Seismic Damage Analysis of Piled Pier System Constructed on Soft Clay Ground

Abstract

Due to the complex clay–pile interaction and significant amplification effect of soft clay, the seismic performance of the piled bridge in soft clay ground is largely unassured. In this study, a suite of both parametric and fragility analyses was performed to investigate the seismic performance of piled pier systems installed in soft clays, in which a validated hyperbolic–hysteretic model and an equivalent elastic–perfectly plastic model were employed to depict the dynamic behaviors of the clay and pile–pier system, respectively. The clay–pile–pier systems were found to be effectively influenced by the factors, namely, ground motion intensity, bridge girder mass, and pile flexural rigidity, to varying extents. The seismic response of the pile was comparatively more complex, which was generally nonlinear against each of the factors considered and predominantly influenced by the kinematic effects induced by the surrounding clays. Furthermore, the maximum curvature response was found to be more applicable to describing the evolving damage states of the pile–pier systems under seismic shakings. Subsequently, a total of four different damage states of the pile–pier system were quantified in terms of the curvature ductility, and the plots of probability of the clay–pile–pier system exceeding one specific damage stage against the ground motion intensity were obtained from the fragility analyses.