A mechanical approach for the punching shear provisions in the second generation of Eurocode 2

The revision of a code is a long-term project that shall fulfil several aims, comprising the enhancement of the ease-of-use and incorporating updated state-of-the-art. With respect to the revision of Eurocode 2 concerning the punching shear provisions, this task allowed also for the opportunity to enhance the understanding of the code and physical phenomenon by designers. The original EN1992-1-1:2004 punching provisions were adapted from an empirical equation for design based on the regression analyses performed by Zsutty in the 1960s for shear in beams and later reworked in Model Code 1990 for punching shear. These expressions did not show any link to the physical response of a structure, making difficult to designers to clearly understand how to engineer their designs. Instead of continuing with this approach, CEN/TC250/WG1 took the decision in 2016 to ground the punching provisions on a mechanical model that could be explained to engineers, allowing for a transparent understanding of the design equations and phenomena. To that aim, the Critical Shear Crack Theory, already implemented in Model code 2010 at that time, was selected as representative of the state-of-the-art. Following that decision, a large effort has been performed to implement this theory into the Eurocode, keeping its simplicity of use and generality. This paper is aimed at presenting the theoretical ground of the theory as well as the manner in which it is drafted for the future generation of Eurocode 2.