A Study on the Flexural Behavior of Concrete Beams Reinforced with GFRP Rebars under Fatigue

Abstract

Structural-member failure is largely classified into static failure and fatigue failure, which is caused by the damage accumulated in the structure with the lapse of time. The material fails at a stress that is much lower than the breaking stress under repeated stress or strain, and it generally shows rapid brittle failure. Bridges, concrete pavements, marine structures, railways, and high-speed railway structures are exposed to at least several-milliontimes repeated load during their lifetime and are likely to be affected by the fatigue failure caused by repeated loads rather than by static failure. As many studies have been conducted on the FRP rebar, which is a popular alternative to reinforcing steel bars, the CFRP, GFRP, and hybrid FRP rebars have been commercialized. Most of the studies on them involve static load, however, and few studies have thus far been conducted on their fatigue behavior. Therefore, to secure safety and availability against fatigue during the lifetime of a structure, the fatigue characteristics and S-N correlation must be applied to the design and analysis of the aforementioned rebars. In this study, static and fatigue bending tests were conducted, using three types of FRP rebars (CFRP, GFRP, and hybrid FRP), which have been commercialized. A static bending test was conducted to determine the fatigue load, and the fatigue characteristics of the concrete beam reinforced with FRP rebars, which can be used for fatigue examination, maintenance, and endurance limit estimation of the concrete structure built with FRP rebars, was identified. The use of the S-N correlation was also suggested for the estimation of the fatigue life.