International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Wind Analysis on Residential Building using STAAD-Pro.
Mrs. Rakhi Shelke1, Prajakta N. Badhe2
12
(Department of Civil Engineering, Priyadarshini College of Engineering, Nagpur/RTMNU, India)
Abstract:-This paper presents a comparative study of wind loads to decide the design loads of a multistoried
building. The significance of this work is to estimate the design loads for a structure which is subjected to wind
loads in a particular region. It is well known fact that the earthquake loads may be estimated in particular zone with
a specified zone factor. Then the wind load of that zone can also be estimated based on the basic wind speed and
other factors of that particular region. However, the wind velocity is stochastic and time dependent. In the present
study a multistoried building is analyzed for wind loads using IS 875 code. The wind loads are estimated based on
the design wind speed of that zone with a variation of 20%.
Keywords: Zone factor, wind loads, design loads, high rise buildings.
I. INTRODUCTION
Recently there has been a considerable increase in the number of tall buildings both residential and
commercial, and the modern trend is aiming towards taller structures. Thus the effects of lateral loads like winds
loads, earthquake forces are attaining high importance and almost every designer faces the problem of providing
adequate strength and stability against lateral loads. For this reason it is necessary to estimate wind load acting on
high-rise building design.
The importance of wind engineering is emerging in India ever since the need for taller and slender
buildings is coming forth. Considering the ever increasing population as well as limited space, horizontal expansion
is no more a viable solution especially in metropolitan cities. There is enough technology to build super-tall
buildings today, but in India we are yet to catch up with the technology which is already established in other parts of
the world.
A comparison of wind loads on low, medium and high rise buildings by Asia-Pacific codes has shown
varying degrees of agreement as studied by Holmes, J.D., Tamura, Y., and Krishna P[1]. An attempt has been
made to develop information through wind tunnel studies on I-shape and cross shape buildings by Raj R., Kumar
A., and Ahuja, K.[2]. For preliminary design including the proportioning of the structure, the variation of wind
force on a structure with variation of site parameters and structural parameters have been studied by Halder and
Datta[3] based on Indian wind code. It is found that the evolution of tall building’s structural systems and the
technological driving force behind tall building developments. For the primary structural systems, a new
classification – interior structures and exterior structures – is presented by Ali and Moon[4].
The structural design consideration, the lateral force-resisting system, sloping outer concrete columns, long
span post-tensioned transfer girder and other design challenges are faced in the design of tall buildings [5]. The
comparison of the Indian Code (IS) and International Building Codes (IBC) in relation to the seismic design and
analysis of ordinary RC moment resisting frame (OMRF), intermediate RC moment-resisting frame (IMRF) and
Special RC moment-resting frame (SMRF) presented by Itti et al [6]. The development of high strength concrete,
higher grade steel, new construction techniques and advanced computational technique has resulted in the
emergence of a new generation of tall structures that are flexible, low in damping, slender and light in weight [7].
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Many times, wind engineering is being misunderstood as wind energy in India. On the other hand, wind
engineering is unique part of engineering where the impact of wind on structures and its environment being studied.
More specifically related to buildings, wind loads on claddings are required for the selection of the cladding systems
and wind loads on the structural frames are required for the design of beams, columns, lateral bracing and
foundations. Wind in general governs the design when buildings are above 150 m height. However the other force
which effect most on high rise building are the lateral forces caused by earthquakes. When buildings grow taller,
they become flexible and they are moving away from the high frequency earthquake waves. This paper describes
wind and seismic analysis of high-rise building in various zones of Indian subcontinent. For the analysis purpose a
twelve story reinforced concrete framed structure is selected. The wind loads are estimated by Indian code IS: 875
(Part-3)-1987 [8].
2. Wind analysis
The basic wind speed (Vb) for any site shall be obtained IS 875 and shall be modified to get the design wind velocity
at any height (Vz) for a chosen structure.
Vz = Vb k1 k2 k3
Where, Vz = design wind speed at any height z in m/s, Vb = Basic wind speed in m/s, k1 = probability factor (risk
coefficient), k2 = terrain roughness and height factor and k3 = topography factor
The basic wind speed map of India, as applicable at 10 m height above mean ground level for different zones of the
country selected from the code. The design wind pressure at any height above mean ground level shall be obtained
by the following relationship between wind pressure and wind velocity.
Pz = 0.6 Vz2
Where, Pz = wind pressure in N/m2 at height z and Vz = design wind speed in m/s at height z.
