Constitutive model for fibre reinforced concrete by coupling the fibre and aggregate interlock resisting mechanisms

Abstract

This paper describes the development of a constitutive model for Fibre Reinforced Concrete (FRC) by combining the fibre and aggregate interlock resisting mechanisms. The proposed model predicts the normal and shear stresses in function of the crack opening and sliding displacements. For this purpose, two well established aggregate interlock models and three fibre pull-out models reported in the literature are used, and their predictive performance is assessed in the context of the present study. In order to understand the impact of the variables involved in the model, a parametric study, targeting different maximum aggregate diameters, concrete compressive strengths and fibre volume ratios, is conducted. The results show that higher concrete compressive strengths and fibre volume ratios lead to higher normal and shear stresses. Finally, the predictive performance of the model is assessed by comparing the numerical predictions with experimental results collected from the literature. Results show that the model is capable of predicting the shear peak-stress with good accuracy, however the post-peak response is generally overestimated. A modification to the aggregate interlock models is proposed in order to adapt the original formulations for FRC. The results of the modified version show an overall much better agreement between the numerical and experimental results.