Punching Shear Design of Waffle Slabs at Internal Column Connections

This paper presents two models to design waffle slabs against concentric and eccentric punching shear. The suggested design models modify the current code provisions in two ways by replicating the loss of shear surface area of waffle slabs on the code shear critical section, implementing a modified concrete shear strength equation, and introducing a factor to account for the moment transfer for waffle slabs–column connections subjected to eccentric punching shear. The proposed models were verified with the test results of flat slabs from the literature and then applied to predict the punching shear of waffle slabs. The models agree well with the test results of waffle slabs and the test results of flat slabs.