Regularisation methods for modelling flexural dominant lightly reinforced concrete walls

Abstract

Localisation can occur in distributed plasticity fibre models when a strain-softening response at the section restricts the spread of damage due to the unloading of stress in adjacent sections/elements. Past studies have developed regularisation schemes for the concrete compression response and reinforcement tension response to achieve mesh objective simulations for the failure of reinforced concrete (RC) walls. However, for walls designed with low amounts of longitudinal reinforcement, the response and failure are controlled by the tensile behaviour, including concrete cracking and reinforcement fracture. The aim of this study was to develop reliable regularisation approaches that could be implemented into fibre models to simulate the cracking and reinforcement fracture response for lightly reinforced concrete walls. Methods for regularisation of both the reinforcement and concrete material properties using a fracture energy method were proposed to minimise the effect of element size on the strain localisation during nonlinear analysis of lightly reinforced concrete walls. The proposed regularisation techniques were validated against the measured response of tested lightly reinforced walls subjected to both monotonic and cyclic loading to ensure that both the cracking strength, ultimate strength, and ultimate drift capacity could be accurately simulated. The local strain response was also investigated to highlight the post-processing of model outputs required to achieve objective simulation results. The results indicate that the models implementing the proposed regularisation of concrete and reinforcement constitutive models could accurately predict the global hysterical response as well as the local strain response of lightly reinforced concrete walls.