As 4055-2006 Wind Loads for Housing

LICENCE for AS 4055-2006 4055-2006 Wind loads for housing

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AS 4055—2006 4055—2006 (Incorporating Amendment No. 1)

. ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

A S 4 0 5 5 — 2 0 0 6

Australian Standard

®

Wind loads for housing

This Australian Standard® Standard® was prepared by Committee BD-099, BD-099, Wind Loads for Housing. It was approved on behalf of the C ouncil of Standards Australia on 7 November 2005. This Standard was published on 6 January 2006.


The following are represented represented on Committee Committee BD-099: • • • • • • • • • • • •

Australian Building Building Codes Board Australian Glass and and Glazing Association Australian Institute of Building Building Surveyors Australian Windows Association Association Building Designers Association of Australia Clay Brick and Paver Institute Concrete Masonry Association of Australia Cyclone Testing Station (JCU) Housing Industry Association Master Builders Australia National Timber Development Council Roofing Tile Association of Australia

This Standard was issued in draft draft form for comment comment as DR 04347. Standards Australia wishes to acknowledge the participation of the expert individuals that contributed to the development of this Standard through their representation on the Committee and through the public comment period.

Australian Standards® are are living documents documents that reflect progress in in science, technology and and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments that may have been published since the Standard was published. Detailed information about Australian Standards, drafts, amendments and new projects can be found by visiting Standards Australia welcomes suggestions for improvements, and encourages readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at , or write to Standards Australia, GPO Box 476, Sydney, NSW 2001.

AS 4055—2006 4055—2006 (Incorporating Amendment No. 1)


Australian Standard

®


First published as AS 4055—1992. Second edition 2006. Reissued incorporating Amendment Amendment No. 1 (July 2008).

COPYRIGHT

© Standards Australia All rig hts are res erv ed. No par t o f t his wor k m ay be rep rod uce d o r c opie d i n a ny for m o r b y any means, electronic or mechanical, including photocopying, without the written permission of the publisher. Published by Standards Australia GPO Box 476, Sydney, NSW 2001, Australia ISBN 0 7337 7087 8

AS 4 055— 2006

2

PREFACE


This Standard was prepared by the Standards Australia Committee BD-099, Wind loads for housing to to supersede AS 4055—1992. This Standard incorporates Amendment No. 1 (July 2008) . The changes required by the Amendm Ame ndment ent are indi cated in the text by a mar margin ginal al bar and amen amendme dment nt num number ber aga against inst the clause, note, table, figure or part thereof affected. This Standard will be referenced in the Building Code of Australia 2006 edition (BCA 2006), thereby superseding in part the previous edition, AS 4055—1992, which will be withdrawn 12 months from the date of publication of this edition. The objective of this Standard is to provide designers, builders and manufacturers of building products that are affected by wind loading with a range of wind speed classes that can be used to design and specify such products for use in housing that are within the limitations in this Standard. This edition differs from the previous edition as follows: (a)

Wind speeds are specified for the serviceability and ultimate strength/stability limit states only. Permissible stress has been omitted.

(b)

The Standard Standard has been updat updated ed to reflect the latest latest technical technical knowledge on wind forces as represented by the 2002 edition of AS/NZS 1170.2.

(c)

The table of classes for site conditions has been updated.

(d)

Pressure factors have been made normative and calculation calculation methods given for determining pressures and forces.

(e)

New racking tables have been included in limit states format.

(f)

A more detailed commentary has has been added (Appendix A) to clarify the relationship of this Standard to AS/NZS 1170.2 and to giv e background to some of the clauses.

The term ‘informative’ has been used in this Standard to define the application of the Appendix to which it applies. An ‘informative’ appendix is only for information and guidance. Not es to the text cont Notes contain ain info inform rmatio ation n and gui guidance dance . They are not an inte integr gral al par partt of the Standard.

3

AS 4 055— 2006

CONTENTS


Page SECTION 1 SCOPE AND GENERAL 1.1 SCOPE ............................... .................................................................. ..................................................................... ...................................................... .................... 4 1.2 LIMITATIONS .............................. ................................................................ .................................................................... ........................................... ......... 4 1.3 NORMATIVE REFERENCES................................................ REFERENCES.................................................................................. .................................... .. 4 1.4 DEFINITIONS .............................. ................................................................. ..................................................................... ........................................... ......... 5 1.5 NOTATION ............................. ............................................................... ..................................................................... ................................................. .............. 6 SECTION 2 WIND LOADS 2.1 CLASSIFICATION CLASSIFICATION ............................. ............................................................... .................................................................... ...................................... .... 8 2.2 RELATIONSHIP TO WIND REGION AND SITE CONDITIONS ............................ 8 2.3 SELECTION OF TERRAIN CATEGORY....................... CATEGORY......................................................... ......................................... ....... 11 2.4 SELECTION OF TOPOGRAPHIC CLASS ................................ .............................................................. .............................. 11 2.5 SELECTION OF SHIELDING CLASS............................................ CLASS..................................................................... ......................... 13 SECTION 3 CALCULATION OF PRESSURES AND FORCES FORCES 3.1 PRESSURE COEFFICIENTS ............................... ................................................................. .................................................... .................. 15 3.2 CALCULATION OF PRESSURES................ PRESSURES................................................... ........................................................... ........................ 16 3.3 CALCULATION OF FORCES .................................. .................................................................... ............................................... ............. 16 3.4 PRESSURES FOR TYPICAL APPLICATIONS.............................. APPLICATIONS....................................................... ......................... 17 SECTION 4 UPLIFT FORCES..................................................... FORCES....................................................................................... ......................................... ....... 19 SECTION 5 RACKING FORCES 5.1 RACKING FORCES .................................. .................................................................... ............................................................... ............................. 20 5.2 AREA OF ELEVATION ................................. ................................................................... .......................................................... ........................ 20 APPENDICES A COMMENTARY....................................... COMMENTARY..... .................................................................... ................................................................ .............................. 37 B WORKED EXAMPLE FOR THE DETERMINATION OF TOPOGRAPHY ........... 46 C WORKED EXAMPLES FOR THE SELECTION OF TERRAIN CATEGORY AND SHIELDING CLASS......................................................................... CLASS................................................................................................. ........................ 48 D WORKED EXAMPLE FOR RACKING FORCES ................................. ................................................... .................. 50

AS 4 055— 2006

4

STANDARDS AUSTRALIA

Australian Standard



S E C T I O N

1

S C O P E

A N D

G E N E R A L

1.1 SCOPE

This Standard specifies site wind speed classes for determining design wind speeds and wind loads for housing within the geometric limits given in Clause 1.2. The classes are for use in the design of housing and for design, manufacturing and specifying of building products and systems used for housing. Wind loads for houses not complying with the geometric limits given in Clause 1.2 are outside the scope of this Standard. NOTE S: 1

Commentary on the clauses of this Standard is given in Appendix A.

2

A worked example for the determination of topography is given in Appendix B.

3

Worked examples for the determination of terrain category and shielding class are given in Appendix C.

4

A worked example for racking forces is given in Appendix D.

5

Where houses do not comply with the geometric and other limitations of this Standard, use AS/NZS 1170.0 and AS/NZS 1170.2.

1.2

LIMITATIONS

For the purpose of this Standard, the following conditions (geometric limits) shall apply (see Figure 1.1): (a)

The distance from ground level to the underside of eaves shall not exceed 6.0 m from ground level to the highest point of the roof, neglecting chimneys shall not exceed 8.5 m.

(b)

The width (W ( W ) including roofed verandas, excluding eaves, shall not exceed 16.0 m, and the length ( L L)) shall not exceed five times the width.

(c)

The roof pitch shall not exceed 35°.

The tables in Section 5 are based on floor to ceiling height of 2.4 m and a floor depth of 0.3 m (floor level down to ceiling below). 1.3 NORMATIVE REFERENCES

The following referenced documents are indispensable for the application of this Standard:

©

AS/NZS 1170 1170.0 1170.2

Structural design actions Part 0: General principles Part 2: Wind actions

ABCB BCA

Building Code of Australia

Standards Australia

www.standards.org.au

AS 4 055— 2006

5

Eaves 900 mm max.

A1


Roof pitch 3 5 ˚ ˚ max.

Roof pitch 35˚ max. Height to top of roof, ridge or gable and 8.5 m max.

Height from ground level to underside of eaves except for gable ends 6.0 m max.

One or two storey 16.0 m max.

16.0 m max.

Height to eaves except gable ends 6.0 m max.

Height at any section through the house 8.5 m max.

(a) Sections

L W

L

16.0 m max.

5 W

W

16.0 m max. L

Edge of eaves External wall

L L W

16.0 m max.

(b) Plan view

FIGURE 1.1

GEOMETRY

1.4 DEFINITIONS

For the purpose of this Standard, the definitions below apply. 1.4.1 Average slope

Slope measured by averaging the steepest slope and the least slope through the top half of the hill, ridge or escarpment. 1.4.2 Bottom of hill, ridge or escarpment

Area at the base of the hill, ridge or escarpment, where the average slope is less than 1 in 20. 1.4.3 Height

Distance from ground level to the underside of eaves or to the highest point of the roof neglecting chimneys; or the height of each storey at external walls (see Figure 1.1).

ww w.s tan dard s.o rg. au

© Standards

Australia

AS 4 055— 2006

6

1.4.4 House

Class 1 or 10 building as defined by the Building Code of Australia (BCA) with the geometric limitations specified in Clause 1.2. . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

1.4.5 Length

Maximum overall distance between outside edges of the external walls of a house or shape (see Figure 1.1). 1.4.6 Plan

Basic rectangular-, square- or L-shaped layout, or simple combinations of these (see Figure 1.1). 1.4.7 Racking forces

Forces that occur in walls parallel to the wind direction. 1.4.8 Width

Maximum distance from wall to wall in the direction perpendicular to the length, including roofed verandas but excluding eaves (see Figure 1.1). 1.5 NOTATION

Unless otherwise stated, the notation used in this Standard shall have the following meaning: C1 to C4

= cyclonic wind classes

C1 serv to C4 serv = cyclonic wind classes for serviceability

A1

C p

= pressure coefficient (external, internal or net, as appropriate)

C p,e p,e

= external pressure coefficient

C p,i p,i

= internal pressure coefficient

C p,n p,n

= net pressure coefficient

d

= average horizontal distance distance measured from the crest of the escarpment escarpment or hill to the near top-third zone

FS, PS, NS

= shielding classes, full shielding, partial shielding and no shielding

G

= dead load; or permanent action (self-weight or ‘dead’ action)

©

H

= height of a hill, hill, ridge or escarpment escarpment

H 0

= maximum distance from the ground to the underside underside of the bearer bearer in the lower floor

h

= average roof height

h0

= half the height height of the wall (half of the floor to ceiling height)

K l

= local pressure factor

L, M, T, O

= lower, middle and top third of hill, ridge or escarpment and over-top zone for escarpments

L

= length length of a house; or lower part of a hill, ridge or escarpment

M s

= shielding multiplier

M t

= topographic multiplier

M 6.5,cat 6 .5,cat

= terrain category multiplier at height ( h)

Standards Australia


AS 4 055— 2006

7

N1 to N6

= non non-cy -cyclon clonic ic wind class classes es

N1 serv to N6 serv = non-cyclonic wind classes for serviceability A1


= design wind pressure pressure acting normal to a surface, in kilopascals qu

A1

A1

= free stream stream dynamic gust pressure, pressure, in kilopascals

Not applicable

TC1 to TC3

= terrain categories

T1 to T5

= topographic classes

V h

= design gust wind speed at height ( h)

V h,s h,s

= design gust wind speed at height ( h) for serviceability limit state

V h,u h,u

= design gust wind speed at height ( h) for ultimate strength limit state

W

= width of a house

W s

= serviceability wind action

W u

= ultimate wind action

α

= angle of roof pitch

φ a

= average slope measured by averaging the steepest slope and the least slope through the top half of the hill, ridge or escarpment

γ

= load factor

ρ air air

= density of air, which shall be be taken as 1.2 kg/m 3


© Standards

Australia

AS 4 055— 2006

8

S E C T I O N

2.1


2

W I N D

L O A D S

CLASSIFICATION

The system of 10 classes is set out in Table 2.1 together with the associated design gust wind speeds (V ( V h) for the serviceability and ultimate limit states. It incorporates both noncyclonic (N) and cyclonic (C) winds. TABLE 2.1 DESIGN GUST WIND SPEED ( V h ) FOR CLASSIFICATION Design gust wind speed ( V h) at height ( h) m/s

Win d c las s Regions A and B (non-cyclonic)

Regions C and D (cyclonic)

Serviceability limit state ( V h,s )

Ultimate limit state ( V h,u )

N1 N2 N3

— — C1

26 26 32

34 40 50

N4 N5 N6

C2 C3 C4

39 47 55

61 74 86

2.2 RELATIONSHIP TO WIND REGION AND SITE CONDITIONS

The selection of wind speed class for a house depends on the conditions at the site of the house. The class shall be determined from Table 2.2 using the following site conditions determined as stated:

©

(a)

Geographic wind speed region of the site as defined in Figure 2.1 (Region A, B, C or D, as given in AS/NZS 1170.2).

