Simulation of push-out tests of corroded reinforced concrete specimens by means of cohesive interface elements with frictional behavior

Abstract

Loss of bond between steel and concrete is one of the effects of corrosion of reinforced concrete specimens. In order to study that, push-out tests were designed and carried out in previous works, in which the specimens were slices cut from concrete prisms reinforced with a smooth steel tube. This allows adhesion and friction to be investigated, avoiding influence of bar deformations on bond stress. The prisms were subjected to accelerated corrosion tests within the framework of a general study of cracking of concrete due to reinforcement corrosion, as presented in previous conferences. In this work simulation of the bond tests has been carried out in order to study numerically the effect of adherence and friction, by using three-dimensional models of the specimens. The simulations have been carried out within the finite element framework COFE (Continuum Oriented Finite Element), which implements elements with an embedded adaptable crack to reproduce fracture of concrete according to the standard cohesive model. Additionally, joint elements with cohesive softening and friction have been programmed to reproduce the behavior of the steel-concrete interface. The numerical and experimental results of specimens not subjected to accelerated corrosion show a good agreement, which confirms that a cohesive-frictional law is adequate to reproduce the interface behavior. In addition, the effect of adhesion and friction on bond has been studied separately in the simulations. In the paper, the main aspects of the push-out tests are introduced, formulation of the joint elements is presented, and the numerical and experimental results are analyzed, with special focus on the numerical aspects of the constitutive law of the joint elements.