Experimental and Analytical Investigation of Strengthening Reinforced Concrete Beams Using CFRP Sheets under Flexural Loading
Authors
1. Aenghreed Ali Shandel, Civil Engineering Department, Al-Musayyib Technical Institute, Al-Furat Al-Awsat Technical University, Babylon, Iraq
Publication Details
Journal: Vijoriya International Journal for Research & Innovation
ISSN: 3107-9806
Volume: 2 Issue: 1
Year: January – June 2026
Published on: 28 April, 2026
Pages: 60 - 74
DOI: https://doi.org/10.65595/vijri.v2i1.006
Abstract
In this study, an experimental and analytical investigation of the flexural behavior of reinforced concrete (RC) beams that are strengthened using carbon fiber reinforced polymer (CFRP) sheets is performed. Four RC beam specimens subjected to four-point bending were tested and consisted of one specimen without any modifications, acting as the control beam, and other three specimens which had distinct CFRP strengthening schemes applied. The three types of strengthening consisted of applying a single layer of CFRP, two layers of CFRP and two layers of CFRP with end anchoring using U-wraps. Important parameters studied include the cracking load, yielding load, ultimate load, midspan deflection, stiffness, ductility and failure modes.From the experimental data, a significant increase in the flexural capacity due to CFRP strengthening can be seen. The ultimate load increased by 28.3%, 43.5% and 53.3% in specimens with single-layer, two-layer and anchored CFRP, respectively, compared to the control beam. Furthermore, the CFRP strengthened specimens showed improvement in terms of cracking load, yielding load, stiffness and crack development. There was some decline in ductility when additional layers of CFRP were used due to the increase in stiffness of the specimens. Flexural failure of the beam was the dominant failure mode in the control beam whereas the mode changed to flexural failure with debonding of CFRP in the strengthened specimens. End anchoring contributed to the delay of premature debonding.
Analytical predictions were close to experimental results with error percentages between 3.7% and 5.4%, indicating reliability of the analytical method in evaluating the flexural strength of CFRP strengthened beams.
Keywords: Reinforced Concrete Beams; CFRP Strengthening; Flexural Behavior; Load-Deflection Response; Structural Stiffness