WIND PRESSURE DISTRIBUTION ON ELEVATED STRUCTURES WITH CURVED ROOFS

Abstract

The evaluation of design wind loads on various surfaces of a building .requires information about pressure coefficients and design wind speed. The values of pressure coefficients on surfaces of canopies, roofs and walls are normally determined by model studies performed in wind tunnels or sometimes from the measurements on prototype. Certain parameters like wind velocity, wind direction, shape of building, its height, slope of roof and permeability affect wind loads on roof. Industrial buildings covering large area are provided with sloping or curved roof. Various types of curved roofs generally employed are domical roofs, hyperbolic roofs and cylindrical roofs (shapes of parabolic or semi circular). In the present study, an attempt has been made to observe the effect of varied wind incidence angle and rise to height ratio on the values of wind pressure coefficients on the curved roof elevated structures. In order to attain the required target, 9 models of perpex sheet representing buildings with semi-circular cylindrical roof on elevated structures are made and tested in wind tunnel to find the wind pressure distribution on such structures. The test results indicated that for wind incidence angle of 900, the maximum positive pressure and suction values on the roof increase from rise to height ratio 1:4.0 to 1:1.5 and then decrease from rise to height ratio 1:1.5 to 1:0.5 and for all faces A, B, C and D the average Cp value decreases from rise to height ratio 1:4.0 to 1:0.5. Results also indicate that the overall maximum suction value of 2.36 was observed at wind incidence angle of 0=600 for the rise to height ratio 1:1.5, hence wind incidence angle of 0=600 and rise to height ratio 1:1.5 are concluded as the critical values for curved (semi-circular) roof elevated structures.