Seismic behavior and vulnerability of thin-walled stirrup-confined CFST piers: Pseudo-dynamic experimental and numerical analysis

The pseudo-static test is a widely used, cost-effective method for evaluating seismic resistance. However, its reliance on monotonic cyclic loading fails to replicate inertial forces. It neglects the influence of strain rates on materials, thus limiting its ability to simulate pier failure mechanisms accurately during actual earthquake events. This study conducted pseudo-dynamic tests and elastoplastic analyses using solid-shell elements on stirrup-confined concrete-filled steel tube (CFST) piers. The investigation focused on the effects of stirrup confinement on displacement response, stiffness degradation, and voiding phenomena under seismic loading. Additionally, an incremental dynamic analysis (IDA) was performed, utilizing the finite element model's precision in predicting peak displacements to assess the vulnerability of stirrup-confined CFST piers. The findings demonstrate that stirrup confinement significantly reduces displacement magnitude, mitigates stiffness degradation, alleviates void formation, and substantially decreases the risk of earthquake-induced damage.