Numerical study on the anti-impact performance of novel concrete-filled steel tubular joint with corrugated web and cover plates

To improve the impact resistance of the traditional concrete-filled steel tubular (CFST) bolt-welded hybrid joint, a novel connection configuration with the corrugated web and the cover plate was proposed in this study. The failure modes and bearing mechanism of the novel connection under vertical dynamic impact load were studied in detail based on the finite element model validated against the previous test results. The falling-debris impact on top of the joint column can be simplified as the drop hammer of the non-deformed discrete shell rigid body. The effect of the design parameters including the dimensions of the cover plate and corrugated web was analyzed numerically. Results show that the existence of the cover plate increases the bending capacity of the steel beam and delays the fracture of the connection. The fracture and local buckling of the web are delayed due to the folding effect of the corrugated web. The energy consumption of the joint with the cover plate and the corrugated web is 20.2%–52.8% higher than that of the traditional joint, in which the corrugated web and bottom flange with cover plate contribute 6.6%–8.3% and 16.3%–32.2% respectively. The time history curves of the internal force of the joints are mainly consisted of the beam mechanism stage, the catenary mechanism stage and the failure stage. Through the parameter analysis, it is suggested that the long diameter of the bolt hole is 0.08–0.09 times of the beam height and the thickness of the cover plate is 0.42–0.50 times of the flange thickness to reach the optimum impact resistance. Furthermore, a simplified calculation method for the impact resistance considering the effect of the corrugated web and the cover plate is proposed. Impact energy can be absorbed by the bending effect and the catenary effect of the joint. The relative errors of the predicted impact resistance and energy absorption by theoretical formulas are within +10% compared with the experimental and numerical results.