SHEAR BEHAVIOR OF COLUMN-BEAM JOINTS OF CONCRETE-FILLED SQUARE STEEL COLUMNS WITH DISCONTINUED JOINT ZONES

To investigate the shear behavior of column-beam joints of concrete filled square steel columns with discontinued joint zones, five joint specimens were tested under cyclic loadings. The failure patterns and the skeleton curves showed that the shear bearing capacity and ductility of the joint were improved with the increase in the relative dimension of the joint (the sectional area of the joint divided by the sectional area of the column) and the relative reinforcement ratio (the mesh reinforcement ratio of the joint divided by the reinforcement ratio of the beam). Based on the Modified Compression Field Theory (MCFT) and the simplification of the stress boundary conditions of the joint, an analytical for calculating the shear bearing capacity of the joint under combined actions of axial and shear loads was established. The peak shear stresses calculated by the proposed model agreed well with experimental results.