Multi-hazard Earthquake-Tsunami Structural Fragility Assessment Framework

Abstract

A probabilistic multi-hazard earthquake-tsunami fragility assessment framework is presented, which accounts for the effect of accumulated damage on the structure due to earthquake loading on its subsequent tsunami response. The fragility assessment framework involves simulating structural response using advanced three dimensional (3D) nonlinear finite-element structural model subjected to sequential earthquake-tsunami loading at multiple seismic and tsunami intensity levels, using back to back nonlinear response history analyses (NRHA) and nonlinear static pushover (NSP) analyses. A modern earthquake-tsunami code designed four story reinforced concrete (RC) special moment resisting frame (SMRF) building is used as an application example to illustrate the proposed framework. Results indicate that the effect of accumulated damage due to earthquake loading is more pronounced in reducing the stiffness of the structure compared to the reduction in structural capacity. Moreover, the tsunami structural capacity required to achieve a given probability of damage exceedance decreases with increasing seismic intensity, especially at lower damage states.