eathquake resistance design of open ground storey building
TRANSCRIPT
EATHQUAKE RESISTANCE DESIGN OF
OPEN GROUND STOREY BUILDING
SIRIPURAPU PRUDHVIRAJ1, Dr. VEEREDHI LAKSHMI SHIREEN BANU2
1 Student, Malla Reddy Engineering College (Autonomous), Maisammaguda, Medchal(M), Malkajgiri(D),
500100 2Professor, Malla Reddy Engineering College (Autonomous), Maisammaguda, Medchal(M),
Malkajgiri(D), 500100
Abstract— Now a day’s reinforced concrete (RC) wall-frame buildings are widely recommended for urban construction in areas with
high seismic hazard. Presence of shear walls imparts a large stiffness to the lateral force resisting system of the RC building. Proper
detailing of shear walls can also lead to ductile behavior of such structures during strong earthquake shaking. One of the major parameters
influencing the seismic behavior of shear wall frame buildings is the shear wall area ratio. Thus shear wall area ratio is set as a key
parameter which is needed to be study.
An analytical study is performed to evaluate the effect of Shear Wall Area to floor area ratio (SWA/FA %) on the seismic behavior of
multistoried RC structures with open storey at ground floor. For this purpose, 2 building models that have 9 and 13 stories are generated.
For G+9 SWA/FA % is decreased from 0.48% to 0.31% and analysed. For G+13 SWA/FA % is increased from 0.32% to 0.4% and
analysed. Then, the behavior of these building models under earthquake loading is examined by carrying out response spectrum analysis
using structural analysis software E-TABS. Response spectrum analysis is done according to seismic code IS 1893:2002. The main
parameters considered in this study are the relation SWA / FA % has with storey displacement, storey drift, storey shear and storey
stiffness. The analytical results indicated that building models with more SWA / FA % behaved adequately under earthquake loads.
Keywords— Response spectrum analysis, storey displacement, storey drift, storey shear, storey stiffness, Etabs
I. INTRODUCTION
In the last few decades, shear walls have been used extensively in countries especially where high seismic risk is observed. The
major factors for inclusion of shear walls are ability to minimize lateral drifts, inter storey displacement and excellent performance
in past earthquake record. Shear walls are designed not only to resist gravity loads but also can take care overturning moments as
well as shear forces. They have very large in plane stiffness that limit the amount of lateral displacement of the building under lateral
loadings. Shear walls are intended to behave elastically during moderate or low seismic loading to prevent non-structural damage
in the building. However, it is expected that the walls will be exposed to inelastic deformation during less or frequent earthquakes.
Thus, shear walls must be designed to withstand forces that cause inelastic deformations while maintaining their ability to carry
load and dissipate energy. Structural and non-structural damage is expected during severe earthquakes however; collapse prevention
and life safety is the main concern in the design.
The shear wall area to floor area ratio (also referred to as shear wall ratio), the wall aspect ratio, and the wall configuration in plan
are indicated as important parameters that affect the detailing of a shear wall for RC design. However, among these parameters,
shear wall ratio is also accepted as an essential parameter affecting the global performance of a building under severe ground motions.
Therefore, shear wall ratio is set as a key parameter to be investigated in this analytical study. The effect of shear wall ratio on
structural vulnerability could be evaluated by the variation of different parameters such as roof or inter storey drift with increasing
shear wall ratio. Lateral forces exerted by strong ground motions induce deformations on buildings leading to structural damage.
Global deformations in a structure such as roof drift and inter storey drifts are good indicators of expected damage of a building
under earthquake loading. Even so, the relationship between drift and shear wall ratio have not been deeply investigated as of now.
Independent of shear wall ratio, current building codes recommend certain limits for roof and inter storey drifts obtained from both
linear and nonlinear analyses. Eurocode 8 (European Committee for Standardization 2003) limits the elastic design inter storey
drifts, whereas the Structural Engineers Association of California (SEAOC) (1999) and Applied Technology Council (ATC) (1996)
have limits on inelastic inter storey drifts for specified performance levels. The Turkish Earthquake Code (TEC) (2007) also restricts
the inter storey drifts in linear elastic performance analysis.
