This article presents the results of experimental investigation of FRP relaxations in pre-stressing methods. Test variables were the type of fibers, the level of pre-stressing, and the size and shape of fibers. The main goal of this research is to describe relaxation of fiber-reinforced polymer-based material and time. Test results showed that the relaxation of FRP materials include fiber relaxation, resin relaxation, and microscopic tearing of fibers. Test results also show that the relaxation of AFRP materials is higher than that of CFRP and GFRP.
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