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IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE)
e-ISSN : 2278-1684, p-ISSN : 2320–334X
PP 80-89
www.iosrjournals.org
Innovation in engineering science and technology (NCIEST-2015) 80 | Page
JSPM’S Rajarshi Shahu College Of Engineering,Pune-33,Maharashtra ,India
Effect of Plan Shapes on the Response of Buildings
Subjected To Wind Vibrations
B. S. Mashalkar 1
, G. R. Patil 2
, A.S.Jadhav.3
1
M.E. (Structure) Student, Department of Civil Engineering Rajarshi Shahu College of Engineering,
Tathawade,Pune,Maharashtra-India
2
Assistant Professor Department of Civil Engineering Rajarshi Shahu College of Engineering,
Tathawade, Pune, Maharashtra-India Email- 1
bhagys.m@gmail.com
3
B.E.Student, Department of Civil Engineering Rajarshi Shahu College of Engineering, Tathawade, Pune,
Maharashtra-India
Abstract: The development of new architectural forms of buildings and flexible structural systems are
vulnerable to wind action. For desirable performance of these buildings, we require better understanding of
interaction between building and wind. Structures are classified as rigid and flexible. This paper presents a
comparative study of effect of wind on plans with different irregular shapes as I, C, T and L. The significance of
this work is to estimate the design load of the structure subjected to wind in a particular region. The wind load
is estimated based on basic wind speed and other factors as type of topography, terrain, and the use of building
and its risk factor for that particular region. The present investigation deals with the calculation of wind loads
for structural frame with different plan shapes and the results are compared with respect to permissible drifts of
individual buildings. In this analysis it is found that the amount of drift is considerably changed with respect to
shape of the structure. And also found that wind load on the building is maximum when it has maximum exposed
area.
Keywords: Wind loads, high rise buildings, drift, irregular plan buildings.
I. Introduction
Resent advances in the development of high strength materials coupled with more advanced
computational methods and design procedures have lead to a new generation of tall buildings which are slender
and light. These buildings are very sensitive to the two common dynamic loads as wind and earthquakes. It is
necessary to address the serviceability issue, such as human comfort and integrity of structural components
during the strong winds. While designing high-rise buildings and its cladding for wind load, the designers refer
to relevant codes/standards to pick the wind pressure coefficients and wind force coefficients. The Indian code
IS: 875 (part-3)-1987 gives the design pressure coefficients and force coefficients for buildings having different
side ratios and height, but this code remains silent about the pressure coefficients on typical plan shape tall
buildings such as L, C, T and I.
The aim of present study is to examine the effects of wind on tall structure under different geometric
plan configuration of tall building having same parameters. All the tall buildings with different plan
configuration have been modeled in E Tabs software and then comparative study has been executed.
A. Importance of Wind Loads on the Tall Buildings
Wind is a phenomenon of great complexity because of many flow situations arising from the
interaction of wind with structures. Wind is composed of multitude of eddies of varying sizes and rotational
characteristics carried along in a general stream of air moving relative to the earth’s surface. These eddies give
wind its gusty or turbulent character. The gustiness of strong winds in the lower levels of the atmosphere largely
arises from interaction with surface features. The average wind speed over a time period of the order of ten
minutes or more tends to increase with height, while the gustiness tends to decrease with height.
B. Effects of wind load
A mean wind force acts on a building. This mean wind force is derived from the mean wind speed and
the fluctuating wind force produced by the fluctuating flow field. The effect of the fluctuating wind force on the
building or part thereof depends not only on the characteristics of the fluctuating wind force but also on the size

e-ISSN : 2278-1684, p-ISSN : 2320–334X
PP 80-89
and vibration characteristics of the building or part thereof. Therefore, in order to estimate the design wind load,
it is necessary to evaluate the characteristics of fluctuating wind forces and the dynamic characteristics of the
building. The factors generally considered in determining the fluctuating wind force are:
1) Wind turbulence (temporal and spatial fluctuation of wind) 2) Vortex generation in wake of building
3) Interaction between building vibration and surrounding air flow for most buildings, the effect of fluctuating
wind force generated by wind turbulence is predominant. In this case, horizontal wind load on structural frames
in the along-wind direction is important. However, for relatively flexible buildings with a large aspect ratio,
horizontal wind loads on structural frames in the across-wind and torsional directions should not be ignored
II. Literature Review
Isyumov overviews the action of wind on tall buildings and structures with emphasis on the overall
wind-induced structural loads and responses also discussed the local wind pressures on components of the
exterior envelope and the effects of buildings on winds in pedestrian areas.
Ahsan Kareem his discussion encompasses modeling of wind field; structural aerodynamics;
computational methods; dynamics of long -period structures; model – to full-scale monitoring; codes/standards
and design tools; damping and motion control devices.
Prof. Sarita Singla, Taranjeet Kaur, Megha Kalra and Sanket Sharma Behaviour of R.C.C. Tall
Buildings Having Different Shapes Subjected to Wind Load.
Ritu Raj and Ashok Kumar Ahuja Wind Loads on Cross Shape Tall Buildings It is observed that base
shear, base moments and twisting moments developed due to wind loads are not only influenced by wind
directions, but also highly affected by cross-sectional shapes.
M. Glória Gomes, A. Moret Rodrigues, Pedro Mendesn were discussed about Wind Effects On And
Around L- And U-Shaped Buildings with experimental models.
I.I Objective of the study
i. To Study the behavior of tall structures when subjected to along wind loads.
ii. To study the effect of shape of the building in plan on the behavior of the structure.
iii. To determine the effect of wind load on various parameters like storey drifts, lateral displacements in
the building.
III. Scope Of The Present Study
The scope of the present work included the study of the wind load estimation on tall buildings for the
structural design purpose with the analytical approach in IS 875: part 3-1987 and the analysis of the building
had been done by using E tabs software and the performance was analyzed by varying the shape of structure.
Different shapes of the building studied were:
a)L shape
b) C shape
c) I shape
d) T shape
IV. Parameters Of The Building
1. Different cases of the building analysed were as under:
a) G+11 storeyed L shaped framed building. (Fig. 1)
b) G+11 storeyed C shaped framed building. (Fig. 2)
c) G+11 storeyed I shaped framed building. (Fig. 3)

