Copula-based hazard analysis of office buildings exposed to potential earthquake-fire impacts

Buildings in service may be exposed to multiple hazards such as earthquake and fire at the same time. It is important to consider the probability of such hazards as joint events in the risk assessment of buildings. However, there has been a lack of rigorous consideration of fire and earthquake as joint events in the existing literature on multi-hazard analysis of buildings. This paper presents an investigation into the multi-hazard analysis of office buildings exposed to fire-earthquake impacts. A selected region is adopted to illustrate the development of a probabilistic model for the region-specific earthquake intensity, in terms of the peak ground acceleration (PGA). The Gumbel distribution is applied, which can explain 98.3 % of the uncertainty in earthquake intensity for the study area. Additionally, the general fire load density (FLD) is employed as the potential fire-related hazard predictive parameter. The copula method is used to develop the joint probability distribution model for fire-earthquake scenarios in the specific area. In the development of the probability distribution model for the PGA, the recorded PGA data from past earthquakes is used in conjunction with the PGA attenuation function, which is useful for addressing the scarcity of seismic parameters. When the joint probability distribution of the model parameters exceeds 0.5, the joint probability results obtained from the model parameters are advantageous. Therefore, the joint probability should be calculated according to the joint distribution of bivariate discrete random variables for “low probability, high consequence” events. Subsequently, a decision analysis is conducted for multi-hazard events involving earthquakes and fires. The results indicate that for compartments with FLD values in the interval [200, 1000], safety decisions should be structured according to a graded standard. Finally, a steel structure case is included to demonstrate the performance of the structure under earthquake-fire multi-hazard conditions.