1. Wind effects on buildings
Rajesh Kumar,
Chanchal Sonkar
M.Tech., 1st year

2. OUTLINE
 Introduction
 Necessity
 Experimental setup
 Analytical study
 Graphical study
 Conclusion

3. Introduction
 Types of loads-
(1). Dead load - Relatively constant over time (IS:875-part #1)
(2). Imposed load –Temporary of short duration(IS:875-part #2)

4. Contd…
(3). Environmental loads- Wind, rain, snow, ice, seismic,
ponding etc.
Side Wall
Leeward wall
Windward wall
Roof
Wind force
Source:www.lsuagcenter
.com

5. Necessity
In the past, predicting the probable behavior of building components
under extreme winds has been difficult.
Of all the environmental loads on buildings and structures, wind load is
perhaps one of the most damaging load.
Source:www.lsuagcenter.com

6. Contd…
 Scientists classify wind intensity and damage potential differently for
hurricanes, tornados, and general wind storms.
Types of storms -
(1). Wind storms
(2). Dust Storm
(3). Sand Storm
(4). Cyclones (South Pacific and Indian Ocean )
(5). Hurricane (Atlantic and Northeast Pacific)
(6). Typhoon (Northwest Pacific )
etc.
 Follows IS:875 (Part # 3)

7. Experimental setup
 Wind load on overhangs in a low gable building in presence of free
standing wall.
 Building model was made on a geometry scale of 1:25 and a study was
conducted in an open circuit wind tunnel.
 Plan dimension 280mmx156mm and wall height 156mm
with roof slope 25 degrees, with an overhang eaves length
of and 60mm free standing wall of height 66mm.
 Effects on pressure variation have been studied on both upper and lower
sides of the overhang.

8. Contd…
Free Standing wall
(Boundary wall)
280 mm=L
Overhang wall
Fig. 2: Lay out of pressure taps in overhang

9. Contd…
Source: www.DisasterSafety.org

10. Analytical study
 Wind pressure measured on the roof of building models are
expressed in the form of a non dimensional pressure coefficient
defined as –
Cp(i) = 2( Pi – Po)/ρU2
Instantaneous surface
pressure Static (ambient, atmospheric)
reference pressure
Air density
Mean velocity
measured
 Mean Value = (Cp(1) + Cp(2) + Cp(3)+……..)/N
Total No. Of samples

11. Contd…
Cp(min) =Min. of Cp(i) ; Cp(max) = Max. of Cp(i)

12. Graphical study
 Individual local pressure coefficients on eaves at various zones
(1).For mean pressure coefficients-
At upper surface
(3>4>1>2)
At lower surface

13. Contd…
(2).For maximum pressure coefficients-
At upper surface
(3>1>4>2)
At lower surface

14. Conclusions
 Commonly used roof angle of 25o was considered, and
corner, edge and center load on overhangs have been evaluated
 Net peak upward pressure shows maximum positive value in the
presence of free standing wall, located at a distance of 3h.

15. References
 Stathopoulos, T., Luchian, H. (1994) .Wind-induced forces on eaves of low
building. J. wind Eng. Ind. Aerodynamic, vol 52, pp 249-261.
 Stathopoulos, T., (1981) .Wind load on eaves of low buildings., J. Struct.
Div., ASCE, 107, ST10, Proc. Paper 16543: 1921-1934.
 Journal of Wind & Engineering, Vol. 5, No. 1, Jan 2008, pp. 39-46
“Alok David John, Ajay Gairola, Prem Krishna”
(Indian Institute of Technology, Roorkee )