Typhoon risk and climate-change impact assessment for cultural heritage asset roofs

Abstract

Recent catastrophic events in Southeast Asia have emphasized that roofs made of wood/steel frames and lightweight metal roofing sheets are the most vulnerable component in the building envelope when subjected to typhoon-induced wind uplift. This also applies to aging cultural heritage (CH) assets, which deserve special consideration because of their intangible value for local communities, and their essential role for inclusive and sustainable socio-economic development through cultural tourism.This paper introduces a simulation-based framework for fragility analysis and typhoon risk assessment of CH-asset roofs. Fastener pullout and roof-panel pullover are explicitly considered in the proposed framework to model the progressive failure of the roof system. A simplified roof geometry is assumed, requiring limited information about the structure under investigation and low computational resources. Such a low computational burden allows modeling wind-induced demands and component capacities probabilistically as well as considering the effects of load redistributions due to fastener failure and fastener/roof-panel corrosion. Variance-based sensitivity analysis (i.e., Sobol’ indices) based on polynomial chaos expansions of the limit state function is also performed, highlighting the parameters most affecting typhoon-fragility variance and then requiring special attention during data collection. Climate-change impact on the typhoon risk estimates is finally investigated through the use of various scenarios and a time-dependent function modifying the wind hazard profile of the site where the assets of interest are located.The proposed framework is applied to 25 CH assets in Iloilo City, Philippines. The required input data was collected through rapid visual surveying combined with new technologies, such as drones. It is shown that the proposed framework can be adopted in practice for both risk prioritization at a building-portfolio level and simplified risk assessment at a building-specific level.