loads to be considered for a particular situation is to be based on engineering judgement. 2. TEMPERATURE

EFFECTS

2.1 Expansion and contraction due to changes in temperature of the materials of a structure shall be considered in design. Provision shall be made either to relieve the stress by provision of expansion/contraction joints in accordance with IS : 3414-1968* or design the structure to carry additional stresses due to temperature effects as appropriate to the problem. 2.1.1 The temperature range varies for different regions and under different diurnal and seasonal conditions. The absolute maximum and minimum temperature which may be expected in different localities in the country are indicated in Fig. 1 and 2 respectively. These figures may be used for guidance in assessing the maximum variations of temperature. 2.1.2 The temperatures indicated in Fig. 1 and 2 are the air temperatures in the shade. The range of variation in temperature of the building materials may be appreciably greater or less than the variation of air temperature and is influenced by the condition of exposure and the rate at which the materials composing the structure absorb or radiate heat. This difference in temperature variations of the material and air should be given due consideration. 2.1.3 The structural analysis must take into account: (a) changes of the mean ( through the section ) temperature in relation to the initial temperature ( st ), and (b) the temperature gradient through the section, *Code of practice for designand installationofjoints in buildings.

5

fS t 835 ( Part 5 ) - 19&t

The territorial measllred from Based upon

Survey

~0 Government Responsibility

waterr of India the appropriate of India

of India

map

Copyright

for the correctness

FIG. 1

extend into base line. with

the sea to a distance

the permission

of

of the Surveyor

twelve

nautical

General

of India.

1993 of internal

details

rests with the publishers,

CHART SHOWINGHIGHESTMAXIMUMTEMPERATURE 6

milar

IS I 875 ( Part 5 ) - 1987

?2

60

6

,/.s

I I

76 \.

60 \

\

66 I

I

‘,.

66

92

MAP

The territorial waters of India extend into the sea to a distance measured from the appropriate base line.

Baaedupon Survey of India map with the permission Q Government Responsibility

of India Copyright for the correctness

Fxo.

2

CHART

%

OF INDIA

of twelve

of the Surveyor

General

1

nautical of India.

1993 of internal

&~Y,v~N~

details

rests with the publishers.

LOWESTMINIMUMTEMPERATURE 7

miles

IS : 875 (. Part 5 ) - 1981 2.1.3.1 It should be borne in mind that the changes of mean temperature in relation to the initial are liable to differ as between one structural element and another in buildings or structures, as for example, between the external walls and the internal elements of a building. The distribution of temperature through section of single-leaf structural elements may be assumed linear for the purpose of analysis. 2.1.3.2 The effect of mean temperature changes tl, and ts, and the temperature gradients u1 and vs in the hot and cold seasons for single-leaf structural elements shall be evaluated ori the basis of analytical principles. Nom 1 - For portions of the structure below ground level, the variation of temperature is generally insignificant. However, during the period of construction when the portions of the structure are exposed to weather elements, adequate provision should be made to encounter adverse effects, if any. NOTE 2 - If it can be shown by engineering principles, 0; if it is known from experience, that neglect of some or all the effects of tern erature do not affect the structural safety and rerviceability, they need not be cons~3 ered in design.

3. HYDROSTATIC

AND SOIL PRESSURE

3.1 In the design ofstructures or parts of structures below ground level, such as retaining walls and ‘other walls in basement floors. the pressure exerted by soil or water or both shall be duly accounted for on the basis of established theories. Due allowance shall be made for possible surcharge from stationary or moving loads. When a portion or whole of the soil is below the free water surface, the lateral earth pressure shall be evaluated for weight of soil diminished by buoyancy and the full hydrostatic pressure. 3.1.1 All foundation slabs and other footings subjected to water pressure shall be designed to resist a uniformly distributed uplift equal to the of overturning of foundation under full hydrostatic pressure. Checking considering buoyant wei ght of submerged condition shall be done foundation. 3.2 While determining the lateral soil pressure on column like structural members, such as pillars which rest in sloping soils, the width of the member shall be taken as follows ( see Fig. 3 ): Ratio of Effective Width to Actual Width

Actual Width of Member

Beyond 0.5 m and up to 1 m

3-o 3.0 to 2.0

Beyond

2-o

Less than O-5 m 1m

The relieving pressure of soil in front of the concerned may generally not be taken into account.

