Service-life multi-hazard risk assessment of structures: framework and application

Fragility and risk assessment of civil engineering structures against various design loads and their combinations need to be conducted to evaluate structural vulnerability. This is typically done at the design stage. However, during the service (design) life, it is important to investigate the change (increase) in the risk posed to the structure on account of multiple hazards. This article discusses a holistic novel framework that considers aging effects in addition to major or minor structural damage resulting from independent hazards. The framework is illustrated for independent action of earthquake and fire hazards on reinforced concrete (RC) buildings with varied occupancies while considering continuous structural deterioration on account of chloride- and carbonation-induced corrosion over a building’s service life. The change in the structure’s performance in the fire over its service life, in terms of incident risk and the resistance period, is evaluated for a combination of environmental effects and multi-hazard effects of earthquake and fire. The results from this study indicate that there is a significant increase in the risk of post-earthquake fire if continuous structural degradation due to environmental factors and minor damage due to earthquakes is not addressed.