The aim of this study was to find out the punching shear failure mechanism of RC slabs through experimental investigation and nonlinear finite element analysis. In the nonlinear finite element analysis, 3D Nonlinear Cementitious 3 constitutive model was specifically applied to concrete material to express the stress – strain relationship of concrete subjected to triaxial compressive stress states. As a result, it was found that triaxial compressive region was formed in the vicinity of the loading plate, and the compression failure of concrete in this region caused punching shear failure of the RC slab. Therefore, a pyramid shell model was proposed based on the load bearing mechanism formed around the vicinity of the loading plate. Finally, the evaluation formula for the punching shear resistance derived from this pyramidal shell model was in good agreement with the previous experimental results.
