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Journal of Engineering Research

Journal of Engineering Research

Abstract

This study presents the findings of an experiment conducted on eleven identical fiber-reinforced concrete beams with two large rectangular openings strategically positioned at the maximum shear zone. The primary objective of the experiment was to compare various strengthening techniques for these beams. The beams were subjected to two-point loading while supported in a simply supported manner. Two reference specimens were included: a solid control beam and a control beam with two large openings. The remaining beams were externally strengthened using a range of methods around the openings, including vertical and inclined schemes. Strengthening materials such as GFRP sheets, steel plates, steel bars, epoxy Sikadur 31cf, and GFRP bars with epoxy were utilized. The study focused on investigating parameters of interest, including shear capacity, failure mode, ultimate and first cracking load, crack pattern, ductility, and beam stiffness. The introduction of web openings resulted in a reduction of approximately 59.8% in shear capacity compared to a control solid beam. However, the application of strengthening techniques proved effective in enhancing shear capacity, first crack strength, and load-deflection behavior. The strengthening materials restored shear capacity by 40% to 146% and reduced deflection by 27.5% to 62.5% compared to the reference beam with openings. Ductility increased by 4% to 106%, and stiffness improved by 7% to 97% compared to the control beam with openings. The inclined reinforcement scheme exhibited greater efficacy in enhancing the load-carrying capability of the beams. Among the various strengthening materials employed, inclined GFRP sheets demonstrated the highest effectiveness and superior performance.

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