نوع مقاله : پژوهشی
نویسندگان
1 دانشگاه امیرکبیر
2 دانشکده مهندسی عمران ، دانشگاه امیرکبیر تهران
3 دانشکده شیمی ، دانشگاه امیرکبیرتهران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
This study investigates the development of cracks and the enhancement of ductility in concrete beams by introducing newly designed hybrid GFRP rebars incorporating polyurethane foam cores as a means to overcome the well-known limitations of conventional GFRP reinforcement. Although reinforced concrete is widely used due to its high compressive strength, economic feasibility, and adaptability to various structural applications, the corrosion of steel reinforcement remains a major concern that can significantly reduce structural durability and increase maintenance costs. GFRP rebars have emerged as a promising alternative due to their excellent corrosion resistance, low weight, and favorable mechanical properties; however, their inherently low elastic modulus often leads to excessive deflection, wider cracks, and brittle failure modes in concrete members. To address these drawbacks, this research proposes a hybrid GFRP rebar system in which a lightweight and highly energy-absorbing polyurethane foam core is embedded to reduce brittleness, enhance deformation capacity, and improve flexural performance. Four concrete beam specimens—one reinforced with steel rebars, one with standard GFRP, and two with hybrid GFRP rebars containing 4-mm and 8-mm foam cores—were tested through laboratory experiments and numerical simulations using ABAQUS to evaluate flexural behavior, crack patterns, and ductility indices. The experimental and numerical results exhibited strong agreement, confirming the reliability of the adopted CDP model in simulating concrete behavior and failure mechanisms. Beams reinforced with hybrid rebars demonstrated notably improved ductility compared with standard GFRP, with the 8-mm core specimen showing a 131% increase in ductility over the standard GFRP beam and a 37% increase over the 4-mm core specimen. Furthermore, the failure modes shifted from brittle shear failure in the standard GFRP beam to shear-flexural and predominantly flexural failures in the hybrid beams, indicating a more uniform stress distribution and enhanced energy absorption due to the foam core. These findings highlight the potential of polyurethane-foam-integrated GFRP rebars as an innovative and effective solution for improving serviceability, ductility, and overall structural performance in concrete beams.
کلیدواژهها [English]
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