Analytical model for describing the dynamic bond-slip behavior between steel plates and reactive powder concrete

Steel-reactive powder concrete composite structures are vulnerable to blasts or collisions. The bond performance between reactive powder concrete (RPC) and steel plates plays a crucial role in determining the dynamic response of these structures. Although numerous studies have examined the static bond behavior between RPC and steel plates, research on the dynamic bond behavior of the steel-RPC interface remains limited. This study performed double shear push tests to examine the dynamic bond behavior at the steel-RPC interface. The results revealed that under dynamic loading, the failure mode of the steel-RPC-steel specimen is characterized by partial interface damage, with RPC fragments randomly bonded to the steel plate. The interfacial bond strength increases with loading velocity, rising by 10 times at the impact velocity of 5000 mm/s. This rate-dependent behavior is attributed to changes in the failure mode of the interface and the lateral inertial forces. Based on experimental data, analytical models were proposed to predict the dynamic increase factor (DIF) for peak slip and bond strength at the interface. The proposed formula was applied to finite element (FE) simulations of RPC sandwich tubes (RPCST) under blast loading. The mid-height displacement and failure mode of the FE model, considering bond failure, were basically consistent with the experimental results. This research lays the foundation for reliably predicting the response of steel-RPC composite structures under dynamic loading.