Effects of shape on the wind instigate response of high rise buildings

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 09 | September-2015, Available @ http://www.ijret.org 65
EFFECTS OF SHAPE ON THE WIND-INSTIGATE RESPONSE OF
HIGH RISE BUILDINGS
M. R. Wakchaure1
, Sayali Gawali2
1
Professor, Civil Engineering Department, Amrutvahini College of Engineering Sangamner, Maharashtra, India
2
Post Graduate Student, Civil Engineering Department, Amrutvahini College of Engineering Sangamner,
Maharashtra, India
Abstract
A large number of structures that are being constructed at present tend to be wind-sensitive because of their slenderness, shapes,
size, lightness and flexibility. With the ever increase in the vertical growth of urban cities, high rise buildings are being
constructed in large numbers. In this study, analytical investigation of different shapes of buildings are taken as an example and
various analytical approaches are performed on the building. These plans are modeled and wind loads are found out according to
I.S 875(part 3)-1987 by taking gust factor and without taking gust factor. These models are compared in different aspects such as
storey drift, storey displacement, storey shear, etc. for different shapes of buildings by using finite element software package
ETAB’s 13.1.1v. Among these results, which shape of building provide sound wind loading to the structure as well as the
structural efficiency would be selected.
Key Words: Storey displacement, Storey drift, Storey shear, Gust, Wind load
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1. INTRODUCTION
A building having height more than 15 m as per National
building code 2005 of India is called high rise building. Due
to rapid growth of population, expensive land prices, to
improve aesthetic view of city and restriction in horizontal
development due to less space, vertical growth is the
ultimate option available. Wind is the large scale horizontal
movement of free air. It plays an important role in design of
tall structures because it exerts loads on buildings. The
response of structures to wind depends on the characteristics
of wind. As the height of building increases, there is more
danger against high velocity of wind force at high level.
1.1 Wind Effects on Structures
Wind is randomly varying dynamic phenomenon. Wind
loading is complex live load that varies both in time and
space. Wind effects on structures can be classified as static
and dynamic. Static wind effects causes elastic bending and
twisting of structure. Wind gusts are the major dynamic
effects on the on the structures which induce large dynamic
motions, including oscillations. Hence, dynamic analysis is
essential for tall structures.
It is important to evaluate the characteristics of fluctuating
wind forces and the dynamic characteristics of the building.
The wind induced building response of tall buildings can be
reduced by means of aerodynamic based design and
modifications that change the flow pattern around the
building or break up the wind affecting the building face.
The use of aerodynamic building forms is an effective
method of reducing the wind loads on buildings.
2. METHODOLOGY
In this study, the gust response factors and the equivalent
static wind loads for various along wind response
components at different shape of building as per I.S
875(part3)-1987 are calculated and analysed with the help of
ETAB’s 13.1.1v.
Table -1: Parameters considered for the study
No. of Storey 50
Bottom storey height 3m
Storey height 3m
Soil type Medium
Wind zone I
Shape of buildings Rectangular, square,
circular and elliptical
Thickness of slab 0.125m
Beam size 0.3m x 0.6 m
Column size 1m x 1m
Material Properties
Grade of concrete M40
Grade of steel Fe500
Dead load intensities
FF on floors 1.75 kN/m²
FF on roof 2 kN/m²
Live load intensities
LL on floors 2 kN/m²
LL on roof 1 kN/m2

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2.1 Building Models
Fig-1: Plan and 3-D view of square building
Fig-2: Plan and 3-D view of rectangular building
Fig-3: Plan and 3-D view of circular building
Fig-4: Plan and 3-D view of elliptical building
Table -2: Model Plan dimensions
Name of
parameter
Square
shape
Rectangul
ar shape
Circular
shape
Elliptical
shape
Plan dimension in
x-direction
50 m 70 m 28.20 m 38 m
Plan dimension in
y-direction
50 m 35.714 m 28.20 m 20.95 m
2.2 Linear Analysis
2.1.1 Pressure coefficients
Pressure coefficients are applicable to structural elements
like walls and roofs as well as to the design of cladding. The
calculation process implies the algebraic addition of Cpe and
Cpi obtain the final wind loading. External pressure
coefficient depends on wind direction, structure
configuration in plan, its height versus width ratio and,
characteristics of roof and its shape. Internal pressure
coefficients are largely dependent on the percentage of
openings in the walls and their location with reference to
wind direction.
