Nonlinear Response of Steel Storage Racks Under Progressive Collapse Scenarios

Steel storage racks, widely used in industrial and commercial facilities, are lightweight yet highly stressed structures composed of thin-walled cold-formed steel members. Their susceptibility to progressive collapse arises from semi-rigid connections, local instabilities, asymmetric bracing layouts, and limited ductility, which may trigger disproportionate failure under accidental actions such as impacts or abnormal loads. This study investigates the progressive collapse behavior of braced pallet racking systems through an integrated experimental–numerical approach. The results highlight the critical role of connection behavior and bracing configuration in governing collapse mechanisms. While systems with limited bracing exhibit more ductile responses and develop catenary action, highly braced configurations may experience brittle failure due to constrained deformation capacity. The comparison between static and dynamic analyses enabled the evaluation of dynamic amplification effects through the derivation of Dynamic Increase Factors. The findings emphasize the need for performance-based design approaches that explicitly account for connection ductility, axial–flexural interaction, and load redistribution mechanisms. This study provides new insights into the progressive collapse response of cold-formed steel rack systems and contributes to the development of resilience-oriented design strategies for enhancing their robustness under accidental loading conditions.