Performance of concrete filled steel tubular (CFST) members with circumferential gap under lateral impact

Abstract

To investigate the influence of circumferential gap on the impact-resistance capacity of CFST columns, 12 CFST specimens were tested under constant axial load and lateral impact loading at mid-span. The test parameters included gap ratio, impact velocity, and slenderness ratio. The failure mode, impact force versus time curves, and deflection versus time curves of CFST specimens with circumferential gap were experimentally investigated and compared with those of the reference samples without any gap. Based on the test results, the failure mode, impact force history, deflection response, and energy dissipation of the specimens were experimentally investigated, and the influence of the above parameters on the impact-resistance of CFST specimens was analyzed. To further explore the force transfer mechanism of CFST with gap under lateral impact, a finite element analysis (FEA) model was established, and the influence of the gap on the contact stress, internal force transfer mechanism, and dynamic flexural capacity of CFST specimens was analyzed. Lastly, a simplified formula for predicting the dynamic flexural capacity of CFST considering the influence of circumferential gap was proposed, which could provide a reference for practical engineering applications.