Improving the flexural behavior of RC beams strengthening by near-surface mounting

Abstract This article presents the experimental investigations undertaken to evaluate the strengthening and enhancement characteristics of near-surface mounted (NSM) devices using different types of bars. A total of 4 concrete beams (150 mm × 300 mm × 1,500 mm) were reinforced in flexure. Three beams strengthened with different embedments of NSM (carbon fiber-reinforced polymer [CFRP], Glass fiber-reinforced polymer [GFRP], and steel) bars, and one unstrengthened beam used as a control beam were tested under monotonic static loading to determine the enhancing influence of the fiber-reinforced polymer (FRP) reinforcement. The performance of different bars used to establish the concrete is examined. A general methodology to evaluate the improving flexural behavior of RC beams strengthened with NSM–FRP bars is presented. A quantitative criterion governing debonding failure is established. The proposed bond model assumes linear elastic behavior for the concrete, adhesive, and NSM–FRP bars, following the same philosophy as the American concrete institute [ACI] provisions for bond analysis and design to control the cracks. So FRP reinforcements show substantial deformation before failure when the cross-sectional area is based on a permissible strain during service, so there is no need to check the deformability. The results of the tests show that using NSM–CFRP bars improves the flexural capacity and stiffness of the strengthened concrete beams of other types.