2.1.2 Force coefficients
The value of force coefficients apply to a building or
structure as a whole, and when multiplied by the effective
frontal area A, of the building or structure and by design
wind pressure, pd gives the total wind load on that particular
building or structure.
2.1.3 Parameters considered for linear analysis
Design wind speed: The basic wind speed (Vz) for any site
shall be obtained from Fig.1 IS: (875(Part 3)-1987) and shall
be modified to include the following effects to get design
wind velocity at any height (Vz) for the chosen structure:
a) Risk level
b) Terrain roughness, height and size of structure; and
c) Local topography
Vz = Vb.k1.k2.k3
Vz= hourly mean wind speed in m/s, at height z
Vb = regional basic wind speed in m/s
k1 = probability factor (risk coefficient) (Clause 5.3.1 of IS:
875(Part 3)-1987)
k2 = Terrain and height factor (Clause 5.3.2 of IS: 875(Part
3)-1987)
k3 = topography factor (Clause 5.3.3 of IS: 875(Part 3)-
1987)
Design Wind Pressure: The design wind pressure at any
height above mean level shall be obtained by the Following
relationship between wind pressure and wind velocity:
Pz=0.6 Vz
2
Where, Pz= Design wind pressure in N/m2 at height 'z' m
Vz = design wind velocity in m/s at height „z‟ m
Wind Load on Individual Members: (IS: 875 (Part 3)
F = (Cpe – Cpi) APZ
Where, Cpe = external pressure coefficient,
Cpi = internal pressure- coefficient,
A = surface area of structural or cladding unit and
Pz = design wind pressure.
Table -3: Parameters considered for linear analysis
Name of
parameter
Square
shape
Rectangular
shape
Circular
shape
Elliptical
shape
(k1) 1 1 1 1
(k3) 1 1 1 1
Terrain category II II II II
Class of structure B C C C

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Table -4: Linear Wind loads (KN)
Floo
r no.
Squar
e
Rectangular
Circular EllipticalX Y
1 131.78 166.15 84.77 105.17 32.78
5 142.76 180.75 92.22 114.41 35.66
10 166.03 207.77 106.01 131.52 41.00
15 177.54 226.14 115.38 143.15 44.62
20 185.91 238.39 121.63 150.91 47.04
25 192.68 247.47 126.26 156.65 48.83
30 199.57 256.71 130.97 162.50 50.65
35 205.23 263.41 134.40 166.74 51.98
40 208.27 269.98 137.74 170.90 53.27
45 211.32 275.70 140.66 174.52 54.40
50 214.40 281.25 143.50 178.04 55.50
Chart -1: Wind intensity in X-direction
Chart -2: Wind intensity in Y-direction
From linear analysis, it was seen from table-4 that with the
increase in the height of building the wind intensities were
also increasing and wind intensities were decreasing with
the variation of shapes from square to elliptical. The
variation of wind intensity is shown in chart 1 and chart 2.
2.2 Gust Factor Method
A gust factor, defined as the ratio between a peak wind gust
and mean wind speed over a period of time, can be used
along with other statistics to examine the structure of the
wind.
Constants and parameters used for gust factor analysis are:
i. T = Time period (pg.48, IS 875(part-3)-1987)
ii. Cf = Force coefficient for clad building (fig. 4 of IS
875(part-3)-1987)
iii. gf = Peak Factor and Roughness Factor (fig. 8 of IS
875(part-3)-1987)
iv. B = Background factor (fig. 9 of IS 875(part-3)-
1987)
v. S = Size reduction factor (fig. 10 of IS 875(part-3)-
1987)
vi. Ø = Constant
vii. E = Gust energy factor (fig. 11 of IS 875(part-3)-
1987)
viii. β = (pg.52, IS 875(part-3)-1987)
ix. G = Gust factor
x. Fx = Along wind load on the structure on a strip
area at any height
Table -5: Parameters considered for gust factor analysis
Name of
parameter
Square
model
Rectangular
model
Circular
model
Elliptical
model
Tx 1.9 1.61 2.54 2.18
Ty 1.9 2.25 2.54 2.94
Cf 1.25 1.1 0.7 0.2
gf 0.85 0.85 0.85 0.85
B 0.85 0.85 0.85 0.85
Ø 0 0 0 0
β 0.016 0.016 0.016 0.016
Table -6: Wind loads with gust factor (KN)
Floor
no.
