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Title: Effect of Compressive Glass Fiber-Reinforced Polymer Bars on Flexural Performance of Reinforced Concrete Beams

Author(s): Sina Hassanpour, Alireza Khaloo, Mojtaba Aliasghar-Mamaghani, and Hooman Khaloo

Publication: Structural Journal

Volume: 119

Issue: 6

Appears on pages(s): 5-18

Keywords: compressive reinforcement; ductility; flexural strength; glass fiber-reinforced polymer (GFRP) bar; reinforced concrete (RC) members

DOI: 10.14359/51734792

Date: 11/1/2022

This research studies the effect of glass fiber-reinforced polymer (GFRP) bars as compressive reinforcement in reinforced concrete (RC) beam members. Three singly and six doubly reinforced GFRP-RC beams were tested under a four-point loading configuration. The effect of compressive reinforcement on the load-bearing capacity, ductility, stiffness, and failure mode is determined. Also, the compressive performance of GFRP bars is evaluated by testing GFRP-RC cylinders. According to the results, GFRP bars in compression had a limited contribution to enhancing flexural strength, and the maximum increment in the flexural capacity of doubly reinforced beams compared to singly reinforced specimens was 5%. GFRP-RC cylinders demonstrated a similar pattern, as the maximum strength increase compared to control specimens was 8%. Based on the evaluation of GFRP behavior, the contribution of bars in compression is limited due to the maximum strain that concrete withstands under compression. Considering the singly reinforced specimens, due to the presence of compressive GFRP bars, the stiffness of the doubly reinforced beams was reduced (up to 16%); however, the curvature and ductility were increased (up to 10% and 35%, respectively). In the end, a method based on deformations at the near-peak and peak load capacity was proposed to calculate the ductility of beams. The method predicts ductility enhancement due to compressive bars, as was observed in experiments, and also makes a distinction on failure modes.