Punching shear strength improved by upward panel in reinforced concrete transfer slabs

In reinforced concrete transfer slab systems, the use of upward panel can improve the punching shear strength as well as decrease the slab thickness, to offer better architectural plan and constructability. Compared to conventional drop panel, the upward panel increases the tension zone depth on the slab section. Thus, the validity of the upward panel needs to be verified. In this study, the influence of upward panel on the punching shear strength of transfer slabs was investigated. According to the test results, the use of the upward panel with diagonal reinforcement increased the punching shear strength of the transfer slab specimens by 100-128%. In particular, the diagonal reinforcement for connection between the upward panel and slab significantly contributed to punching shear strength. The test results were compared to the predicted punching shear strength of the design codes and strut-tie method.