Experimental study on seismic behavior of outer end-plate reinforced connection

Due to the bolts loosening and even brittle fracture of the core-bolt and stiffened end-plate connection between concrete-filled square steel tubular column and steel beam under earthquake action, the welded connection and bolted-welded connection reinforced by outer end-plates were presented. Six concrete-filled steel tubular column and steel beam joints were tested under low-cyclic loading. The failure process and characteristics of the welded joints and bolted-welded joints reinforced by outer end-plates were analyzed and compared with the core-bolt and stiffened end-plate joint in different construction details and beam-to-column stiffness ratio, and the hysteretic loops, bearing capacity, ductility and energy dissipation, strength and stiffness degradation of the joints were also studied. The test results indicate that when the beam-to-column stiffness ratio is smaller, the failure modes of the two kinds of new joints are plastic hinge failure at the end of beams, which is same as the core-bolt and stiffened end-plate joint. However, when the beam-to-column stiffness ratio is larger, the weld crack failure occurs in the core zone of the welded connection reinforced by outer end-plates and the bending failure occurs in the column end of the bolted-welded connection reinforced by outer end-plates. Compared with the core-bolt and stiffened end-plate connection, the two types of new joints have higher bearing capacity and better safety reserve, full hysteretic loops, good seismic performance indicators, and meet the seismic design requirements of strong joint and weak component. © 2019, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.