Seismic behaviour of the corner joints of a frame under biaxial cyclic loading

In this study, two two-dimensional (2D) and three three-dimensional (3D) beam-column joints are tested under pseudo-static loadings to investigate the influence of loading types on the seismic behaviour of beam-column joints, especially for the hysteretic behaviour and failure modes. The main experimental parameters are the loading types (uniaxial loading, biaxial symmetrical loading (BS loading), and biaxial centre symmetrical loading (BCS loading)) and the width-to-thickness ratio of the steel column (D/t = 22 and 33). In a 3D joint, BS loading comprised of two equal forces applied at the two beam ends in the same direction while BCS loading comprised of two equal forces applied at the two beam ends in the opposite directions. The results indicate that the loading types affect the bearing capacities of the specimens. The bending moment of the specimens under BCS loading are 20% lower compared to specimens under unidirectional loading, while the bending moment of the specimens under BS loading are similar to those under unidirectional loading. Width-to-thickness ratio of the square steel column is one of the key factors that affect the bending moment of the specimens. According to the test results, FEM models of test specimens are established by using ABAQUS. The numerical results are in good agreement with the experimental results.