A new approach to Multi-hazard analysis

Multi-hazard engineering is increasingly recognized as a serious worldwide concern. In this paper, the principle of multi-hazard is applied to an essential steel structure (a hospital) located in California, US. The studied structure is assumed to be exposed to a sequence of three different cascading hazards (earthquake, blast, and fire). First, non-linear time-history analyses are performed and the seismic response of the structure is evaluated. The seismic input is assumed to cause damage to the hospital’s power supply which it turns to generate an explosion. The probability of explosion is estimated accounting for the probabilities of fuel leakage, fuel concentration, and ignition. A set of twelve blast intensity levels is considered in the analysis, corresponding to the different quantity of fuel content inside the tank. Afterward, a fire hazard is generated following the explosion, whose intensity level is evaluated using the compartmental heat flux. The effect of the fire is translated into an increase in the steel’s temperature, and damage is consequently evaluated. A methodology is proposed to accumulate the cascading damage caused by multi-hazard based on the conditional probability of occurrence. This method is capable of predicting the damage severity of the structural and non-structural components with a high accuracy. The proposed multi-hazard method is considered a significant step in improving the accuracy of loss estimation and in providing risk mitigation measures within the resilience-based environment. The results obtained in this paper verify the effectiveness and the practicality of the proposed method.