8

structural

member

-f

IS : 875 ( Part 5 ) - 1987

2b TO 3b

c

Fro. 3

SKETCH SHOWING EFFECTIVE WIDTH OF PILLAR FOR CALCULATINO SOIL PRESSURE

3.3 Safe guarding ing and horizontal able effect shall be lr~z~t;;; to the

of structures and structural members against over-tumsliding shall be verified. Imposed loads having favot+ disregarded for the purpose. Due consideration shall possibility of soil being permanently or temporarily

4. FATIGUE 4.1 General - Fatigue cracks are usually initiated at points of high stress concentration. These stress concentrations may be caused by or associated with holes ( such as bolt or rivet holes in steel structures ), welds including stray or fusions in steel structures, defects in materials, and local and general changes in geometry of members. The cracks usually propogate if loading is continuous. Where there is such loading cycles, sudden changes of shape of a member or part of a member, specially in regions of tensile stress and/or local secondary bending, shall be avoided, Suitable steps shall be taken to avoid critical vibrations due to wind and other causes. 4.2 Where necessary, permissible stresses shall be reduced to allow for the effects of fatigue. Allowance for fatigue shall be made for combinations of stresses due to dead load and imposed load. Stresses due to wind and earthquakes may be ignored when fatigue is being considered unless otherwise specified in the relevant codes of practice. 9

18:875(Part5)-1687 Each element of the structure shall be designed for the number of stress cycles of each magnitude to which it is estimated that the element is liable to be subjected during the expected life of the structure. The number of cycles of each magnitude shall be estimated~ in the light of available data regarding the probable frequency of occurrence of each type of loading. NOTB- Apart from the general observations made herein the code is unable to provide any precise guidance in estimating the probablistic behaviour and response of structures of various types arising out of repetitive loading approaching fatigue conditions in structural members, joints, materials, etc.

5. STRUCTURAL

SAFETY DURING

CONSTRUCTION

5.1 All loads required to be carried by the structures or any part of it due to storage or positioning of construction materials and erection equipment including all loads due to operation of such equipment, shall be considered as erection loads. Proper provision shall be made, including temporary bracings to take care of all stresses due to erection loads. The structure as a whole and all parts of structure in conjunction with the temporary bracings shall be capable of sustaining these erection loads without exceeding the permissible stresses specified in respective codes of practice. Dead load, wind load and such parts of imposed load as would be imposed on the structure during the period of erection shall be taken as acting together with erection loads. 6. ACCIDENTAL

LOADS

6.0 General-The occurrence of accidental loads with a significant value, is unlikely on a given structure over the period oftime under consideration, and also in most cases is of short duration. The occurrence of an accidental load could in many cases be expected to cause severe consequences unless special measures are taken: The accidental following:

loads arising out of human

action

include

the

a) Impacts and collisions, b) Explosions, and c) Fire. Characteristic of the above stated loads are that they are not a comequence of normal use and that they are undesired, and that extensive efforts are made to avoid them. As a result, the probability of occurrence of an accidental load is small whereas the consequences may be severe. 10

IS: 875 (Parts)-

1987

The causes of accidental loads may be: a) inadequate safety of equipment ( due to poor design or poor maintenance ); and b) wrong operation ( due to insufficient teaching or training, indisposition, negligence or unfavourable external circumstances ). In most cases, accidental loads only develop under a combination of several unfavourable occurrence. In practical applications, it may be nccessary to neglect the most unlikely loads. The probability of occurrence of accidental loads which are neglected may differ for different consequences of a possible failure. A data base for a detailed calculation of the probability will seldom be available. NOTE- Dcfcrmination of Accidsrrtal Loads - Types and magnitude of accidental loads should preferably be based on a risk analysis. The analysis should consider all preventive measures for factors influencing the magnitude of the action, including accidental situations. Generally, only the principal load bearing system need be designed for relevant ultimate limit statea.

