Reliability of light-frame roofs in high-wind regions. II: Reliability analysis

The majority of residential construction in the United States is light-fram e wood construction. An increasingly large number of homes are being built in coastal areas subject to hurricanes. In response to devastating losses i n these areas following hurricanes, and the increased risk to homeowners, i nsurers, and local, state, and federal government, attention is being focus ed on improving the performance of residential construction subject to coas tal hazards. One of the most significant performance issues identified is t hat of maintaining the integrity of the roof system during a hurricane. Rel iability analysis provides one possible tool for evaluating performance or relative risk (safety) of structural components. In this study, a reliabili ty analysis is conducted for a simple gable-end roof. Specific limit states (modes of failure) considered include loss of sheathing and failure of the roof-to-wall connection. Statistical information on element and subsystem capacity is obtained from previous laboratory tests and analytical studies. Statistics of the wind load acting on individual roof-sheathing components were determined in the first part of this two-part paper. In the present p aper, the reliability of light-frame roof components subject to wind uplift is investigated, and results presented, for three baseline coastal residen tial structures. The results confirm that there are a relatively small numb er of sheathing panels and roof-to-wall connections that dominate the failu re probability.