Wind Fragility of Roof Cladding and Trusses for Australian Contemporary Housing

Abstract

This study develops a reliability-based fragility method to predict the roof damage for contemporary houses in non-cyclonic regions of Australia. The overloading of roof connections is considered as the limit state, and deemed to cause the roof sheeting loss and roof truss failures. A finite element method is employed to evaluate the wind uplift forces in roof connections. The finite element model consists of metal roof sheets and battens, timber roof trusses, wall top plates, and the cladding-to-batten, batten-to-rafter/truss and rafter/truss-to-wall connections. The finite element method is able to capture the load sharing and redistribution of the roof system. A Monte Carlo simulation in conjunction with the finite element method are employed to conduct the wind fragility assessment, which enables the probabilistic characterization of wind demands, uplift capacities and structural response for roof connections. The proposed fragility method is illustrated on a representative contemporary house built in suburbs of Brisbane and Melbourne. At a 500-year gust wind speed, considerable damage to roof cladding and trusses is predicted for the representative contemporary house in Brisbane with windward wall dominant openings.