Experimental investigation of reinforced concrete T-beams strengthened in shear with externally bonded CFRP sheets

An experimental investigation was undertaken into the effectiveness of unanchored and anchored externally bonded (EB) U-wrapped carbon fibre reinforced polymer (CFRP) shear strengthening for reinforced concrete T-beams at a range of realistic sizes. The T-beam sizes, geometry and reinforcement were chosen to reflect existing slab-on-beam structures with low levels of transverse steel shear reinforcement. Geometrically similar reinforced concrete T-beams were tested across three sizes ranging from 360 to 720 mm in depth and with different amounts of EB CFRP shear reinforcement. The beams were subjected to three-point bending with a span to depth ratio of 3.5. All the beams failed in diagonal shear. The experimental results indicate significant variability in the capacity of unstrengthened control beams, and a number of these control beams showed greater shear capacity than their EB CFRP strengthened counterparts. Greater thicknesses of CFRP reinforcement did not lead to increased shear capacity compared with lesser thicknesses of unanchored or anchored EB CFRP, but anchored EB CFRP did lead to moderate increases in shear capacity compared to both control and unanchored EB CFRP strengthened beams.