EFFECT OF POROSITY ON WIND PRESSURE DISTRIBUTION ON LOW-RISE BUILDINGS

Abstract

Wind pressures for the design of various structures are invariably obtained from design Codes and Standards. The information regarding wind pressure coefficients are given in codes of practices of various countries but sometimes they are incomprehensive. Wind tunnel investigations continue to be a vital tool to cover up the limitations of codal practice. The purpose of wind tunnel testing is to provide the designer with information of local wind pattern. The present thesis focuses on the effect of openings on wind pressure distribution on low rise buildings as it is found that in this area investigation has not been done in detail. The first model tested is a 300 mm x300 mm x 150mm size model with openings varying from 0%, 25%, 50% and 100% of the wall area. The openings are provided only on the windward wall and the angle of wind incidence is kept at 0º, 90º and 180º. It is through the testing of this model that much of the basic wind tunnel and wind pressure data knowledge is gathered. Model 2 also has similar dimensions as model 1 but the location of the pressure tappings is varied. Openings are provided on the leeward wall too in addition to the windward wall as in the previous case. Model 2 is used to study the effect of leeward opening on the wind pressure distribution on the sidewalls. It has pressure tappings placed strategically on the sidewalls as the sidewalls are the critical location for wind pressure for a flat roof building. Model 3 is a 400 mm x 400 mm x150 mm pitched roof structure with openings of 0%, 25%, 50% and 100% of the wall area. The openings are provided on windward walls as well as on leeward walls with pressure tappings provided only on the roof in order to verify the pressure measurement as roof is the critical location for a pitched roof building. Model 3 is used to study the effect of openings on the pitched roof structure. Using Models 2 and 3 the possibility of different combinations of the opening is also explored to study the subsequent effects more precisely. In the end, the combination of all the three model tests proved to be helpful in understanding the wind distribution pattern, effect of wind incidence angle on the wind pressure; the effect of openings and the effects of the combination of the openings on the wind pressure.