INTRODUCTION
1.1. RCC R CC FRAME STRUCTURES STRUCTURES
An RCC framed structure is basically an assembly of slabs, beams, columns and foundation inter -connected to each other as a unit. The load transfer, in such a structure takes place from the slabs to the beams, from the beams to the columns and then to the lower columns and finally to the foundation which in turn transfers it to the soil. The floor area of a R.C.C framed structure building is 10 to 12 percent more than that of a load bearing walled building. Monolithic construction is possible with R.C.C framed structures and they can resist vibrations, earthquakes and shocks more effectively than load bearing walled buildings. Speed of construction for RCC framed structures is more rapid.
Fig 1.1: RCC R CC Frame Frame Compon Componee nts
1.2. REINFORCED CONCRETE
Reinforced concrete is a composite material in which concrete's relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength and ductility. The reinforcement is usually embedded passively in the
1
concrete before the concrete sets. The reinforcement needs to have the following properti properties at least least for the the strong strong and and durable durable constru constructi ction: on:
High relative strength
High toleration toler ation of tensil tensilee stra strain in
Good bond to the concrete, irrespecti irrespec tive ve of pH, moisture, and simil similar ar factor.
Thermal
compatibility,
not
causing
unacceptable
stresses
in
response
to
changing temperatures.
1.3. OBJECTIVE
1.
To check the behaviour of multi-s ulti-store torey y regular regular and irregular irregular buildi building ng on software (STAADPro. & ETABS).
2.
To under understa stand nd the accuracy acc uracy of softwares software s for analysis analysis and desig des ign n for plan and elevation elevation Irregular Irregularit ity. y.
3.
To compare the results results and behaviour behaviour of structures structures on both the software.
1.4. DIFFERENT DIFFERENT METHODS USED USED FOR DESIGN
1.
Workin Wor king g stress stre ss method
2.
Limit Limit state stat e method
3.
Ultim Ultima te load method method
1.4.1. WORKING STRESS METHOD
It is based on the elastic theory assumes reinforced concrete as elastic material. The stress strain curve of concrete is assumed as linear from zero at neutral axis to maximum value at extreme fibre. This method adopts permissible stresses which are obtained by dividing ultimate stress by factor known as factor of safety. For concrete factor of safety 3 is used and for steel it is 1.78. This factor of safety accounts for any uncertainties in estimation of working loads and variation of material properties. In Working stress method, the structural members are designed for working loads such that the stresses developed are within the allowable stresses. Hence, the failure criterions are the stresses. This method is simple and reasonably reliable. This method has been deleted in IS 456-2000, but the concept of this method is retained for checking the serviceab serviceability, ility, states of deflection deflection and cracki crack ing. ng.
2
concrete before the concrete sets. The reinforcement needs to have the following properti properties at least least for the the strong strong and and durable durable constru constructi ction: on:
High relative strength
High toleration toler ation of tensil tensilee stra strain in
Good bond to the concrete, irrespecti irrespec tive ve of pH, moisture, and simil similar ar factor.
Thermal
compatibility,
not
causing
unacceptable
stresses
in
response
to
changing temperatures.
1.3. OBJECTIVE
1.
To check the behaviour of multi-s ulti-store torey y regular regular and irregular irregular buildi building ng on software (STAADPro. & ETABS).
2.
To under understa stand nd the accuracy acc uracy of softwares software s for analysis analysis and desig des ign n for plan and elevation elevation Irregular Irregularit ity. y.
3.
To compare the results results and behaviour behaviour of structures structures on both the software.
1.4. DIFFERENT DIFFERENT METHODS USED USED FOR DESIGN
1.
Workin Wor king g stress stre ss method
2.
Limit Limit state stat e method
3.
Ultim Ultima te load method method
1.4.1. WORKING STRESS METHOD
It is based on the elastic theory assumes reinforced concrete as elastic material. The stress strain curve of concrete is assumed as linear from zero at neutral axis to maximum value at extreme fibre. This method adopts permissible stresses which are obtained by dividing ultimate stress by factor known as factor of safety. For concrete factor of safety 3 is used and for steel it is 1.78. This factor of safety accounts for any uncertainties in estimation of working loads and variation of material properties. In Working stress method, the structural members are designed for working loads such that the stresses developed are within the allowable stresses. Hence, the failure criterions are the stresses. This method is simple and reasonably reliable. This method has been deleted in IS 456-2000, but the concept of this method is retained for checking the serviceab serviceability, ility, states of deflection deflection and cracki crack ing. ng.
2
1.4.2. LIMIT STATE METHOD
In this method, the structural elements are designed for ultimate load and checked for serviceability (deflection, cracking etc.) at working loads so that the structure is fit for use throughout its life period. As in working stress method this method does not assume stress stre ss strain curve curve as linear. linear. This This method gives gives econom eco nomica icall sections. sec tions. 1.4.3. 1.4. 3. ULTIM ULTIMATE ATE LOAD METHOD
In this method structural elements are designed for ultimate loads which are obtained by multiplying the working loads with a factor known as load factor. Hence, the designer can able to predict the excess load the structure can carry beyond the working loads without collapse. Hence, this method gives the true margin of safety. This method considers the actual stress strain curve of concrete and the failure criteria is assumed as ultimate strain. This method gives very economical sections. However it leads to excessive deformations and cracking. This method is failed to satisfy the serviceability and durability requirements. To overcome these drawbacks, the limit state method has been devel developed oped to take take care of both both streng strength and and serviceabili serviceability ty requi requireme reme nts.
1.5. STAADPro.
One of the most famous analysis m methods ethods for analysis is “Moment Distribution Method”, which is based on the concept of transferring the loads on the beams to the
supports at their ends. Each support will take portion of the load according to its K ; K is the stiffness factor, which equals ( EI/L). EI/L). E , and L is constant per span, the only variable is I ; moment of inertia. I depend on the cross section of the member. To use the moment distribution method, you have to assume a cross section for the spans of the continuous beam. beam. To anal analy yze the the fr ame, ame, “Stiffness Matrix Method” is used which depends upon matrices. The main formula of this method is [P] = [K] x [ Δ]. [P] is the force matrix = Dead Load, Live Load, Wind Load, etc. [K] is the stiffness factor matrix. K= (EI/L). (EI/L). [Δ [Δ] is the displacement displaceme nt matrix. STAAD was the first structural software which adopted Matrix Methods for analysis. The stiffness analysis implemented in STAAD is based on the matrix displacement method. In the matrix analysis of structures by the displacement method, the structure is first idealized into an assembly of discrete structural components (frame members or finite elements). Each component has an assumed form of displacement in a manner which which satisf sa tisfies ies the force equilibri equilibrium um and displacem displace me nt compatibil c ompatibilit it y at a t the joints.
