Finite element model and test results for punching shear failure of RC slabs

Abstract

AbstractThe nonlinear finite element analysis of pin-supported reinforced concrete slabs of moderate thickness is the main subject of this paper. This is an important issue of the mechanics of concrete structures. Thus, a nonlinear FE analysis of RC slab models subjected to punching shear was initiated and the comparison of the numerical and test results was made. The prediction engine of the crack pattern due to bending and extension is incorporated in the Mindlin-type (moderately thick) slab model together with other nonlinear features. This is in order to formulate an alternative model of RC slab in relation to the layered models or fully three-dimensional models. New formulas were applied for 3D constitutive relationships for concrete and for tension stiffening effect. Prediction of punching shear was facilitated by Podgórski’s failure criterion for concrete. On the one hand, a considerable advantage of the proposed approach is a relatively low numerical effort in comparison with the existing models, while on the other hand the applied model clearly describes the physical behaviour of a real slab. A supporting test programme for validation was run. Three RC slabs with a system of double-headed studs as the reinforcement against punching were tested by the authors in ITB Strength Tests Laboratory. The results for the units constructed as square slabs with a central short column subjected to full-scale tests were initially compared with assessments based on standard provisions and technical approvals. As a result of this approach, the overall prediction of the nonlinear behaviour of the test model, including the model of shear failure, is in accordance with the experimental data.