RESEARCH ON THE ANTI-COLLAPSE CAPACITY OF CFST COLUMN-CORRUGATED WEB H-SHAPED STEEL BEAM HAUNCH JOINT WITH HYBRID BOLTED WELDING CONNECTION

Establishes a numerical model using ABAQUS/Implicit for analyzing the progressive collapse of concrete-filled steel tubular (CFST) column to flat web H-shaped steel beam joint. In the joint configuration, a corrugated web steel beam and a welded haunch were employed to improve the anti-collapse capacity. The failure mode and failure mechanism of the joints under vertical loading and the folding effect of the corrugated web are analyzed. The results show that the failure of CFST column to flat web beam joint (J-WB-O) started at the connection between the ring plate and the beam, while the initial failure of the CFST column-corrugated web beam haunch joint (J-CW-AP) appeared at the end of the welded haunch, which delayed the fracture of the lower flange of the beam. Moreover, for the specimen J-WB-O, the entire beam section contributed to anti-collapse capacity. For the specimen J-CW-AP, the corrugated web seldom contributed to anti-collapse capacity in the initial loading stage. After the fracture of the bottom flange of the specimen J-CW-AP, the corrugated web began to contribute to anti-collapse capacity. As the cracks propagated upwards, the sections of the corrugated web were under tension gradually. The fracture and local buckling of the web were delayed due to the folding effect of the corrugated web. Compared with the specimen J-WB-O, the bearing capacity and ductility of the specimen J-CW-AP increased by 67.2% and 62.3%, respectively. Furthermore, a simplified calculation method of anti-collapse capacity is proposed based on the analysis of resistance mechanism.