(b)

The terrain category that surrounds or is likely to surround the site within the next 5 years, as defined in Clause 2.3 (TC1, TC2, TC2.5 or TC3).

(c)

The topographic class of the site, as defined in Clause 2.4 (T1, T2, T3, T4 or T5).

(d)

The shielding class of the house, as defined in Clause 2.5 (FS, PS or NS).

Standards Australia


AS 4 055— 2006

9

TABLE 2.2 WIND CLASSIFICATION FROM WIND REGION AND SITE CONDITIONS Win d c las lasss . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Topographic class Win d region

TC

T1

T2

T3

T4

T5

FS

PS

NS

FS

PS

NS

FS

PS

NS

FS

PS

NS

FS

PS

NS

3

N1

N1

N1

N2

N2

N2

N2

N3

N3

N2

N3

N3

N3

N3

N4

2.5

N1

N1

N2

N2

N3

N3

N2

N3

N3

N3

N3

N4

N3

N4

N4

2

N1

N2

N2

N2

N3

N3

N3

N3

N3

N3

N4

N4

N4

N4

N4

1

N2

N3

N3

N3

N3

N4

N3

N4

N4

N4

N4

N4

N4

N5

N5

3

N2

N2

N3

N3

N3

N4

N3

N4

N4

N4

N4

N4

N4

N5

N5

2.5

N2

N3

N3

N3

N4

N4

N3

N4

N4

N4

N4

N5

N4

N5

N5

2

N2

N3

N3

N3

N4

N4

N4

N4

N5

N4

N5

N5

N5

N5

N6

1

N3

N4

N4

N4

N5

N5

N4

N5

N5

N5

N5

N6

N5

N6

N6

3

C1

C1

C2

C2

C2

C3

C2

C3

C3

C3

C3

C3

C3

C4

C4

2.5

C1

C2

C2

C2

C3

C3

C3

C3

C3

C3

C4

C4

C4

C4

NA

1,2

C2

C2

C2

C2

C3

C3

C3

C4

C4

C3

C4

C4

C4

NA

NA

3

C2

C3

C3

C3

C4

C4

C3

C4

C4

C4

NA

NA

NA

NA

NA

2.5

C2

C3

C3

C3

C4

C4

C4

NA

NA

C4

NA

NA

NA

NA

NA

C3

C3

C4

C4

NA

NA

C4

NA

NA

NA

NA

NA

NA

NA

NA

Region A

A

Region B

B

Region C

C

Region D

D

1,2

LEGEND: FS = full shielding PS = partial shielding NS = no shielding N = non-cyclonic C = cyclonic N/A N/ A = not applicable, that is, beyond the scope of this Standard (use AS/NZS 1170.2) TC = terrain category


© Standards

Australia

AS 4 055— 2006


10

) y l n o k e y r e r o C t i l r r l n o e e t T n n e ° n 1 o r o a B i l 1 D M c n a r M o t i g s u e A ° R ( 2 4 1

a b e e r a M

r n a o e b t l n r l i u e v D h t s A n w o T

C n o i g e R

e d i a r l e e v d i A R

n i w r a D

) C ( m a h d n y W

C n d o i n a s g l e d R s I n a s l a B I s C m n t o s n o s i o i i r g c g h e o e C R C R

©

° 0 2

C n o i g e R

Standards Australia

a l o o l o r r a o r r B u n u n u K e o h n a v I

m k 0 m m 5 k k 0 0 0 5 1 1

B g r e ° n e o n b 5 i a a 2 g b d e s n r R i u B B

n o t p m a h k c o R

a b m e o l o g w o o y o K T

a l e o l i B

e l l i v s n i l l o C

d n a l s B I k l n o o i f r g o e N R i d ° n 0 i r 3 o C

d n a l s I e w A o H n o i d r g o e L R

y e n d y S

e k r u o B

a r r e b n a C e d i a l e d A

a r e m o o W

n d w o n t a e l k e r r o u M B t s e W B

s g n i r p S e c i l A

n o i g e R

B n o i g e e R m o o r B

n o d y o r C

e l a S t s a E

D n o i g e R

n o i t c n u J e n a a y r w o r e l c a l s h u a t y M G t l a C

n o ° v r 5 a 2 n r a C

° 7 2

e i l r o o g l a K

e c n a r e p s E

i a d i h t r w y n e a r u P o G M

t r a b o H

° 0 4

e n r u o b l e M

r e i t b n u m o a M G

A n o i g e R

r a B e l b r m C a a M e n r i o t s g l l e i R M

° 0 2

° 5 3

y n a b l A

g n o l e e G

A n o i g e R

. y t i r a l c r o f d e v o m e r ° n 5 e e 4 b e v a h A n o i g e R f o s n o i g e r b u s n o i t c e r i d d n i w e h T . 2 . 0 7 1 1 S Z N / S A m o r f s i p a m s i h T : E T O N

n e d a e r e G H ° B 0 3 n o i g e R


D D N A C , B , A S N O I G E R F O S E I R A D N U O B 1 . 2 E R U G I F

11

AS 4 055— 2006

2.3 SELECTION OF TERRAIN CATEGORY

The terrain category for a housing site is a measure of the lowest effective surface roughness from any radial direction within a distance of 500 m of the proposed housing site. It shall be based on the likely terrain five years hence. . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

The terrain category for a housing site shall be identified by the notation TC1, TC2, TC2.5 or TC3 and shall be determined as follows: (a)

Terrain Category 1 (TC1) Exposed open terrain with few or no obstructions. This This condition exists only for isolated houses in flat, treeless, poorly grassed plains of at least 10 km width. This category is applicable for water surfaces for serviceability design.

(b)

Terrain Category 2 (TC2) Open terrain terrain including including sea coast areas, areas, airfields, airfields, grassland grassland with few well-scattered obstructions, such as isolated trees and uncut grass, having heights from 1.5 m to 10.0 m.

(c)

Terrain Category 2.5 (TC2.5) Terrain with with a few trees, isolated obstructions, such as agricultural land, cane fields or long grass, up to 600 mm high. This category is intermediate between TC2 and TC3 and represents the terrain in developing outer urban areas.

(d)

Terrain Category 3 (TC3) Terrain with numerous closely spaced obstructions having the size of houses. The minimum density of houses and trees, except for Regions C and D, shall be the equivalent of 10 house-size obstructions per hectare. Substantial well-established trees shall be considered as obstructions except in Regions C and D where a maximum of TC2.5 applies for the equivalent of 10 house-size obstructions per hectare.

In urban situations, roads, rivers or canals less than 200 m wide shall be considered to form part of normal ‘Terrain Category 3’ terrain. Parks and other open spaces less than 250 000 m 2 in area shall also be considered to form part of normal ‘Terrain Category 3’ terrain provided they are not within 500 m of each other, or not within 500 m of open country. Housing sites less than 200 m from the boundaries of open areas larger than these, e.g., golf courses, that are completely surrounded by urban terrain, shall be considered to have the terrain category applicable to the open area itself. Shielding provisions may still apply to these sites. Housing sites less than 500 m from the edge of a development shall be classified as the applicable terrain that adjoins the development, i.e., TC1, TC2, TC2.5 or TC3, as applicable. NOTE : Fo r work w ork ed e xam xample ple s, see App Append endix ix C.

2.4 SELECTION OF TOPOGRAPHIC CLASS

The topographic class determines the effect of wind on a house because of its location on a hill, ridge or escarpment and the height and average slope of the hill, ridge or escarpment. The topographic class for a housing site shall be identified by the notation T1, T2, T3, T4 or T5 and shall be determined from Table 2.3 and Figure 2.2. NOTE S: 1

The method defined in Table 2.3 and Figure 2.2 is suitable for the purpose of either mapping the wind classes of an area or assessing the wind class of an individual site.

2

For a worked example to determine topographic class, see Appendix B.


© Standards

Australia

AS 4 055— 2006

12

The bottom of a hill, ridge or escarpment shall be that area at the base of the hill, ridge or escarpment where the average slope is less than 1 in 20, e.g., creek, river valley or flat area. The average slope of a hill, ridge or escarpment ( φ a) shall be the slope measured by averaging the steepest slope and the least slope through the top half of the hill, ridge or escarpment.


NOTE S: 1

Often the average slope will not occur at the actual proposed housing site and should be appraised by considering the adjacent topography

2

For the determination of topography, see Appendix B.

The top-third zone (T) extends for an equal distance ( d ) either side of the crest of an escarpment as shown in Figure 2.2. The value of d is the average horizontal distance measured from the crest of the escarpment to the near top-third zone. A rise in terrain shall be considered an escarpment where one average slope is less than 1 in 20 and the other average slope is greater than 1 in 10. The over-top zone (O) of an escarpment shall be taken to extend to a distance of 4 H 4 H past past the crest of an escarpment. TABLE 2.3 TOPOGRAPHIC CLASSIFICATION FOR HILLS, RIDGES OR ESCARPMENTS Hill height ( H ) below which T1 applies for all sites on Ave rag ragee slo s lope pe Lowerthe hill, ridge or ( φ a ) third zone escarpment (L) (m) <1:10

H <

Mid-third zone (M)

Over-top zone (O) (for 4 H past past crest of escarpments only)

Top-third zone (T) H ≤ 30

m

>30 H >30

m

T1

T1

T1

T1

T1

20

T1

T1

T2

T2

T1

9

T1

T1

T2

T3

T1

≥ 1:10

<1:7.5

≥ 1:7.5

<1:5

H <

≥ 1:5

<1:3

—

T1

T2

T3

T4

T2

—

T1

T2

T4

T5

T3

≥ 1:3

©

All H

Site location (see Figure 2.2)

Standards Australia


AS 4 055— 2006

13

A1

d

d

T . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

H/3

Av e r ag e

s

lope

1:20

M

H/3

L

H/3

(a) Hills

d

d

T Av e r ag e

s

lope

1:10

O Av e ra g e

s

lope

1:20

H/3

Av e r a g e

s

lope

1:20 M

L

H/3

4 H

H/3

( b ) E s carpment s

LEGEND: = height of the hill, ridge or e s carpment d = average hori z ontal di s tance mea s ured from the c re s t of the e s carpment to the near top-third z o n e L = lower third of the hill, ridge or e s carpment M = middle third of the hill, ridge o r e s carpment T = top third of the hill, ridge or e s carpment O = overtop z one (for e s carpment only) H

FIGURE 2.2 TOPOGRAPHIC ZONES FOR AVERAGE SLOPE

2.5 SELECTION OF SHIELDING CLASS

Where the wind speed on a house is influenced by obstructions of similar size to the house, shielding shall be considered and shall be based o n the likely shielding five years hence. The shielding class for a housing site shall be identified by the notation FS, PS or NS, and shall be determined as follows: (a)

Ful l shie Full shieldi lding ng (FS (FS)) Full shielding shielding shall apply where at at least two rows of houses or similar size permanent obstructions surround the house being considered. In Regions A and B, heavily wooded areas provide full shielding.


