Finite element analysis of reinforced concrete beams strengthened by FRP composites under flexural loading

In this study, the behaviour of reinforced concreted beams strengthened with fiber Reinforced Polymer (FRP) composites is modelled by using finite element method under Flexural loads. Rectangular cross section reinforced concrete beams obtained by using low strength concrete, insufficient bending and shear reinforcement are strengthened using U shaped carbon and glass fiber (CFRP and GFRP) fabrics in transverse and longitudinal directions. The Flexural behaviour of the beams is determined by the four-point bending experiment and verified using Finite Element Method (FEM). The parameters required in the FEM program were obtained from experimental studies, literature and some basic formulas commonly used in modelling. Model parameters, such as mesh size, geometric shape, dilation angle and viscosity and some models proposed by researchers are used to confirm reinforced concrete beam samples behaviour by FEM numerical analysis. Load and boundary conditions are defined like the experimental studies. The load-displacement behaviour of the control RC beam was confirmed by FEM analysis and the model of strengthened beams with FRP composites was introduced. FRP composites in FEM program are defined as shell elements on surfaces of the beam. The FEM results were compared with the experimental studies. parametric studies are carried out by only changing the shape of retrofit or by only changing longitudinal and transverse reinforcement while keeping the retrofit shape fixed. According to the FEM analysis results, model parameters, like mesh size, geometric shape, dilation angle and viscosity have significant effect on the reinforced concrete beam behaviour, and the most suitable parameters have been determined. The flexure behaviour of RC beams strengthened by CFRP or GFRP was confirmed by a good convergence with FEM analysis. In addition, the strength capacity and deflection values of RC beams were confirmed by the FEM analysis. By using the FEM models, new numerical samples were produced and the parameters affecting the strengthening were determined.