3
STAAD stands for Structural Analysis and Design. STAAD.Pro is a general purpose structural analysis and design program with applications primarily in the building industry – commercial buildings, bridges and highways structures, and industrial structures etc. The program hence consists of the following facilities to enable this task:1. Graphical model generation utilities as well as text editor based commands for creating the mathematical model. Beam and column members are represented using lines. Walls, slabs and panel type entities are represented using triangular and quadrilateral finite elements. Solid blocks are represented using brick elements. These utilities allow the user to create the geometry, assign properties, orient cross sections as desired, assign materials like steel, concrete, timber, aluminium, specify supports, apply loads explicitly as well as have the program generate loads, design parameters etc. 2. Analysis engines for performing linear elastic and p-delta analysis, finite element analysis, frequency extraction and dynamic response. 3. Design engines for code checking and optimization of steel, aluminium and timber members. Reinforcement calculations for concrete beams, columns, slabs and shear walls. Design of shear and moment calculations for steel members. 4. Result viewing, result verification and report generation tools for examining displacement diagrams, bending moment and shear force diagrams, beam, plate and solid tress contours, etc. 5. Peripheral tools for activities like import and export of the data from and to other widely accepted formats, links with other popular softwares for footing design, steel connection design, etc.
1.6. ETABS
ETABS stands for Extended Three dimensional Analysis of Building Systems.
ETABS
was used to create the mathematical model of the Burj Khalifa, designed by Chicago, Illinois-based Skidmore, Owings and Merrill LLP (SOM). ETABS is commonly used to analyze: Skyscrapers, parking garages, steel & concrete structures, low rise buildings, portal frame structures, and high rise buildings. The input, output and numerical solution techniques of ETABS are specifically designed to take advantage of the unique physical and numerical characteristics associated with building type structures. A complete suite of Windows graphical tools and utilities are included with the base 4
package, including a modeller and a postprocessor for viewing all results, including force diagrams and deflected shapes. 1. ETABS provides both static and dynamic analysis for wide range of gravity, thermal and lateral loads. Dynamic analysis may include seismic response spectrum or accelerogram time history. 2. ETABS can analyze any combination of 3-D frame and shear wall system, and provides complete interaction between the two. The shear wall element is specially formulated for ETABS and is very effective for modelling elevator core walls, curved walls and discontinuous walls. This wall element requires no mesh definition and the output produced is in the form of wall forces and moments, rather than stresses. 3. A wide range of gravity, thermal and lateral loads may be applied for analysis. Lateral loads include automated UBC, BOCA and NBCC seismic and wind load along with ATC seismic and ASCE wind. 4. Steel
Frame,
Concrete
Frame
and
Concrete/Masonry
Shearwall
design
capabilities based upon AISC- ASD, LFRD, UBC and ACI-89 codes. 5. Outputs-
storey
displacements,
mode
shapes
and
periods,
lateral
frame
displacements, frame member forces are obtained at each level of the frame. 6. Special features available on ETABS are design of various shapes of Columns such as T-column, L-Column, and Poly shaped column. Design of Beams with varying depths 7. Shear walls with and without openings according to Indian Code can be provided in ETABS software.
5
LITERATURE REVIEW
2.0. General
Most of the work for analysis of multi storey building has been done on STAADPro. Evaluation of forces and moments for Dead load, Live load and Seismic load considered. But there is very less work has been done using load combination.
M C Griffith and A V Pinto (2000) have investigated the specific details of a 4-story,
3-bay reinforced concrete frame test structure with unreinforced brick masonry (URM) infill walls with attention to their weaknesses with regards to seismic loading. The concrete frame was shown to be a “weak -column strong- beam frame” which is likely to exhibit poor post yield hysteretic behaviour. The building was expected to have maximum lateral deformation capacities corresponding to about 2% lateral drift. The unreinforced masonry infill walls were likely to begin cracking at much smaller lateral drifts, of the order of 0.3%, and completely lost their load carrying ability by drifts of between 1% and 2%. [1]
Sanghani and Paresh (2011) studied the behaviour of beam and column at various
storey levels. It was found that the maximum axial force generated in the ground floor columns, max reinforcement required in the second floor beams. [2]
Poonam et al. (2012) Results of the numerical analysis showed that any storey,
especially the first storey, must not be softer/weaker than the storeys above or below. Irregularity in mass distribution also contributes to the increased response of the buildings. The irregularities, if required to be provided, need to be provided by appropriate and extensive analysis and design processes. [3]
Prashanth.P et al. (2012) investigated the behaviour of regular and irregular multi
storey building structure in STAADPro. and ETABS. Analysis and design was done according to IS-456 and IS-1893(2002) code. Also manually calculations were done to compare results. It was found that the ETABS gave the lesser steel area as that of STAADPro. Loading combinations were not considered in the analysis and influence of storey height on the structural behaviour was not described. [4]
6
MODELLING OF RCC FRAMES
3.0. RCC FRAME STRUCTURE
An RCC framed structure is basically an assembly of slabs, beams, columns and foundation inter-connected to each other as a unit. The load transfer, in such a structure takes place from the slabs to the beams, from the beams to the columns and then to the lower columns and finally to the foundation which in turn transfers it to the soil.
3.1. General
Case I
Regular Building
Case II
Irregular Building
3.1.1. Case I: Regular Building
A 32m x 20m 12-storey multi storey regular structure is considered for the study. Size of the each grid portion is 4m x 4m. Height of each storey is 3m and total height of the building is 36m. Plan of the building considered is shown in the figure 3.1.
Fig 3.1: Plan of the Building
7
Table 3.1: Building Description
3.1.2.
Length x Width
32x20m
No. of storeys
12
Storey height
3m
Beam
450x450mm
Column 1-6 storeys exterior perimeter line
800mm (diameter)
Column 1-6 storeys interior portion
600x600mm
Column 7-12 storeys
500x500mm
Slab thickness
125mm
Thickness of main wall
230mm
Height of parapet wall
0.90m
Thickness of parapet wall
115mm
Support conditions
Fixed
Case II: Irregular Building
A 32m X 20m 12-storey multi storey irregular structure is considered for the study. Size of each grid portion is 4m x 4m. Plan of the building considered is shown in the figure 3.2.
