Consideration of creep coefficient of RC beam reinforced by GFRP rebar with minimum 900 MPa guaranteed tensile strength

Abstract

Since FRP rebars developed up to present are produced without specific guidelines on their content ratio, fiber type, and surface shape, the performance capacity of FRP reinforced concrete (RC) members cannot be fully guaranteed even though the concrete members were designed according to the existing design guidelines. Moreover, since investigations of FRP RC members have focused mainly on their short-term behavior, knowledge of their long-term behavior (i.e., creep and shrinkage effects) of FRP RC members is greatly needed for a proper design of the members. In order to verify material and structural creep behavior of a deformed glass FRP (GFRP) rebar with a guaranteed tensile strength of minimum 900 MPa manufactured from modified braidtrusion process, long-term material and structural creep tests of the GFRP rebar and GFRP RC beam, respectively, were conducted. The material creep test result showed that a service life of 100 years can be guaranteed when the sustained load magnitude is less than 50 % of the maximum tensile load capacity of the rebar. The structural creep test results showed that current design guidelines either overestimate or underestimate the long-term deflection of GFRP RC members. Therefore, a coefficient accounting for the time-dependent characteristics must be properly selected.