Collapse formula is classified into three groups. They are flexural failure, flexural-punching shear failure and punching shear failure. It is very difficult to analyse puching shear failure. This paper assumes that a slab consists of concrete layers and steel layers which are on the plnae stress field, and that the neutral surface of the slab moves according to concrete crack's growing. Then author simulates punching shear failure of reinforces concrete slabs by finite element method.
　Comparing with the experimental results, this paper emphasizes that this analytical method can simulate the failure process, deflection and ultimate strength of reinforces concrete slabs.