e-ISSN : 2278-1684, p-ISSN : 2320–334X
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d) G+11 storeyed T shaped framed building. (Fig. 4)
Various parameters of the buildings adopted were as under: Total Height = 34.5 m
Grid Size = 4 m x 4 m
Size of Columns = 450 mm x 450 mm
Size of Beams at each floor = 200mm x 600 mm
Thickness of slab = 150mm
Grade of Concrete in Columns = M30
Grade of Concrete in Beams = M20
Grade of steel = Fe 500
All supports were assumed to be fixed.
Plan
Fig. 1 Plan and 3D view of L shaped Building

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Fig. 2 Plan and 3D view of C shaped Building
Fig. 3 Plan and 3D view of I shaped Building

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Fig. 4 Plan and 3D view of T shaped Building
A. Loadings Considered
i. Dead Loads:The loads of the beams and columns had been taken in account by E tabs.
ii. LiveLoad-The live loads had been taken as 3.00 kN/m2
at all floors.
iii.Super dead load had been calculated and applied to slabs and beams i.e SDL = 9KN/m2
.
B. Wind Load Calculations based Upon the Codal Provisions
For all buildings with different shapes parameters considered are same throughout the structural frame.
The models were analysed in E tabs for Pune region.
Parameters considered for Wind analysis are as follows: Terrain Category: III
Structure Class: B
Basic Wind Velocity, Vb : 39 m/s
L Shape:
Plan Length: 34.5m
Plan Width: 34.5m Face width = 34.5 m; Face depth = 34.5 m k1 = 1;
k3 = 1;
Vb = 39 m/s
Vz = Vb x k1 x k2 x k3
Cf = 1.25
C Shape:

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Plan Length: 33m Plan Width: 22.5m Face width = 33 m; Face depth = 34.5 mk1=1
k3 = 1;
Vb = 39 m/s
Cf = 1.25
I Shape:
Plan Length: 24m Plan Width: 26m Face width = 24 m; Face depth = 34.5 m k1 = 1;
k3 = 1;
Vb = 39 m/s
Cf = 1.23
T Shape:
Plan Length: 34m Plan Width: 10m Face width = 24 m; Face depth = 34.5 m k1 = 1;
k3 = 1;
Vb = 39 m/s
Vz = Vb x k1 x k2 x k3 Cf = 1.23
C. Load Combinations
Load combinations were considered as per IS 875(part 5)
Table I. Wind Forces At Different Height Of The Building in KN Vb= 39m/s
HEIGHT L SHAPE I SHAPE C SHAPE T SHAPE

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STOREY 1
42.06 31.29 44.9 44.33
STOREY2
84.12 62.59 89.98 88.66
STOREY3
84.12 62.59 89.98 88.66
STOREY4
84.46 62.84 90.34 89.03
STOREY5
88.83 66.1 95.02 93.64
STOREY6
95.59 71.12 102.34 100.75
STOREY7
100.94 75.1 107.97 106.4
STOREY8
105.3 78.35 112.63 110.99
STOREY9
108.63 80.82 113.19 114.5
STOREY10
111.91 83.27 119.7 117.96
STOREY11
115.02 85.58 123.03 121.23
TERRACE
58.29 43.37 62.35 61.44
Fig.5 Variation of Wind Force with height
V. Results And Discussion
The behavior of different buildings when subjected to wind load have been discussed further.
A. Effect of the Shape of the Building on Storey Drifts:
The Storey drifts for L, C, Tand I shaped building are compared in Table II and Fig.6.

