Nonlaminated Pin-Loaded Carbon Fiber Reinforced Plastic Straps for Shear Enhancement of Concrete

Increasingly, existing concrete structures are being assesses as having insufficient capacity in shear; the development of an efficient and durable means of upgrading such structures is becoming of utmost importance. An exciting solution is the use of tensioned non-laminated carbon fiber reinforced plastic (CFRP) straps as active (stressed) external shear reinforcement for concrete. The use of an active system has several advantages over a passive (unstressed) reinforcement system. In particular, the prestressed CFRP straps provide confinement and enhance the performance of the concrete. Details of a series of tests carried out on a concrete beam strengthened using these novel CFRP shear reinforcing elements are presented. The strain in each of the straps was measured during testing and valuable insight into the shear behavior of the concrete beam was gained. It was found that the strengthened beam had a much higher shear capacity than the predicted resistance of an equivalent unstrengthened beam.