© Standards

Australia

AS 4 055— 2006

14

The application of full shielding shall be appropriate for typical suburban development greater than or equal to 10 houses, or similar size obstructions per hectare. The effects of roads or other open areas with a distance measured in any direction of less than 100 m shall be ignored. However, the first two rows of houses abutting permanent open areas with a least dimension greater than 100 m, such as parklands, large expanses of water and airfields, shall be considered to have either partial shielding or no shielding.


(b)

Par tial shie Partial shieldin lding g (PS (PS)) Partial shielding shielding shall apply to intermediate intermediate situations situations where there are at least 2.5 houses, trees or sheds per hectare, such as acreage type suburban development or wooded parkland. In Regions C and D, heavily wooded areas shall be considered to have partial shielding.

(c)

No shie shieldi lding ng (NS (NS)) No shielding shall apply where there are no permanent obstructions or where there are less than 2.5 obstructions per hectare, such as the first two rows of houses or single houses abutting open parklands, open water or airfields.

NOTE : Fo r work w ork ed e xam xample ple s, see App Append endix ix C.

©

Standards Australia


AS 4 055— 2006

15

S E C T I O N

3

C A L C U L A T I O N A N D


O F

P R E S S U R E S

F O R C E S

3.1 PRESSURE COEFFICIENTS 3.1.1 Wind classes N1 to N6 (non-cyclonic)

For houses with wind classes N1 to N6 (in Regions A and B), the pressure coefficients in Table 3.1 shall be used. TABLE 3.1 PRESSURE COEFFICIENTS FOR WIND CLASSES N1 TO N6 (REGIONS A AND B FOR ULTIMATE STRENGTH AND SERVICEABILITY) Housing component

Factored external pressure coefficient ( C p,e K l )

Internal pressure coefficient ( C p,i )

Net pressure coefficient ( C p,n )

Roof (a)

General, including all trusses and rafters

(b)

Cladding, fasteners and immediate supporting members within 1200 mm of edges, e.g., battens and purlins

− 0.9

+0.4

0.2 − 0.3

− 1.1

+0.7

− 1.8

0.2

− 2.0

Wal ls (a) (b)

General, including all studs Cladding, fasteners and corner windows within 1200 mm of edges

+0.7 − 0.65

− 0.3

+0.2

+1.0 − 0.85

− 1.3

+0.2

− 1.5

3.1.2 Wind classes C1 to C4 (cyclonic)

For houses with wind classes C1 to C4 (i n Regions C and D) the following pressure coefficients shall be used: (a)

Internal pressure coefficients—Ultimate strength........................... C p,i p,i = 0.7 or − 0.65. Serviceab Servi ceability ility ................. .................................. .................................. .................................. .............................. ............. C p,i p,i = 0.2 or − 0.3.

(b)

Net pres pressur suree coeffi co efficien cients— ts—Ulti Ultimate mate stre strengt ngth h ... ... ... ... ... ... ... ... ... ... ... ..... ..... ... (se (seee Table Tab le 3.2) 3 .2)..


© Standards

Australia

AS 4 055— 2006

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TABLE 3.2 PRESSURE COEFFICIENTS FOR WIND CLASSES C1 TO C4 (REGIONS C AND D—CYCLONIC—FOR ULTIMATE STRENGTH) . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Factored external pressure coefficient ( C p,e K l )

Housing component

Internal pressure coefficient ( C p,i )

Net pressure coefficient ( C p,n )

Roof (a) (b)

General, including all trusses and rafters

− 0.9 +0.4

+0.7 − 0.65

− 1.6

Cladding, fasteners and immediate supporting members within 1200 mm of edges, e.g., battens and purlins

− 1.8

+0.7

− 2.5

− 0.65

− 1.35

+0.7

+0.7 − 0.65

− 1.3

+0.7

− 2.0

+1.05

Wal ls (a)

General, including all studs

(b)

Cladding, fasteners and corner windows within 1200 mm of edges

+1.35

3.2 CALCULATION OF PRESSURES A1

The design wind pressures ( p ( p), ), in kilopascals, shall be determined for structures and parts of structures as follows: p = p = q u C p

. . . 3.1

where A1

p

= design wind pressure pressure acting normal to a surface, in kilopascals NOTE : Pr es essur sures es are tak taken en as pos positi iti ve, indi cat ing pres sur sures es abov abovee amb ambien ientt and negative, indicating pressures below ambient.

qu A1

= free stream dynamic gust pressure = qu

=

0.5ρ air

[V ]

2

h

/ 1000

ρ air of air, air, which shall be taken as 1.2 1.2 kg/m air = density of V h C p

3

= design gust wind wind speed, as given in Table 2.1

= pressure coefficient, as given in Clause 3.1 (external, internal or net, as appropriate)

3.3 CALCULATION OF FORCES

The design wind forces shall be determined for structures and parts of structures by multiplying the pressure by the area under consideration and applying the resultant force at the centre of the area normal to the surface. NOTE : Ad dit dition ional al AS/NZS 1170.2.

inform inf ormati ati on

on

cal cul ati ating ng

press pre ssures ures

and

forc es

may

be

found fou nd

in

Uplift forces are determined by taking the uplift pressure (negative pressure coefficients indicate outward forces on a surface) by the total area of the roof (see Section 4). Racking forces are determined for the overall house by taking the appropriate vertical projected area and applied by distributing the force to the bracing walls or panels (see Section 5).

©

Standards Australia


AS 4 055— 2006

17

3.4 PRESSURES FOR TYPICAL APPLICATIONS

Based on the net pressure coefficients in Tables 3.1 and 3.2, ultimate limit state design pressures for the N and C categories are as given in Table 3.3. Serviceability limit state design pressures from N and C categories are as given in Table 3.4. . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

A1

TABLE 3.3 ULTIMATE STRENGTH PRESSURES FOR WIND CLASSIFICATION FROM THE NET PRESSURE COEFFICIENTS GIVEN IN CLAUSE 3.1 Wal ls

Win d c las lasss

Away fro m corners(1) C p,n =

1.0

Roo fs

Wit hin 1200 mm of corners(2)

Away fro m edg es (1) C p,n =

C p,n = − 1.5

C p,n = − 1.1

kPa

kPa

kPa

kPa

kPa

N1

0.69

− 1.04

− 0.76

0.49

− 1.39

N2

0.96

− 1.44

− 1.06

0.67

− 1.92

N3

1.50

− 2.25

− 1.65

1.05

− 3.00

N4

2.23

− 3.35

− 2.46

1.56

− 4.47

N5

3.29

− 4.93

− 3.61

2.30

− 6.57

N6

4.44

− 6.66

− 4.88

3.11

− 8.88

C p,n = − 1.35

C p,n = − 2.0

C p,n = − 1.6

C1

− 2.03

− 3.00

− 2.40

1.58

− 3.75

C2

− 3.01

− 4.47

− 3.57

2.34

− 5.58

C3

− 4.44

− 6.57

− 5.26

3.45

− 8.21

C4

− 5.99

− 8.88

− 7.10

4.66

− 11.09

C p,n =

0.7

Wit hin 1200 mm of edges(2)

1.05

C p,n = − 2.0

C p,n = − 2.5

NOT ES: 1

General area s, including wall studs more than 1200 mm from c orners and roof trusses and rafters more than 1200 mm from edges.

2

Areas of cladding and fasteners within 1200 mm of wall corners or roof edges; windows within 1200 mm of wall corners; immediate supporting members such as battens and purlins within 1200 mm of roof edges.


© Standards

Australia

AS 4 055— 2006

18

A1

TABLE 3.4 SERVICEABILITY PRESSURES FOR WIND CLASSIFICATION FROM THE NET PRESSURE COEFFICIENTS GIVEN IN CLAUSE 3.1


Wal ls

Win d c las lasss

Away fro m corners(1) C p,n =

1.0

Roo fs

Wit hin 1200 mm of corners(2) C p,n =

− 1.5

Away fro m edg es (1) C p,n = − 1.1

C p,n =

0.7

Wit hin 1200 mm of edges(2) C p,n = − 2.0

kPa

kPa

kPa

kPa

kPa

N1 serv

0.41

− 0.61

− 0.45

0.28

− 0.81

N2 serv

0.41

− 0.61

− 0.45

0.28

− 0.81

N3 serv

0.61

− 0.92

− 0.68

0.43

− 1.23

N4 serv

0.91

− 1.37

− 1.00

0.64

− 1.83

N5 serv

1.33

− 1.99

− 1.46

0.93

− 2.65

N6 serv

1.82

− 2.72

− 2.00

1.27

− 3.63

C1 serv

0.61

− 0.92

− 0.68

0.43

− 1.23

C2 serv

0.91

− 1.37

− 1.00

0.64

− 1.83

C3 serv

1.33

− 1.99

− 1.46

0.93

− 2.65

C4 serv

1.82

− 2.72

− 2.00

1.27

− 3.63

NOT ES:

©

1

General area s, including wall studs more than 1200 mm from c orners and roof trusses and rafters more than 1200 mm from edges.

2

Areas of cladding and fasteners within 1200 mm of wall corners or roof edges; windows within 1200 mm of wall corners; immediate supporting members such as battens and purlins within 1200 mm of roof edges.

Standards Australia


AS 4 055— 2006

19

S E C T I O N


4

U P L I F T

F O R C E S

Table 4.1 gives net design uplift pressures for the determination of anchoring requirements at tops of w alls. The pressures shall be applied as uplift on the entire roof surface. A1

TABLE 4.1 NET DESIGN UPLIFT PRESSURES, kPa Serviceability limit state

Ultimate strength limit state Roof type

Win d c las s Tile roof

Sheet roof (see Note 2)

Tile roof

Sheet roof (see Note 2)

N1 N2 N3

0 0 0

0.05 0.05 0.28

0.04 0.34 0.93

0.44 0.74 1.33

N4 N5 N6

0.10 0.56 1.10

0.60 1.06 1.60

1.74 2.89 4.16

2.14 3.29 4.56

C1 C2 C3

0 0.10 0.56

0.28 0.60 1.06

1.68 2.85 4.54

2.08 3.25 4.94

C4

1.10

1.60

6.38

6.78

NOTES NO TES : 1

The net desi gn uplift press ures given in Table 4.1 are based on the following load combinations: W s − G .

(a)

Serviceability limit state:

(b)

Ultimate strength limit state:

(c)

W u

W u −

γ G G .

and W s have been calculated as s et out in Section 3 where appropriate, using the pressure coefficients as given in Section 3.

2

Load combination factor γ = = 0.8.

3

= G =

4

Sheet roof includes metal tile roof.

0.9 kPa for tile roof,


= G =

V h = V h,u

or

V h,s

as

0.4 kPa for sheet roof.

© Standards

Australia

AS 4 055— 2006

20

S E C T I O N

5

R A C K I N G

F O R C E S

5.1 RACKING FORCES


Racking forces are lateral (horizontal) forces transferred to the foundations through bracing provided for each storey of the house and the subfloor. The forces occur in walls parallel to the wind direction and are calculated from the horizontal component of wind blowing on the external envelope of the house and resisted by bracing walls. Racking forces shall be calculated as follows: (a)

Determine the wind class as given in Section 2.

(b)

Determine area of elevation of the house as given in Clause 5.2.

(c)

Determine the wind pressure as given in Tables 5.1 for buildings presenting a fl at vertical ver tical surf surface ace to the win wind. d.

