Multi-variate seismic demand modelling using copulas: Application to non-ductile reinforced concrete frame in Victoria, Canada

Joint probabilistic characteristics of key structural demand variables due to intense ground shaking are important for quantitative seismic loss estimation. Current damage-loss models require inputs of multiple seismic demand parameters, such as maximum/residual inter-storey drift ratio (ISDR) and peak floor acceleration (PFA). This study extends current seismic demand estimation methods based on incremental dynamic analysis (IDA) by characterising dependence among different engineering demand parameters (EDP) using copulas explicitly. The developed method is applied to a 4-storey non-ductile reinforced concrete (RC) frame in Victoria, British Columbia, Canada. The developed multi-variate seismic demand model is integrated with a storey-based damage-loss model to assess the economic consequences due to different earthquake loss generation modes (i.e. non-collapse repairs, collapse, and demolition). Results obtained from this study indicate that the effects of multi-variate seismic demand modelling on the expected seismic loss ratios are significant. The critical information is the limit state threshold for demolition. In addition, consideration of a realistic dependence structure of maximum and residual inter-storey drift ratios can be important for seismic loss estimation as well as for multi-criteria seismic performance evaluation.