2.1. Wind Load on Individual Members (F)
When calculating the wind load on individual member such as roof and walls, and individual cladding units
and their fittings, it is essential to take account of the pressure difference between opposite force such elements or
units. For clad structures, it is therefore necessary to know the
internal pressure as well as the external pressure.
F = (Cpe– Cpi) A Pd
Where; Cpe = external pressure coefficient,
Cpi = internal pressure coefficient (Table No.4),
A = surface area of structural element or cladding unit, and
Pd = design wind pressure in N/m2.
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Fig.1: Centre line Fig.2: Typical
Plan Floor Plan
II. DESIGN EXAMPLE
This example studies the effect of the wind and earthquake using the Indian code on a twelve-story office
building 18x30 m shown in Fig.2. The storey height is 3m. The structural system resisting lateral forces consist of
beam, columns and shear walls as shown in the Fig.1. Interior columns are 0.7m x 0.7m, exterior columns are 0.5m
x 0.5m in X and Y directions shear walls are 0.25mx6.0m and beams are 0.3m x 0.6m.The building is located in
seismic zone 3 and medium soil. The live load is 3 kN/m2, and the average dead load of each floor is 7000 kN
and for the roof floor equal to 4000 kN.
III. ANALYSIS RESULTS
Wind loads: The wind loads are calculated for a zone whose basic wind speed is 44 m/s, then design
wind speed (Vz) and the design wind pressures (pz) are calculated.
Vz = Vb k1 k2 k3 = 44 X 1.00 X k2 X 1.00 = 44 k2 (m/s)
Pz = 0.6 Vz2 = 0.6 X (44 k2)2 = 1.1616 K22 KN/m2
Category = 2, Class = B structures
…….
External pressure coefficient (Cpe) :
ϕ = 00 -------- +0.7 -0.4 -0.7 -0.7
ϕ =90 0
-------- -0.5 -0.5 +0.8 -0.1
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Mathematical Modeling(G+10)
A multi storied framed building
Width 9m
Length 15m
No. of storey’s G+10
Height 34.25m
Height of ground storey 3m
Height of floor to floor 3m
Spacing of frame along length 3m
Spacing of frame along width 3m
Wind data
Wind zone Nagpur
Vb 44 m/s IS 875-Pt.3 sec5.2
Terrain category 2 IS 875Pt.3sec5.3.2.1
Design factors
Risk coefficient factor K1 1 IS 875-Pt.3 sec5.3.1 table1
Terrain & height factor K2 IS 875-Pt.3 sec5.3.2.2 table2
Topography factor K3 1 IS 875-Pt.3 sec5.3.3.1
Table-1:
Ht. from ground k2 (m) V2 (m/s) Pz ( kN/m2)
1.116
upto 10m 0.98 43.16
1.209
15m 1.02 42.88
1.281
20m 1.05 46.2
1.406
30m 1.1 48.4
50m 1.15 50.06 1.536
For 33m 1.425 kN/m²
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Mathematical Modelling (G+15)
A multi-storied framed building
Width 9m
Length 15m
No. of storey’s G+15
Height 49.25m
Height of ground storey 3m
Height of floor to floor 3m
Spacing of frame along length 3m
Spacing of frame along width 3m
Wind data
Wind zone Nagpur
Vb 44 m/s IS 875-Pt.3 sec5.2
Terrain category 2 IS 875-Pt.3 sec5.3.2.1
Design factors
Risk coefficient factor K1 1 IS 875-Pt.3 sec5.3.1 table1
Terrain & height factor K2 IS 875-Pt.3 sec5.3.2.2 table2
Topography factor K3 1 IS 875-Pt.3 sec5.3.3.1
The wind loads are evaluated for various wind zones with variation of basic wind speeds for V b= 44 m/s. It is found
that the total wind force increases with increase in basic wind speed.
The maximum deflection (mm) for G+10 building has been shown in table-2, whereas in graph-1, the nature of
graph for G+10 building for both cases i.e. no wind and wind can be studied.
Table-2: Maximum deflection for G+10 building.
G+10
Storey height(m) Max. Deflection(mm)
No Wind Wind
33 12.923 147.179
30 12.837 144.13
27 12.537 138.843
24 12.022 131.024
21 11.293 120.614
18 10.349 107.638
15 9.188 92.238
12 7.81 74.644
9 6.209 55.134
6 4.377 34.272
3 2.31 13.626
0 0 0
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Graph-1: Maximum deflection graph for G+10 building
Table-3 gives the maximum deflection (mm) for G+15 building, where as the graph-2 shows maximum deflection
for G+15 building for both cases i.e. no wind and wind.
