Investigation of the Bar–Anchor–Fiber System for Preventing Concrete Cover Delamination in Flexural Strengthening of RC Beams with FRP

Document Type : Original Article

Authors

Department of Civil Engineering, Faculty of Engineering, University of Qom, Qom, Iran.

Abstract

Flexural strengthening of reinforced concrete structures using fiber-reinforced polymers is an effective technique for rehabilitation and performance enhancement. However, premature failure modes, including debonding of the FRP laminate from concrete and concrete cover delamination at the tensile face, limit utilization of FRP capacity. A two-phase experimental program was conducted. Twelve RC beams were fabricated and tested under four-point bending. In the first phase, eight beams comprised four groups: reference beams, beams strengthened using externally bonded reinforcement on grooves, near-surface mounted beams without anchorage (NU115), and NSM beams strengthened using the Bar-Anchor-Fiber technique (NA115). In the second phase, four NSM beams strengthened with BAF were fabricated with anchorage lengths of 150 and 200 cm (NA150 and NA200) to evaluate anchorage length effects. Results demonstrated that BAF completely eliminated CCD and significantly enhanced ultimate load capacity and ductility. NA115 load capacity increased by up to 71% compared with reference beams. Increasing anchorage length improved flexural capacity and ultimate deformation, with NA200 exhibiting the highest performance. Accordingly, the end-anchorage system of HMFRP bars and bar length in the Bar-Anchor-Fiber configuration play decisive roles in fully mobilizing CFRP capacity, while BAF provides an effective solution for enhancing the load-carrying capacity of FRP-strengthened RC structures.

Keywords

Main Subjects

References

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