(d)

Determine the wind pressure as given in Tables 5.2 to 5.13 using the width (shorter dimension) of the building and roof pitch of the building being designed. Pressures are given for single storey and upper storey of two storeys for both long and short sides of the building, and for lower storey of two storeys or subfloor for both long and short sides of the building.

(e)

Calculate racking force, in kilonewtons, as follows: Total racking force = Area of elevation (m 2) × Lateral wind pressure (kPa).

The racking force shall be calculated for both directions (long and short sides) of the building. The total racking force for each storey or level of the building shall be determined as the sum of the forces on each of the areas facing the direction being considered. Racking forces shall be calculated to address the most adverse loading situation. NOTE S: 1

For intermediate values between those given in Tables 5.1 to 5.13, use linear interpolation.

2

For the explanation of Tables 5.1 to 5.13, see Appendix A.

3

For worked examples, see Appendix D.

5.2 AREA OF ELEVATION

Area of elevation appropriate for calculation of racking forces shall be as shown in Figures 5.1 to 5.3. The wind direction used shall be that resulting in the greatest load for the length and width of the building, respectively. As wind can blow from any direction, the elevation used shall be that for the worst direction. In the case of a single-storey house with a gable at one end and a hip at the other, the gable end facing the wind will result in a greater amount of load at right angles to the width of the house than the hip end facing the wind. For complex building shapes, buildings that are composed of a combination of storeys or rectangles (that is, L, H or U shapes) the shapes may be considered individually and forces added together later or the total area as a whole can be calculated. Irrespective of which method is used, racking forces shall be calculated to address the most adverse situation. If a veranda, or the like, is present and is to be enclosed, it shall be included in the ‘area of elevation’ calculations. Where there is more than one floor level in a building, each level shall be considered separately for the purpose of calculating the racking forces at each level. ©

Standards Australia


AS 4 055— 2006

21

Wind direction 1


Gable end

Wind direction 2

Hip end

(a) Plan

Area of elevation

h 0

Floor level

(b) Wind direction 1

Area of elevation (gable ends)

Area of elevation

h 0

Floor level

(b) Wind direction 2 NOTES: 1

h 0 =

half the height of the wall (half of the floor to ceiling height).

2

For wind direction 2, the pressure on the gable end is determined from Table 5.1 5.1 and the pressure on the hip section of the elevation is determined from Tables 5.2 to 5.13. The total of racking forces is the sum of the forces calculated for each section.

3

The area of elevation of the triangular portion portion of eaves overhang up to 1000 mm wide may be ignored in the determination of area of elevation.

FIGURE 5.1 ww w.s tan dard s.o rg. au

DETERMINING AREA OF ELEVATION FOR A SINGLE-STOREY BUILDING © Standards

Australia

AS 4 055— 2006

22


Wind direction 1

Gable end

A1

Hip end

Wind direction 2

Hip end

(a) Plan A re a o f elevation

h o

Floor level Single-storey section

A re a o f e l ev a t i o n (gable end)

A re a o f e l e va t i o n (gable end) Ceiling level

ho

Floor level

h o

Upper storey of two-storey section

Lower storey of two-storey section

(b) Wind direction 1 A re a o f e l e va t i o n

h o

Floor level

A re a o f e l e va t i o n

Upper floor level Ceiling level

Upper storey of two-storey section

h o

Lower storey of two-storey section

(c) Wind direction 2

NOTES: 1

ho =

2

For lower storey of two-storey section lower storey ceiling).

3

The area of elevation of the triangular portion of eaves overhang up to 1000 mm wide may be ignored in the determination of area of elevation.

half the height of the wall (half of the floor to ceiling height).

FIGURE 5.2

©

Standards Australia

ho =

half the height of the lower storey (i.e., lower storey floor to

DETERMINING AREA OF ELEVATION FOR A TWO-STOREY OR SPLIT LEVEL BUILDING


AS 4 055— 2006

23

Wind directi on 2 . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Wind direction 3

Hip end

Gable end

Wind direction 1

(a) Plan

Area of elevation

Floor

h 0

H 0

In the subfloor of a two-storey construction, the maximum distance ( H 0 ) from the ground to the underside of the bearer in the lower floor shall be 1800 mm. (b) Wind direction 1

Area of elevation Floor

Area of elevation

Floor h 0

h 0

(c) Wind direction 2  H i p e n d

( d ) W i n d d i r e c t i o n 3  Gable G able end

NOTES: 1

h 0 =

2

For houses on sloping ground, the area of elevation will vary depending upon upon the wind direction or elevation being considered. The racking force calculated for the worst case should be selected.

3

The area of elevation of the triangular portion portion of eaves overhang up to 1000 mm wide may be ignored in the determination of area of elevation.

half the height from the ground to the lower-storey floor.

FIGURE 5.3


DETERMINING AREA OF ELEVATION FOR SUBFLOORS

© Standards

Australia

AS 4 055— 2006

24

TABLE 5.1 VERTICAL SURFACES (FLAT WALLS, GABLE ENDS AND SKILLION ENDS)— PRESSURE (kPa) ON AREA OF ELEVATION . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Wind direction Wind dir ection

Wind direction

Wind direction Wind direction

Wind direction


Wind direction

Wind class

Pressure (kPa)

N1

0.66

N2

0.92

N3

C1

1.44

N4

C2

2.14

N5

C3

3.16

N6

C4

4.26

NO TE: For der NOTE: deriva iva tio tion n of the se val values ues,, ref er to Paragraph A5.2, Appendix A.

©

Standards Australia


AS 4 055— 2006

25

TABLE 5.2 HIP ROOFS AND SIDE WIND ON GABLE ROOFS— PRESSURE (kPa) ON AREA OF ELEVATION— SINGLE STOREY OR UPPER FLOOR OF TWO STOREYS . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Single storey or upper floor of two storeys, 2.4 m storey, 0.3 m floor Roof pitch (degrees)

Wid th (m) 0

5

10

15

20

25

30

35

W

Win d d irectio n

N1: Wind on side

Wind dire ction

W

4

0.61

0.53

0.48

0.44

0.44

0.52

0.56

0.55 0.55

5

0.61

0.52

0.46

0.41

0.42

0.50

0.54

0.53 0.53

6

0.61

0.50

0.44

0.39

0.42

0.50

0.53

0.54 0.54

7

0.61

0.49

0.42

0.38

0.43

0.51

0.53

0.54 0.54

8

0.61

0.47

0.40

0.37

0.43

0.51

0.52

0.54 0.54

9

0.61

0.46

0.39

0.36

0.44

0.52

0.51

0.54 0.54

10

0.61

0.45

0.38

0.35

0.44

0.52

0.51

0.54 0.54

11

0.61

0.44

0.36

0.35

0.45

0.52

0.51

0.55 0.55

12

0.61

0.42

0.34

0.35

0.45

0.52

0.51

0.55 0.55

13

0.61

0.41

0.33

0.36

0.46

0.52

0.52

0.55 0.55

14

0.61

0.40

0.31

0.36

0.46

0.53

0.52

0.56 0.56

15

0.61

0.39

0.30

0.36

0.47

0.53

0.52

0.56 0.56

16

0.61

0.39

0.29

0.37

0.47

0.53

0.52

0.56 0.56

W

Wind direction

W

Wind direction

N1: Wind on end 4

0.67

0.62

0.59

0.55

0.55

0.57

0.59

0.58 0.58

5

0.67

0.61

0.57

0.53

0.53

0.56

0.58

0.57 0.57

6

0.67

0.60

0.56

0.52

0.53

0.56

0.57

0.57 0.57

7

0.67

0.59

0.54

0.50

0.52

0.56

0.56

0.57 0.57

8

0.67

0.58

0.53

0.49

0.52

0.56

0.56

0.57 0.57

9

0.67

0.57

0.51

0.48

0.52

0.56

0.55

0.57 0.57

10

0.67

0.56

0.50

0.47

0.52

0.56

0.54

0.57 0.57

11

0.67

0.55

0.49

0.46

0.52

0.56

0.54

0.57 0.57

12

0.67

0.55

0.47

0.46

0.52

0.56

0.54

0.57 0.57

13

0.67

0.54

0.46

0.46

0.52

0.56

0.55

0.57 0.57

14

0.67

0.53

0.45

0.46

0.53

0.56

0.55

0.57 0.57

15

0.67

0.52

0.44

0.46

0.53

0.56

0.55

0.58 0.58

16

0.67

0.52

0.43

0.46

0.53

0.56

0.55

0.58 0.58


© Standards

Australia

AS 4 055— 2006

26

TABLE 5.3 HIP ROOFS AND SIDE WIND ON GABLE ROOFS— PRESSURE (kPa) ON AREA OF ELEVATION— LOWER STOREY OF TWO STOREYS . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Lower storey of two storeys, 2.4 m storey, 0.3 m floor Roof pitch (degrees)

