The residual displacement analysis of RC bridge piers installed in liquefiable soils

Seismic damage investigations have shown that RC bridges installed in liquefiable sites are more prone to excessive residual displacement. However, the coupled interaction mechanism of different factors on residual displacement of the bridge remains unclear, and the contributions of these factors to residual displacement still not yet been ranked. Focusing on this gap, a refined finite element (FE) modelling method for a liquefiable soil-structure system was validated. Four FE models were established for the nonlinear dynamic time history analyses (NDTHAs). Critical seismic responses were analysed and compared among four FE models. Influences of three key factors on residual displacement were discussed and ranked, including the soil-pile nonlinear interaction (SPNI), the soil nonlinearity (SN) and the soil liquefaction (SL). Results indicated that the SL contributes most to the residual displacement, followed by the SPNI, and the contribution of the SN is the smallest. In addition, the SPNI increases the residual displacement by reducing soil constraints on the pile, the SL increases the residual displacement by providing an additional post-earthquake soil geometric force to the pile, and the SL further reduces soil constraints and provides greater post-earthquake soil geometric force.