Experimental Study of the Shear Capacity of Steel Beam-to-L-CFST Column Connections

This paper aims to investigate the shear performance of a new and innovative type of vertical stiffener connection between steel beams and L-shaped columns composed of concrete-filled steel tubes connected by transverse and vertical steel plates (L-CFST columns) in high-rise residential buildings. Quasi-static cyclic loading tests were performed on five full-scale specimens to investigate the panel zone behaviours. Based on the experimental results, the hysteretic responses, skeleton curves of the shear force–deformation, ductility, stiffness degradation, energy dissipation and strain are discussed. The variables studied in these experiments include the joint type, axial compression ratio, cross-sectional area and width-to-thickness ratio of the vertical stiffener, and presence of concrete. The results indicate that the cross-sectional area of the vertical stiffeners plays a critical role in the performance of the panel zone. Two types of failure modes were observed outside the panel zone: fracturing of the vertical stiffeners and fracturing of the beam flange connecting plate. Shear deformation of the panel zone was obvious in the exterior joint specimens, and the corresponding maximum shear deformation reached 0.05 rad. Furthermore, the scopes of the panel zone in the corner and exterior joint specimens were determined by the strain distribution.