6.1 Impacts

and Collisions

6.1.1 General - During an impact, the kinetic impact energy has to be absorbed by the vehicle hitting the structure and by the structure itself. In an accurate analysis, the probabihty of occurrence of an impact with a certain energy and the deformation characteristics of the object hitting the structure and the structure itself at the actual place nhust be considered. Impact energies for dropped objects should be based on the actual loading capacity and lifting height.

Common sources of impact are: a) vehicles; b) dropped objects from cranes, fork lifts, etc; c) cranes out of control, crane failures; and d) flying fragments. The codal requirements regarding impact from

are given in 6.1.2 and 6.1.3.

vehicles and cranes

6.1.2 Collisions Between Vehicles and Structural Elements - In road tra&z, the requirement that a structure shall be able to resist collision may be assumed to be fulfilled if it is demonstrated that the structural element is able to stop a fictitious vehicle, as described in the following. It is assumed that the vehicle strikes the structural element at height of 1.2 m in any possible direction and at a speed of 10 m/s ( 36 km/h ). 11

IS : 875 ( Part 5 ) - 1987 The fictitious vehicle shall be considered to consist of two masses ml and ma which during compression of the vehicle produce an impact force increasing uniformly from zero, corresponding to the rigidities Cr and Cs. It is assumed that the mass ml is breaked completely before the braking of mass m, begins. The following numerical

values should be used:

ml = 400 kg, Cr = 10 000 kN per m the vehicle is compressed. ms = 12 no0 kg, C’s = 300 kN per m the vehicle is compressed. NOTE- The described fictitious collision corresponds in the case of a non-elastic structural element to a maximum static force of 630 kN for the mass ml and 600 kN for the mass ms irrespective of the elasticity. It will, therefore, be on the safe side to assume the static force to be 630 kN.

In addition, braking of the mass ml will result in an impact wave, the effect of which will depend to a great extent on the kind of structural element concerned. Consequently, it will not always be sufficient to design for the static force. 6.1.3 Safe0 Railings - With regard to safety railings put up to protect structures against collision due to road traffic, it should be shown that the railings are able to resist on impact as described in 6.1.2. NOTE - When a vehicle collides with safety railings, the kinetic energy of the veh+e will be absorbed in part by the deformation of the railings and, in part by the deformation of the vehicle. The part of the kinetic energy which the railings should be able to absorb without breaking down may be determined on the basis of the assumed rigidity of the vehicle during the compression.

6.1.4 Crane Impact Load on BuJer Stab - The basic horizontal load Py ( tonnes ), acting along the crane track produced by impact of the crane on the buffer stop, is calculated by the following formula: where V-

speed at which the crane is travelling at the moment of impact ( assumed equal to half the nominal value ) (m/s>; F = maximum shortening of the buffer, assumed equal to 0.1 m for light duty, medium-duty and heavy-duty cranes with flexible load suspension and loading capacity not exceeding 50 t, and O-2 m in every other cranes; and M - the reduced crane mass (t.s*/m); and is obtained by the formula: M

a-

(4 + Q)

; [++ 12

-Qq

IS z 875 ( Part 5 ) - 1987 where g = acceleration due to gravity ( 9.81 m/s* ); Ph = crane bridge weight (t); Pt = crab weight (t); k = a coefficient, assumed equal to zero for cranes with flexible load suspension and equal to one for cranes with rigid suspension; Q = crane loading capacity (t); Lk = crane span (m); and 1 = nearness of crab (m). 6.2 Explosions 6.2.1 General - Explosions may cause impulsive loading on a structure. The following types of explosions are particularly relevant: a) Internal gas explosions which may be caused by leakage of gas piping ( including piping outside the room ), evaporation from volatile liquids or unintentional evaporation from surface material ( for example, fire ); b) c) d) e)

Internal dust explosions; Boiler failure; External gas cloud explosions; and External explosions of high-explosives ( TNT, dynamite ).