The International journal of analytical and experimental modal analysis
Volume XII, Issue VI, June/2020
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II. LITERATURE SURVEY
Riddell et al. a study was performed by to define the general features of the buildings located in Vina del Mar that experienced the
1985 Chile earthquake and to identify the related earthquake damage. Data of 178 low and midrise buildings representing a stock
of 322, of which 319 have shear walls, were used in the evaluation. Most of these buildings were designed with considerably high
shear wall ratios (varying between 3.0 and 8.0%, with an average of 6.0%), independent of the number of stories. As an outcome of
this study, it can be stated that the higher the shear wall ratio used in a building, the lower the possibility of having damage in the
structural system during a strong ground motion.
Wallace and Moehle an analytical procedure is proposed by to predict the variation of roof drift with shear wall ratio. Fig. 2.1(a)
is generated following this procedure for building models having different shear wall ratios, and the effect of shear wall ratio on the
behavior is obtained for different shear wall aspect ratios. Wallace and investigated the response of shear wall buildings by using
the same procedure. Fig. 2.1(b) shows the estimated periods of the buildings with different shear wall ratios. This study indicated
that buildings with a shear wall ratio more than 1.5% in the direction of loading that has a shear wall aspect ratio equal to or less
than 5 are expected to experience roof drifts less than 1.0% under strong ground motions.
Hassan and Sozen “Seismic Vulnerability Assessment of Low-Rise Buildings in regions with infrequent earthquakes” A
simplified method proposed which enables ranking an inventory of low-rise (up to five stories) monolithic RC buildings based on
their seismic vulnerability level from low to high by using column and wall indexes. This method requires only structural dimensions
as the input and is based on effective wall and column indexes plotted in a two-dimensional form. The wall index including RC and
masonry infill walls is the ratio of the effective wall area at the base of the building to the total floor area. The column index is the
ratio of the effective column area at the base to the total floor area. The effective areas are proposed to be taken as the area of 100%
of RC walls, 10% of non-reinforced infill walls, and 50% of columns.
Ersoy and Tekel “Seismic strengthening of RC structures with exterior shear walls” In earthquake-resistant design, when a dual
system is used, the general approach is using a shear wall area to floor area ratio of about 1.0% as a rule of thumb. Some approximate
shear wall ratios are proposed in the literature to be used in preliminary design stages of shear wall-frame buildings. These ratios
are generally based on empirical values that are obtained from building surveys performed after severe earthquakes. This study
investigates the performance of exterior RC shear walls (ESW) that are placed parallel to the building’s sides. In reality, installing
a shear wall to a structural system will surely improve the seismic capacity of the structure. The main concern is whether the design
methods for the connection of old and new elements can satisfy codes. To make it clear, an experimental program was carried out
on two-storey three dimensional RC models. The program includes a reference model and a strengthened model. Additionally,
numerical solutions are presented and compared with the results of the experiments.
European Committee for Standardization Lateral forces exerted by strong ground motions induce deformations on buildings
leading to structural damage. Global deformations in a structure such as roof drift and inter story drifts are good indicators of
expected damage of a building under earthquake loading. Even so, the relationship between drift and shear wall ratio have not been
deeply investigated as of now. Independent of shear wall ratio, current building codes recommend certain limits for roof and inter
story drifts obtained from both linear and nonlinear analyses.
Gulkan and Utkutug investigated the relationship between roof drift and shear wall ratio by taking into account the shear wall
aspect ratio, which is represented as H/D [Fig. 2.2(a)]. The study by Gulkan and Utkutug emphasized the importance of a minimum
shear wall ratio that should be used in the design of RC buildings. Maximum compressive concrete strain of the shear wall member
was also investigated as a control criterion in this study. When the strain is restricted to a level of 0.003, for large wall aspect ratios,
H/D, and axial load levels, considerably higher wall ratio is required to meet this strain criterion. In Fig. 2.2(b), a strain level of
0.003 is shown with a horizontal line, and based on these results under increasing axial load ratios (N*), approximately
1.5%shearwall ratio is required to satisfy the demand for the most unfavorable conditions.
