This report describes the use of near surface mounted (NSM) reinforcement as a technique for increasing the flexural capacity of concrete bridges. The principle of NSM reinforcement is to introduce additional reinforcement into the concrete section in such a way that it acts compositely with the rest of the section in the same way as if it were cast into the concrete. The aim of the project was to investigate the performance of concrete beams and slabs strengthened with NSM FRP reinforcement. The specific objectives were to review available information on the use of NSM reinforcement, to provide guidance on its use for concrete bridge deck strengthening and to incorporate the use of NSM strengthening into the Highways Agency standard for FRP strengthening (BD 85).
The project consisted primarily of a desk study, aimed at making use of existing information and practice to provide guidance to enable the technique to be used in a safe, consistent and cost-effective manner. A small series of tests was also undertaken and used to verify any proposed design approach and to provide information on the practical issues that could be incorporated into the design guidelines. The focus of the study was on flexural strengthening. While it is recognised that the technique may provide significant benefits for shear strengthening, detailed study of this application was beyond the scope of this project.
Details of the test programme were formulated based on the results of the literature review. The results of the load tests were used to supplement the information already available and to validate the proposed design approach. The report contains a description of the design, fabrication and strengthening of the beams. It also presents details of the load tests including behaviour under load, strength, mode of failure, and comparisons of the load test capacity with that derived from theoretical calculations.
The report includes a practical design procedure which can be used for NSM FRP strengthening systems. The procedure is based on the literature review and test programme described in the earlier sections of the report. It is consistent with the design approach previously developed for externally bonded FRP strengthening which forms the basis of BD 85, the Highways Agency standard relating to the strengthening of bridges using FRP.
The results of this research have been incorporated into the draft standard for the strengthening of bridge using fibre reinforced polymer (BD 85) in the Highways Agency’s Design Manual for Roads and Bridges.

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