Nonlinear Finite Element Analyses of FRP-Strengthened Concrete Slabs under Fixed-Point Cyclic Loading

A finite element model denoted as FEM-C is developed in this paper for prediction of structural responses of fiber-reinforced polymer (FRP)–strengthened concrete slabs under fixed-point cyclic load. First, a finite element model named as FEM-S, which is of the same geometry as the FEM-C model, is developed and validated for analyses of structural behavior of FRP-strengthened concrete slabs under static load. Then, the finite element model is extended for analyses of structural behavior of FRP-strengthened reinforced concrete (RC) slabs under fixed-point cyclic loading in the FEM-C model, with degradations of material properties of concrete, steel reinforcement, and FRP due to cyclic loading taken into account. Geometric and material nonlinearity and bond-slip effects between FRP and concrete are included in these models. The finite element (FE) models are validated through numerical examples and demonstrated to be effective and accurate for modeling the structural behavior of FRP-strengthened RC slabs under static and cyclic loading. The FEM-C model can also model the bond-slip behavior between the FRP and concrete well. Furthermore, the effects of parameters on the structural performance of the FRP-strengthened concrete slab under fixed-point cyclic loading, including different types and widths of FRPs, are investigated using the FEM-C model. It is learned that the computed central deflection of the CFRP-strengthened slab is approximately 18% less than that of the GFRP-strengthened slab. In addition, it is found that the RC slab strengthened with 150 mm wide FRP strips performs better than that with 102 mm wide FRP strips, with approximately 8% less central deflection and 10% less slip.