Investigating the Behavior of Steel Beams Reinforced with CFRP and GFRP
Subject Areas : Analysis of Structure and EarthquakeMehdi Khanloo 1 , Heydar Dashti Nasserabadi 2 * , مرتضی جمشیدی 3
1 - Faculty Member Of Azad Islamic University Nowshajr Brancj
2 - Department of Civil Engineering, Chalous Branch, Islamic Azad University, Chalous, Iran
3 - استادیار وعضوهیات علمی گروه عمران دانشگاه آزاداسلامی واحد چالوس.
Keywords: Strengthening, steel beams, polymer fibers, numerical study, ABAQUS,
Abstract :
In order to strengthen damaged steel beams, fiber-reinforced materials particularly carbon and glass fibers are utilized to enhance their flexural capacity and stiffness while delaying yielding. These materials are effective for repairing damaged beams, mitigating corrosion effects, and extending structural service life. Carbon fibers are more suitable for flange strengthening, whereas glass fibers are preferable for web reinforcement. The primary focus of this study is the seismic performance assessment of steel beams numerically strengthened with Fiber Reinforced Polymer (FRP) composites using the finite element software ABAQUS. In this research, seven IPE (I-beam) sections commonly used in Iran were analyzed. The FRP fibers were applied in three different configurations: beneath the bottom flange, on both sides of the web, and a combination of both. These configurations were examined and analyzed accordingly. The results of the study indicate that FRP reinforcement has a limited effect on initial stiffness (increasing it by 3% to 10%), but significantly enhances post-yield stiffness. Installing fibers beneath the tensile flange leads to more nonlinear beam behavior, while installation on both web sides results in a more linear response. Furthermore, the findings reveal that after yielding, the beam stiffness reduces by 80% to 97%, with carbon fiber composites experiencing a greater reduction compared to glass fibers. Ductility of beams reinforced with FRP composites decreased by 11% to 16%, with web-side reinforcement exhibiting higher ductility than other configurations. The combined reinforcement (flange + web) yields the highest post-yield stiffness, where glass FRP composites outperform carbon FRP in this configuration. From an economic perspective, the study exhibits that carbon FRP is up to 55% more expensive than glass FRP. The reinforcement costs in the three configurations—under the bottom flange, on both web sides, and combined—were estimated to be 54%, 48%, and 45% higher, respectively, compared to glass FRP alternatives.
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