Characteristics of wind pressures on large cantilevered roofs: effect of roof inclination

Wind pressure distributions on both surfaces of a cantilevered roof are measured on a wind tunnel model. The investigation covers a down-sloping roof configuration at −5° roof angle and two up-sloping roof configurations of roof angles 5° and 10°. The results supplement an earlier study made on a horizontal roof. The wind pressure pattern on the upper surface of an up-sloping roof suggests that there exists a preferred mode of flow separation on that surface. The pattern shows two localized regions of high suction, which are separately located towards the two ends of the roof span. On the up-sloping roofs, this pressure pattern is observed in the time-averaged mean distribution as well as during the occurrence instant of a peak total uplifting force on the roof. On the horizontal roof, this particular pattern of flow separation is not obviously observed in the time-averaged mean wind pressure pattern but is revealed by the conditional sampling technique which captures the wind pressure distribution during the generation of a peak uplifting force on the roof. The wind pressure signals are analysed to study the characteristics of the total wind force on the roof and also the wind forces on individual roof surfaces.