The coda1 requirement regarding in 6.2.2.

internal gas explosions is given

6.2.2 Explosion Efect in Closed Rooms - Gas explosion may be caused, for example, by leaks in gas pipes ( inclusive of pipes outside the room ), evaporation from volatile liquids or unintentional evaporation of gas from wall sheathings ( for example, caused by fire ). NOTE 1 - The concentration of the the explosion. and with little possibility sures may occur.

effect of explosiona depends on the exploding medium, the explosion, the shape of the room, possibilities of ventilation of the ductility and dynamic properties of the structure. In rooms for relief of the pressure from the explosion, very large pres-

Internal overpressure from an internal gas explosion in rooms of sizes comparable to residential rooms and with ventilation areas consisting of window glass breaking at a pressure of 4 kN/m’ ( 3-4 mm machine made glass ) may be calculated from the following method: a) The overpressure is assumed to depend on a factor A/V, where A is the total window area in m’, V is the volume in m* of the room considered.

13

18:875(PartS)-1387 b) The internal prersure is assumed Room in one closed room.

to act simultaneously

c) The action q. may be taken M static

upon

all walls

and

action.

If account ir taken of the time curve of action, the following ( Fig. 4 ) rchematic correqondence between pressure and time is arrumed, where 11 is the time from the atart of combustion until maximum prerrure ia reached, and f, is the &me from maximum pressure to the end of comburtion. For 11 and t,. the most unfavourable valuer rhould be chosen in relation to the dynamic proper&a of the structures. However, the valuer should be chosen within the intervals as given in Fig. 5. Noxut 2 - Figure 4 is based on tertr with gar explosions in room corresponding to ordinary residential flats and rhould, therefore, not be applied to considerably different conditions. The figure corresponds to an explosion caurpd by town gas and it might therefore, be somewhat on the safe aide in rooms where there is only the poaSbility of gaKI with a lower rate of combustion. The prenure may he applied solely in one room or in more rooma at the same time. In the latter case, all room8 are incorporated in the volume V. Only windows or other similarly weak and light weight structural clementr may be taken to be ventilation areaa even through certain limited structural parts break at pressures less

than qO.

Figure 4 is given purely BS guide and probability of occurrence should be checked in each case using appropriate values.

of an explosion

6.3 Vertical Load on Air Raid Shelters 6.3.1 Characteristic Values - As regards buildings in which the individual floors are acted upon by a total characteristic imposed action of up to 5.8 kN/ma, vertical actions on air raid shelters generally locared below ground level, for example, basement, etc, should be considered to have the following characteristic values: a) Buildings with up to 2 storeys

28 kN/m*

b) Buildings with 3 to 4 storeys c) Buildings with more than 4 storeys d) Buildings of particularly stable construction irrespective of the number of storeys

34 kN/m* 41 kN/m* 28 kN/ms

In the case of buildings with floors that are acted upon by a characteristic imposed action larger than 5.0 kN/m*, the above values should be increased by the difference between the average imposed action on all storeys above the one concerned and 5-O kN/m*. NOTE 1 - By storeys it is understood,

every

utilizable

storey above the shelter,

NOTE 2 - By buildings of a particular stable construction it is understood, buildinFs in which the load-bearing atructurea are made from reinforced in-situ concrete,

14

IS : 875 ( Part 5 ) - 1987

A

-m V Flo.-4

SKETCHSHOWING

RELATIONB-N

-1

PRESSUREAND TIME

e IkN/m2) t

FICL 5 SKETCH

SHOWING

TIME INTERVAL

AND

PRESSURE

6.4 Fire 6.4.1 General - Possible extraordinary loads during a fire may be considered as accidental actions, Examples are loads from people along escape routes and loads on another structure from structure failing because of d tie. 6.4.2 Thermal Efect During Fire - The thermal effect during fire may be determined from one of the following methods: resistance required fire a) Time-temperature curve and the ( minutes ), or b) Energy balance method. If the thermal effect during fire is determined method, the fire load is taken to be: Q = 12tb 15

from energy balance

1s : 875 ( Part 5 ) - 1987 where q = tb =

fire action ( K J per m* floor ), and required fire resistance ( minutes ) ( see IS : 1642-1960*

).

