Influence of soil liquefaction effect on seismic failure mechanism of river-crossing simply-supported girder bridges subjected to near-fault ground motions.

• Failure mechanism of river-crossing simply-supported girder bridge was investigated when soil liquefaction is considered. • Finite element model was developed considering simply-supported girder bridge and surround sites as an integral system. • Investigation of pile–pier displacement demand and failure mode. • Bending pattern of pile–pier and failure mechanism. • Sliding bearing behavior under near-fault ground motions. Soil liquefaction induced by strong earthquake could cause severe failure to bridges, particularly for river crossing simply-supported girder bridges. Consequently, it is an urgent task to clarify the influence of soil liquefaction on the seismic failure of this bridge-ground system. To this end, two-dimensional finite element (FE) simulation method focusing on liquefiable site-structure was validated based on a published centrifuge test at first. Then 2 refined FE models were established for a typical river-crossing simply-supported girder bridge with the only difference whether considering site liquefaction. Near-fault ground motions were selected for nonlinear dynamic analysis. Seismic responses of two models were compared to investigate the influence of soil liquefaction on bridge failure mode. The comparison results indicated that soil liquefaction significantly changed seismic response of bridge-ground system, such as site displacement performance, pile–pier displacement demand, pile–piers bending mode, sliding bearing deformation, leading to higher bridge failure risk and change of failure mode. [ABSTRACT FROM AUTHOR]