Deformation capacity of shear-strengthened concrete beams reinforced with FRP bars: Experimental and analytical investigations

This paper presents an analytical model, which was developed based on the variable angle truss, to estimate the shear deformations of fiber-reinforced polymer (FRP) reinforced concrete beams strengthened in shear. The influences of the strengthening system in enhancing the shear strength and shear stiffness of the strengthened beams are considered in the proposed model. The proposed shear deformation is then incorporated into the deflection approach recommended in ACI 440.1 R (2015) to calculate the total deformation of beams. The developed model is validated with the available experimental results of shear-strengthened specimens. The obtained ratio between analytical and experimental deformations and its corresponding standard of deviation at service loads are 1.075 and 0.123, respectively. A test program comprising eight specimens with different aspect ratios strengthened in shear by carbon FRP (CFRP) laminates is conducted to further verify the proposed model. Three groups of tested specimens with aspect ratios of 1.7, 2.3, and 2.8 are enhanced in shear by two U-wrapping CFRP shear strengthening techniques, namely continuous sheets, and 50 mm strips at 100 mm spacings. The experimental results indicate that the proposed model predicts accurately the load-displacement curves and deformations at service loads of the tested beams. The obtained average ratios of analytical over experimental deformations at the service loads ranged from 1.061 to 1.075.