Fig 3.2: Plan of the Building 8
Table 3.2: Building Description
Length x Width
32x20m
No. of storeys
12
Storey height
3m
Beam along length
400x450mm
Beam along width
400x400mm
Column
750x750mm
Slab thickness
125mm
Thickness of main wall
230mm
Height of parapet wall
0.90m
Thickness of parapet wall
115mm
Support conditions
Fixed
3.2. Material Specifications Table 3.3: Material
Grade of Concrete ,M25
f ck = 25N/mm2
Steel
f y = 415N/mm2 25kN/m3
Density of Concrete
ϒc=
Density of Brick walls considered:
ϒ brick =
20kN/m3
3.3. Loading
Loads acting on the structure are dead load (DL), Live load and Earthquake load (EL), Dead load consists of Self weight of the structure, Wall load, Parapet load and floor load. Live load: 3kN/m2 is considered, Seismic zone: V, Soil type: II, Response reduction factor: 5, Importance factor: 1, Damping: 5%. Members are loaded with dead load, live load and seismic loads according to IS code 875(Part1, Part 2) and IS 1893(Part1):2002. 3.3.1. Selfweight
Self weight comprises of the weight of beams, columns and slab of the building.
9
3.3.2. Dead load
All permanent constructions of the structure form the dead load. The dead load comprises of the weights of walls, partition floor finishes, floors and other permanent constructions in the building. Dead load consists of: (a) Wall load
= (unit weight of brick masonry x wall thickness x wall height) = 20 kN/m3 x 0.230m x 3m = 13.8 kN/m (acting on the beam)
(b) Wall load (due to Parapet wall at top floor) = (unit weight of brick masonry x parapet wall thickness x wall height) = 20 kN/m3 x 0.115m x 0.90m = 2.07 kN/m (acting on the beam) (c) Floor load (due to floor thickness) = (unit weight of concrete x floor thickness) = 25 kN/m3 x 0.125m = 3.125 kN/m2 (acting on the beam) 3.3.3. Live load
Live loads include the weight of the movable partitions, distributed and concentrated load, load due to impact and vibration and dust loads. Live loads do not include loads due to wind, seismic activity, snow and loads due to temperature changes to which the structure will be subjected to etc. Live load varies acc. to type of building. Live load= 3kN/m2 on all the floors. 3.3.4. Seismic load
Seismic load can be calculated taking the view of acceleration response of the ground to the superstructure. According to the severity of earthquake intensity they are divided into 4 zones. 1. Zone II 2. Zone III 3. Zone IV 4. Zone V According to the IS-code 1893(part1):2002, the horizontal Seismic Coefficient A h for a structure can be formulated by the following expression Ah = (ZISa)/ (2Rg) Where Z= Zone factor depending upon the zone the structure belongs to. 10
For Zone II (Z= 0.1) For Zone III (Z= 0.16) For Zone IV (Z= 0.24) For Zone V (Z= 0.36) I= Importance factor, for Important building like hospital it is taken as 1.5 and for other building it is taken as 1. R= Response reduction factor Sa/g= Average Response Acceleration Coefficient Here Seismic load is considered along two directions- EQ LENGTH and EQ WIDTH.
3.4. Loading Combination
The structure has been analyzed for load combinations considering all the previous loads in proper ratio. Combination of self-weight, dead load, live load and seismic load was taken into considerat ion according to IS- code 875(Part 5). Table 3.4: Load Combination
LOAD COMBINATION
SR. NO. 1.
2.
3.
4.
5.
ETABS DCON1
DCON2
PRIMARY
FACTOR
STAADPro
LOAD
GENERATED INDIAN CODE
Self load
1.50
GENRAL_STRUCTURE 7
Dead load
1.50
Self load
1.50
Dead load
1.50
Live load
1.50
Self load
1.20
GENERATED INDIAN CODE
Dead load
1.20
GENRAL_STRUCTURE 3
Live load
1.20
EQ (along length)
1.20
Self load
1.20
GENERATED INDIAN CODE
Dead load
1.20
GENRAL_STRUCTURE 5
Live load
1.20
EQ (along length)
-1.20
Self load
1.20
GENERATED INDIAN CODE GENRAL_STRUCTURE 1
DCON3
DCON4
DCON5
GENERATED INDIAN CODE
11
GENRAL_STRUCTURE 4
6.
Dead load
1.20
Live load
1.20
EQ (along width)
1.20
Self load
1.20
GENERATED INDIAN CODE
Dead load
1.20
GENRAL_STRUCTURE 6
Live load
1.20
EQ (along width)
-1.20
Self load
1.50
Dead load
1.50
EQ (along length)
1.50
Self load
1.50
Dead load
1.50
EQ (along length)
-1.50
Self load
1.50
Dead load
1.50
EQ (along width)
1.50
Self load
1.50
Dead load
1.50
EQ (along width)
-1.50
Self load
0.90
Dead load
0.90
EQ (along length)
1.50
Self load
0.90
Dead load
0.90
EQ (along length)
-1.50
Self load
0.90
Dead load
0.90
EQ (along width)
1.50
Self load
0.90
Dead load
0.90
EQ (along width)
-1.50
DCON6
GENERATED INDIAN CODE
7.
DCON7 GENRAL_STRUCTURE 8
GENERATED INDIAN CODE
8.
9.
10.
DCON8 GENRAL_STRUCTURE 10
DCON9
GENERATED INDIAN CODE GENRAL_STRUCTURE 9
GENERATED INDIAN CODE DCON10
GENRAL_STRUCTURE 11
GENERATED INDIAN CODE
11.
DCON11
GENRAL_STRUCTURE 12
GENERATED INDIAN CODE
12.
DCON12 GENRAL_STRUCTURE 14
13.
DCON13
GENERATED INDIAN CODE GENRAL_STRUCTURE 13
14.