Square Rectangular Circular Elliptical
X Y X Y
1 96.46 116.57 67.26 94.77 30.17 29.22
5 111.76 134.82 78.52 109.81 35.17 33.85
10 136.45 162.67 95.85 132.90 42.91 40.80
15 153.23 181.94 107.96 149.22 48.41 45.84
20 165.27 194.96 116.17 160.49 52.06 49.17
25 175.29 204.68 122.30 168.74 54.74 51.67
30 183.98 214.61 128.60 177.10 57.98 54.23
35 191.70 223.33 134.15 184.53 60.85 56.44
40 197.03 229.23 137.91 189.55 62.69 57.96
45 203.04 235.21 141.72 194.60 64.47 59.52
50 209.79 241.27 145.57 200.41 66.31 61.10
Chart -3: Wind intensity in X-direction

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3. RESULTS AND DISCUSSION
In this section, behavior of different buildings when
subjected to wind load have been discussed.
Chart -4: Wind intensity in Y-direction
3.1 Wind Intensity
It is the pressure exerted by the wind on the structure. The
wind intensity for square, rectangular, circular and elliptical
shape building are compared in table 7 and it is graphically
represented in chart 5, 6, 7 and 8.
Table -7: Comparison of wind loads without gust factor (X-direction) (kN)
Table -8: Comparison of wind loads without gust factor (Y-direction) (kN)
Storey
No.
Height
m
Wind
intensity
Wind
intensity %
Decrease
Wind
intensity %
Decrease
Wind
intensity %
Decrease
(kN) (kN) (kN) (kN)
0 0 131.780 84.769 35.674 105.172 20.191 32.784 75.123
10 30 166.029 106.008 36.151 131.523 20.783 40.997 75.307
20 60 185.911 121.630 34.576 150.906 18.829 47.039 74.698
30 90 199.569 130.974 34.371 162.499 18.575 50.653 74.619
40 120 208.267 137.744 33.862 170.899 17.942 53.271 74.422
50 150 214.397 143.496 33.070 178.036 16.960 55.496 74.115
Table -9: Comparison of wind loads with gust factor (X-direction) (kN)
Storey
No.
Height
m
Wind
intensity
Wind
intensity %
Decrease
Wind
intensity %
Decrease
Wind
intensity %
Decrease
(kN) (kN) (kN) (kN)
0 0 96.457 116.566 -20.847 94.773 1.746 30.172 68.719
10 30 136.446 162.674 -19.223 132.902 2.597 42.915 68.548
20 60 165.272 194.964 -17.965 160.494 2.891 52.061 68.500
30 90 183.979 214.612 -16.651 177.101 3.738 57.981 68.485
40 120 197.028 229.230 -16.344 189.554 3.793 62.695 68.180
50 150 209.786 241.265 -15.006 200.406 4.471 66.310 68.392
Storey
No.
Height
m
Wind
intensity
Wind
intensity %
Decrease
Wind
intensity %
Decrease
Wind
intensity %
Decrease
(kN) (kN) (kN) (kN)
0 0 131.780 166.147 -26.079 105.172 20.191 32.784 75.123
10 30 166.029 207.775 -25.144 131.523 20.783 40.997 75.307
20 60 185.911 238.395 -28.231 150.906 18.829 47.039 74.698
30 90 199.569 256.710 -28.632 162.499 18.575 50.653 74.619
40 120 208.267 269.979 -29.631 170.899 17.942 53.271 74.422
50 150 214.397 281.253 -31.183 178.036 16.960 55.496 74.115

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Table -10: Comparison of wind loads with gust factor (Y-direction) (kN)
Storey
No.
