Volume 27, Issue 4 (July 1999)
A New Dynamic Wind Load Cycle to Evaluate Mechanically Attached Flexible Membrane Roofs
In North America, at present, no test procedure exists for certifying roofing systems under dynamic wind loads. To develop such a dynamic test procedure, the National Research Council of Canada (NRC) formed an industry-based consortium during 1994. The consortium is known as the Special Interest Group for Dynamic Evaluation of Roofing Systems (SIGDERS). This paper reports SIGDERS' progress on dynamicload cycle development. Wind tunnel investigations were carried out using two flexible roofing membranes: poly(vinyl chloride) (PVC) and ethylene propylene diene monomer (EPDM). Using the wind tunnel pressure records as source data and comparing the membrane responses of PVC with EPDM, SIGDERS developed a dynamic load cycle. With input from industries, building owners, and roofing associations, the developed load cycle has been generalized and extended to evaluate the ultimate strength of flexible membrane roofs. To validate the newly developed load cycle, several membrane roofing systems were investigated and then reported separately. The SIGDERS load cycle in a laboratory mimics failure modes similar to those observed in the field.