Calculating the thickness of FRP jacket for shear and torsion strengthening of RC T-girders

Failure of a structural element under diagonal compression is brittle in nature and could compromise the structure ductility in seismic design. In many cases, strengthening using FRP Jackets might be the optimum solution to prevent such failures. A procedure for calculating the thickness of the FRP jacket required to resist combined shear and torsion is proposed. The proposed procedure was used to calculate the FRP thickness required for the strengthening of three T-girders subjected to combined shear and torsion. The girders were constructed and tested using a test setup designed to subject the specimen to combined shear and torsion with relatively low moment up to failure. Three strengthening techniques namely; U-jacket, extended U-jacket and full jacket were implemented using ± 45° carbon fiber reinforced polymers (CFRP). The theoretical predications were compared to the experimental results. The procedure was found to provide reasonable conservative estimates.