Combining finite element analyses and mechanical models for the assessment of reinforced concrete slabs

The influence of the level of deformation of the flexural reinforcement on the punching strength is well-established and mechanically founded since the pioneer works of Kinnunen and Nylander. In code provisions, this influence is sometimes reflected by means of indirect parameters such as the flexural reinforcement ratio or by means of mechanical approaches accounting for the ratio between the applied load and the flexural resistance of the specimen. The level of deformation of flexural reinforcement is nevertheless complex in many situations. In order to provide a consistent approach to determine the punching strength, it has been recently proposed to couple refined finite element (FE) models (using a multi-layered shell formulation) with a robust strain-based failure criterion in shear. The goal of this paper is to review specific case studies in which redistributions after cracking may govern the overall behavior of reinforced concrete slabs. The numerical global response is then combined with the failure criterion of the Critical Shear Crack Theory, that can directly consider the influence of the flexural response on the punching or shear capacity.