Anchorage Length of Near-Surface Mounted Fiber-Reinforced Polymer Bars for Concrete Strengthening—Experimental Investigation and Numerical Modeling

Near-surface mounted (NSM) fiber-reinforced polymer (FRP) bars are being increasingly recognized as a valid alternative to externally bonded FRP laminates for enhancing flexural and shear strength of deficient concrete, masonry and timber members. Ultimate capacity and service performance of strengthened members are deeply influenced by the bond characteristics of the strengthening system on which, in the case of NSM bars, limited data is available to date. This paper follows up to previous investigations on the mechanics of bond of NSM bars to concrete. Experimental results completing a previous test series are reported and discussed, and a global evaluation of results of three different test series is attempted. A three-dimensional finite element model for bond of NSM reinforcement is proposed and calibrated on the basis of some experimental results.