DCON14
GENERATED INDIAN CODE GENRAL_STRUCTURE 15
12
3.5. Modelling in ETABS a) Case I: Regular Building
(a)
(b)
Fig 3.3: (a) Front Elevation, (b) Side Elevation of the Building
Fig 3.4: 3-D View of the G+11 storey building in ETABS
13
Loading Pattern Dead Load
Fig 3.5: Wall and Parapet load distribution in ETABS
Live Load
Fig 3.6: Live Load distribution (Plan View) 14
Seismic Load
Fig 3.7: Seismic Load (along length) on the Building
Fig 3.8: Seismic Load (along width) on the Building 15
EQ along length on the First Storey
Fig 3.9: EQ along length on the First Storey
EQ along length on the Last Storey
Fig 3.10: EQ along length on the Last Storey
16
b) Case II: Irregular Building
(a)
(b)
Fig 3.11: (a) Front Elevation, (b) Side Elevation of the Building
Fig 3.12: 3-D View of the G+11 storey building in ETABS
17
Loading Pattern Dead Load
Fig 3.13: Wall and Parape Parape t load distribution distribution
Live Load
Fig 3.14: Live Load distribution
18
Seismic Load
Fig 3.15: Seismic Load (along length) on the Building
Fig 3.16: Se ismic Load (along width width)) on the the Building Building 19
EQ along length on the First Storey
Fig 3.17: EQ along length on the First Storey
EQ along length on the Last Storey
Fig 3.18: EQ along length on the Last Storey
20
3.6. Modelling in STAADPro. a) Case I: Regular Building
(a)
(b)
Fig 3.19: (a) Front Elevation, (b) Side Elevation of the Building
Fig 3.20: 3-D View of the G+11 storey building in STAADPro.
21
Loading Pattern Selfweight of the building
Fig 3.21: Self Weight of the Building
Dead Load
Fig 3.22: Wall load distribution 22
(a)
(b)
Fig 3.23: (a) Parapet load on the last floor (b) Floor load (Plan View)
Live Load
Fig 3.24: Live Load distribution on the Building
Seismic Load
(a)
(b)
Fig 3.25: (a) Seis mic Load (along length) (b) Seismic load (along width) on building
23
b) Case II: Irregular Building
(a)
(b)
Fig 3.26: (a) Front Elevation, (b) Side Elevation of the Building
Fig 3.27: 3-D View of the G+11 storey building in STAADPro.
24
Loading Pattern Selfweight of the building
Fig 3.28: Self Weight of the Building
Dead Load
Fig 3.29: Wall load distribution 25
(a)
(b) th
Fig 3.30: (a) Wall and Parapet load on the 6 floor (b) Floor Load
Fig 3.31: Live Load distribution
(a)
(b)
Fig 3.32: (a) Seismic Load (along length) (b) Seismic Load (along width)
26
RESULTS AND OBSERVATIONS
Some of the sample analysis and design results have been shown below for beams and columns of various floor of the building. 4.1. ETABS software a) Case I: Regular Building
(a)
(b)
Fig 4.1: (a) B.M . Diagram for Selfweight (b) Shear Force diagram for Selfweight
Fig 4.1(a): shows that the beams undergo sagging in middle portion and hogging in end portion due to Selfweight. Beams behave like continuous beam.
Fig 4.2: Max Stress Diagram for load (0.9Self +0.9Dead +1.5EQlength)
Figure shows that the max stress in the range 60-70kN/m2 is produced at the bottommost storey and decreases with the increase in storey height. 27
4.1.1. BEAM NO. B53 of top floor
Fig 4.3: Beam B53
Fig 4.4: B.M . Diagram for load combination 1.5(Selfweight + De ad + EQlength)
Above figure shows that the reaction of 11.59kN and 52.38kN is produced at left and right end of the beam respectively due to load combination 1.5(Selfweight + Dead + EQlength). Maximum shear force of 52.38kN is obtained at right end of the beam.
Maximum axial force, s hear force, B.M. of the beam B53 Table 4.1: Analysis Data
Forces Axial Force (P)
1.51 kN
Shear Force (V2)
74.57 kN
Shear Force (V3)
0.051 kN
Bending Moment (M2)
0.09 kN-m
Bending Moment (M3)
35.62 kN-m 28
ETABS CONCRETE DESIGN
Fig 4.5: Concrete Design of Beam 53 of Regular building
Fig 4.6: Concrete Design of Beam B53 (Envelope) of Regular building
Fig 4.5 shows that moment is 13250.97kN-m for designing beam and steel provided is 586mm2 . Fig 4.6 shows that controlling load combination for flexural and shear is DCON13 (0.9 Self +0.9Dead +1.5EQwidth) and DCON14 (0.9Self +0.9Dead 1.5EQwidth). 29
4.1.2. COLUMN NO. C30 of storey 11
Fig 4.7: Column C30
(a)
(b)
Fig 4.8: (a) Axial Force (b) B.M. Diagram for load 1.5(Self +Dead load +EQlength)
Above fig. 4.8(a) shows that axial force is maximum at the bottom storey columns and minimum at top storey columns. Fig 4.8(b) shows that bending moment decreases with increase in the storey height.
30
Maximum axial force, shear force, B.M. of the column C30 of storey11 Table 4.2: Analysis Data
Column forces/ B.M. Axial Force (P)
10.61 kN
Shear Force (V2)
33.42 kN
Shear Force (V3)
63.45 kN
Torsion (T)
0.008 kN -m
Bending Moment (M2)
85.29 kN -m
Bending Moment (M3)
73.84 kN -m
ETABS CONCRETE DESIGN
Fig 4.9: Concrete Design of Column C30 (Flexural Details) of Regular building
As column is designed according to sway analysis and design load is 208.041kN and design moment is 712.01kN-m. Steel obtained acc. to design load is 2000mm2 .
31
Fig 4.10: Concrete Design of Column C30 of Re gular building
st
4.1.3. Area of Steel obtained from ETABS for beams of 1 floor
Table 4.3: Area of Steel for beams of 1 st floor
Beam No.
