Evaluation of shear-deficient lightweight RC beams retrofitted with adhesively bonded CFRP sheets

A series of twenty-two shear-deficient lightweight reinforced concrete (LWRC) beams were casted and tested under four-point flexural loading to investigate the structural behaviour of shear-deficient LWRC beams retrofitted with adhesively bonded carbon fibre reinforced polymers (CFRP) sheets. The variables investigated in the study include as follows: shear-span to effective-depth ratio and different retrofitting schemes. The overall response of the LWRC beams, the onset of cracking, crack development and ductility were investigated. The experimental results indicated that the contribution of the CFRP to restore the shear capacity of the shear-deficient LWRC beams was significant. The ultimate shear strength of the retrofitted LWRC beams increased significantly (23–96%) depending on the technique used. The use of the CFRP transformed the mode of failure of some LWRC beams into a more ductile flexural one. The most effective technique for enhancing the shear capacity of the LWRC beams was the CFRP jacketing, followed by the U-strips, inclined strips, and side strips, respectively. The dominant failure mode for the retrofitted LWRC beams was the CFRP debonding from the beams surface by shearing of the concrete skin. An analytical model was developed and showed good correlation with the test results of this investigation.