Retrofitting of severely shear-damaged concrete t-beams using externally bonded composites and mechanical end anchorage

The effectiveness of using an externally bonded carbon-fiber-reinforced polymer (EB-CFRP) system with mechanical end anchorage to retrofit severely shear-damaged reinforced concrete (RC) beams is examined in this paper. A total of 14 tests were performed on eight RC beams with a T-shaped section and low compressive strength. To represent a severe shear-damage condition, five beams were tested to failure, retrofitted, then retested to failure for a second time. Test parameters included the number of EB-CFRP layers and type of end anchorage system. The results demonstrated that retrofitting of severely shear-damaged RC T-beams with EB-CFRP composites and proper mechanical end anchorage can fully restore the original shear capacity of the beams. The use of a sandwich composite panel in combination with a threaded anchor rod inserted through the entire web width (thru-bolt) as an end anchorage system was more effective than using the panel with side powder-actuated fasteners. Increasing the number of EB-CFRP layers did not result in additional gain in shear capacity. The accuracy and validity of four different international guidelines/standards were examined by comparing their predictions with the experimental results.