Height
m
Wind
intensity
Wind
intensity %
Decrease
Wind
intensity %
Decrease
Wind
intensity %
Decrease
(kN) (kN) (kN) (kN)
0 0 96.457 67.265 30.265 94.773 1.746 29.222 69.704
10 30 136.446 95.846 29.755 132.902 2.597 40.803 70.096
20 60 165.272 116.165 29.713 160.494 2.891 49.174 70.247
30 90 183.979 128.604 30.099 177.101 3.738 54.235 70.521
40 120 197.028 137.912 30.004 189.554 3.793 57.959 70.583
50 150 209.786 145.574 30.608 200.406 4.471 61.101 70.875
Chart -5: Wind intensity in X-direction (without gust)
Chart -6: Wind intensity in Y-direction (without gust)
Chart -7: Wind intensity in X-direction (with gust)
Chart -8: Wind intensity in Y-direction (with gust)
3.2 Storey Displacement
It is displacement caused by the lateral force on the each
storey level of structure. The storey displacement for square,
rectangular, circular and elliptical shape building are
compared in table 11 and it is graphically represented in
chart 9, 10, 11 and 12.
Table -11: Comparison of storey displacement without gust factor (X-direction) (mm)
Storey
No.
Height
m
Storey
displacement
Storey
displacement %
Decrease
Storey
displacement %
Decrease
Storey
displacement %
Decrease
(mm) (mm) (mm) (mm)
0 0 0.8 0.5 37.500 0.7 12.500 0.2 75.000
10 30 27.6 17.7 35.870 24 13.043 6.5 76.449
20 60 52.7 33.7 36.053 46.1 12.524 12.4 76.471
30 90 72.5 46 36.552 63.7 12.138 17 76.552
40 120 85.9 54.2 36.903 75.7 11.874 20.1 76.601
50 150 92.9 58.3 37.244 82 11.733 21.6 76.749

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Table -12: Comparison of storey displacement without gust factor (Y-direction) (mm)
Storey
No.
Height
m
Storey
displacement
Storey
displacement
%
Decrease
Storey
displacement
%
Decrease
Storey
displacement
%
Decrease
(mm) (mm) (mm) (mm)
0 0 0.8 1.1 -37.500 0.8 0.000 0.2 75.000
10 30 27.7 38.2 -37.906 26 6.137 7 74.729
20 60 53.1 74.1 -39.548 50.3 5.273 14 73.635
30 90 73.1 102.8 -40.629 69.3 5.198 19.7 73.051
40 120 86.9 123.1 -41.657 82.3 5.293 24 72.382
50 150 94.2 134.4 -42.675 89.1 5.414 26.6 71.762
Table -13: Comparison of storey displacement with gust factor (X-direction) (mm)
Storey
No.
Height
m
Storey
displacement
Storey
displacement
%
Storey
displacement
%
Storey
displacement
%
(mm) (mm) Decrease (mm) Decrease (mm) Decrease
0 0 0.7 0.6 14.286 0.8 -14.286 0.2 71.429
10 30 25.2 21.7 13.889 26 -3.175 7.4 70.635
20 60 48.7 37.6 22.793 50.4 -3.491 14.2 70.842
30 90 67.5 49.9 26.074 69.7 -3.259 19.5 71.111
40 120 80.5 58.1 27.826 83 -3.106 23.1 71.304
50 150 87.4 62.1 28.947 90.1 -3.089 24.9 71.510
Table -14: Comparison of storey displacement with gust factor (Y-direction) (mm)
Storey
No.
