Experimental Study on Wedge Anchorage Performance of Prestressed BFRP Laminates for Flexural Strengthening of Reinforced Concrete Components

This study investigated the anchoring effect of wedge anchorages on prestressed basalt fiber–reinforced polymer (BFRP) laminates. Compared with traditional carbon fiber–reinforced polymer (CFRP) laminates, BFRP laminates have a larger ultimate fracture strain, lower elastic modulus, and smaller prestress loss, making them cost-effective prestressed materials. Fifteen fiber-reinforced polymer (FRP) laminate–anchorage assemblies were prepared to investigate the effects of FRP type, anchorage type, mat type, and presetting load level on the static tensile behavior of FRP laminate–anchorage assemblies. The differences in the failure modes, load versus displacement (L–D) curves, and strain development of the FRP laminates were analyzed. The results demonstrated that, first, the anchorage efficiency of the CFRP laminate–anchorage assembly was higher than that of BFRP. Since the elastic modulus and transverse shear strength of the BFRP laminates were much lower than those of the CFRP laminates, the application of the traditional CFRP anchorage easily damaged the BFRP laminates. Therefore, a specific design and optimization are required for BFRP laminate anchorages. Second, an anchorage with a retracted stressing end wedge was prone to obtain higher normal stress and thus achieve a higher anchoring capacity. Third, the sandpaper mat improved the friction between the FRP laminate and wedges and alleviated the stress concentration phenomenon of the FRP laminate at the stressing end of the anchorage. Finally, an increased presetting load on the wedges could slightly improve the assemblies’ ultimate bearing capacity and stiffness; however, the enhanced presetting load aggravated the stress concentration phenomenon at the stressing end of the anchorage.