Chai and Kunnath developed graphs for estimating minimum thickness to be provided for the shear wall based on various
parameters, namely ground motion intensity, longitudinal reinforcement ratio, floor weight, wall-floor area ratio, and number of
stories. Results were presented in terms of storey height to wall thickness with respect to various parameters. Study showed that
thicker walls are required for lower a/v ratios (peak ground acceleration to peak ground velocity ratio) indicating softening of site
conditions with decreasing a/v ratios. Minimum wall thickness arrived at was compared to that of code provisions.
Sharany Haque, khan Mahmud Amanat “Seismic Vulnerability of Columns of RC frame Buildings with Open ground Storey”.
Earthquake vulnerability of buildings with open ground floors is well known around the world. Under the present socio economic
context of developing nations like Bangladesh, construction of such buildings is unavoidable. These types of buildings should
not be treated as ordinary RC framed buildings. The calculation of earthquake forces by treating them as ordinary frames results in
an underestimation of base shear. When RC framed buildings having brick masonry infill on upper floor with open ground floor
is subjected to earthquake loading, base shear can be more than twice to that predicted by equivalent earthquake force method with
or without infill or even by response spectrum method when no infill in the analysis model. It can be suggested that the base shear
calculating by equivalent static method may at least be doubled for the safer design of the columns of open ground floor.
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III. MODELLING
In the present study lateral load analysis is performed on four building models that have two nine and thirteen stories with the same
plans but different shear wall area ratios are generated for the application of response spectrum analysis. Response Spectrum
Analysis is carried out by using seismic code IS 1893:2002. The Shear wall area ratio is determined by dividing the total shear wall
area in one principal direction to the plan area of the ground floor (∑Aw/Ap). In this analytical study, shear wall area ratio of about
0.48%, 0.31 and 0.32% and 0.40% are selected to investigate the seismic behavior of multistoried G+9 and G+13 RC buildings with
ground floor as open ground storey respectively.
A. Description of the Building Model’s
TABLE I
DESCRIPTION OF BUILDING MODELS
Model Id Number
of Storey
SWA / FA %
X -Direction Y -Direction
1 9 0.48 0.48
2 9 0.31 0.31
3 13 0.32 0.32
4 13 0.40 0.40
Fig. 1 Plan layout of nine storey building with 0.48 SWA/FA%
Fig. 2 Isometric view and front elevation of nine storey building with 0.48 SWA/FA%
Fig. 3 Plan layout of nine storey building with 0.31 SWA/FA%
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Fig. 4 Isometric view and front elevation of nine storey building with 0.31 SWA/FA%
Fig. 5 Plan layout of thirteen storey building with 0.32 SWA/FA%
Fig. 6 Isometric view and front elevation of thirteen storey building with 0.32 SWA/FA%
Fig. 7 Plan layout of thirteen storey building with 0.4 SWA/FA%
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Fig. 8 Isometric view and front elevation of thirteen storey building with 0.4 SWA/FA%
B. Design Data:
1. Material Properties:
Young’s modulus of (M20) concrete, E = 22.360 x 106 kN/m²
Density of Reinforced Concrete = 25 kN/m³
Modulus of elasticity of brick masonry = 3500 x 10³ kN/m²
Density of brick masonry = 19.2 kN/m³
Assumed Dead load intensities
Floor finishes = 1.5 kN/m²
Live load = 4 kN/ m²
2.Member properties:
Thickness of Slab = 0.125m
Column size = (0.9 m x 0.6 m)
Beam size = (0.3 m x 0.6 m)
Thickness of wall = 0.250 m
Thickness of shear wall = 0.175, 0.225, 0.275 and 0.325m
Earthquake Live Load on Slab as per clause 7.3.1 and 7.3.2 of IS 1893 (Part-I) - 2002 is calculated as:
Roof (clause 7.3.2) = 0
Floor (clause 7.3.1) = 0.5 x 4 = 2 kN/m2
IV. RESULTS AND DISCUSSION
A. Storey Displacement:
The below tables and graphs represents the relationship between storey vs. displacement for different SWA/FA% of G+9 and
G+13 buildings (0.48%, 0.31%, 0.32% and 0.40%), performed by using Response Spectrum Analysis.
