DYNAMIC BEHAVIOR OF MECHANICALLY-ATTACHED WATERPROOFING SYSTEMS SUBJECTED TO WIND PRESSURES VARYING IN BOTH SPACE AND TIME

Abstract

The present paper investigates the wind resistant performance of a mechanically-attached waterproofing system installed on flat roofs of middle-rise and high-rise buildings with or without parapets considering the wind pressure variations in both space and time. First, wind pressure distributions on the roofs were measured in a turbulent boundary layer. The condition providing the most critical negative peak pressure coefficient irrespective of wind direction and pressure tap location was detected for each building. Then, we developed a test method for evaluating the wind resistant performance of the roofing system using three Pressure Loading Actuators (PLAs) and a chamber to which a full-scale specimen was attached. The chamber was divided into three spaces by using thin silicon sheets. The PLAs generated different fluctuating pressures in these spaces using the time history of wind pressure coefficients measured at three different points near the windward corner of the roof in an oblique wind. The membrane deformations and the wind forces acting on the fasteners of the roofing system were measured. The results indicated that horizontal forces nearly equal to or larger than the vertical ones were generated on the fasteners, which may cause pulling out of fasteners more easily. The failure mode was found to be different from that observed in a ramp pressure loading test. Finally, we developed a model of finite element analysis, which was validated by the experiment. The results of analysis for a wide area of roofing system indicated that relatively large horizontal forces were generated on the fasteners in the field region of the roof for buildings with parapets.