Wid th (m) 0

5

10

15

20

25

30

W

W

Wind direc tion

N1: Wind on side

35

Win d d irectio n

4

0.61

0.58

0.56

0.54

0.54

0.60

0.62

0.61

5

0.61

0.58

0.55

0.53

0.53

0.59

0.61

0.60

6

0.61

0.57

0.54

0.52

0.52

0.59

0.60

0.59

7

0.61

0.57

0.53

0.51

0.52

0.59

0.59

0.59

8

0.61

0.56

0.53

0.50

0.52

0.58

0.58

0.59

9

0.61

0.55

0.52

0.49

0.52

0.58

0.58

0.59

10

0.61

0.55

0.51

0.48

0.52

0.58

0.57

0.59

11

0.61

0.54

0.50

0.48

0.52

0.58

0.57

0.59

12

0.61

0.54

0.49

0.48

0.52

0.58

0.57

0.59

13

0.61

0.53

0.48

0.48

0.52

0.58

0.57

0.59

14

0.61

0.53

0.47

0.48

0.52

0.58

0.57

0.59

15

0.61

0.52

0.46

0.48

0.53

0.58

0.57

0.59

16

0.61

0.52

0.45

0.48

0.53

0.58

0.57

0.59

W

Wind direction

N1: Wind on end

©

4

0.67

0.65

0.64

0.63

0.62

0.63

0.64

0.63

5

0.67

0.65

0.63

0.62

0.61

0.62

0.63

0.63

6

0.67

0.64

0.63

0.61

0.61

0.62

0.63

0.62

7

0.67

0.64

0.62

0.60

0.61

0.62

0.62

0.62

8

0.67

0.64

0.62

0.60

0.61

0.62

0.62

0.62

9

0.67

0.63

0.61

0.59

0.60

0.62

0.61

0.62

10

0.67

0.63

0.60

0.58

0.60

0.61

0.61

0.61

11

0.67

0.63

0.60

0.58

0.60

0.61

0.60

0.61

12

0.67

0.62

0.59

0.58

0.60

0.61

0.60

0.61

13

0.67

0.62

0.58

0.58

0.60

0.61

0.60

0.61

14

0.67

0.62

0.58

0.58

0.60

0.61

0.60

0.61

15

0.67

0.61

0.57

0.57

0.60

0.61

0.60

0.61

16

0.67

0.61

0.57

0.57

0.60

0.61

0.60

0.61

Standards Australia


AS 4 055— 2006

27



Wid th (m) 0

5

10

15

20

25

30

35

W

Wind direc tion

N2: Wind on side

Win d d irectio n

W

4

0.84

0.74

0.67

0.61

0.61

0.72

0.77

0.76

5

0.84

0.71

0.64

0.57

0.58

0.69

0.75

0.74

6

0.84

0.69

0.61

0.55

0.59

0.70

0.74

0.74

7

0.84

0.67

0.58

0.53

0.59

0.70

0.73

0.74

8

0.84

0.65

0.56

0.51

0.60

0.71

0.72

0.75

9

0.84

0.64

0.54

0.49

0.61

0.71

0.71

0.75

10

0.84

0.62

0.52

0.48

0.61

0.72

0.70

0.75

11

0.84

0.60

0.50

0.48

0.62

0.72

0.71

0.75

12

0.84

0.59

0.47

0.49

0.63

0.72

0.71

0.76

13

0.84

0.57

0.45

0.49

0.63

0.73

0.71

0.77

14

0.84

0.56

0.43

0.50

0.64

0.73

0.72

0.77

15

0.84

0.55

0.42

0.50

0.65

0.73

0.72

0.77

16

0.84

0.53

0.40

0.51

0.65

0.73

0.72

0.78

W

Wind direction

W

Wind direction

N2: Wind on end 4

0.92

0.86

0.81

0.77

0.76

0.79

0.82

0.81

5

0.92

0.84

0.79

0.74

0.73

0.77

0.81

0.79

6

0.92

0.83

0.77

0.72

0.73

0.77

0.79

0.79

7

0.92

0.82

0.75

0.70

0.73

0.77

0.78

0.79

8

0.92

0.80

0.73

0.68

0.72

0.77

0.77

0.79

9

0.92

0.79

0.71

0.66

0.72

0.77

0.76

0.79

10

0.92

0.78

0.69

0.65

0.72

0.77

0.75

0.78

11

0.92

0.77

0.68

0.64

0.72

0.77

0.75

0.79

12

0.92

0.76

0.66

0.64

0.72

0.77

0.75

0.79

13

0.92

0.75

0.64

0.64

0.73

0.77

0.75

0.79

14

0.92

0.73

0.62

0.64

0.73

0.77

0.76

0.79

15

0.92

0.72

0.60

0.64

0.73

0.77

0.76

0.80

16

0.92

0.71

0.59

0.64

0.73

0.77

0.76

0.80


© Standards

Australia

AS 4 055— 2006

28



Wid th (m) 0

5

10

15

20

25

30

W

W

Wind dire ction

N2: Wind on side

35

Wind direc tion

4

0.84

0.81

0.78

0.75

0.75

0.83

0.85

0.84

5

0.84

0.80

0.77

0.73

0.73

0.82

0.84

0.83

6

0.84

0.79

0.75

0.72

0.73

0.81

0.83

0.82

7

0.84

0.78

0.74

0.70

0.72

0.81

0.82

0.82

8

0.84

0.78

0.73

0.69

0.72

0.81

0.81

0.82

9

0.84

0.77

0.71

0.68

0.72

0.81

0.80

0.81

10

0.84

0.76

0.70

0.67

0.72

0.81

0.79

0.81

11

0.84

0.75

0.69

0.66

0.72

0.80

0.79

0.81

12

0.84

0.74

0.68

0.66

0.72

0.80

0.79

0.81

13

0.84

0.74

0.66

0.66

0.72

0.80

0.79

0.82

14

0.84

0.73

0.65

0.66

0.73

0.80

0.79

0.82

15

0.84

0.72

0.64

0.66

0.73

0.80

0.79

0.82

16

0.84

0.72

0.63

0.66

0.73

0.80

0.79

0.82

W

Wind direction

N2: Wind on end

©

4

0.92

0.90

0.89

0.87

0.86

0.87

0.88

0.87

5

0.92

0.90

0.88

0.85

0.85

0.86

0.87

0.87

6

0.92

0.89

0.87

0.84

0.85

0.86

0.87

0.86

7

0.92

0.89

0.86

0.84

0.84

0.86

0.86

0.86

8

0.92

0.88

0.85

0.83

0.84

0.85

0.85

0.86

9

0.92

0.88

0.84

0.82

0.84

0.85

0.84

0.85

10

0.92

0.87

0.84

0.81

0.83

0.85

0.84

0.85

11

0.92

0.87

0.83

0.80

0.83

0.85

0.84

0.85

12

0.92

0.86

0.82

0.80

0.83

0.85

0.83

0.85

13

0.92

0.86

0.81

0.80

0.83

0.84

0.83

0.85

14

0.92

0.85

0.80

0.80

0.83

0.84

0.83

0.85

15

0.92

0.85

0.79

0.79

0.83

0.84

0.83

0.85

16

0.92

0.85

0.78

0.79

0.83

0.84

0.83

0.85

Standards Australia


AS 4 055— 2006

29



Wid th (m) 0

5

10

15

20

25

30

35

W

Wind direction

N3, C1: Wind on side

Wi n d d i r e c t i o n

W

4

1.30

1.20

1.00

0.95

0.96

1.10

1.20

1.20

5

1.30

1.10

1.00

0.89

0.91

1.10

1.20

1.20

6

1.30

1.10

0.95

0.85

0.91

1.10

1.20

1.20

7

1.30

1.10

0.91

0.82

0.93

1.10

1.10

1.20

8

1.30

1.00

0.88

0.79

0.94

1.10

1.10

1.20

9

1.30

0.99

0.84

0.77

0.95

1.10

1.10

1.20

10

1.30

0.97

0.81

0.75

0.95

1.10

1.10

1.20

11

1.30

0.94

0.78

0.75

0.97

1.10

1.10

1.20

12

1.30

0.92

0.74

0.76

0.98

1.10

1.10

1.20

13

1.30

0.90

0.71

0.77

0.99

1.10

1.10

1.20

14

1.30

0.87

0.68

0.78

1.00

1.10

1.10

1.20

15

1.30

0.85

0.65

0.79

1.00

1.10

1.10

1.20

16

1.30

0.83

0.62

0.79

1.00

1.10

1.10

1.20

W

Wind direction

W

Wind direction

N3, C1: Wind on end 4

1.40

1.30

1.30

1.20

1.20

1.20

1.30

1.30

5

1.40

1.30

1.20

1.20

1.10

1.20

1.30

1.20

6

1.40

1.30

1.20

1.10

1.10

1.20

1.20

1.20

7

1.40

1.30

1.20

1.10

1.10

1.20

1.20

1.20

8

1.40

1.30

1.10

1.10

1.10

1.20

1.20

1.20

9

1.40

1.20

1.10

1.00

1.10

1.20

1.20

1.20

10

1.40

1.20

1.10

1.00

1.10

1.20

1.20

1.20

11

1.40

1.20

1.10

1.00

1.10

1.20

1.20

1.20

12

1.40

1.20

1.00

1.00

1.10

1.20

1.20

1.20

13

1.40

1.20

1.00

1.00

1.10

1.20

1.20

1.20

14

1.40

1.10

0.97

1.00

1.10

1.20

1.20

1.20

15

1.40

1.10

0.94

1.00

1.10

1.20

1.20

1.20

16

1.40

1.10

0.92

1.00

1.10

1.20

1.20

1.20


© Standards

Australia

AS 4 055— 2006

30



Wid th (m) 0

5

10

15

20

25

30

W

W

Wind d ire ction


35

Wind direc tion

4

1.30

1.30

1.20

1.20

1.20

1.30

1.30

1.30

5

1.30

1.20

1.20

1.10

1.10

1.30

1.30

1.30

6

1.30

1.20

1.20

1.10

1.10

1.30

1.30

1.30

7

1.30

1.20

1.20

1.10

1.10

1.30

1.30

1.30

8

1.30

1.20

1.10

1.10

1.10

1.30

1.30

1.30

9

1.30

1.20

1.10

1.10

1.10

1.30

1.20

1.30

10

1.30

1.20

1.10

1.00

1.10

1.30

1.20

1.30

11

1.30

1.20

1.10

1.00

1.10

1.30

1.20

1.30

12

1.30

1.20

1.10

1.00

1.10

1.30

1.20

1.30

13

1.30

1.20

1.00

1.00

1.10

1.30

1.20

1.30

14

1.30

1.10

1.00

1.00

1.10

1.30

1.20

1.30

15

1.30

1.10

1.00

1.00

1.10

1.20

1.20

1.30

16

1.30

1.10

0.98

1.00

1.10

1.20

1.20

1.30

W

Wind direction

N3, C1: Wind on end

©

4

1.40

1.40

1.40

1.40

1.30

1.40

1.40

1.40

5

1.40

1.40

1.40

1.30

1.30

1.30

1.40

1.40

6

1.40

1.40

1.40

1.30

1.30

1.30

1.40

1.30

7

1.40

1.40

1.30

1.30

1.30

1.30

1.30

1.30

8

1.40

1.40

1.30

1.30

1.30

1.30

1.30

1.30

9

1.40

1.40

1.30

1.30

1.30

1.30

1.30

1.30

10

1.40

1.40

1.30

1.30

1.30

1.30

1.30

1.30

11

1.40

1.40

1.30

1.30

1.30

1.30

1.30

1.30

12

1.40

1.30

1.30

1.30

1.30

1.30

1.30

1.30

13

1.40

1.30

1.30

1.20

1.30

1.30

1.30

1.30

14

1.40

1.30

1.30

1.20

1.30

1.30

1.30

1.30

15

1.40

1.30

1.20

1.20

1.30

1.30

1.30

1.30

16

1.40

1.30

1.20

1.20

1.30

1.30

1.30

1.30

Standards Australia


AS 4 055— 2006

31



Wid th (m) 0

5

10

15

20

25

30

35

W

Wind direction


Win d d irection

W

4

2.00

1.70

1.60

1.40

1.40

1.70

1.80

1.80

5

2.00

1.70

1.50

1.30

1.30

1.60

1.80

1.70

6

2.00

1.60

1.40

1.30

1.40

1.60

1.70

1.70

7

2.00

1.60

1.40

1.20

1.40

1.60

1.70

1.70

8

2.00

1.50

1.30

1.20

1.40

1.60

1.70

1.70

9

2.00

1.50

1.30

1.10

1.40

1.70

1.70

1.70

10

2.00

1.40

1.20

1.10

1.40

1.70

1.60

1.70

11

2.00

1.40

1.20

1.10

1.40

1.70

1.60

1.80

12

2.00

1.40

1.10

1.10

1.50

1.70

1.70

1.80

13

2.00

1.30

1.10

1.10

1.50

1.70

1.70

1.80

14

2.00

1.30

1.00

1.20

1.50

1.70

1.70

1.80

15

2.00

1.30

0.97

1.20

1.50

1.70

1.70

1.80

16

2.00

1.20

0.93

1.20

1.50

1.70

1.70

1.80

W

Wind direction

W

Wind direction


2.10

2.00

1.90

1.80

1.80

1.80

1.90

1.90

5

2.10

2.00

1.80

1.70

1.70

1.80

1.90

1.80

6

2.10

1.90

1.80

1.70

1.70

1.80

1.80

1.80

7

2.10

1.90

1.70

1.60

1.70

1.80

1.80

1.80

8

2.10

1.90

1.70

1.60

1.70

1.80

1.80

1.80

9

2.10

1.80

1.70

1.50

1.70

1.80

1.80

1.80

10

2.10

1.80

1.60

1.50

1.70

1.80

1.80

1.80

11

2.10

1.80

1.60

1.50

1.70

1.80

1.80

1.80

12

2.10

1.80

1.50

1.50

1.70

1.80

1.80

1.80

13

2.10

1.70

1.50

1.50

1.70

1.80

1.80

1.80

14

2.10

1.70

1.40

1.50

1.70

1.80