Area of steel (mm )
Area of steel
(mm )
(450 X 450 mm)
( Bottom Reinforceme nt)
( Top Reinforcement)
B1
685
967
B2
680
936
B3
680
935
B4
680
935
B5
680
935
B6
680
935
B7
680
936
B8
685
967
B9
652
1015
32
B10
655
1021
B11
655
1021
B12
652
1015
B13
685
967
B14
604
980
B15
604
980
B16
604
980
B17
604
980
B18
602
980
B19
602
979
B20
602
979
B21
602
980
B22
604
980
B23
652
1015
B24
601
979
B25
601
978
B26
601
978
B27
601
979
B28
655
1021
B29
604
980
B30
601
979
B31
601
978
B32
601
978
B33
601
979
B34
604
980
B35
655
1021
B36
602
980
B37
602
978
B38
602
978
B39
602
980
B40
604
980
B41
652
1015 33
B42
680
936
B43
680
935
B44
680
935
B45
680
935
B46
680
935
B47
680
936
B48
685
967
B49
698
981
B50
665
1029
B51
668
1035
B52
669
1036
B53
669
1036
B54
669
1036
B55
668
1035
B56
616
994
B57
665
1029
B58
698
981
B59
693
950
B60
617
994
B61
618
995
B62
618
996
B63
618
995
B64
617
994
B65
616
994
B66
693
950
B67
692
948
B68
614
992
B69
615
992
B70
614
992
B71
615
993
B72
615
992
B73
614
992 34
B74
614
992
B75
692
948
B76
698
981
B77
693
950
B78
616
994
B79
665
1029
B80
617
994
B81
668
1035
B82
618
994
B83
669
1036
B84
618
996
B85
669
1036
B86
618
996
B87
669
1036
B88
617
994
B89
668
1035
B90
616
994
B91
665
1029
B92
693
950
B93
698
981
st
4.1.4. Area of Steel obtained from ETABS for columns of 1 storey
Table 4.4: Area of Steel for column of 1st storey
Column
Section (mm)
Area of steel (mm2 )
C1
800 (diameter)
4021
C2
800 (diameter)
4021
C3
800 (diameter)
4021
C4
800 (diameter)
4021
C5
800 (diameter)
4021
35
C6
800 (diameter)
4021
C7
800 (diameter)
4021
C8
800 (diameter)
4021
C9
800 (diameter)
4021
C10
800 (diameter)
4021
C11
800 (diameter)
4021
C12
800 (diameter)
4021
C13
800 (diameter)
4021
C14
800 (diameter)
4021
C15
800 (diameter)
4021
C16
800 (diameter)
4021
C17
800 (diameter)
4021
C18
800 (diameter)
4021
C19
800 (diameter)
4021
C20
800 (diameter)
4021
C21
800 (diameter)
4021
C22
800 (diameter)
4021
C23
800 (diameter)
4021
C24
800 (diameter)
4021
C25
800 (diameter)
4021
C26
800 (diameter)
4021
C27
600 X 600
2880
C28
600 X 600
3709
C29
600 X 600
3709
C30
600 X 600
2880
C31
600 X 600
3737
C32
600 X 600
4801
C33
600 X 600
4801
C34
600 X 600
3737
C35
600 X 600
3845 36
C36
600 X 600
4918
C37
600 X 600
4918
C38
600 X 600
3845
C39
600 X 600
3857
C40
600 X 600
4931
C41
600 X 600
4931
C42
600 X 600
3857
C43
600 X 600
3845
C44
600 X 600
4918
C45
600 X 600
4918
C46
600 X 600
3845
C47
600 X 600
3737
C48
600 X 600
4801
C49
600 X 600
4801
C50
600 X 600
3737
C51
600 X 600
2880
C52
600 X 600
3709
C53
600 X 600
3709
C54
600 X 600
2880
4.1.5. Area of Stee l obtained from ETABS for columns of 3 rd storey to 12 th storey
Table 4.5: Area of Steel for columns of 3 rd storey to 12 th storey
Storey
Column
Area of Steel (mm2 )
3rd
800 mm (dia)
4021
3rd
600 X 600 mm
2880
4t h
800 mm (dia)
4021
4t h
600 X 600 mm
2880
37
5t h
800 mm (dia)
4021
5th
600 X 600 mm
2880
6t h
800 mm (dia)
4021
6t h
600 X 600 mm
2880
7t h
500 X 500 mm
2000
8t h
500 X 500 mm
2000
9t h
500 X 500 mm
2000
10t h
500 X 500 mm
2000
11t h
500 X 500 mm
2000
12t h
500 X 500 mm
2000
Table 4.5 shows that the steel area decreases with increase in storey height and become constant after 6t h storey level.
4.1.6. Storey Overturning Moment for structure
STOREY OVERTURNING MOMENTS 120000
s t n e m 100000 o M 80000 g ) n m i n r N 60000 u k t r ( e v 40000 O y e r 20000 o t S 0
EQ length (X-Direction) EQ width (Y-Direction)
Storey Fig 4.11: Graph of Storey Vs Overturning Moment
As per above graph it has been concluded that the storey overturning moment decreases with increase in storey height in both x and y-directions for EQlength and EQwidth respectively 38
4.1.7. Storey Shear for structure
STOREY SHEAR
4500 EQ length (X-Direction)
4000
) 3500 N k ( 3000 r a2500 e h S2000 y e r1500 o t S1000
EQ width (Y- Direction)
500 0 1
2
3
4
5
6
7
8
9
10 11 12
Storey Fig 4.12: Graph of Storey Vs Storey Shear
As per above graph it has been concluded that the storey shear decreases with increase in storey height in both x and y-directions for EQlength and EQwidth respectively.
4.1.8. Max Storey Displacement for structure
MAX STOREY DISPLACEMENT 40
t n 35 e m e 30 c a l p s ) 25 i D m20 m y ( e r 15 o t S 10 x a 5 M
EQ length( in X-Direction) EQ width(in Y-Direction)
0 e s a B
1
2
3
4
5
6
7
8
9 0 1 2 1 1 1
Storey
Fig 4.13: Graph of Storey Vs Max Storey Displacement
As per above graph it has been concluded that the max storey displacement increases with increase in storey height in both x and y-directions for EQlength and EQwidth respectively. 39
b) Case II: Irregular Building
(a)
(b)
Fig 4.14: (a) B.M. (b) Shear Force diagram for Dead load
Fig 4.15: Max Stress Diagram for load combination 1.5(Self +dead +Live)
Figure shows that the max stress in the range 14-21kN/m2 is produced at the bottommost storey and decreases with the increase in storey height, from storey 2 nd to 11t h storey a stress of (-7 to +7kN/m2) is acting .
