Abstract: To study the behaviour of concrete bridge deck slabs strengthened with Near Surface Mounted (NSM) Fiber Reinforced Polymer (FRP) bars, an experimental test of this strengthened concrete deck slab was carried out. In this experimental test, the material of strengthening FRP and strengthening configuration were varied to investigate the influence of those structural parameters. It was found that the ultimate strengths of strengthened concrete deck slabs were enhanced significantly by using the NSM strengthening method. Interestingly, the variation of strengthening FRP bar materials had no strong effect on the behaviour of strengthened concrete deck slabs due to the lateral restraint stiffness. To develop further study of the behaviour of NSM strengthened concrete deck slabs, a finite element analysis (FEA) of the test specimens was proposed. In the comparison of the results from numerical analysis and the test results, the FEA results showed good correlation with the test results. Thereafter, a series of parametric study was conducted with this numerical model, which included concrete strengths, lateral restraint stiffness, span-to-depth ratio, elastic modulus of FRP bars, strengthening percentage and reinforcement percentage. It was shown that increasing the lateral restraint stiffness and reinforcement percentage would result in higher loading-carrying capacity but weakened the strengthening effect. In addition, the ultimate capacity of strengthened concrete deck slabs was enhanced by increasing the concrete strengths and elastic modulus of FRP bars. As expected, the ultimate strengths of concrete deck slabs were reduced by increasing the span-to-depth ratios. Based on the study of experimental and numerical results, it can be concluded that the material properties of FRP and strengthening percentages should be determined according to the concrete strength, lateral restraint stiffness and reinforcement ratio of deck slabs in the structural design.

Key words: NSM, FRP, bridge deck, FEA