Long-term performance monitoring of GFRP-reinforced concrete beams using sensor-mounted supplemental rebars under harsh environmental conditions

Abstract

Fiber-optic sensors (FOS) are increasingly being used in reinforced-concrete (RC) structures for their accuracy and durability. One of the drawbacks of FOS is their fragility at installation. One recently developed method to address such deficiency is to install the FOS on a short bar (supplemental bar) that is rigidly connected to the structural reinforcement bars prior to concrete pouring. However, the durability of such systems under harsh environmental conditions has not been well established. In order to better understand the behavior of the aforementioned FOS systems under harsh environmental conditions, seven half-scale RC beams with glass fiber-reinforced polymer bars were exposed to four different exposure regimes, in the present study. After 14 months of exposure to harsh environmental conditions, the RC beams were subjected to static flexural testing to evaluate the FOS system behavior under each environmental condition. In addition, the strain responses of the sensors mounted on the supplemental bars and those in the main bars were monitored to validate the newly developed FOS mounting system. The results of this study show that the proposed FOS mounting system can efficiently capture the actual strain in all environmental conditions tested in this study except immersion exposure under high alkali solution. In addition, the flexural deformation and the exposure impact to the beam capacity were evaluated.