The fire action is defined as the total quantity of heat produced by complete combustion of all combustible material in the fire compartment, inclusive of stored goods and equipment together with building structures and building materials. NOTE -

7. OTHER

LOADS

7.1 Other loads not included in the present code such as special loads due to technical process, moisture and shrinkage effects, etc, should be taken into account where stipulated by building design codes or established in accordance with the performance requirement of the structure.

8. LOAD COMBINATIONS 8.0 General - A judicious combination of the loads ( specified in Parts 1 to 4 of this standard and earthquake ), keeping in view the probability of: a) their acting together, and b) their disposition in relation to other loads and severity of stresses or deformations caused by combinations of the various loads is necessary to ensure the required safety and economy in the design of a structure. 8.1 Load Combinations - Keeping the aspect specified in 8.8, the various loads should, therefore, be combined in accordance with thestipulations in the relevant design codes. In the absence of such recommendations, the following loading combinations, whichever combination produces the most unfavourable effect in the building, foundation or structural member concerned may be adopted ( as a general guidance ). It should also be recognized in load combinations that the simultaneous occurrence of maximum values of wind, earthquake, imposed and snow loads is not likely, a) DL b) DL+IL c) DLf WL d) DL+EL

e) DL+TL f) DL+IL+

WL g) DL+IL+EL

*Code of

practice

for safety of buildings

construction.

16

( general

) : Materials

and

details

of

IS : 875 ( Part 5 ) - 1987 h) DL+ IL+ 71,

.i) DLi- WL-t_ TL k) DL+EL+ 7-L m) DL+ILfWL+TL n) DL+IL+EL+TL ( DL EL =

dead load, IL = imposed load, WL = wind load, earthquake load, IL = temperature load ).

=

NOTE 1 - When snow load is present on roofs, load for the purpose of above load combinations.

replace

imposed

load

by

snow

NOTE 2 - The relevant design codes shall be followed for permissible stresses when the structure is -designed by working stress method and for partial safety factors when the structure is designed by limit state design method for each of the above load combinations. NOTE 3 - Whenever imposed load (IL) is combined the appropriate part of imposed load as specified in IS both for evaluating earthquake effect and for combined combination.

with earthquake load (EL), should be used load effects used in such

: 1893- 1984f

NOTE 4For the purpose of stability of the structure as a whole against overturning, the restoring moment shall he not less than 1’2 times the maximum overturning moment due to dead load plus 1’4 times the maxrmum overturning moment dlle to imposed loads. In cases where dead load provides the restoring moment, only 0.9 times the dead load shall be considered. The restoring moments due to imposed loads shall be ignored. under times

shall have a factor against sliding NOTE 5 - The structure the most adverse combination of the applied loads/forces. the dead load shall be taken into account.

of not less than 1’4 In this case, only 0’9

NOTE 6 -‘Where the bearing pressure on soil due to wind alone is less than 25 percent of that due to dead load and imposed load, it may be neglected in design. Where this exceeds 25 percent foundation may be so proportioned that the pressure due to combined effect of dead load, imposed load and wind load does not exceed the allowable bearing pressure by more than 25 percent. When earthquake effect is included, the permissible increase is allowable bearing pressure in the soil shall be in accordance with IS : 1893-1984*. Reduced imposed load (IL) specified iti. Part 2 of this rtandard for the design of supporting structures should not be applied in combination with earthquake forces. load combinations NOTE 7 - Other loads and accidental with appropriately. are covered under NOTE 8 - Crane load combinations ( see 6.4 of Part 2 of this standard ).

not included

should

dealt

*Criteria

for earthquake

resrstant

design

of structures 17

(jourth

Part

2 of this standard

rsuision ).

be

IS : 875 CPart 5 ) - 1987

Panel on Loads ( Other than Wind Loads ), BDC 37 : P3 Repesenting

Convener

SHRI T.N. SUBBARAO DR S. V. LONKAR ( Altcrnafr )

