Numerical Simulation Methodology for Seismic Analysis of Coupled Building Ruins and Emergency Rescue Supports

The nonlinear interaction between post-earthquake building ruins and emergency rescue supports (ERS) plays a crucial role in determining the secondary-collapse risk during urban search-and-rescue operations. This study addresses the existing gap by developing a FEM-integrated FDEM restart-based re-editing methodology. This methodology reconstructs the transition from intact structures to semi-ruined configurations and incorporates ERS components, while preserving collapse-state mechanical fields. Two typical interaction mechanisms between building ruins and ERS are explored, considering realistic rescue scenarios: surface-to-surface frictional contact and nail-connected anchorage. A representative analysis is conducted on a building ruin with emergency rescue timber supports (ERTS) subjected to four typical aftershocks. Results indicate that the global response is primarily influenced by contact behavior; surface-to-surface contact results in higher frictional and hysteretic energy dissipation, which improves overall stability. Long-period and pulse-like aftershocks significantly amplify interface slip, stress transfer, and energy demand, compared to near-fault and far-field motions. Three evaluation indices—peak relative displacement, peak transferred stress, and interface energy—are proposed to assess deformation compatibility, localized stress demand, and interfacial energy dissipation. The methodology offers a practical, physically consistent tool for evaluating building ruin-ERS performance and supports rescue-oriented design strategies to prevent secondary collapse.