Experimental Research and Principle on Strengthened T-Beam with External Pre-Stressed Variable Section CFRP Sheets Based on Moment

Abstract

An innovative external pre-stressed strengthening method, in which FRP (fiber reinforced polymer) sheet is placed outside of the concrete section and anchored in multiple-point, is based on moment of beam to change the area of section of FRP sheet along the length of beam. This strengthening method is that two ends of FRP sheet are first anchored by tightening WSGA (Wave-shaped-gear-anchor), then the FRP sheet is tensioned by tightening WSGG (Wave-shaped-gear-grip) on the middle of FRP sheet and accordingly pre-stressing force is built in FRP sheet. Two same 7m long reinforced concrete T-beams are strengthened at two sides of the beam with above strengthen technique, another same beam is strengthened with sticking CFRP sheet strengthen technique. Test results of strengthen beams indicate that this innovative external pre-stressed CFRP sheets strengthen technique could significantly improve the cracking load, yield load, ultimate load and stiffness of RC beams. The width of flexural cracks in concrete beams is effectively controlled and the strength capacity of the CFRP sheets is exploited.