TABLE 2
Storey displacements of G+9 building with 0.48 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
mm
Y-Dir
mm
X-Dir
mm
Y-Dir
mm
Story9 27 Top 7.1 1.641E-02 0.1 9.2
Story8 24 Top 6.5 2.008E-02 0.1 8.5
Story7 21 Top 5.8 1.977E-02 0.1 7.6
Story6 18 Top 5.1 1.785E-02 0.1 6.8
Story5 15 Top 4.3 1.718E-02 0.1 6
Story4 12 Top 3.6 1.864E-02 4.633E-02 5.1
Story3 9 Top 3 1.759E-02 3.617E-02 4.4
Story2 6 Top 2.4 1.763E-02 4.719E-02 3.7
Story1 3 Top 1.8 0.1 0.1 3.1
Base 0 Top 0 0 0 0
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Fig. 9 Storey displacements of G+9 building with 0.48 SWA/FA% for EQ X
Fig. 10 Storey displacements of G+9 building with 0.48 SWA/FA% for EQ Y
TABLE 3
Storey displacements of G+9 building with 0.31 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
mm
Y-Dir
mm
X-Dir
mm
Y-Dir
mm
Story9 27 Top 7.2 2.138E-02 4.621E-02 12
Story8 24 Top 6.5 1.967E-02 4.804E-02 11
Story7 21 Top 5.8 1.721E-02 4.27E-02 9.9
Story6 18 Top 5.1 1.335E-02 3.495E-02 8.7
Story5 15 Top 4.3 1.036E-02 2.91E-02 7.5
Story4 12 Top 3.6 8.092E-03 2.534E-02 6.3
Story3 9 Top 2.9 9.014E-03 2.81E-02 5.2
Story2 6 Top 2.4 8.363E-03 2.479E-02 4.2
Story1 3 Top 1.8 2.094E-02 0.1 3.2
Base 0 Top 0 0 0 0
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Fig. 11 Storey displacements of G+9 building with 0.31 SWA/FA% for EQ X
Fig. 12 Storey displacements of G+9 building with 0.31 SWA/FA% for EQ Y
TABLE 4 Storey displacements of G+13 building with 0.32 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
mm
Y-Dir
mm
X-Dir
mm
Y-Dir
mm
Story13 39 Top 27.3 1.1 1.2 25.4
Story12 36 Top 25 1 1.1 23.1
Story11 33 Top 22.6 0.9 0.9 20.8
Story10 30 Top 20.2 0.8 0.8 18.5
Story9 27 Top 17.7 0.7 0.7 16.2
Story8 24 Top 15.2 0.6 0.6 13.8
Story7 21 Top 12.7 0.5 0.5 11.5
Story6 18 Top 10.2 0.4 0.4 9.3
Story5 15 Top 7.8 0.3 0.3 7.2
Story4 12 Top 5.7 0.2 0.2 5.3
Story3 9 Top 3.7 0.2 0.2 3.7
Story2 6 Top 2.1 0.1 0.1 2.3
Story1 3 Top 0.9 0.1 0.1 1.2
Base 0 Top 0 0 0 0
Fig.13 Storey displacements of G+13 building with 0.32 SWA/FA% for EQ X
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Fig. 14 Storey displacements of G+13 building with 0.32 SWA/FA% for EQ Y
TABLE 5
Storey displacements of G+13 building with 0.4 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
mm
Y-Dir
mm
X-Dir
mm
Y-Dir
mm
Story13 39 Top 18.6 1 0.9 21.4
Story12 36 Top 17 1 0.8 19.5
Story11 33 Top 15.3 0.9 0.7 17.6
Story10 30 Top 13.6 0.8 0.6 15.7
Story9 27 Top 11.9 0.7 0.6 13.7
Story8 24 Top 10.2 0.6 0.5 11.8
Story7 21 Top 8.5 0.5 0.4 9.9
Story6 18 Top 6.9 0.4 0.3 8
Story5 15 Top 5.4 0.3 0.3 6.3
Story4 12 Top 4 0.2 0.2 4.7
Story3 9 Top 2.7 0.2 0.1 3.3
Story2 6 Top 1.7 0.1 0.1 2.1
Story1 3 Top 0.8 0.1 0.1 1.2
Base 0 Top 0 0 0 0
Fig.15 Storey displacements of G+13 building with 0.4 SWA/FA% for EQ X
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Fig.16 Storey displacements of G+13 building with 0.4 SWA/FA% for EQ Y
B. Storey Drift
The below tables and graphs represents the relationship between storey vs. drifts for different SWA/FA% of G+9 and G+13
buildings (0.48%, 0.31%, 0.32% and 0.40%), performed by using Response Spectrum Analysis.
