Externally bonded fibre-reinforced polymer (FRP) systems are widely used for flexural strengthening of reinforced concrete (RC) members because of their high strength-to-weight ratio, corrosion resistance, and ease of installation. This study investigates the flexural behaviour of RC beams strengthened with carbon fibre-reinforced polymer (CFRP), polyethylene terephthalate fibre-reinforced polymer (PET-FRP) laminates and their hybrid combinations. Fifteen full-scale RC beams, each measuring 2000 mm in length, 300 mm in depth, and 150 mm in width, were tested under flexure in a four-point bending configuration to assess the effects of different FRP types, number of layers, hybrid stacking sequences, and U-wrap anchorage systems. Detailed assessments of load–deflection behaviour, load–strain response of reinforcing steel, load–strain behaviour of FRP laminates, beam ductility, and failure modes were carried out. The results showed that a single CFRP layer increased the yield and ultimate loads by 13% and 39%, respectively, relative to the control beam, whereas two CFRP layers increased them by 48% and 70%. For the two-layer hybrid systems, CFRP–PET-FRP and PET-FRP–CFRP increased the ultimate load by 53% and 49%, respectively, compared with the control beam. The introduction of U-wrap anchorage generally delayed premature debonding and enhanced the post-yield deformation capacity, with the PCP-U specimen exhibiting 67% higher ultimate ductility and 200% higher failure ductility than the corresponding unanchored PCP specimen. Comparison with ACI 440.2R-17 and CEB-FIB design guidelines indicated that ACI predictions showed closer agreement with the experimental results for the specimens investigated. The findings highlight the potential of hybrid combination CFRP and PET-FRP systems in providing a balanced improvement in strength and ductility for flexural deficient RC beams, although the effectiveness depends strongly on the laminate stacking sequence and anchorage configuration.
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