Height
m
Storey
displacement
Storey
displacement
%
Decrease
Storey
displacement
%
Decrease
Storey
displacement
%
Decrease
(mm) (mm) (mm) (mm)
0 0 0.7 1.2 -71.429 0.8 -14.286 0.2 71.429
10 30 25.7 39.8 -54.864 28.3 -10.117 7.5 70.817
20 60 50.6 70 -38.340 55 -8.696 14.9 70.553
30 90 71.2 94.5 -32.725 76 -6.742 21.1 70.365
40 120 86.3 111.8 -29.548 90.4 -4.751 25.7 70.220
50 150 95.6 121.5 -27.092 97.9 -2.406 28.5 70.188
Chart -9: Storey displacement in X-direction (wog)
Chart -10: Storey displacement in Y-direction (wog)
Chart -11: Storey displacement in X-direction (wg)
Chart -12: Storey displacement in Y-direction (wg)

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3.3 Storey Drift
It is the displacement of one level relative of the other level
above or below. The storey drift for square, rectangular,
circular and elliptical shape building are compared
and it is graphically represented in chart 13,14,15,16.
Table -15: Comparison of storey drift without gust factor (X-direction)
Storey
No.
Height
m
Storey
drift
Storey
drift %
Decrease
Storey
drift %
Decrease
Storey
drift %
Decrease
0 0 0.271 0.177 34.686 0.239 11.808 0.068 74.908
10 30 0.924 0.588 36.364 0.806 12.771 0.213 76.948
20 60 0.763 0.479 37.221 0.673 11.796 0.173 77.326
30 90 0.567 0.349 38.448 0.503 11.287 0.125 77.954
40 120 0.347 0.206 40.634 0.312 10.086 0.074 78.674
50 150 0.2 0.136 32.000 0.191 4.500 0.083 58.500
Table -16: Comparison of storey drift without gust factor (Y-direction)
Storey
No.
Height
m
Storey
drift
Storey drift %
Decrease
Storey
drift %
Decrease
Storey
drift %
Decrease
0 0 0.271 0.366 -35.055 0.256 5.535 0.005 98.155
10 30 0.918 1.3 -41.612 0.883 3.813 0.002 99.782
20 60 0.751 1.099 -46.338 0.736 1.997 0.003 99.601
30 90 0.551 0.838 -52.087 0.547 0.726 0.003 99.456
40 120 0.329 0.539 -63.830 0.335 -1.824 0.004 98.784
50 150 0.179 0.297 -65.922 0.205 -14.525 0.061 65.922
Table -17: Comparison of storey drift with gust factor (X-direction)
Storey
No.
Height
m
Storey
drift
Storey
drift %
Decrease
Storey
drift %
Decrease
Storey
drift %
Decrease
(mm) (mm) (mm) (mm)
0 0 0.246 0.173 29.675 0.258 -4.878 0.076 69.106
10 30 0.849 0.583 31.331 0.885 -4.240 0.243 71.378
20 60 0.71 0.482 32.113 0.741 -4.366 0.2 71.831
30 90 0.529 0.349 34.026 0.558 -5.482 0.147 72.212
40 120 0.323 0.207 35.913 0.348 -7.740 0.087 73.065
50 150 0.186 0.137 26.344 0.206 -10.753 0.088 52.688
Table -18: Comparison of storey drift with gust factor (Y-direction)
Storey
No.
Height
m
Storey
drift
Storey drift %
Storey
drift
%
Storey
drift
%
(mm) (mm) Decrease (mm) Decrease (mm) Decrease
0 0 0.244 0.302 -23.770 0.276 -13.115 0.074 69.672
10 30 0.818 1.088 -33.007 0.969 -18.460 0.26 68.215
20 60 0.657 0.929 -41.400 0.81 -23.288 0.232 64.688
30 90 0.462 0.714 -54.545 0.606 -31.169 0.184 60.173
40 120 0.247 0.459 -85.830 0.373 -51.012 0.127 48.583
50 150 0.118 0.259 -119.492 0.221 -87.288 0.114 3.390

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Chart -13: Storey drift in X-direction (wog)
Chart -14: Storey drift in Y-direction (wog)
Chart -15: Storey drift in X-direction (wg)
Chart -16: Storey drift in Y-direction (wg)
3.4 Storey Shear
The summation of design lateral forces at levels above the
storey under consideration. The storey shear for square,
rectangular, circular and elliptical shape building are
compared and it is graphically represented in chart
17,18,19,20.
Table -19: Comparison of storey shear without gust factor (X-direction) (kN)
Storey
No.