IOSR Journal of XXXXXXXX (IOSRJXXXX)
e-ISSN : XXXX-XXXX, p-ISSN : XXXX-XXXX
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Table II. Storey Drifts At Different Heights in M.
Vb=39m/s
STOREY
T L % Decrease C % Decrease I % Decrease
STOREY 1 0.312 0.218 30.12 0.146 53.20 0.105 66.34
STOREY2 0.703 0.611 13.08 0.409 41.82 0.294 58.17
STOREY3 0.785 0.696 11.33 0.454 42.16 0.316 59.74
STOREY4 0.762 0.674 11.54 0.433 43.17 0.298 60.89
STOREY5 0.716 0.632 11.73 0.4 44.13 0.275 61.59
STOREY6 0.66 0.58 12.12 0.363 45 0.248 62.42
STOREY7 0.595 0.521 12.43 0.322 45.88 0.219 63.19
STOREY8 0.523 0.455 13.00 0.276 47.22 0.188 64.05
STOREY9 0.444 0.385 13.28 0.228 48.64 0.154 65.31
STOREY10 0.361 0.311 13.85 0.178 50.69 0.119 67.03
STOREY11 0.276 0.236 14.49 0.128 53.62 0.083 69.92
TERRACE 0.2 0.169 15.5 0.083 58.5 0.051 74.5
Fig. 6. Variation of Storey drift
Peak Storey drift is minimum as compared to intermediate storey’s i.e for T shaped building it is 0.2
mm, in L shaped building it is 0.169 mm, in C shaped building it is0.083mm and in I shaped building is 0.051
mm. The percentage reduction in peak storey drift in L shaped building is 15.5%, C shaped building is 58.5%
and in I building is 74.5% as compared to peak storey drift in T building. From Figure 6 it is clear that the storey
drifts are reduced with the increase in number of sides of the building with the same column stiffness and grid
size due to reduction in effective area (Ae) of wind load application.

APPLICATION OF REGRESSION ANALYSIS FOR SURFACE WATER QUALITY MODELING
B. Effect of the Shape of The Building on Lateral Displacements:
Table III. Comparison Of Lateral Displacements in M.
Vb=39m/s
STOREY
T L % Decrease C % Decrease I % Decrease
STOREY 1 0.5 0.3 40 0.2 60 0.2 60
STOREY2 2.6 2.2 15 1.4 46.1 1 61.5
STOREY3 4.9 4.2 14 2.8 42.8 2 59.1
STOREY4 7.2 6.2 14 4.1 43.05 2.9 59.72
STOREY5 9.4 8.1 13.8 5.3 43.61 3.7 60.6
STOREY6 11.4 9.8 14.03 6.4 43.8 4.5 60.5
STOREY7 13.1 11.4 13 7.4 43.5 5.1 61.0
STOREY8 14.7 12.7 13.6 8.2 44.2 5.7 61.2
STOREY9 16 13.8 13.75 8.9 44.37 6.1 61.8
STOREY10 17.1 14.7 14.0 9.4 45.0 6.5 61.9
STOREY11 17.9 15.4 14 9.8 45.25 6.7 62.5
TERRACE 18.5 15.8 14.5 10 45 6.9 62.7
Fig. 7. Variation of Lateral Displacements with height
The lateral joint displacements in L, C, T and I shaped buildings at different heights are compared in
Table 3 and Figure 7. From the results, it is observed that with the change in shape of building from T to I, the
lateral displacements of the building decreases.

APPLICATION OF REGRESSION ANALYSIS FOR SURFACE WATER QUALITY MODELING
It is minimum at the bottom most part and increasing with height of the building and maximum at the
top of the building. Shape affects on the point displacement of the structure. Point displacement of T shaped
building is more as compared to L, C and I shaped buildings. The peak point displacement in case of T building
is 18.5 mm, for L building it is 15.8 mm, for C building it is 10 mm and for I, it is 6.9 mm.
VI. Conclusions
A G+11 storied building of different shapes- T, L, C and I, having Same parameters with equal stiffness of the
columns at each storey has been analyzed.
 With the change in shape of building from T to I, the storey drifts and the lateral displacements of the
building decreased.
 The percentage reduction in peak storey drift in L shaped building is 15%, in C building is 58.6% and
in I building is 74.5% as compared to peak storey drift in T building.
 Based upon the above results, it is concluded that shape of the structure plays an important role in
resisting wind loads. I shaped building has lesser storey drifts, lesser lateral displacements at the points as
compared to T, L and C shaped building.
 From the above discussion, it can be concluded that as velocity increases, the storey drift and storey
displacement also increases.
 It has been observed that displacement and storey drift in T, C and L shaped buildings is more than I
shaped building. This may due to asymmetry of T, C and L type buildings.
 This is due to the distance of extreme point of building from CG is more in case of T, C and L type
plan than I type plan.
Acknowledgment
In the process of preparing and completing this paper, I was in contact either directly or indirectly with
many people, academicians and wholesaler. They have contributed towards my understanding and thought.
In particular, I wish to express my greatest appreciation to my Guide, Prof. G. R. Patil, for his
encouragement, guidance, critics, and motivations. Without his continued support and interest, this study would
have been the same as presented here. I am deeply indebted to our Prof. R. S. Karale, Head of The Department
(Civil Engineering) and to our principal sir Dr. D. S. Bormane.
At the same moment, I am grateful to all my family members for their support and encouragement. My
sincere appreciations also to my friends for their support and help.
I hope my findings in this study will expand the knowledge in this field and contribute to all of us in
future.
References
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