Investigation of the punching shear behaviors of reinforced concrete slab–steel reinforced concrete L-shaped column connections

To study the punching behaviors of reinforced concrete (RC) slab–steel reinforced concrete (SRC) L-shaped column connections, four slab–column connection tests were designed and completed, and a new punching shear resistance measure proposed. The test variables were column section shape, slab thickness and column cap. The test results show that the failure mode of L-shaped column was mainly two-way shear. Meanwhile, increasing slab thickness and installing column cap can effectively improve the ultimate bearing capacity of the slab–column connection. The punching angles formed by the punching cone and horizontal direction at the final failure of the connection were between 23.5° and 49.5°. In addition, a numerical simulation analysis was carried out using ABAQUS software, and the effects of various parameters on the performance of slab–column connections were studied. It was found that the change of column section shape will lead to more complex shear stress distribution and stress concentration phenomenon. However, the punching capacity of the special-shaped column was higher than that of the equivalent square column with the same section area. As a new punching shear resistance measure, inverted T-shaped steel can effectively improve the ultimate bearing capacity of the connections. In addition, when the ratio of slab thickness to web width of inverted T-shaped steel was less than 0.75, the failure mode of the connection changed from brittle punching failure to flexural failure.