Height
m
Storey shear
Storey
shear %
Decrease
Storey
shear %
Decrease
Storey
shear %
Decrease
(kN) (kN) (kN) (kN)
0 0 13980.735 9181.982 34.324 11393.930 18.503 3551.140 74.600
10 30 12041.085 7931.808 34.127 9842.439 18.260 3067.626 74.524
20 60 9401.61 6220.733 33.833 7718.960 17.897 2405.855 74.410
30 90 6550.215 4333.736 33.838 5377.159 17.909 1676.105 74.411
40 120 3485.775 2320.950 33.417 2879.251 17.400 897.645 74.248
50 150 321.465 215.245 33.043 267.123 16.904 83.248 74.104
Table -9: Comparison of storey shear without gust factor (Y-direction) (kN)
Storey
No.
Height
m
Storey
shear
Storey
shear %
Decrease
Storey
shear %
Decrease
Storey
shear %
Decrease
(kN) (kN) (kN) (kN)
0 0 13975.845 17996.685 -28.770 12092.5306 13.475 3555.0198 74.563
10 30 12036.195 15546.344 -29.163 10429.4282 13.349 3071.5056 74.481
20 60 9396.72 12192.637 -29.754 8179.7516 12.951 2409.7343 74.356
30 90 6518.055 8494.122 -30.317 5698.7774 12.569 1676.1052 74.285
40 120 3453.615 4549.063 -31.719 3051.5243 11.643 897.6452 74.009
50 150 289.305 421.880 -45.825 282.998 2.180 83.2475 71.225

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Table -9: Comparison of storey shear with gust factor (X-direction) (kN)
Storey
No.
Height
m
Storey
shear
Storey
shear %
Decrease
Storey
shear %
Decrease
Storey
shear %
Decrease
(kN) (kN) (kN) (kN)
0 0 12573.615 8915.481 29.094 12282.829 2.313 3969.000 68.434
10 30 11068.875 7859.618 28.994 10806.057 2.374 3498.495 68.393
20 60 8805.45 6265.258 28.848 8487.108 3.615 2783.305 68.391
30 90 6210.885 4339.087 30.137 5967.661 3.916 1965.336 68.357
40 120 3352.275 2338.503 30.241 3214.616 4.106 1058.619 68.421
50 150 314.535 218.360 30.577 300.688 4.403 99.469 68.376
Table -9: Comparison of wind loads with gust factor (Y-direction) (kN)
Storey
No.
Height
m
Storey
shear
Storey
shear %
Decrease
Storey
shear %
Decrease
Storey
shear %
Decrease
(kN) (kN) (kN) (kN)
0 0 12587.025 14815.455 -17.704 13013.246 -3.386 3727.399 70.387
10 30 11081.385 13002.693 -17.338 11448.710 -3.315 3272.592 70.468
20 60 8817.96 10313.509 -16.960 8991.669 -1.970 2595.666 70.564
30 90 6210.885 7257.578 -16.853 6322.492 -1.797 1824.255 70.628
40 120 3352.275 3881.193 -15.778 3405.835 -1.598 982.173 70.701
50 150 314.535 361.898 -15.058 318.557 -1.279 91.655 70.860
Chart- 17: Storey shear in X-direction (wog)
Chart- 18: Storey shear in Y-direction (wog)
Chart- 19: Storey shear in X-direction (wg)
Chart- 20: Storey shear in Y-direction (wg)

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4. CONCLUSION
1. The percentage reduction in peak wind intensity for
circular building is 16.96 %, 74.115 % for elliptical
building and it is more by 31.183 % for rectangular
building when compared with square building without
gust factor. The percentage reduction in peak wind
intensity for circular building is 4.471 %, 68.392 % for
elliptical building and it is more by 15 % for
rectangular building when compared with square
building with gust factor.
