Physics-informed data-augmented prediction of post-earthquake residual bearing capacity for pile foundations with soil-structure interaction

During seismic events, the underground components of bridge pile foundations are particularly susceptible to damage. Because subsurface damage cannot be directly observed, assessing the functional degradation of affected bridges becomes both time-consuming and uncertain. Therefore, reliable and rapid assessment of post-earthquake pile bearing capacity is critical for seismic recovery. To address this issue, this study proposes an innovative framework that integrates an attention-enhanced gated recurrent unit (AttGRU) network with the beam on nonlinear Winkler foundation (BNWF) approach to calibrate the residual load-carrying capacity of piles after earthquakes. The AttGRU network serves as a metamodel to accurately reproduce the nonlinear seismic time-history responses of the pile–soil system. The data-driven predictions of soil pressure and soil–pile relative displacement are used to modify the p–y curves in the BNWF model. The predicted pile-head inertial force and soil displacement time histories are then quasi-statically applied to the modified BNWF model to capture pile damage induced by both inertial and kinematic loading mechanisms. Subsequent pushdown analysis of the damaged specimens under a suite of representative ground motions is conducted to evaluate the post-earthquake vertical bearing capacity. Finally, an optimal degradation model of vertical bearing capacity is developed.