An experimental study on shear strengthening of RC lightweight deep beams using CFRP

This paper presents the results of an experimental investigation on shear strength enhancement of reinforced concrete deep beams externally reinforced with fiber reinforced polymer (FRP) composites. A total of six deep beam specimens of two different classes, as-built (unstrengthened) and retrofitted were tested in the experimental evaluation program. Two composite systems namely carbon/epoxy laminates and carbon/epoxy sheets were used for retrofit evaluation. A comparative study of the experimental results with published analytical models, including the ACI 440 model, was also conducted in order to evaluate the different analytical models and identify the influencing factors on the shear behavior of FRP strengthened reinforced concrete deep beams. Experimental results indicated that the composite systems provided substantial increase in ultimate strength of strengthened beams as compared to the as-built beam specimen. The strength gain caused by the CFRP sheets was in the range of 30–58% Analytical Comparison indicated that the shear span-to-depth ratio (a/d) is an important factor that actively controls the shear failure mode of beam and consequently influences on the shear strength enhancement.