Nonlinear 2D Finite-Element Modeling of RC Beams Strengthened with Prestressed NSM CFRP Reinforcement

Abstract

This paper presents a comprehensive two-dimensional (2D) nonlinear finite-element (FE) analysis of reinforced concrete (RC) beams strengthened with prestressed or non-prestressed near-surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) reinforcement. In this model, the bond-slip relationship between the steel reinforcement and surrounding concrete as well as that between the NSM CFRP reinforcement and concrete substrate are precisely modeled with cohesive interface elements. Based on the smeared crack approach, the tensile and shear behavior for concrete cracking are considered using appropriate models. The prestressing effect was enforced in the NSM CFRP reinforcement using the equivalent temperature method, and the anchoring effect of U-shaped steel end anchors on the NSM CFRP reinforcement is properly implemented in the model. Moreover, the radial stresses induced by the tensile steel bars on the surrounding concrete are properly considered, and the bar-end concrete cover separation failure mode is successfully captured. Comparisons between the numerical and experimental results confirm that the proposed FE method is appropriate for predicting the load-deflection curves, failure modes, and cracking patterns of the strengthened beams. Based on this study, the 2D FE model is utilized to conduct a parametric study and can be used to aid in realistic structural applications and optimization of the use of prestressed/non-prestressed NSM reinforcement for strengthening RC beams.