TABLE 6
Storey drifts of G+9 building with 0.48 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir Y-Dir X-Dir Y-Dir
Story9 27 Top 0.000217 0.000003 0.000003 0.000258
Story8 24 Top 0.00023 0.000001 0.000001 0.000272
Story7 21 Top 0.000239 0.000001 0.000002 0.000281
Story6 18 Top 0.000242 0.000001 0.000002 0.000282
Story5 15 Top 0.000237 0.000001 0.000002 0.000276
Story4 12 Top 0.000224 0.000002 0.000004 0.000258
Story3 9 Top 0.000202 0.000005 0.000008 0.000229
Story2 6 Top 0.000239 0.000017 0.000022 0.000292
Story1 3 Top 0.000604 0.000019 0.000032 0.001026
Base 0 Top 0 0 0 0
Fig.17 Storey drifts of G+9 building with 0.48 SWA/FA% for EQ X
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Fig. 18 Storey drifts of G+9 building with 0.48 SWA/FA% for EQ Y
TABLE 7
Storey drifts of G+9 building with 0.31 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir Y-Dir X-Dir Y-Dir
Story9 27 Top 0.000223 0.000001 0.000005 0.00034
Story8 24 Top 0.000238 0.000001 0.000002 0.000371
Story7 21 Top 0.000247 0.000001 0.000003 0.000392
Story6 18 Top 0.000248 0.000001 0.000002 0.000403
Story5 15 Top 0.000242 0.000001 0.000001 0.0004
Story4 12 Top 0.000226 0.000001 0.000003 0.000379
Story3 9 Top 0.000204 0.000001 0.000001 0.000337
Story2 6 Top 0.000238 0.000007 0.000016 0.000388
Story1 3 Top 0.000591 0.000007 0.000018 0.001082
Base 0 Top 0 0 0 0
Fig.19. Storey drifts of G+9 building with 0.31 SWA/FA% for EQ X
Fig.20.Storey drifts of G+9 building with 0.31 SWA/FA% for EQ Y
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TABLE 8
Storey drifts of G+13 building with 0.32 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir Y-Dir X-Dir Y-Dir
Story13 39 Top 0.000758 0.000031 0.000034 0.000745
Story12 36 Top 0.000789 0.000032 0.000035 0.000765
Story11 33 Top 0.000813 0.000032 0.000035 0.000777
Story10 30 Top 0.000833 0.000033 0.000036 0.000783
Story9 27 Top 0.000843 0.000033 0.000035 0.00078
Story8 24 Top 0.00084 0.000032 0.000035 0.000766
Story7 21 Top 0.000822 0.000031 0.000033 0.000738
Story6 18 Top 0.000784 0.000029 0.000031 0.000695
Story5 15 Top 0.000727 0.000026 0.000029 0.000635
Story4 12 Top 0.000647 0.000023 0.000025 0.000558
Story3 9 Top 0.000543 0.000019 0.000021 0.000464
Story2 6 Top 0.000435 0.00003 0.000036 0.000402
Story1 3 Top 0.000286 0.000035 0.000038 0.000398
Base 0 Top 0 0 0 0
Fig.21 Storey drifts of G+13 building with 0.32 SWA/FA% for EQ X
Fig.22 Storey drifts of G+13 building with 0.32 SWA/FA% for EQ Y
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TABLE 9
Storey drifts of G+13 building with 0.40 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir Y-Dir X-Dir Y-Dir
Story13 39 Top 0.000535 0.000029 0.000025 0.000614
Story12 36 Top 0.000553 0.00003 0.000025 0.000633
Story11 33 Top 0.000564 0.000031 0.000026 0.000644
Story10 30 Top 0.00057 0.000031 0.000026 0.00065
Story9 27 Top 0.000569 0.000031 0.000026 0.000648
Story8 24 Top 0.000559 0.00003 0.000026 0.000636
Story7 21 Top 0.00054 0.000029 0.000025 0.000613
Story6 18 Top 0.00051 0.000028 0.000023 0.000579
Story5 15 Top 0.000468 0.000026 0.000022 0.00053
