Simulation of Punching Failure: Failure Mechanism and Size-Effect

Finite element simulation of punching failure in reinforced structures is investigated. The non-linear material behavior sidered by superimposing elastoplastic behavior of steel cement and the tensile cracking behavior of concrete. The simulation of failure is performed for a slab. It is shown that the mode of failure-characterized by a localized inclined reproduced. This simulation dicates that the failure mechanism results from micro-crack co- alescence phenomenon at the top of the slab followed by a propagation towards the corner of the slab-column. The size-effect is reproduced numerically. It is shown modification of the tensile stress distribution along the crack reflects the influence of the size. A size-effect law is based on the adjustment of the numerical results. 1229 1 Introductory remarks Reinforced concrete slabs supported on columns fail by punching when a column suddenly perforates the slab by extrusion of a co- plug of concrete. A review of this failure phenomenon has been presented by Regan and Braestrup (1985). The approach ado- here is concerned with the numerical simulation of this failure mechanism. Further details are given by Menetrey et al. (1994), (1995a), and (1995b ). 2 Numerical model 2.1 Preliminaries reinforced concrete model uncouples the actions of steel rein- forcement and concrete. The incremental flow theory of plasticity is considered as the framework of the constitutive model description. steel model is characterized by a bi-linear stress-strain be- and an identical response under traction and compression. The concrete model is characterized by a triaxial strength which delimited by a new 3-parameter failure criterion described by Menetrey and Willam ( 1995). A non-associated flow rule is deri- so as to reproduce the dilatancy of the plastic strains obser- in concrete triaxial experiments as reported by Menetrey et (1995a). 2 ..