40
4.1.9. BEAM NO. B26 of top floor 12
Fig 4.16: Beam B26 of Irregular building
Maximum Axial force, Shear force, B.M. of the beam B26 Table 4.6: Analysis Data
Forces Axial Force (P)
-0.347 kN
Shear Force (V2)
56.23 kN
Shear Force (V3)
0.024 kN
Torsion (T)
0.066 kN-m
Bending Moment (M2)
0.047 kN-m
Bending Moment (M3)
26.94 kN-m
ETABS CONCRETE DESIGN
Fig 4.17: Concrete Design of Beam 26 of Irregular building 41
Fig 4.18: Concrete Design of Beam 26 (Envelope)
4.1.10. COLUMN NO. C18 of storey 11
Fig 4.19: Column C18
Maximum axial force, shear force, B.M. of the column C18 of storey11 Table 4.7: Analysis Data Forces
Axial Force (P)
-118.49 kN
Shear Force (V2)
9.18 kN
Shear Force (V3)
4.02 kN
Torsion (T)
0.48 kN-m
Bending Moment (M2)
88.69kN-m
Bending Moment (M3)
92.96 kN-m 42
(a)
(b)
Fig 4.20: (a) B.M. (b) Axial Force diagram for load combination 1.2(Self +Dead +Live +EQwidth)
ETABS CONCRETE DESIGN
Fig 4.21: Concrete Design of Column C18 43
Fig 4.22: Concrete Design of Column C18 (Flexural Details)
4.1.11. Area of Steel obtained from ETABS for beams of 1 st floor
st
Table 4.8: Area of Steel for beams of 1 floor
Beam No.
Area of steel (mm )
Area of steel
(mm )
( Bottom Reinforcement)
( Top Reinforcement)
B1
644
520
B2
645
520
B3
669
520
B4
669
520
B5
655
520
B6
655
520
B7
636
520
B8
641
520
B9
626
520
B10
620
520
B11
566
520
B12
571
520
B13
566
520
B14
571
520
44
B15
620
520
B16
626
520
B17
641
520
B18
636
520
B19
655
520
B20
655
520
B21
669
520
B22
669
520
B23
645
520
B24
644
520
B25
604
463
B26
643
463
B27
640
463
B28
640
463
B29
643
463
B30
604
463
B31
591
463
B32
631
463
B33
628
463
B34
594
463
B35
630
463
B36
599
463
B37
593
463
B38
630
463
B39
594
463
B40
604
463
B41
642
463
B42
602
463
B43
602
463
B44
593
463
45
B45
599
463
B46
628
463
B47
631
463
B48
595
463
B49
594
463
B50
630
463
B51
594
463
B52
569
463
B53
642
463
B54
630
463
B55
606
520
B56
565
520
B57
565
520
B58
606
520
B59
670
520
B60
618
520
B61
618
520
B62
670
520
B63
661
520
B64
599
520
B65
599
520
B66
661
520
B67
634
463
B68
633
463
B69
634
463
B70
633
463
B71
632
463
B72
633
463
4.1.12. Area of Steel obtained from ETABS for columns
All columns of 1st to 12th Storey have steel area = 4500 mm2 46
4.1.13. Storey Overturning Moment for structure
) m N k ( s t n e m o M g n i n r u t r e v O y e r o t S
STOREY OVERTURNING MOMENTS 60000 50000 EQ length (X- direction)
40000
EQ width (Y- direction)
30000 20000 10000 0
Storey Fig 4.23: Graph of Storey Vs Overturning Moment
As per above graph it has been concluded that the storey overturning moment decreases with increase in storey height in both x and y-directions for EQlength and EQwidth respectively.
4.1.14. Storey Shear for structure
STOREY SHEAR 2500
) 2000 N k ( r1500 a e h S y1000 e r o t S 500
EQ length (X- direction) EQ width (Y- direction)
0 1
2
3
4
5
6
7
8
9 10 11 12
Storey Fig 4.24: Graph of Storey Vs Storey Shear
As per above graph it has been concluded that the storey shear decreases with increase in storey height in both x and y-directions for EQlength and EQwidth respectively. 47
4.1.15. Max Storey Displacement for structure
) m35 m ( t 30 n e m25 e c20 a l p s 15 i D y10 e r 5 o t S x 0 a M
MAX STOREY DISPLACEMENT
X - Direction Y - Direction
e s a B
1
2
3
4
5
6
7
8
9
0 1
1 1
2 1
Storey Fig 4.25: Graph of Storey Vs Max Storey Displacement due to EQ length
As per above graph it has been concluded that the max storey displacement increases with increase in storey height along x-direction for EQlength load and varies constantly (app.) along y-direction for EQlength.
4.1.16. Max Storey Displacement for structure
MAX STOREY DISPLACEMENT ) 30 m m25 ( t 20 n e m15 e c a 10 l p s i D 5 y e r 0 o t S x a M
X - Direction Y - Direction
e 1 s a B
2
3
4
5
6
7
8
9 0 1 2 1 1 1
Storey
Fig 4.26: Graph of Storey Vs Max Storey Displacement due to EQ width
As per above graph it has been concluded that the max storey displacement increases with increase in storey height along x-direction for EQwidth load and varies constantly (app.) along y-direction for EQwidth load. 48
4.2. STAADPro. a) Case I: Regular Building
(a)
(b)
Fig 4.27: (a) B.M . (b) Shear Force diagram for load 1.5(Se lf +Dead – EQlength)
4.2.1. Beam No. 1835 of top floor
Fig 4.28: Beam 1853
Fy(kN) 80
Mz(kNm) 80
80
70.7
80
61.7
40
40
40
40
653
2.67
653 1
2
684 3
684 1
2
3
-12.8 -28.6
40
80
-20 40
80
(a)
4
4
40
40
80
80
(b)
Fig 4.29: (a) B.M. (b) S.F. diagram for load 1.2(Self +De ad +Live +EQlength)
49
Maximum axial force, shear force, B.M. of the beam 1853 Table 4.9: Analysis Data
Forces Axial Force (Fx )
52.71 kN
Shear Force (Fy )
77.17 kN
Shear Force (Fz)
4.82 kN
Torsion (Mx )
0.14 kN-m
Bending Moment (My )
9.97 kN-m
Bending Moment (M z)
88.35 kN-m
STAADPro. CONCRETE DESIGN
Fig 4.30: Concrete Design of Beam 1835 (Hogging) of Regular building
50
Fig 4.31: Concrete Design of Beam 1835 (Sagging) of Regular building
4.2.2. COLUMN NO. 1602 of storey 11
Fig 4.32: Column C1602 51
Fig 4.33: B.M. diagram for load combination 1.5(Self +De ad – EQlength)
Maximum axial force, shear force, B.M. of the column 1602 Table 4.10: Analysis Data
