An experimental investigation on flexural behavior of RC beams strengthened with prestressed CFRP strips using a durable anchorage system

This paper investigates the effectiveness and feasibility of a prestressed carbon fiber-reinforced polymer (CFRP) system for strengthening reinforced concrete (RC) beams. The proposed prestressing system with a novel anchorage allows the utilization of full capacity of the CFRP strips. Eight small-scale and two large-scale concrete beams strengthened different configuration of prestressed CFRP strips are tested under static loading conditions up to failure. The main parameters considered include the level of prestressing applied, ranging from 20% to 70% of the tensile strength of the CFRP strips, and the use of mechanical anchorages at both ends of the CFRP strips. Thanks to the durable anchorage, the full range of flexural behavior was investigated including post-debonding. The results indicate that the beams strengthened using prestressed CFRP strips exhibited a higher first-cracking, steel-yielding, and experimental nominal moments as the level of prestressing force increased up to a certain point. After analyzing prestress effects in small scale tests, an optimum prestress level for strengthening concrete beams using CFRP strips is proposed and verified in large scale tests.