| Abstract | At the National Research Council of Canada in November 1994, members of the North American roofing community {manufacturers, building owners, industry association and research agencies} met and agreed that a means of evaluating the effect of dynamic wind loads on roofing systems was necessary. Thus, a Special Interest Group on Dynamic Evaluation of Roofing Systems (SIGDERS) was created. The mandate of SIGDERS joint research program is to carry out generic, pre-competitive research of benefit to all its members. During the Phases 1, 2, 3 and 4 objectives were identified; tasks were developed and executed through approval process by the Steering Committee members. For each of the Phase, SIGDERS deliverables were presented to the members via formal technical meetings and fulfilled all established tasks. Based on the focused effort, recently, SIGDERS made two major contributions to the roofing community by publishing national dynamic wind uplift standard (CSA, 2004) and a guide for wind design of mechanically attached roof assemblies (Baskaran and Smith, 2005). In addition, SIGDEERS technology was transferred via more than 100 peer reviewed publications (www.sigders.ca). Currently, SIGDERS is in its Phase V operation. Objective 3 of the Phase V is 'Update CSA A123.21-04 Standard to include Wind Resistance Evaluation of Fully Bonded System'. Existing CSA standard is applicable to mechanically attached roofing system (MARS). In the MARS, the waterproofing membrane is integrated with the assembly by use of mechanical fasteners. In the fully bonded systems (FBS), the waterproofing membrane is integrated with the assembly by use of adhesives. To update the CSA standard, among other parameters, following two key variables need detailed investigation:Part A: Effect of specimen size on the wind uplift performance and Part B: Appropriate load cycle to simulate wind effects on the FBS.This report focuses on these two parameters. Wind uplift performances of identical systems (same components) with only variation in the specimen sizes {(12' x 24' versus 8' x 8') (3658 mm x 7515 mm) versus (2438 mm x 2438 mm)} were compared. Similarly, by constructing two identical specimens of same size, systems were subjected to the existing load cycle in the CSA standard and its revised version to account for wind gusts for rigid systems. For the presentation of the data in this report, the existing load cycle in the CSA standard is labelled as Method 1 where as the revised load cycle is labelled as Method 2. All investigations were made in the Dynamic Roofing Facility (DRF) of the National Research Council of Canada. Baskaran and Ko (2009) documented the DRF's features. |
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