Modelling and Equivalent Analysis of Seismic Pier-Top Pounding in Bridges: A Critical Review

Seismic pier-top pounding in high-speed railway bridges transfers short-duration girder-restraint contact forces into bridge piers, coupling local contact damage with global vibration and possible base yielding. This critical review evaluates how evidence and modelling strategies can be transferred from local contact mechanics to pier response and, ultimately, to whole-bridge seismic demand. The literature is synthesized across experimental and refined numerical characterization, reduced-order contact–structure modelling, response-equivalent-pulse construction, and nonlinear whole-bridge analysis. A qualitative evidence-confidence grading is introduced to distinguish the strength and transferability of the available evidence based on study independence, evidence type, and configuration similarity. The primary scope is high-speed railway bridges, while the underlying contact–structure modelling principles are transferable to conventional railway and highway bridges with comparable pier-top restraints, subject to bridge-specific calibration. Conventional spring-dashpot models are computationally efficient but sensitive to contact stiffness, damping, restitution, and damage assumptions, whereas refined finite-element models resolve local response at substantially greater computational cost. Static, impulse-equivalent, and prescribed pulse representations can reduce analysis effort, but agreement in force or impulse alone does not ensure equivalence in pier displacement, base moment, plastic rotation, or residual demand. Demand-oriented pulses can reproduce selected component-level responses within a calibrated applicability domain, while response-triggered loading remains a conditional system-level reduction requiring reliable event logic, state updating, and independent benchmark validation. Future research should prioritize realistic restraint tests, identifiable parameter ranges, multi-demand validation, uncertainty quantification and damage-updatable repeated-impact models. These advances can provide a mechanics-based basis for performance-oriented restraint assessment, while practical design application requires consistency with code-based seismic restraint provisions and post-earthquake track-system serviceability criteria.