Modelling punching shear failure using XFEM

Flat plate concrete structures are easy to construct and cheap to build. However, they are susceptible to a type of brittle failure known as “punching shear”, where columns punch through the floor leading to progressive collapse. Since predicting punching shear is important to enhance the structural behaviour for such buildings, a 2-d axisymmetric model was developed representing a circular column to model punching crack propagation in detail. This was done using the extended finite element method (XFEM). The XFEM results showed good agreement between crack location and areas of highest principal strain. They were also able to capture crack propagation and the effect this has on the stress state under punching failure. It is concluded that explicit modelling of fracture is beneficial in order to capture the full response of the slab and that continuum models are insufficient to do this.