| The flexural behavior of reinforced concrete beams strengthened with carbon fiber reinforced polymer (CFRP) is the focus of this research. The flexural behavior discussed in this research is about two main serviceability properties of the beams, the flexural crack width and deflection, within service load level. For monotonic loading condition, a universal analytical model is developed, which considers nonlinearity in both concrete compressive constitutive relation and concrete tensile softening effect. The model proposed in this study is applicable to plain concrete, reinforced concrete beams and reinforced concrete beams strengthened with FRP. The direct analytical results from the model are moment-curvature relations. Based on the moment-curvature relation, the further results of load-crack mouth opening displacement (CMOD) and load-deflection relations can be obtained. To look at the fatigue behavior of reinforced concrete beams, an analytical model for service level cyclic load is proposed. The cyclic-dependent concrete properties, such as compressive strength, fracture modulus and tensile modulus, are considered in this model. The cyclic-dependent rigidity relation and deflection versus number of cycles relation are given from the analytical model. To validate the analytical models for both monotonic load and cyclic load, experimental works are performed. The experimental results are compared with the model predicted results and good correlations are found. The model for monotonic load gives results for both CMOD and deflection predictions. The analytical model for cyclic load also gives results of flexural behaviors of the beams, which explain the phenomenon observed from test data, such as the flexural rigidity remains stable after the drop from early loading cycles. |
