Behavior of RC box beam strengthened with basalt FRP using end anchorage with grooving

In recent days, many structures are strengthened with fiber-reinforced polymer to make use of the existing reinforced concrete structures to the current needs. Although investigations on the behavior of undamaged fiber-reinforced polymer-strengthened reinforced concrete beams anchored with U-strips have been conducted, study on the behavior of RC box beams strengthened with basalt fiber-reinforced polymer using end anchorage with grooving is still lacking. In the present study, the failure mode, ductility, stiffness, and loading-carrying capacity of an RC box beam strengthened with basalt fiber-reinforced polymer using end anchorage with grooving were experimentally and analytically investigated. Test results and analysis showed that: (1) the average crack spacing, average crack depth, and average crack width of specimen anchored with grooving decreased by 10.3%, 2.8%, and 6.2% when compared with that of specimen anchored with U-strips, respectively; (2) the failure mode of specimen anchored with grooving was basalt fiber-reinforced polymer debonding in pure bending zone; (3) the deflection or curvature ductility of specimen anchored with grooving was 33.9% or 32.7% lower than that of specimen anchored with U-strips; (4) a model based on built-up bars for the load-carrying capacities of BFRP-strengthened beams anchored with grooving was proposed.