DESIGN METHOD ON PANEL-ZONE SHEAR BEHAVIOR OF CONNECTION BETWEEN SQUARE COLUMN AND H-SHAPED-STEEL UNEQUAL-DEPTH BEAM WITH EXTERNAL-DIAPHRAGM

To evaluate the panel-zone shear behavior of a H-shaped steel unequal-depth beam-to-column connection with external-diaphragm, seven specimens are fabricated and tested under cyclic loading. Based on the test results, twenty three-dimensional solid models with different parameters are established, and the nonlinear finite element analysis has been carried out. The results show that the shear failure modes can be classified to an entire panel zone mode and a partial panel zone mode by introducing the concept of the minimum column-beam strength ratio of the connection. Moreover, the shear behavior of the panel zone is affected by various parameters, including beam depth ratio (d_b1/d_b2), the size of external diaphragms, and width-to-thickness ratio (D/t) of a steel column. Furthermore, based on the yield line theory, test results and numerical results, the design formulas on shear strength have been proposed and the calculated results show a good agreement with the test results and numerical results. The proposed formulas can evaluate the shear strength of the panel zone with adequate accuracy and be adopted in practical design.