WIND PRESSURE DISTRIBUTION ON A LOW-RISE BUILDING WITH PYRAMIDAL ROOF

Abstract

Wind pressures on flat, gabled and monosloped roofs of low-rise buildings have been studied extensively during the last few years. Several post disaster studies have revealed that similar standards of low rise building construction have suffered a disparity in wind induced damage apparently depending on the geometry. Studies have shown that hip roof dwellings have enjoyed better performance compared to similarly constructed gable roof. Pyramidal type of roof resembles a hipped roof in shape but its behaviour may be different from hipped roof. Based on the response to severe wind loading, pyramidal type roof can be an alternative in coastal areas subjected to high speed winds. The present dissertation has been carried out to study the distribution of mean, fluctuating and peak values of pressure on a pyramidal type of roof. It. involves testing on 1/50 scale rigid model of a square shape enclosure about 5.5 x 5.5 x 2.4 m high. The model was fitted with a datachable type of ; roof so that it could be fitted with roofs of different slopes (0°, 100, 20° & 300), to enable a study of the effect of this parameter. Models have been tested in the terrain condition corresponding to a power law index of 0.14. Pressure coefficients have been calculated for different wind incidence angles. Results have been presented in the form of tables, graphs and contours. The results show that increase in roof slope reduces the suction on windward roofing units and increase it on leeward roofing units over their central parts and also at points close to the edge of roof wall junctions. Suction at points around the apex of the roof increases with the increase in roof slope from 0° to 20° and for further increase in slope this value decreases