Cracking behavior analysis of reinforced concrete structures by using a cohesive fracture model

Abstract

The simulation of cracking behavior in reinforced concrete structures is one of the most challenging tasks of engineering practice due to the highly complex phenomena which arise in the structural element under both ultimate and service loads such as the interaction between concrete and steel reinforcement, crack coalescence and branching, and multiple crack propagation. In the literature, the most known and well-established constitutive models for concrete are based on a continuum representation for this material, in which both kinematic and static variables (i.e. strains and stresses) possess regular spatial distributions. However, due to the discrete nature of the cracks, this hypothesis should be removed for a concrete cracking analysis to be correct. In this context, the present work aims to investigate the cracking behavior, in terms of crack width and crack spacing, in reinforced concrete structures by means of a discrete fracture approach implemented in a finite element framework. In particular, such a model relies on an inter-element cohesive model to simulate crack onset and propagation used in combination with an embedded truss model to reproduce the mechanical behavior of the steel rebars as well as their interaction with the surrounding concrete. The adopted integrated model has been employed to perform numerical simulations for predicting the load-carrying capacity and the related crack pattern of real-scale reinforced concrete structural elements. Comparisons with experimental outcomes, in terms of loading curve, crack width and crack spacing, have demonstrated the capabilities and effectiveness of the proposed model to investigate the cracking behavior in reinforced concrete structures providing more accurate crack patterns, than existing models.