1.80

1.80

15

2.10

1.70

1.40

1.50

1.70

1.80

1.80

1.90

16

2.10

1.70

1.40

1.50

1.70

1.80

1.80

1.90


© Standards

Australia

AS 4 055— 2006

32



Wid th (m) 0

5

10

15

20

25

30

W

W

Wind direction


35

Wind direction

4

2.00

1.90

1.80

1.70

1.70

1.90

2.00

2.00

5

2.00

1.90

1.80

1.70

1.70

1.90

2.00

1.90

6

2.00

1.80

1.80

1.70

1.70

1.90

1.90

1.90

7

2.00

1.80

1.70

1.60

1.70

1.90

1.90

1.90

8

2.00

1.80

1.70

1.60

1.70

1.90

1.90

1.90

9

2.00

1.80

1.70

1.60

1.70

1.90

1.90

1.90

10

2.00

1.80

1.60

1.60

1.70

1.90

1.80

1.90

11

2.00

1.70

1.60

1.50

1.70

1.90

1.80

1.90

12

2.00

1.70

1.60

1.50

1.70

1.90

1.80

1.90

13

2.00

1.70

1.50

1.50

1.70

1.90

1.80

1.90

14

2.00

1.70

1.50

1.50

1.70

1.90

1.80

1.90

15

2.00

1.70

1.50

1.50

1.70

1.90

1.80

1.90

16

2.00

1.70

1.50

1.50

1.70

1.90

1.80

1.90

W

Wind direction

N4, C2: Wind on end

©

4

2.10

2.10

2.10

2.00

2.00

2.00

2.10

2.00

5

2.10

2.10

2.00

2.00

2.00

2.00

2.00

2.00

6

2.10

2.10

2.00

2.00

2.00

2.00

2.00

2.00

7

2.10

2.10

2.00

1.90

2.00

2.00

2.00

2.00

8

2.10

2.10

2.00

1.90

2.00

2.00

2.00

2.00

9

2.10

2.00

2.00

1.90

1.90

2.00

2.00

2.00

10

2.10

2.00

1.90

1.90

1.90

2.00

2.00

2.00

11

2.10

2.00

1.90

1.90

1.90

2.00

1.90

2.00

12

2.10

2.00

1.90

1.90

1.90

2.00

1.90

2.00

13

2.10

2.00

1.90

1.90

1.90

2.00

1.90

2.00

14

2.10

2.00

1.90

1.90

1.90

2.00

1.90

2.00

15

2.10

2.00

1.80

1.80

1.90

2.00

1.90

2.00

16

2.10

2.00

1.80

1.80

1.90

2.00

1.90

2.00

Standards Australia


AS 4 055— 2006

33



Wid th (m) 0

5

10

15

20

25

30

35

W

Wind direction


Win d d irection

W

4

2.90

2.50

2.30

2.10

2.10

2.50

2.60

2.60

5

2.90

2.40

2.20

1.90

2.00

2.40

2.60

2.50

6

2.90

2.40

2.10

1.90

2.00

2.40

2.50

2.50

7

2.90

2.30

2.00

1.80

2.00

2.40

2.50

2.50

8

2.90

2.20

1.90

1.70

2.10

2.40

2.50

2.60

9

2.90

2.20

1.80

1.70

2.10

2.40

2.40

2.60

10

2.90

2.10

1.80

1.60

2.10

2.50

2.40

2.60

11

2.90

2.10

1.70

1.70

2.10

2.50

2.40

2.60

12

2.90

2.00

1.60

1.70

2.10

2.50

2.40

2.60

13

2.90

2.00

1.60

1.70

2.20

2.50

2.40

2.60

14

2.90

1.90

1.50

1.70

2.20

2.50

2.50

2.60

15

2.90

1.90

1.40

1.70

2.20

2.50

2.50

2.60

16

2.90

1.80

1.40

1.70

2.20

2.50

2.50

2.70

W

Wind direction

W

Wind direction


3.20

2.90

2.80

2.60

2.60

2.70

2.80

2.80

5

3.20

2.90

2.70

2.50

2.50

2.60

2.80

2.70

6

3.20

2.80

2.60

2.40

2.50

2.60

2.70

2.70

7

3.20

2.80

2.60

2.40

2.50

2.60

2.70

2.70

8

3.20

2.80

2.50

2.30

2.50

2.60

2.60

2.70

9

3.20

2.70

2.40

2.30

2.50

2.60

2.60

2.70

10

3.20

2.70

2.40

2.20

2.50

2.60

2.60

2.70

11

3.20

2.60

2.30

2.20

2.50

2.60

2.60

2.70

12

3.20

2.60

2.20

2.20

2.50

2.60

2.60

2.70

13

3.20

2.50

2.20

2.20

2.50

2.60

2.60

2.70

14

3.20

2.50

2.10

2.20

2.50

2.60

2.60

2.70

15

3.20

2.50

2.10

2.20

2.50

2.60

2.60

2.70

16

3.20

2.40

2.00

2.20

2.50

2.60

2.60

2.70


© Standards

Australia

AS 4 055— 2006

34



Wid th (m) 0

5

10

15

20

25

30

W

W

Wind dire ction


35

Wind direc tion

4

2.90

2.80

2.70

2.60

2.60

2.80

2.90

2.90

5

2.90

2.70

2.60

2.50

2.50

2.80

2.90

2.80

6

2.90

2.70

2.60

2.50

2.50

2.80

2.80

2.80

7

2.90

2.70

2.50

2.40

2.50

2.80

2.80

2.80

8

2.90

2.70

2.50

2.40

2.50

2.80

2.80

2.80

9

2.90

2.60

2.40

2.30

2.50

2.80

2.70

2.80

10

2.90

2.60

2.40

2.30

2.50

2.80

2.70

2.80

11

2.90

2.60

2.40

2.30

2.50

2.80

2.70

2.80

12

2.90

2.50

2.30

2.30

2.50

2.70

2.70

2.80

13

2.90

2.50

2.30

2.30

2.50

2.70

2.70

2.80

14

2.90

2.50

2.20

2.30

2.50

2.70

2.70

2.80

15

2.90

2.50

2.20

2.30

2.50

2.70

2.70

2.80

16

2.90

2.50

2.10

2.30

2.50

2.70

2.70

2.80

W

Wind direction

N5, C3: Wind on end

©

4

3.20

3.10

3.00

3.00

3.00

3.00

3.00

3.00

5

3.20

3.10

3.00

2.90

2.90

2.90

3.00

3.00

6

3.20

3.10

3.00

2.90

2.90

2.90

3.00

2.90

7

3.20

3.00

2.90

2.90

2.90

2.90

2.90

2.90

8

3.20

3.00

2.90

2.80

2.90

2.90

2.90

2.90

9

3.20

3.00

2.90

2.80

2.90

2.90

2.90

2.90

10

3.20

3.00

2.90

2.80

2.90

2.90

2.90

2.90

11

3.20

3.00

2.80

2.80

2.80

2.90

2.90

2.90

12

3.20

3.00

2.80

2.70

2.80

2.90

2.90

2.90

13

3.20

2.90

2.80

2.70

2.80

2.90

2.80

2.90

14

3.20

2.90

2.70

2.70

2.80

2.90

2.80

2.90

15

3.20

2.90

2.70

2.70

2.80

2.90

2.80

2.90

16

3.20

2.90

2.70

2.70

2.80

2.90

2.80

2.90

Standards Australia


AS 4 055— 2006

35



Wid th (m) 0

5

10

15

20

25

30

35

W

Wind dire ction


Wind direc tion

W

4

3.92

3.38

3.11

2.84

2.84

3.38

3.51

3.51

5

3.92

3.24

2.97

2.57

2.70

3.24

3.51

3.38

6

3.92

3.24

2.84

2.57

2.70

3.24

3.38

3.38

7

3.92

3.11

2.70

2.43

2.70

3.24

3.38

3.38

8

3.92

2.97

2.57

2.30

2.84

3.24

3.38

3.51

9

3.92

2.97

2.43

2.30

2.84

3.24

3.24

3.51

10

3.92

2.84

2.43

2.16

2.84

3.38

3.24

3.51

11

3.92

2.84

2.30

2.30

2.84

3.38

3.24

3.51

12

3.92

2.70

2.16

2.30

2.84

3.38

3.24

3.51

13

3.92

2.70

2.16

2.30

2.97

3.38

3.24

3.51

14

3.92

2.57

2.03

2.30

2.97

3.38

3.38

3.51

15

3.92

2.57

1.89

2.30

2.97

3.38

3.38

3.51

16

3.92

2.43

1.89

2.30

2.97

3.38

3.38

3.65

W

Wind direction

W

Wind direction


4.32

3.92

3.78

3.51

3.51

3.65

3.78

3.78

5

4.32

3.92

3.65

3.38

3.38

3.51

3.78

3.65

6

4.32

3.78

3.51

3.24

3.38

3.51

3.65

3.65

7

4.32

3.78

3.51

3.24

3.38

3.51

3.65

3.65

8

4.32

3.78

3.38

3.11

3.38

3.51

3.51

3.65

9

4.32

3.65

3.24

3.11

3.38

3.51

3.51

3.65

10

4.32

3.65

3.24

2.97

3.38

3.51

3.51

3.65

11

4.32

3.51

3.11

2.97

3.38

3.51

3.51

3.65

12

4.32

3.51

2.97

2.97

3.38

3.51

3.51

3.65

13

4.32

3.38

2.97

2.97

3.38

3.51

3.51

3.65

14

4.32

3.38

2.84

2.97

3.38

3.51

3.51

3.65

15

4.32

3.38

2.84

2.97

3.38

3.51

3.51

3.65

16

4.32

3.24

2.70

2.97

3.38

3.51

3.51

3.65


© Standards

Australia

AS 4 055— 2006

36



Wid th (m) 0

5

10

15

20

25

30

W

W

Wind direc tion


35

Wind direction

4

3.92

3.78

3.65

3.51

3.51

3.78

3.92

3.92

5

3.92

3.65

3.51

3.38

3.38

3.78

3.92

3.78

6

3.92

3.65

3.51

3.38

3.38

3.78

3.78

3.78

7

3.92

3.65

3.38

3.24

3.38

3.78

3.78

3.78

8

3.92

3.65

3.38

3.24

3.38

3.78

3.78

3.78

9

3.92

3.51

3.24

3.11

3.38

3.78

3.65

3.78

10

3.92

3.51

3.24

3.11

3.38

3.78

3.65

3.78

11

3.92

3.51

3.24

3.11

3.38

3.78

3.65

3.78

12

3.92

3.38

3.11

3.11

3.38

3.65

3.65

3.78

13

3.92

3.38

3.11

3.11

3.38

3.65

3.65

3.78

14

3.92

3.38

2.97

3.11

3.38

3.65

3.65

3.78

15

3.92

3.38

2.97

3.11

3.38

3.65

3.65

3.78

16

3.92

3.38

2.84

3.11

3.38

3.65

3.65

3.78

W

Wind direction

N6, C4: Wind on end

©

4

4.32

4.19

4.05

4.05

4.05

4.05

4.05

4.05

5

4.32

4.19

4.05

3.92

3.92

3.92

4.05

4.05

6

4.32

4.19

4.05

3.92

3.92

3.92

4.05

3.92

7

4.32

4.05

3.92

3.92

3.92

3.92

3.92

3.92

8

4.32

4.05

3.92

3.78

3.92

3.92

3.92

3.92

9

4.32

4.05

3.92

3.78

3.92

3.92

3.92

3.92

10

4.32

4.05

3.92

3.78

3.92

3.92

3.92

3.92

11

4.32

4.05

3.78

3.78

3.78

3.92

3.92

3.92

12

4.32

4.05

3.78

3.65

3.78

3.92

3.92

3.92

13

4.32

3.92

3.78

3.65

3.78

3.92

3.78

3.92

14

4.32

3.92

3.65

3.65

3.78

3.92

3.78

3.92

15

4.32

3.92

3.65

3.65

3.78

3.92

3.78

3.92

16

4.32

3.92

3.65

3.65

3.78

3.92

3.78

3.92

Standards Australia


37

AS 4 055— 2006

APPENDIX A COMMENTARY . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

(Informative) A1 COMMENT ON TABLE 2.1—WIND CLASSIFICATION

This Standard has been derived for houses as a group or large numbers of buildings. In general, the level of reliability for the group is similar to that found, by applying AS/NZS 1170.2. However, it is recognized that a correct application of this Standard may lead to some houses with more conservative design loads, and others with less conservative design loads. It is important to categorize each building on a case-by-case basis. Each site should be assessed individually for its wind classification. Each building would be assessed for compliance with geometry and for evaluation of pressures. The classification was originally based on the permissible stress ‘W’ classes. An approximate 50% increase in wind pressures occurs from one class to the next higher one, that is, N2 to N3, N3 t o N4, etc. Once a particular building site has been classified using the methods set out in Section 2, the ultimate wind speed for that class represents the design wind speed for the house and includes the effects of— (a)

the importance level which is set by the BCA (the design wind loading level associated with housing) NOTE : S ee Not Notee 1 to Clau se 1.1.

