Moment capacity assessment of hybrid GFRP-steel reinforced concrete beams

Document Type : Research Article

Authors

1 Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, Dien Hong Ward, Ho Chi Minh City, Vietnam

2 Vietnam National University Ho Chi Minh City (VNU-HCM), Linh Xuan Ward, Ho Chi Minh City, Vietnam

Abstract

Combinations of fiber-reinforced polymer (FRP) bars and steel bars to reinforce concrete structures appear an advanced solution, as it combines the advantages of both materials. Research effort has been devoted to steel reinforced concrete (RC) and FRP RC structures, while it has been limited for hybrid FRP-steel RC structures. This study thus aims at assessment of moment–curvature behavior and ultimate moment of hybrid glass FRP (GFRP)-steel RC beam sections. To achieve this aim, fiber models were developed to model beam sections reinforced with different GFRP-steel combinations. These combinations are expressed by the ratio of the GFRP area to the total area of GFRP and steel, namely f/fs, which varies from 0 to 1. The fiber models were verified by comparing with the experimental results with satisfactory agreement. The verified models were then used for parametric investigations considering the effect of concrete strength, steel strength, FRP strength, and f/fs on the behavior and ultimate moment capacity of hybrid GFRP-steel beam sections. When f/fs increases from 0 to 1, the bilinear response transitions to a linear response, and the ultimate moment increases. The pivot point is a phenomenon of the moment–curvature curves when f/fs varies from 0 to 1. Concrete with higher compressive strength, which delays the compression failure, more effectively exploits the tensile strength of GFRP bars. GFRP bars effectively replace low-strength steel bars, resulting in a higher ultimate moment. Multivariate regression analysis was performed, and the established model indicates that the considered parameters exhibit positive effects on the ultimate moment.

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AUT Journal of Civil Engineering
Volume 10, Issue 1
in progress
February 2026

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