Punching-shear behavior of slabs with bar truss shear reinforcement on rectangular columns

In this study, punching-shear tests were performed to investigate the behavior of slabs supported by rectangular columns with capital. The slabs were subjected to an uneven shear transfer in two orthogonal directions by using the rectangular columns and different span lengths. Column capitals were used at the slab-column joints and preassembled bar trusses were placed at the periphery of the column capital to enhance the punching-shear capacity. Furthermore, the corners of the rectangular column and column capital were rounded to alleviate the shear stress concentration at the corners of the critical perimeter for shear. The test results show that the punching-shear strength of the slabs were significantly enhanced by the bar trusses. The shear resistance of the bar trusses was mostly contributed by the diagonal bars undergoing significant strains. On the basis of the results, the effects of the uneven shear transfer and bar truss arrangement on the slab shear behavior were investigated. In addition, the punching-shear strengths predicted by ACI 318-14, Eurocode 2, and KCI 2012 were compared with the test strengths.