Al-Qadisiyah Journal for Engineering Sciences

Combined bending and torsion behavior of externally strengthened RC beams via enlargement section and hybrid reinforcement

Document Type : Research Paper

Authors

Abrar Raheem Hamza 1, 2
Alaa M. Al-Khekany 1
Gy¨orgy L. Bal´azs 3

1 Department of Civil Engineering, College of Engineering, University of Al-Qadisiyah, Qadisiyah, Iraq.

2 Ministry of Education, General Directorate of Education of Qadisiyah, Qadisiyah, Iraq.

3 Department of Construction Materials and Technologies, Faculty of Civil Engineering, Budapest University of Technology and Economics, Budapest, Hungary.

10.30772/qjes.2024.148224.1174
Abstract
The research uses self-consolidating concrete (SCC) reinforced with steel bars, glass fiber reinforced polymer (GFRP), or hybrid reinforcement to improve the torsional capacity of reinforced concrete (RC) structures. Nine beams are cast in normal strength concrete (NSC), and eight are strengthened with steel, GFRP, and hybrid reinforcing bars for the pilot program. The examples are categorized by reinforcing layer thickness (Δh = 50mm and Δh = 75mm) and total depth (325 and 350mm) with a 25mm concrete cover. A control beam was examined for comparison, along with eight reinforced beams of various thicknesses. The tests focus on the impact of raising the Δh value, which increases effective depth, and the GFRP replacement ratio (0% to 100%). All beam specimens were torsional-loaded till failure. Increasing the thickness of RC beams reinforced with steel, GFRP, or hybrid bars (steel and GFRP) to ∆ = 50 mm significantly improved their ultimate torsional capacity. RC ranges rose from 33.33% to 66.67% over the control sample. The ultimate torsional capacity of the reinforced beams, at thickness ∆h = 75 mm, improved from 60% to 100% relative to the control sample.

Keywords

Concrete jacket
GFRP bar
hybrid reinforce
Section enlargement
Torsional strength
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Al-Qadisiyah Journal for Engineering Sciences
Volume 18, Issue 4
Autumn 2025
Pages 465-474

  • Receive Date 26 March 2024
  • Revise Date 10 April 2025
  • Accept Date 20 October 2025

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