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The paper deals with the results of an experimental program aimed at the investigation of the bonding behavior of different types of FRP materials for strengthening: externally bonded carbon (EBR) plates, and bars or strips externally applied according to the Near Surface Mounted (NSM) technique. The overall experimental program consists of 18 bond tests on concrete specimens strengthened with EBR carbon plates and of 24 bond tests on concrete specimens strengthened with NSM systems (carbon, basalt and glass bars and carbon strips). The performances of each reinforcement system are presented, discussed and compared in terms of debonding load, load - slip relationship, and strain distribution; the failure mode of each system is also analyzed. The results of the experimental program allow a comparison of the effectiveness of the various EBR and NSM strengthening systems tested and evidence of some differences in the bond behavior.

The American Concrete Institute (ACI) Committee 440 has recently published a design guide for strengthening of masonry with FRP systems. This paper summarizes and provides comments on the design protocols recommended by ACI 440 for flexural and shear strengthening with FRP systems of unreinforced masonry wall (URM). The development of the design protocols were based on calibration of bond reduction factors derived by a database of test results. This paper presents the rationale behind this approach, the calibration procedure, and its implementation in design protocols for flexural and shear strengthening of URM walls.