Deflection Prediction for FRP-Strengthened Concrete Beams

Due to increasing popularity of using fiber-reinforced polymer (FRP) for external strengthening of concrete structures, an urgent demand for understanding the structural behavior of FRP-strengthened structures has been emerging. Unlike conventional reinforced concrete (RC) structures, FRP-strengthened members can exhibit additional flexural capacity in the postyielding stage. This makes RC models for predicting deflection inapplicable in case of FRP-strengthened structures. Therefore, some models have been explicitly developed for evaluating deflection of the strengthened structures. However, most existing models are empirically based, verified with limited experimental results, and require in some cases sophisticated calculation procedures. Accordingly, there is still a demand for a rational and more convenient model for predicting deflection of FRP-strengthened beams. In the current paper, Bischoff’s model, originally proposed for RC and FRP reinforced structures, was extended. Consequently, the developed model is applicable to FRP-strengthened concrete beams besides its validity to both RC and FRP reinforced beams. Validation of the model with some available test data confirmed its accuracy.