Story4 12 Top 0.000415 0.000023 0.000019 0.000469
Story3 9 Top 0.000348 0.000019 0.000016 0.00039
Story2 6 Top 0.000283 0.000015 0.000013 0.000319
Story1 3 Top 0.000273 0.000024 0.00002 0.000392
Base 0 Top 0 0 0 0
Fig.21 Storey drifts of G+13 building with 0.40 SWA/FA% for EQ X
Fig.22 Storey drifts of G+13 building with 0.40 SWA/FA% for EQ Y
C. Storey Stiffness
The below tables and graphs represents the relationship between storey vs. stiffness for different SWA/FA% of G+9 and G+13
buildings (0.48%, 0.31%, 0.32% and 0.40%), performed by using Response Spectrum Analysis.
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TABLE 10
Storey stiffness values of G+9 building with 0.48 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
kN/m
Y-Dir
kN/m
X-Dir
kN/m
Y-Dir
kN/m
Story9 27 Top 702957.722 0 0 590066.778
Story8 24 Top 1357824.29 0 0 1146635.869
Story7 21 Top 1823988.294 0 0 1553477.739
Story6 18 Top 2177444.545 0 0 1867202.381
Story5 15 Top 2483982.572 0 0 2142545.932
Story4 12 Top 2818864.181 0 0 2447614.198
Story3 9 Top 3292287.344 0 0 2913688.063
Story2 6 Top 3167794.437 0 0 2697384.512
Story1 3 Top 1143330.165 0 0 675340.241
Base 0 Top 0 0 0 0
Fig. 23 Storey stiffness values of G+9 building with 0.48 SWA/FA% for EQ X
Fig. 24 Storey stiffness values of G+9 building with 0.48 SWA/FA% for EQ Y
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TABLE 11
Storey stiffness values of G+9 building with 0.31 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
kN/m
Y-Dir
kN/m
X-Dir
kN/m
Y-Dir
kN/m
Story9 27 Top 643944.441 0 0 425730.425
Story8 24 Top 1218499.495 0 0 782008.053
Story7 21 Top 1634653.395 0 0 1028853.36
Story6 18 Top 1957236.299 0 0 1206621.33
Story5 15 Top 2245796.468 0 0 1359987.255
Story4 12 Top 2579914.812 0 0 1539034.966
Story3 9 Top 3046214.672 0 0 1826191.055
Story2 6 Top 2950335.776 0 0 1785622.339
Story1 3 Top 1073190.774 0 0 584671.983
Base 0 Top 0 0 0 0
Fig.25 Storey stiffness values of G+9 building with 0.31 SWA/FA% for EQ X
Fig.26 Storey stiffness values of G+9 building with 0.31 SWA/FA% for EQ Y
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TABLE 12
Storey stiffness values of G+13 building with 0.32 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
kN/m
Y-Dir
kN/m
X-Dir
kN/m
Y-Dir
kN/m
Story13 39 Top 172877.632 0 0 191089.607
Story12 36 Top 354492.69 0 0 397397.795
Story11 33 Top 496994.588 0 0 565998.86
Story10 30 Top 608552.094 0 0 704587.99
Story9 27 Top 699710.972 0 0 823681.929
Story8 24 Top 779981.167 0 0 933006.107
Story7 21 Top 858598.565 0 0 1042874.085
Story6 18 Top 945805.447 0 0 1165576.466
Story5 15 Top 1055455.623 0 0 1318573.449
Story4 12 Top 1211392.325 0 0 1531868.414
Story3 9 Top 1457339.764 0 0 1866914.282
Story2 6 Top 1886944.772 0 0 2287936.173
Story1 3 Top 2995238.902 0 0 2330725.839
Base 0 Top 0 0 0 0
Fig.27 Storey stiffness values of G+13 building with 0.32 SWA/FA% for EQ X
Fig. 28 Storey stiffness values of G+13 building with 0.32 SWA/FA% for EQ Y
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TABLE 13
Storey stiffness values of G+13 building with 0.40 SWA/FA%
Story Elevation