(b)

directionality (the likelihood of wind occurring at its maximum from the direction for which the house is most vulnerable in terms of the pressures on the envelope);

(c)

height (of the building above the ground);

(d)

terrain roughness (sizes of the obstructions in the wider area around the building site such as trees, grass, open space and size of buildings);

(e)

topography (the position of the site on hills or in valleys); and

(f)

shielding (the effect of specific buildings and other obstructions near to the proposed building).

A2 DERIVATION OF TABLE 2.2—WIND CLASSIFICATION

In determining the application of the N and C classes to the selected site criteria that are given in Table 2.2, the effect of wind events on large numbers of houses, rather than on individual structures, has been considered. The following criteria were selected: (a)

Annual probability of exceedance has been taken as 1/500.

(b)

A 0.95 factor on wind speed was allowed to account for the variation of orientation of houses within suburbs and groups of suburbs.

(c)

A 5% margin has been allowed on the wind speed for the assigning of the N and C classes.

(d)

Average roof height has been taken as 6.5 m (selected as not the worst case but covering the majority of average housing being constructed within the limitations given in Figure 1.1).


© Standards

Australia

AS 4 055— 2006


38

(e)

The terrain/height multiplier ( M ( M 6.5,cat 6 .5,cat) has been derived from AS/NZS 1170.2 with h (average roof height) taken as 6.5 m (s ee Table A2).

(f)

Topographic multiplier ( M t) has been derived from AS/NZS 1170.2 (see Table A3). The values chosen for T2 to T5 represent the average of the ranges for each class (T1 is taken as 1.0 to represent the majority of housing on flat terrain). For the top third, the class changes for slopes greater than 30 m high. The separation zone at the crest has not been included.

(g)

Shielding multiplier ( M s) has been derived from AS/NZ S 1170.2 (see Table A4). TABLE A2 TERRAIN CATEGORY MULTIPLIER ( M 6.5,cat 6 .5,cat ) AT HEIGHT 6.5 Terrain category multiplier ( M 6.5,cat )

Region Terrain Category 1

Terrain Category 2

Terrain Category 2.5

Terrain Category 3

A

1.07

0.94

0.88

0.83

B

1.07

0.94

0.88

0.83

C

0.97

0.97

0.90

0.83

D

0.97

0.97

0.90

0.83

TABLE A3 TOPOGRAPHIC MULTIPLIER ( M t) Topographic class

Val ue of top ogr aph aphic ic mul tip tiplie lie r Range of values calculated using ( M t) applied in calculation of the AS/N ZS 1170. 2 t hat are inc lud ed N and C categories in the class

T1

1.0

1.0 to <1.16

T2

1.2

≥ 1.16

to <1.25

T3

1.3

≥ 1.25

to <1.36

T4

1.42

≥ 1.36

to <1.47

T5

1.57

≥ 1.47

TABLE A4 SHIELDING MULTIPLIER ( M s) Shielding class

Shielding multiplier ( M s )

Full shielding (FS)

0.85

Partial shielding (PS)

0.95

No shi eldi ng (NS )

1.00

A3 COMMENT ON CLAUSE 1.3—GEOMETRIC LIMITS

It is intended that 16 m width limit be applied to the width of the tallest section of the house. For example, in many cases the various sections of a house (that is the basic rectangular box shapes) may be displaced horizontally with respect to each other. This could make the overall floor plan dimension greater than the 16 m limit even though none of the sections of roof might be gr eater than the 16 m. Such a house should be within the limits provided that none of the roof sections parallel to the wind direction being considered are greater than 16 m (neglecting the width of eaves).

©

Standards Australia


AS 4 055— 2006

39

A4 COMMENTARY ON PRESSURE COEFFICIENTS COEFFICIENTS (Section 3)

The pressure coefficients given in Section 3 have been based on A S/NZS 1170.2. The following criteria were used: . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

(a)

The house comprises basically rectangular bluff bodies within the geometric shape limits given in Clause 1.5.

(b)

Roofs are of normal shape (for example, not arched).

(c)

Net pre pressur ssuree coef coeffici ficients ents com compris prisee the addi additio tion n of inte internal rnal and exte externa rnall pre pressur ssures es on the building envelope.

(d)

Pressures include the effects effects of dominant openings for Regions C and D only.

(e)

Pressures include the effects of local high-pressure zones on the leading edges of surfaces of the building envelope.

The pressure factors given for the 1200 mm zones near corners and near edges of roofs reflect the local pressures known to occur in these areas of buildings. AS/N ZS 1170.2 includes a local pressure factor to account for this effect. A5 COMMENTARY ON PRESSURES FOR DETERMINATION OF RACKING FORCES (SECTION 5) A5.1 General, notation and assumptions A5.1.1 General

This Paragraph describes how the equivalent pressures tabulated in Section 5 for use with projected areas, for the calculation of racking loads to be resisted by bracing have been derived. The methods of determination of equivalent pressures for the calculation of racking forces in orthogonal directions for single or upper storey, for lower of two storeys and for subfloor level are given. A5.1.2 Notation

Notatio Not ation n symb s ymbols ols for this Sect Section ion are as foll follows ows:: b

= plan dimension of building or part part of building building perpendicular to wind direction, direction, in metres (see AS/NZS 1170.2)

C pt,roof p t,roof = combined pressure coefficient for the windward and leeward roof areas C pt,wall p t,wall = combined pressure coefficient for the windward and leeward walls d

= plan dimension of building building or part of building building parallel to the wind direction, direction, in metres (see AS/NZS 1170.2)

H F

= depth of upper floor, in metres

H L

= height, floor to ceiling for lower storey of two storeys, in metres

H u

= height, floor to ceiling for single or upper storey, in metres

h

= height to eaves, in metres (see AS/NZS 1170.2)

K c

= pressure combination factor

L

= length of building, in in metres (see Figure A5.1)

qu

= free stream dynamic gust pressure, in kPa, for the ultimate limit state in accordance with Clause 3.2

W

= width of building, in in metres (see Figure A5.1)

α

= roof pitch, in degrees (see AS/NZS 1170.2 and Figure A5.1)

θ

= wind direction, direction, in in degrees (see AS/NZS 1170.2)


© Standards

Australia

AS 4 055— 2006

40

A5.1.3 Assumptions

The following assumptions have been ma de in the derivation of equivalent pressures for use with projected areas for the determination of racking forces: . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

©

(a)

The geometry assumed is a simple outline of the building, which ignores eaves overhangs, fascias and gutters. The projected area for the roof is taken as the area above ceiling level for the single or upper storey (see Figure A5.1).

(b)

Buildings are assumed enclosed underneath the lower floor.

(c)

The floor depth of upper floors ( H ( H F) is assumed to be 0.3 m.

(d)

H u = = H H L = 2.4 m. Pressures calculated for 2.4 m floor to ceiling heights are assumed to apply for walls up to 3.0 m high.

(e)

A pressure combination factor K factor K c = 0.8 is applied where the load effect is the result of the combination of pressures on two or more surfaces. [ K [ K c is not applied in combination with the area reduction factor ( K ( K a).]

(f)

The assumed combined pressure coefficients for the windward and leeward walls ( C pt,wall = 0 ° and θ = 90° are given in Table A5.1 and p t,wall ) for wind directions θ = Table A5.2 respectively.

(g)

The assumed combined pressure coefficients for the windward and leeward roofs ( C pt,roof p t,roof ) for wind parallel to the slope (pitch) of roof are given in Table A5.3.

Standards Australia


AS 4 055— 2006

41

Projected areas for determination of single or upper storey racking loads . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Hips (if hip-end roof)

Ceiling

H u l 2 H u

Floor H F

Ceiling H L

Floor

End elevation

0°

Side elevation

Hips (if hip-end roof) e g d i R

L

W

9 0° Plan

FIGURE A5.1

NOTATION

TABLE A5.1 COMBINED PRESSURE COEFFICIENTS FOR WALLS— WIND DIRECTION PARALLEL TO ROOF SLOPE* Roof pitch ( α ) C pt,wall

α

<

10°

10°

1.1

≤

α

≤ 15°

1.1

= 20° =

α

1.1

α

≥ 25°

1.2

* For θ = = 0° and for hip ends, θ = = 90 90°°


© Standards

Australia

AS 4 055— 2006

42

TABLE A5.2 COMBINED PRESSURE COEFFICIENTS FOR WALLS— WIND DIRECTION PERPENDICULAR TO ROOF SLOPE* . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

d / b

≤1

2

≥4

C pt,wall

1.2

1.0

0.9

* For θ = = 90 90°° for gable or skillion roof ends

TABLE A5.3 COMBINED PRESSURE COEFFICIENTS FOR ROOFS— WIND DIRECTION PARALLEL TO ROOF SLOPE* C pt,roof

Ratio

h/ d

Roof pitch (α ) < 10°

10°

15°

20°

25°

30°

35°

≤ 0.25

0

0

+0.5

+0.8

+0.9

+0.9

+1.0

0.5

0

+0.1

+0.2

+0.6

+0.8

+0.8

+0.9

≥ 1.0

0

+0.1

+0.1

+0.3

+0.6

+0.8

+0.8

* For θ = = 0° and for hip ends, θ = = 90 90°°

A5.2 Equivalent pressures on projected areas A5.2.1 For flat wall surfaces, surfaces, gable or skillion skillion roof ends

The equivalent pressure ( p ( p)) on the projected area shown in Figure A5.2 for calculation of the racking load for bracing in single or upper storey, or the lower of two-storey or subfloor walls is determined from the following equation: p = p = q u C pt,wall p t,wall K c

. . . A5.2(1)

where C pt,wall p t,wall = 1.2, as given in Table A5.2 for d / b = 1 K c

= 0.8, pressure combination factor applicable for the combined effect o pressure on two or more surfaces

NOTE : The ass ump umptio tion n tha thatt coefficient for the walls.

©

Standards Australia

d = = b,

i.e.,

L = W corresponds

to the maximum combined pressure


AS 4 055— 2006

43


W

W


Wind direction

W

W

W


Wind direction

FIGURE A5.2

W

FLAT WALL SURFACES—GABL E AND SKILLION ROOF ENDS

A5.2.2 For side elevations, single or upper storey, storey, gable- or hip-ended hip-ended roofs

The equivalent pressure ( p p)) for the projected areas shown in Figure A5.3 for calculation of the racking load for bracing in single or upper storey walls is determined from the following equation: p =

[

) + C pt,roof (W / 2) tan α ] ( H u / 2) + (W / 2) tan α

q u K c C pt, wall ( H u

/2

. . . A5.2(2)

where C pt,wall Table A5.1 for roof pitch, α p t,wall = value from Table C pt,roof ( h/d ) = ( H u/W ) p t,roof = value from Table A5.3, for roof pitch α , and assuming (h K c

= 0.8, pressure combination factor

NOTE S: 1

The assumption that the roof.

h /d = = H u / W maximizes

the assumed combined pressure coefficients for

2

The reduction in projected area for hip-ended roofs has been ignored in the determination of the equivalent pressures to be applied to the projected areas corresponding to either gable- or hip-ended roofs.

