Seismic fragility analysis of steel moment-resisting frame structure with differential settlement

Abstract

Differential settlement of a foundation is commonly caused by non-uniform movement of the soil underneath a structure, and which can cause crack and damage to the structure. In order to examine the influence of differential settlement on structure's seismic performance, a three-dimensional numerical model of steel moment-resisting frame (SMRF) structure with differential settlement was developed and incremental dynamic analysis (IDA) based seismic fragility assessment was performed. Nonlinear time-history analysis was carried out to evaluate the influence of differential settlement intensity, settlement zone and ground motion intensity followed by IDA and seismic fragility analysis. Results show that the seismic responses of structures with differential settlement are obviously greater than those without differential settlement, and differential settlement of foundation can increase collapse probability during earthquakes. Findings from this study can provide valuable information on the seismic safety evaluation of structure with differential settlement which rarely taken into consideration in current practice. By having this additional information, engineers can have better insight when designing structures under such soil condition to avoid catastrophic failure.