2. The percentage reduction in peak displacement in
circular building is 11.73 %, 76.74 % in elliptical
building ,31.18 % in rectangular building without gust
factor and 28.94 % in rectangular building,71.51 % in
elliptical building and it is more by 3.08 % in circular
building with gust factor in longitudinal direction when
compared with square building. The percentage
reduction in peak displacement in circular building is
5.41 %, 71.76 % for elliptical building and it is more
by 42.67 % for rectangular building without gust factor
and it is 70.18 % in elliptical building, it is more by 27
% in rectangular, 2.40 % in circular building when
compared with square building with gust factor in
transverse direction.
3. The percentage reduction in peak drift in circular
building is 4.50 %, 58.50 % in elliptical building , 32
% in rectangular building without gust factor and 26.44
% in rectangular building,52.68 % in elliptical building
and it is more by 10.75 % in circular building with gust
factor in longitudinal direction when compared with
square building. The percentage reduction in peak drift
in elliptical building is 65.92 % and it is more by 65.92
% for rectangular building and 14.52 % in circular
building without gust factor and it decreased by 3.39 %
in elliptical building, it is more by 119.49 % in
rectangular, 87.28 % in circular building when
compared with square building with gust factor in
transverse direction.
4. The percentage reduction in peak storey shear in
circular building is 16.90 %, 74.10 % in elliptical
building , 33 % in rectangular building without gust
factor and 30.57 % in rectangular building,4.40 % in
elliptical building and 68.37 % in circular building
with gust factor in longitudinal direction when
compared with square building. The percentage
reduction in peak drift in circular building is 2.18
%,71.22 % in elliptical building and it is more by
45.85 % for rectangular building without gust factor
and it decreased by 70.86 % in elliptical building, it is
more by 14 % in rectangular, 1.27 % in circular
building when compared with square building with
gust factor in transverse direction.
5. The gust factor method uses the statistical concepts of
a stationary time series to calculate the response of
structure to a gusty wind. Hence it is important for the
estimation of wind loads on the flexible structures.
6. Buildings having circular or elliptical plan forms have
a smaller surface perpendicular to the wind direction,
the wind pressure is less than in prismatic buildings.
7. From the above results, with the change in shape of
building from square to elliptical the wind intensity,
storey drifts, the lateral displacements, storey shear of
the building decreased. Hence it is conclude that wind
load is reduced by maximum percentage with an
elliptical plan.
REFERENCES
[1] J. A. Amin and A. K. Ahuja “Experimental study of
wind-induced pressures on buildings of various
geometries” Journal of engineering, science and
technology Vol. 3, No. 5, 2011, pp. 1-19.
[2] Prof. Sarita Singla, Taranjeet Kaur, Megha Kalra and
Sanket Sharma “Behaviour of R.C.C. tall buildings
having different shapes subjected to wind load”
Journal on civil and environmental engineering 02,
2012, 3-17.
[3] P. Harikrishna, A. Abraham, S. Arunachalam, S. Selvi
Rajan and G. Ramesh Babu “Pressure measurement
studies on a model of a tall building with different plan
shapes along the height” ,The seventh Asia-Pacific
conference on wind engineering, Taipei, Taiwan,
November 8-12, 2009.
[4] Hemil Chauhan, Manish Pomal, Gyayak Bhuta “A
comparative study of wind forces on high-rise
buildings as per IS 875(III)-1987 and proposed draft
code (2011)” Global research analysis, ISSN no.2277-
8160, Vol. 2, No. 5, May 2013.
[5] ETABS nonlinear Version 9.1.6, Extended 3D
analysis of the building systems, Computer and
Structures.
[6] IS: 875-1987(part 3) “Code of practices for design
loads (other than earth quake) for buildings and
structures”. Bureau of Indian standards, New Delhi
[7] Explanatory handbook on “Indian Standard Code
Practice for Design Loads” (other than earthquake) for
buildings and structures part 3 wind loads [IS 875
(PART 3): 1987]”, Bureau of Indian standards, New
Delhi.
BIOGRAPHIES
1. M. R. Wakchaure, Professor, Civil Engineering
Department, Amrutvahini College Of Engineering,
Sangamner, Maharashtra, India.
2. Sayali J. Gawali, Post Graduate Student,Civil
Engineering Department, Amrutvahini College Of
Engineering, Sangamner, Maharashtra

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