Determination of wind-induced fatigue loading on roof cladding

Strong wind pressures can cause severe fatigue damage to the screw-fastened light gauge steel roofing of low-rise buildings. An approach to determine the fatigue loading of roof cladding is presented here. The rain-flow count method is used to ascertain basic load-cycle distributions of roof pressures, by which total load-cycle distributions are then computed in consideration of the long-term effects of wind climate. The total load-cycle distribution of roof pressure in temperate regions is significantly different from that in cyclonic regions, and the distribution also depends on the location of the roof pressure. It is suggested that the statistical average of the cycle mean levels for a given cycle range be used as an equivalent mean level for this cycle range so that related fatigue tests become more practical. The total load-cycle distributions obtained through the proposed method are compared with those currently used in Australia and Europe. A number of comments have been made on design criteria, wind regions, load-cycle distributions, and numbers of cycles.