Many RC bridges all over the world are approaching the end oftheir design life. Therefore, bridges safety has been in the spotlightto prevent any serious structural problems that might lead to lossof life [1,2]. Efficient and practical strengthening techniques areneeded to prevent potential disasters. FRP composite materialshave proven their effectiveness in the strengthening of existingstructures [3-6]. The development of deflection of RC beams givesa reliable indication of the damage accumulation along with theservice life. Different factors affect the deflection progression of aRC beam, such as concrete creep, shrinkage, fatigue, overloading,and environmental exposures. Fatigue is the most critical factorthat might cause a sudden failure to structural members. Externalbonded (EB) and NSM are the most common practical applicationtechniques of FRP materials. These techniques are becomingextensively used in the strengthening field of RC bridges [7]. Thefatigue behavior of the NSM CFRP strengthening technique is stillnot fully investigated. Moreover, the current design codes andguidelines do not provide practical design guidelines for structuralengineers to predict the fatigue behavior of RC beams strengthenedwith NSM FRP [8]. This study investigates the ability of theanalytical model proposed by Balaguru & Shah [9] for predictingthe deflection response of RC beams strengthened with NSM FRPreinforcement under cyclic loading.
Balaguru and Shah [9] proposed an analytical model forpredicting the accumulation of deflection of non-strengthened RCbeams subjected to cyclic loading. The model ignores differentfactors, such as the shrinkage effect, concrete mix proportion, andthe age at loading. The deflection of a RC beam is calculated on thebasis of the effective moment of inertia taking into considerationthe reduction in stiffness due to the creep strain after several loadcycles. Based on their model, the increase of deflection is attributedto the concrete creep in the compression zone, reduction instiffness due to the flexural cracks, and the strain-softening of steelreinforcement.
RC Plane 3 full crack
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