Tensile strength of the bent portion of vinyl ester GFRP rebars

Glass-fibre reinforced polymer (GFRP) rebars are increasingly used in concrete as an alternative to conventional reinforcing steel, as corrosion issues can be excluded, and the application limits extended. Besides straight reinforcing bars bent rebars are used, e. g. as stirrups to absorb shear stresses. However, there is only a limited number of studies investigating the load bearing and deformation behaviour of bent fibre-reinforced polymer (FRP) bars.

This study aims to experimentally determine the tensile strength of bent vinyl ester GFRP rebars. The failure of bent GFRP rebars occurs primarily in the corners, as a substantial reduction in tensile strength is noticeable at the bent portion. Therefore, tests are performed on L-shaped bent GFRP bars embedded in concrete blocks and subjected to tensile pull-out forces. The GFRP bars examined consist of a matrix of vinyl ester resin and a nominal diameter of 12 mm. A total of six test specimens were examined, with three concrete blocks reinforced with reinforcing steel and three unreinforced in order to investigate the influence of a reinforcement on the failure mode of the test specimens. The results of this study provide a significant contribution to the load-bearing capacity of concrete components reinforced with GFRP bars and show the relevance of the bent portion or the load transfer of the stirrup in concrete.

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