m Location
For EQ X For EQ Y
X-Dir
kN/m
Y-Dir
kN/m
X-Dir
kN/m
Y-Dir
kN/m
Story13 39 Top 383512.536 0 0 276115.072
Story12 36 Top 796356.102 0 0 574927.648
Story11 33 Top 1130996.229 0 0 818840.394
Story10 30 Top 1405329.806 0 0 1019204.759
Story9 27 Top 1640468.36 0 0 1191414.591
Story8 24 Top 1855562.547 0 0 1349273.127
Story7 21 Top 2070186.806 0 0 1507264.195
Story6 18 Top 2307057.843 0 0 1682348.401
Story5 15 Top 2597815.179 0 0 1898706.21
Story4 12 Top 2993965.941 0 0 2194056.554
Story3 9 Top 3617318.461 0 0 2672107.227
Story2 6 Top 4469095.029 0 0 3282944.913
Story1 3 Top 4821186.821 0 0 2699681.493
Base 0 Top 0 0 0 0
Fig. 29 Storey stiffness values of G+13 building with 0.40 SWA/FA% for EQ X
Fig. 30 Storey stiffness values of G+13 building with 0.40 SWA/FA% for EQ Y
D.Storey Shears
The below tables and graphs represents the relationship between storey vs. shears for different SWA/FA% of G+9 and G+13
buildings (0.48%, 0.31%, 0.32% and 0.40%), performed by using Response Spectrum Analysis.
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Fig.31 Storey shears of G+9 building with 0.48 SWA/FA% for EQ X
Fig.32 Storey shears of G+9 building with 0.48 SWA/FA% for EQ Y
Fig. 33 Storey shears of G+9 building with 0.31 SWA/FA% for EQ X
Fig. 34 Storey shears of G+9 building with 0.31 SWA/FA% for EQ Y
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V. CONCLUSIONS
On the basis of the results of the analytical investigation of 9 and 13 storey RC building models with increasing and decreasing
shear wall to floor area ratio (SWA / FA) % by considering the ground floor as open ground storey, the following conclusions are
drawn:
It is observed that as the height increases the displacements are also increases, but by increasing the SWA / FA % the
displacements values decreases. In case of 9 – storey building model maximum displacements are observed when SWA / FA
% = 0.31 and In case of 13 – storey building model when SWA / FA % = 0.32 maximum displacements are observed as
expected.
However, a shear wall ratio less than 0.31 % is not sufficient to limit the observed displacement. Similar effects can be seen in
nine storey model.
It is observed that there is a decrease in storey drift as the storey increases and also when the shear wall ratio is increased from
0.31 to 0.40% in G+13 building.
It is observed that there is a decrease in storey shear as the storey increases and increases when the shear wall ratio is increased.
In case of G+13 building when SWA/FA % = 0.31 the storey shears are more in Y-direction but as the SWA/FA % is increased
to 0.40% the storey shears are more in X-direction than in Y-direction.
It is observed that there is a decrease in storey stiffness as the storey increases and increases when the shear wall ratio is
increased.
The storey stiffness values are more in X-direction as compared to Y-direction.
G+9 and G+13 structures are stiffer for high SWA/FA% i.e., for 0.48% and 0.4% respectively.
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ISSN NO:0886-9367
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