W Wind di rection

FIGURE A5.3

Wi nd direction

W

SIDE ELEVATIONS—SI NGLE OR UPPER STOREY— GABLE- OR HIP-ENDED ROOFS

A5.2.3 Side elevation, elevation, lower storey of two storeys or subfloor, gable- or hip-ended hip-ended roof

The design wind pressure ( p ( p)) on the projected area shown in Figure A5.4 for calculation of the racking force for bracing in the lower storey of two-storey walls is determined from the following equation: ww w.s tan dard s.o rg. au

© Standards

Australia

AS 4 055— 2006

44

p =

[

) + C pt,roof (W / 2 ) tan α ] ( H u + H F + H L / 2) + (W / 2) tan α

q u K u C pt, wall ( H u + H F + H L

/2

. . . A5.2(3)

where


C pt,wall Table A5.1 A5.1 for roof pitch ( α ) p t,wall = value determined from Table C pt,roof p t,roof = value determined from Table A5.3 for roof pitch ( α ) and assuming (h/d ) = ( H u + + H H F + H L )/ )/W W K c


NOTE S: 1

The assumption that h /d = = ( H u + H F + H L )/ W maximizes the assumed combined pressure coefficients for the roof.

2

The reduction in projected area for hip-ended roofs has been ignored in the determination of equivalent pressures to be applied for projected areas for either hip- or gable-ended roofs.

W

W

Wind di recti on

Wi nd direction

FIGURE A5.4 SIDE ELEVATION—LOWER STOREY OF TWO STOREYS OR SUBFLOOR—GABLE- OR HIP-ENDED ROOF

A5.2.4 End elevation, elevation, single or upper storey, hip-ended roof

The design wind pressure (( p p)) on the projected area shown in Figure A5.5 for calculation of racking loads for bracing in single or upper storey walls is determined from the following equation. p =

[

) + C pt,roof (W / 4) tan α ] ( H u / 2 ) + (W / 4) tan α


/2

. . . A5.2(4)

where C pt,wall p t,wall = 1.2 C pt,roof = H u/ L L and p t,roof = value obtained fr om Table A5.3 for roof pitch ( α ) with h/ d = H assuming L assuming L = W K c


W

FIGURE A5.5 ©

Standards Australia

Wind direction

END ELEVATION—SI NGLE OR UPPER STOREY—HIP-E NDED ROOF www.standards.org.au

AS 4 055— 2006

45

A5.2.5 End elevation, elevation, lower storey of two storeys, storeys, hip-ended roof

The equivalent pressure ( p ( p)) on the projected area shown in Figure A5.6 for calculating racking loads for bracing in walls of the lower storey of two-storey walls is determined from the following equation: . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

p =

[

) + C pt,roof (W / 4 ) tan α ] ( H u + H F + H L / 2) + (W / 4) tan α


+

H F + H L

/2

. . . A5.2(5)

where C pt,wall p t,wall = 1.2 C pt,roof obtained from Table A5.3 for roof p t,roof = value h/d = ( H ( H u + + H H F + + H H L)/ L and L and L L = = 1.5W 1.5 W K c

pitch ( α ) and assuming


W

Wind direction

FIGURE A5.6

END ELEVATION—LOWER STOREY OF TWO STOREYS— HIP-ENDED ROOF

A6 CONVERTING WIND SPEEDS

Wind speeds may be approximately converted from metres per second (m/s) to other commonly reported measures of speed as follows: (a)

1 m/s × 3.6 = 1 km/h.

(b)

1 m/s × 1.94 = 1 knot.

(c)

1 m/s × 2.24 = 1 mile/h.


© Standards

Australia

AS 4 055— 2006

46

APPENDIX B WORKED EXAMPLE FOR THE DETERMINATION OF TOPOGRAPHY . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

(Informative) In order to illustrate how to determine the appropriate topographic class, the following example is provided, which relates to Figure B1. Step 1

Identify the top of the hill: RL 110 m.

Step 2

Identify the bottom of the hill: RL 40 m (RL of creek). creek).

Step 3

Calculate the mid-height of the hill: (110 + 40)/2 = RL 75 m.

Step 4

Identify the steepest and least least slope in the top half of the hill: (i)

Least slope = (110 − 75)/350 = 0.10.

(ii)

Steepest slope = (110 − 75)/130 = 0.27.

Step 5

Calculate average slope: (0.1 + 0.27)/2 = 0.185 which relates to a slope o f 1 in 5.4, (i.e., 1/0.185 = 5.4).

Step 6

Identify the location of the house. If the house at site A is located located in in the midthird of the hill, the topographic class for an average slope of 1 in 5.4 is T1 (see Table 2.3).

As the house at site B is in closer proximity to the peak of hill 1 than hill 2, the topographic effect of hill 1 is considered to predominate. Therefore, if the house at site B is located in the near top-third of the hill, the topographic class for an average slope of 1 in 5.4 is T3 (see Table 2.3).

©

Standards Australia


AS 4 055— 2006

47

C r e e k


50

60

60 80

70 80

C r e e k

Hill 2 1 10

Mid 1/3 band t a s e L p e o s l

S s t l o e e p p e e s t

1 00

Lower 1/3 contour

Hill 1

Housing site B

90 80

50

1 10

Mid height contour

1 00 60

Near top 1/3 contour

50 40

0

100

90 80

300

50 70 Housing 60 site A

Creek

200

C r e e k

400

Scale (m)

FIGURE B1


DETERMINATION OF TOPOGRAPHIC CLASS

© Standards

Australia

AS 4 055— 2006

48

APPENDIX C WORKED EXAMPLES FOR THE SELECTION OF TERRAIN CATEGORY AND . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

SHIELDING CLASS

(Informative) The typical surface roughness types encountered in an urban area are represented in Table C1, which is provided to assist in the selection of terrain categories and shielding classes of particular sites. In conjunction with deriving the correct topographic class from Table 2.3, the terrain category and shielding class selected from Table C1 are applied to Table 2.2 for the appropriate geographic region to determine the rationalized wind class for the design of houses or structures. The following examples are provided to clarify the use of Table C1. Example Exa mple A: As the house at location A is sited more than 500 m from the open sea and surrounded for a distance of more than 500 m by a minimum surface roughness greater than 10 houses per hectare except for a small park of less than 500 m in width, the terrain category of the site is TC3. If the house is located within the first two rows of houses adjacent to the park, no shielding is provided by this open space. Example Exa mple B: The house at location B is within a residential subdivision but immediately adjoins a large acreage subdivision. As the least surface roughness for a distance of 500 m in any direction of the site is between 10 and 2.5 houses per hectare, the terrain category at location B is TC2.5. As the site immediately abuts a large acreage subdivision with a surface roughness of between 10 and 2.5 houses per hectare, only partial shielding is provided.

©

Standards Australia


Licensed to Mr Engineered Wood Products on 6 May 2011. 1 user personal user licence only. Storage, distribution or use on network prohibited (10205237).

w w w . s t a n d a r d s . o r g . a u

TABLE

C1

TERRAIN CATEGORY AND SHIELDING CLASSIFICATION FOR REGIONS A AND B

Location 'A'

Description

Waterfront suburbia

Residential suburbia, wellwooded country

Location 'B'

Small open parkland or lake <250 000 m 2

Residential suburbia, well-wooded country

Acr eag eagee subu s uburbi rbi a, isolated buildings, few trees, cane fields, long grass

≥ 10 Houses, etc. per hectare


Airfie Air fie ld isolated trees, large expanses, open water

Residential suburbia, wellwooded country

and canal <200 m wide Surface roughness


Terrain category: Development length

Negli Ne gli gib gible le

500 m

Classification

TC2

Shielding: Development length

2 rows of houses No shielding

Classification

500 m

TC3

Full shielding

TC3

TC3

2 rows of houses

2 rows of houses

No shielding

No shielding

TC2.5

500 m

TC2.5

2 rows of houses

Partial shielding

Negli Ne gli gib gible le

Partial shielding

TC2


500 m

TC2

4 9

TC2

2 rows of houses

2 rows of houses

No shielding

No shielding

TC3

Full shielding

© S t a n d a r d s A u s t r a l i a

A S 4 0 5 5 — 2 0 0 6

AS 4 055— 2006

50

APPENDIX D WORKED EXAMPLE FOR RACKING FORCES . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r

(Informative) The example given in this Appendix, using ultimate limit states design, illustrates the method of determining racking forces on a two-storey house located in Region B, Terrain Category 2.5, having partial shielding and a topographic class T2. For the example, assume that the house is 16 m long, 8 m wide and has a 17.5° pitched, gable-end roof. Step 1

From Table 2.2 (for Region B, TC2.5, T2 T2 and PS) the the wind class is N4.

Step 2

Calculate the upper storey racking for wind wind normal to ridge. From Table 5.8, for W = = 8 m and roof slope = 17.5°, the pressure for wind on side are determined: (1.2 + 1.4)/2 = 1.3. Determine area on which the pressure is to be applied and multiply the area by the pressure to give the racking force in kN. Provide bracing appropriate to resist this force.

Step 3

Calculate the upper upper storey storey racking for wind parallel to ridge (wind on end). From Table 5.8, for W = = 8 m and roof slope = 17.5°, the pressure for wind on side are determined: (1.6 + 1.7)/2 = 1.65. Determine area on which the pressure is to be applied and multiply the area by the

AS 4 055— 2006

50

APPENDIX D WORKED EXAMPLE FOR RACKING FORCES . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

(Informative) The example given in this Appendix, using ultimate limit states design, illustrates the method of determining racking forces on a two-storey house located in Region B, Terrain Category 2.5, having partial shielding and a topographic class T2. For the example, assume that the house is 16 m long, 8 m wide and has a 17.5° pitched, gable-end roof. Step 1

From Table 2.2 (for Region B, TC2.5, T2 T2 and PS) the the wind class is N4.

Step 2

Calculate the upper storey racking for wind wind normal to ridge. From Table 5.8, for W = = 8 m and roof slope = 17.5°, the pressure for wind on side are determined: (1.2 + 1.4)/2 = 1.3. Determine area on which the pressure is to be applied and multiply the area by the pressure to give the racking force in kN. Provide bracing appropriate to resist this force.

Step 3

Calculate the upper upper storey storey racking for wind parallel to ridge (wind on end). From Table 5.8, for W = = 8 m and roof slope = 17.5°, the pressure for wind on side are determined: (1.6 + 1.7)/2 = 1.65. Determine area on which the pressure is to be applied and multiply the area by the pressure to give the racking force in kN. Provide bracing appropriate to resist this force.

Step 4

Calculate lower storey racking for for wind wind normal to ridge. From Table 5.9, for W = = 8 m and roof slope = 17.5°, the pressure for wind on side are determined: (1.6 + 1.7)/2 = 1.65. Determine area on which the pressure is to be applied and multiply the area by the pressure to give the racking force in kN. Provide bracing appropriate to resist this force.

Step 5

Calculate lower storey storey racking for wind parallel to ridge (wind on end). From Table 5.9, for W = = 8 m and roof slope = 17.5°, the pressure for wind on side are determined: (1.9 + 2.0)/2 = 1.95. Determine area on which the pressure is to be applied and multiply the area by the pressure to give the racking force in kN. Provide bracing appropriate to resist this force.

©

Standards Australia


51

AS 4 055— 2006

AMENDMENT CONTROL SHEET

AS 4055—2006 . ) 7 3 2 5 0 2 0 1 ( d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u l a n o s r e p r e s u 1 . 1 1 0 2 y a M 6 n o s t c u d o r P d o o W d e r e e n i g n E r M o t d e s n e c i L

Amendment No. 1 (2008)

CORRECTION SUMMARY: This

Amendment applies to Clauses 1.5, 3.2, Tables 3.3, 3.4 and 4.1, and Figures 1.1, 2.2 and 5.2.

Published on 28 July 2008.

AS 4 055— 2006

52

NOT ES



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ISBN 0 7337 7087 8

As 4055-2006 Wind Loads for Housing

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