Experimental study on mechanical performance of frame connected by improved end-plate joint

Abstract

An improved end-plate joint has been applied to connect H-beams and H-columns in the weak-axis direction. However, there is still a lack of research on the impact of this joint on the strong-axis mechanical behavior of frames. To address this gap, monotonic loading tests were conducted on two steel frames: one braced and the other unbraced, both connected with improved end-plate joints. The mechanical performance of the frames in the strong-axis direction was analyzed based on test phenomena, load-displacement curves, and deformations of the frame and joint core area. Finite element models were established for braced and unbraced frames to investigate the effects of parameters such as cross-brace presence, brace connecting plate presence, stiffener rib configuration, and beam-column joint type on the strong-axis mechanical performance of the frames. A simplified calculation model and stiffness equation for the frames are proposed. The results show that, compared to steel frames with traditional end-plate joints, the initial stiffness, yield load, and ultimate bearing capacity of those with improved end-plate joints are moderately increased. When compared to welded frames, the yield load and ultimate bearing capacity are comparable, while the initial stiffness decreases by 13%. Installing braces significantly enhances the stiffness and bearing capacity of the frame, shifting the failure mode from end-plate bending failure to net section failure of the tension brace.