Forces Axial Force (Fx )
522.99 kN
Shear Force (Fy )
37.37 kN
Shear Force (Fz)
71.26 kN
Torsion (Mx )
0.05 kN-m
Bending Moment (My )
122.130 kN-m
Bending Moment (M z)
114.40 kN-m
STAADPro. CONCRETE DESIGN of column 1602/member 873
Fig 4.34: Main Reinforcement Cross-Section 52
Fig 4.35: Main Reinforcement
st
4.2.3. Area of Steel obtained from STAADPro. for beams of 1 floor
Table 4.11: Area of steel for beams of 1 st floor
Member
Area of steel (mm )
Area of steel
(mm )
(450 X 450 mm)
( Bottom Reinforcement)
( Top Reinforcement)
M1
1257
1885
M2
1257
1963
M3
1257
1885
M4
1257
1963
M5
1257
2413
M6
1257
1885
M7
1257
2413
M8
1257
1963
M9
1257
2413
53
M10
1257
2413
M11
1257
2413
M12
1257
2413
M13
1257
2413
M14
1257
2413
M15
1257
2413
M16
1257
2413
M17
1257
2413
M18
1257
2413
M19
1257
2413
M20
1257
2413
4.2.4. Area of Steel obtained from STAADPro. for columns Table 4.12: Area of steel for columns
Storey
Column
Area of Steel (mm )
Main Reinforce ment
1st
600 X 600 mm
3927
8- T25
1s
800 mm (dia)
3436
7- T25
3r
800 mm (dia)
2827
9- T20
3r
600 X 600 mm
3768
12- T20
4t
800 mm (dia)
2827
9- T20
4t
600 X 600 mm
3768
12- T20
5t
800 mm (dia)
2199
7- T20
5th
600 X 600 mm
1885
6- T20
6t
800 mm (dia)
2199
7- T20
6t
600 X 600 mm
1885
6- T20
7t
500 X 500 mm
1885
6- T20
8t
500 X 500 mm
1885
6- T20
9t
500 X 500 mm
1885
6- T20
10t
500 X 500 mm
1885
6- T20
11t
500 X 500 mm
1885
6- T20
12t
500 X 500 mm
1885
6- T20 54
b) Case II: Irregular Building
(a)
(b)
Fig 4.36: (a) B.M. (b) S.F. diagram for load 1.5(Self +De ad +EQlength)
th
4.2.5. Beam No. 1313 of 6 floor
Fig 4.37: Beam 1313
(a)
(b)
Fig 4.38: (a) B.M. (b) S.F. diagram for load 1.5(Se lf + Dead – EQ width)
55
Maximum axial force, shear force, B.M. of the beam 1313
Table 4.13: Analysis Data
Forces Axial Force (Fx )
35.34 kN
Shear Force (F y )
92.08 kN
Shear Force (Fz)
35.44 kN
Torsion (Mx )
1.43 kN-m
Bending Moment (My )
75.01 kN-m
Bending Moment (Mz)
148.62 kN-m
Fig 4.39: Stress diagram for load combination 1.5(Self + De ad – EQ width)
56
STAADPro. CONCRETE DESIGN of beam 1313 (Member 222)
Fig 4.40: Concrete Design of Beam 1313 (Hogging) of Irregular building
Fig 4.41: Concrete De sign of Beam 1313 (Sagging) of Irregular building 57
st
4.2.6. COLUMN C99 of 1 storey
Fig 4.42: Column C99
Fig 4.43: B.M. diagram for load combination (0.9Self +0.9De ad +1.5EQlength)
Fig 4.44: Stress diagram for load combination (0.9Self +0.9De ad +1.5EQlength)
58
Maximum axial force, shear force, B.M. of the column 99 Table 4.14: Analysis Data
Forces Axial Force (F x )
4056.02 kN
Shear Force (Fy )
101.16 kN
Shear Force (Fz)
145.56 kN
Torsion (Mx )
10.46 kN-m
Bending Moment (M y )
576.62 kN-m
Bending Moment (M z)
476.52 kN-m
STAADPro. CONCRETE DESIGN of column 99(member 249)
Fig 4.45: Main Reinforcement Cross-Section
Fig 4.46: Main Reinforcement 59
st
4.2.7. Area of Steel obtained from STAADPro. for beams of 1 floor
Table 4.15: Area of steel for beams of 1 st floor
Member
Beam Section
Area of steel (mm )
Area of steel (mm )
(mm)
( Bottom Reinforcement)
( Top Reinforcement)
M1
400 x 450
1257
1885
M2
400 x 400
942
1885
M3
400 x 450
942
1473
M4
400 x 400
942
1571
M5
400 x 450
942
1473
M6
400 x 400
942
1571
M7
400 x 450
1257
1885
M8
400 x 400
942
1885
M9
400 x 400
942
1885
M10
400 x 400
942
1885
M11
400 x 450
942
1885
M12
400 x 450
1257
1885
M13
400 x 450
942
1885
M14
400 x 450
942
1885
M15
400 x 450
942
1885
M16
400 x 450
1257
1885
st
4.2.8. Area of Steel obtained from STAADPro. for columns of 1 storey
Table 4.16: Area of s teel for column (750 x 750mm)
Member
Area of Steel (mm2 )
Main Reinforce ment
223
5891
12 – T25
224
3770
12 – T20
225
5027
16 – T20
226
3770
12 – T20
(750 x 750mm)
60
227
3770
12 – T20
228
3770
12 – T20
229
3770
12 – T20
230
5027
16 – T20
231
3770
12 – T20
232
5027
16 – T20
233
3770
12 – T20
234
5027
16 – T20
235
5027
16 – T20
236
5891
12 – T25
237
5027
16 – T20
238
3770
12 – T20
239
5027
16 – T20
240
3770
12 – T20
241
3770
12 – T20
242
3770
12 – T20
243
3770
12 – T20
244
5027
16 – T20
245
3770
12 – T20
246
5891
12 – T25
247
5891
12 – T25
248
5891
12 – T25
249
3770
12 – T20
250
5027
16 – T20
251
3770
12 – T20
252
3770
12 – T20
253
3770
12 – T20
254
3770
12 – T20
255
3770
12 – T20
256
3770
12 – T20
257
3770
12 – T20
258
3770
12 – T20 61
rd
th
4.2.9. Area of Steel obtained from STAADPro. for columns from 3 to 12 storey
Table 4.17: Area of s teel for column (750 x 750mm)
Storey
Area of Steel (mm2 )
Main Reinforce ment
3rd
3770
12 - T20
4th
3770
12 - T20
5th
3770
12 - T20
6th
3770
12 - T20
7th
3770
12 - T20
8th
3770
12 - T20
9th
3770
12 - T20
10t h
3770
12 - T20
11t h
3770
12 - T20
12t h
3770
12 - T20
62
CONCLUSIONS
General
After Discussion of results and observation some of results are summarized. Based on the behaviour of RCC frames on STAADPro. and ETABS some important conclusions are drawn:1. Results of max vertical reactions of a 12-storey regular building. As per table 5.1 it has been concluded that the max reaction produced is
4572.12kN
in
ETABS
and
4624.92kN in STAADPro. due to load 1.5(Self +Dead +Live).
