Enhanced endurance-time-method (EETM) for efficient seismic fragility, risk and resilience assessment of structures

Abstract

Quantifying the seismic fragility, risk, and resilience of structures is a computationally demanding step in the performance-based earthquake engineering framework as it commonly requires a large number of nonlinear dynamic analyses. The Endurance Time Method (ETM), which leverages just a small number of intensifying dynamic loads to obtain full responses of structures from elastic to collapse, has been increasingly used recently for efficient estimates of seismic responses. However, when applied to fragility analyses, ETM may produce imprecise fragility medians and under-estimated dispersions in fragility curves, which thereby results in biased estimates of risk and resilience. To solve this problem, the present study develops an Enhanced ETM (EETM) specialized for accurate and efficient seismic fragility analyses, which further boost accurate and efficient assessment of structural risk and resilience. The developed method is demonstrated using a computationally intensive deep water-bridge model under earthquakes considering the fluid-structure interaction. Merits of EETM on efficiency and accuracy are demonstrated by comparison with ETM and Incremental Dynamic Analysis (IDA) method.