Condition-based updating of the fragility for roof covers under high winds

• We propose a new framework for the fragility of roof covers under high winds.
• The approach models the capacity related terms as functions rather than fixed values.
• It can describe gradual increase of failure probability as the roof cover degrades.
• Results show the importance of considering degradation in obtaining the fragility.

Fragility modeling is a commonly used approach to quantify the risk of a structure subjected to high winds. In order to overcome a limitation of conventional fragility models where the performance of the roof cover is assumed to be fixed, we propose a new framework for obtaining the fragility of roof covers under high winds. The approach models the capacity related terms as functions rather than fixed values. Therefore, it can describe gradual increase of failure probability as the roof cover degrades over time. The parameters for the capacity functions are obtained from sensor measurements. In order to overcome the uncertainties associated with the limited measurements, a Bayesian approach is employed. Although the proposed framework can be applied to any type of roof covers, an illustrative example is given for asphalt shingles. Results show the importance of considering degradation of the roof cover in obtaining the fragility. The proposed approach provides much more comprehensive fragility functions than conventional approaches by considering the degradation of the roof cover.