Gammon

India Limited,

Bombay

Members SHRIS. R. E(ULEARN1 SHRI M. L. MEH~A SHRI S. K. DATTA ( Alternate ) SHRI T. V. S. R. APP~ RAO SHRI NAGESH R. DYER (Ahmfe SARI C. N. SRINIVASAN SUPERINTENDIXQ EXQINEER ( D )

M. N. Dastur 6 Co Ltd, Calcutta Metallurgical & Engineering Consultants Ltd, Ranchi Structural Engineering Campus, Madras

Research

( India )

Centre,

CSIR

)

C. R. Narayana Rao, Madras Central Public Works Department Designs Organization ), New Delhi

EXECUTIVE ENGINEER ( D ) VII ( AIternuta) National Council for Cement DR H. C. VISVESVARAYA Materials, New Delhi

and

( Central Building

BUREAU OF INDIAN STANDARDS Headquarters: Manak Bhavan, 9 Bahadur Shah Zafar Marg, NEW DELHI 110002 Telephones: 323 0131,323 3375,323 9402 Fax : 91 11 3234062,91 11 3239399,91 11 3239362 Telegrams : Manaksanstha (Common to all Offices) Telephone

Central Laboratory:

Plot No. 20/9, Site IV, Sahibabad Industrial Area, Sahibabad 201010 Regional Central ‘Eastern

6-77 0032

Uffices:

: Manak Bhavan, 9 Bahadur Shah Zafar Marg, NEW DELHI 110002 : 1114CIT Scheme,V!I M, V.I.P. Road, Maniktda, CALCUTTA 700054

Northern : SF0 335-336, Sector 34-A, CHANDIGARH

160022

32376 17 337 66 62 60 38 43

: C3.T. Campus, IV Cross Road, CHENNAI 600113 23523 15 .;.; <:; .‘; __ t Western : Manakalaya, E9, BeellTndMarobTelephone Exchange, Andheri (East), , 632 92 95 Southern

MUMBAI 400093 Brsnch Offices: ‘Pushpak’, Nurmohamed Shaikh Marg, Khanpur, AHMEDABAD 360001

550 13 48

$ Peenya Industrial Area, 1st Stage, Bangalore-Tumkur Road, _ BANGALORE 560056

a39 49 55

Gangotri Complex, 5th Floor, Bhadbhada Road, T.T. Nagar, BHOPAL 462003

554021

Plot No. 62-63, Unit VI, Ganga Nagar, BHUBANESHWAR 751001

40 36 27

Kalaikathir Buildings, 670 Avinashi Road, COIMBATORE 641037

21 01 41

Plot No. 43, Sector 16 A, Mathura Road, FARIDABAD 121001

a-28 66 01

Savitri Complex, 116 G.T. Road, GHAZIABAD 201001

6-71 1996

5315 Ward No. 29, R.G. Barua Road, 5th By-lane, GUWAHATI 761003

541137

5-6-56C, L.N. Gupta Marg, Nampally Station Road, HYDERABAD 500001

201083

E-52d Chkaranjan Marg. C-Scheme, JAIPUR 302001

37 29 25

lli’I416

21 66 76

B, Sarvodaya Nagar, KANPUR 206005

Seth Bhawan, 2nd Floor, Behind Leela Cinema, Naval Kishore Road, LUCKNOW 226001

23 69 23

NIT Building, Second Floor, Gokulpat Market, NAGPUR 440010

52 51 71

Patliputra Industrial Estate, PATNA 600013

26 23 05

Institution of Engineers (India) Building 1332 Shivaji Nagar, PUNE 411005

32 36 35

T.C. No. 14/1421, University PO. Palayam, THIRUVANANTHAPURAM

621 17

695034

‘Sales Office is at 5 Chowringhee Approach, PO. Princep Street, CALCUTTA 700072

271085

TSales Office is at Novelty Chambers, Grant Road, MUMBAI 400007

309 65 26

*Sales Office is at ‘F’ Block, Unity Building, Narashimaraja Square, .BANGALORE 560002

222 39 71

Printed at Simco Printing Press, Delhi

IS 875 ALL IN ONE

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