Table 5.1: Comparison of vertical reaction of Regular building
ETABS
STAADPro
Forces Loading
Axial
1.5(Self +Dead –
Force FX
EQlength)
Shear
1.5(Self +Dead
Force FY
+Live)
Shear
1.5(Self +Dead –
Force FZ
EQwidth)
B.M. MX
MY
MZ
Value
140.23kN
4572.12kN
138.11kN
Loading
1.2(Self +Dead +Live – EQlength)
1.5(Self +Dead +Live)
1.2(Self +Dead +Live – EQwidth)
Value
171.48kN
4624.92kN
173.98kN
1.5(Self +Dead
397.17
1.2(Self +Dead +Live –
535.81
+EQwidth)
kN-m
EQwidth)
kN-m
1.5(Self +Dead – EQwidth)
0.35kN-m
1.2(Self +Dead +Live +EQlength)
3.04kN-m
1.5(Self +Dead –
397.74
1.2(Self +Dead +Live +
518.89
EQlength)
kN-m
EQlength)
kN-m
63
2. Max Deformation of members of 12- storey regular and irregular building
Table 5.2: Max Node Displacement
Max Node Displaceme nt (mm) Displacement Direction
Regular building
Irregular building
STAADPro.
ETABS
STAADPro.
ETABS
X
75.48
51.36
106.25
44.9
Y
1.11
0.77
1.062
0.48
Z
81.57
53.47
93.40
42.38
As per above table it has been concluded that the maximum displacement is along xdirection and its value is 106.25mm (in STAADPro.) for irregular building and 53.47mm (in ETABS) along z-direction for regular building. So, more precise results are generated by ETABS which leads to economical design of the building.
3. Design Results of sample beam and column Column C13 of storey 6 from ETABS and Column 851 of storey 6 from STAADPro. of 12 storey – regular building are taken for comparison.
Table 5.3: Steel Reinforcement
Total Reinforcement ( mm2 ) Section STAADPro.
ETABS
Beam (450 x 450mm)
1257
1172
Column (dia-800 mm)
4021
4021
As per above table it has been concluded that the ETABS gave lesser area of steel required as compared to STAADPro. in case of beam whereas in case of column steel calculated is same by both softwares.
64
4. Comparison of Storey Overturning Moments
) m N k ( s t n e m o m g n i n r u t r e v O y e r o t S
STOREY OVERTURNING MOMENTS 120000 100000 80000 Regular Building
60000
Irregular Building
40000 20000 0 e s a B
1
2
3
4
5
6
7
8
9
0 1
1 1
2 1
Storey
Fig 5.1: Storey Vs Storey Overturning Moments due to EQ length in X-direction
As per above graph it has been concluded that the storey overturning moment decreases with increase in storey height along x-direction for EQlength load and they are more in regular building than the irregular building.
5.
Maximum Steel Reinforcement of beam and column of regular and irregular building in ETABS.
Table 5.4: Steel Reinforcement
Total Reinforcement ( mm ) Section Regular Building
Irregular Building
Beam
1595
1293
Column
4931
4500
As per above table it has been concluded that the ETABS gave lesser area of steel reinforcement for irregular building as compared to regular building in case of beams and columns.
65
REFERENCES
[1]
Griffith M. C., Pinto A. V. (2000), “Seismic Retrofit of RC Buildings - A Review and Case Study”, University of Adelaide, Adelaide, Australia and European Commission, Joint Research Centre, Ispra Italy.
[2]
Sanghani bharat k. and Paresh Girishbhai Patel, 2011, “Behaviour of Building Component
in
Various
Zones,” International
Journal
of
Advances
in
Engineer ing Sciences, Vol. 1, Issue 1(Jan. 2011)
[3]
Poonam, Kumar Anil and Gupta Ashok K, 2012, “Study of Response of Structural Journal
of
Irregular Building Frames to Seismic Excitations,” International Civil,
Structural,
Environmental
and
Infrastructure
Engineering
Research and Development (IJCSEIERD), ISSN 2249-6866 Vol.2, Issue 2 (2012) 25-31
[4]
Prashanth.P, Anshuman. S, Pandey. R.K, Arpan Herbert (2012), “Comparison of design results of a Structure designed using STAAD and ETABS Software, ” INTERNATIONAL
JOURNAL
OF
CIVIL
AND
STRUCTURAL
ENGINEERING, ISSN 0976 – 4399, Volume 2, No 3, 2012
[5]
Bureau of Indian Standards: IS- 875, part 1 (1987), Dead Loads on Buildings and Structures, New Delhi, India.
66
[6]
Bureau of Indian Standards: IS- 875, part 2 (1987), Live Loads on Buildings and Structures, New Delhi, India.
[7]
Bureau of Indian Standards: IS- 1893, part 1 (2002), Criteria for Earthquake Resistant Design of Structures: Part 1 General provisions and Buildings, New Delhi, India.
[8]
Hammad Salahuddin, Saqib Habib, Talha Rehman (2010), “Comparison of design of a building using ETABS V 9.5 & STAAD PRO 2005, ” University of Engineering and Technology, Taxila, Pakistan.
67
APPENDIX A A.1)
Comparison of Mode Shapes for regular and irregular building
Regular Building
Irregular Building Mode I
Re gular Building
Irregular Building Mode IV
68
Re gular Building
Irregular Building Mode VIII
Re gular Building
Irregular Building Mode XI
Re gular Building
Irregular Building Mode XII 69