Table-3: Maximum deflection for G+15 building.
G+15
STOREY HEIGHT(M) MAX. DEFLECTION(MM)
No Wind Wind
48 26.321 368.192
45 26.242 362.462
42 25.959 354.326
39 25.471 343.457
36 24.778 329.768
33 23.879 313.255
30 22.773 293.96
27 21.461 271.988
24 19.94 247.481
21 18.21 220.506
18 16.269 191.147
15 14.116 159.598
12 11.748 126.157
9 9.16 91.255
6 6.344 55.65
3 3.293 21.798
0 0 0
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Graph-2: Maximum deflection graph for G+15 building
Table-4 and graph-3 show the comparison for design pressure between G+10 and G+15 storey buildings
respectively.
Table-4: Comparison of Design Pressure for G+10 & G+15
TYPE DESIGN PRESSURE(KN/M2)
G+10 1.425
G+15 1.523
Graph-3: Comparison of design pressure for G+10 and G+15 building.
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
Table-5 and table-6 represents the maximum support reactions and maximum stresses in columns
respectively.
Table-5: Maximum Support Reactions.
MAX. SUPPORT REACTIONS
TYPE CASE FORCE- FORCE- FORCE- MOMENT- MOMENT-Y MOMENT-Z
X KN Y KN Z KN X KNm KNm KNm
G+10 No Wind 5.785 2384 7.668 7.581 0.003 5.814
Wind 46.219 2384 67.784 198.425 1.406 81.501
G+15 No Wind 5.917 3395.1 7.807 7.73 0.003 5.951
Wind 73.372 3395.1 106.795 318.902 1.406 129.675
Table-6: Maximum Stresses in Columns.
MAX. STRESSES IN COLUMNS
TYPE CASE AXIAL SHEAR-YKN SHEAR-Z KN MOMENT-Y MOMENT-Z KNm
FORCE KN KNm
G+10 No Wind 2384 14.05 18.455 30.691 21.682
Wind 2384 47.84 72.725 198.464 81.501
G+15 No Wind 3395.1 18.708 23.862 40.721 29.471
Wind 3395.1 77.282 116.732 318.495 129.675
IV. CONCLUSIONS
The wind loads are estimated for a ten storied RC framed structure and fifteen storied RC Framed
Structure. Based on the results obtained the following conclusions are made:
The wind loads increases with height of structure.
Wind loads are more critical for tall structures than the earthquake loads.
Structures should be designed for loads obtained in both directions independently for critical
forces of wind.
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International Journal of Emerging Trends in Engineering and Basic Sciences (IJEEBS)
ISSN (Online) 2349-6967
Volume 2, Issue 4 (Jul-Aug 2015), PP.93-101
REFERENCES
1) Holmes, J.D., Tamura, Y., and Krishna, P. (2008). “Wind loads on low, medium and high-rise buildings by Asia-Pacific
codes”, Proc. of Int. Conference on Advances in Wind and Structures, (AWAS‟08) May 2008, pp 1-16.
2) Raj R., Kumar A., and Ahuja, K. (2013), “Wind load on I-shape tall buildings”, International Journal of Scientific Research
&Development, Vol.01, May-Jun 2013, pp 20-23.
3) Raj R., Kumar A., and Ahuja K. (2013). “Wind Loads on Cross Shape Tall Buildings”, Journal of Academia and Industrial
Research, Volume 2, July 2013, pp 111-113.
4) Haldera, L., and Duttab, S. C. (2010).‟ Wind effects on multi-stored building: A critical review of Indian codal
provisions with special reference to American standard‟, Asian Journal of Civil Engg, Vol. 11, No. 3 (2010), pp 345-370.
5) Dennis, C.K., and Poon, P.E.(2008)‟ Analysis and Design of a 47-story Reinforced Concrete Structure -Futian Shangri-La
Hotel Tower‟, march2008, pp 1-14.
6) Itti S.V., Pathade A., and Karadi R.B .(2011).‟ A Comparative Study on Seismic Provisions Made in Indian and
International Building Codes for RC Buildings‟, pp 1-14 .
7) Amin, J.A and Ahuja, A.K.(2010).‟ Arodynamic modification to the shape of the buildings: A review of the state-of-the-art‟,
Asian Journal of Civil Engg, Vol. 11 ,june-2010,pp 433-450.
8) IS 875(Part 3): 1987, “Code Of Practice For Design Loads (Other Than Earthquake) for Buildings And Structures – Wind
Loads”, 2nd revision, Bureau of Indian Standard, New Delhi.
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