Abstract

The present study examines wind loads on flat roof low-rise buildings under the effect of the simulated wind speed profile of the downburst phenomena. Examination of buildings is necessary since very few studies have examined non-synoptic winds. Indeed, non-synoptic winds have not been considered in the wind provisions of codes and standards. As a result, the interaction between wind and buildings under these phenomena should be investigated as in the case for the assessment of current well-known Atmospheric Boundary Layer (ABL) winds.
Many trials have been carried out at the wind tunnel of Concordia University to simulate the downburst phenomena. Different configurations have been tried to simulate wind speed profile close to the available target full-scale data. The produced wind speed profile and turbulence intensity are presented in terms of comparisons among the target profile, the ABL profile and downbursts profiles of previous studies.
The size of roof pressure zones and the magnitude of pressure coefficients on flat roofs of low-rise buildings have been examined experimentally in the wind tunnel of Concordia University. Two building models were constructed at a length scale of 1:400 with identical plan dimensions (60 m x 60 m) and two building heights (10 m and 20 m). The models were tested for 7 wind directions: 0°, 15°, 30°, 45°, 60°, 75° and 90°. The pressure measurement results have been presented in terms of contours of enveloped local pressure coefficients. The results of the current study have been compared with those of ABL (same model dimensions) and downburst of previous studies.
It was found that the produced downburst wind speed profile of the current study agrees well with the target full scale data. The velocity increases at a low height and decreases going upwards.
The results of the present study show that the wind direction plays a main role in the pressure coefficient distributions, the most critical wind direction is different for the roof corner and the roof edge. In addition, it was found that the higher building heights experience higher wind loads.