A 1D finite element model for the flexural behaviour of RC beams strengthened with MF-FRP strips

Abstract

Nowadays existing reinforced concrete (RC) structures are often repaired and/or strengthened by using Fibre Reinforced Polymer (FRP) systems. Although externally bonded FRP (EB-FRP) systems are still the most widely employed ones, recent experimental studies and some field applications have demonstrated the potential of mechanically fastened FRP (MF-FRP) laminates for strengthening RC beams and slabs. The advantages of this new technique with respect to the use of EB-FRP systems are mainly in the ease of installation and the higher restraint to the possible delamination of the FRP system from the concrete surface.This paper presents a new Finite Element (FE) model capable of simulating the flexural behaviour of RC beams or slabs strengthened by using MF-FRP strips. Nonlinear bearing-stress-interface-slip laws are considered to describe the behaviour of the mechanical connection between the RC beam and the FRP strip, whereas well-established stress–strain relationships are adopted to model the behaviour of concrete, longitudinal reinforcing steel rebars and composite laminate. The model has been validated by comparing the numerical predictions with several experimental results found in the scientific literature. A good agreement has been observed between experimental and numerical results thus confirming the accuracy of the proposed model.