International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 13 Issue: 01 | Jan 2026
p-ISSN: 2395-0072
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Flexural Behavior of Reinforced Concrete Slabs with HYSD and GFRP Reinforcement Babitha M Mulge1, Dr. Kiran T2 1Student of Master in Technology, Department of Civil Engineering, University of Visvesvaraya College of
Engineering, Bengaluru, Karnataka, India.
2Associate Professor, Department of Civil Engineering, University of Visvesvaraya College of Engineering,
Bengaluru, Karnataka, India. ---------------------------------------------------------------------***---------------------------------------------------------------------1. INTRODUCTION Abstract - Reinforced concrete slabs are important components influencing serviceability performance through their flexural behaviour, stiffness, and deflection characteristics. Due to some considerations like the high elastic modulus and ductile behaviour, High Yield Strength Deformed (HYSD) steel bars are generally preferred for slab reinforcement. On the contrary, in recent times, Glass Fibre Reinforced Polymer (GFRP) bars have attracted interest as an alternative to steel reinforcement by its high tensile strength, corrosion resistance, and durability leverage. However, the lesser modulus of elasticity of GFRP bars leads to different flexural response behaviour, especially under service load levels, when compared to conventionally used steel reinforcement, calling for experimental verification. The present study investigates the flexural behaviour of concrete slabs reinforced with HYSD bars and GFRP bars nominally in laboratory conditions by applying experimental-analytical intervention. Four reinforced concrete slab specimens, which had the same material properties and geometric configurations, were tested; two slabs were reinforced with HYSD bars and the other two with GFRP bars. The flexural loading was carried out in an incremental manner while measuring mid-span deflection during loading. Experimentally determined deflections were compared with theoretical predictions made by elastic analysis formulations. The results presented indicate that under similar loading conditions, slabs reinforced with HYSD bars were stiffer and had lower deflections compared to those reinforced with GFRP bars. Even though higher deflections were recorded for GFRP-reinforced slabs, their flexural behaviour was generally stable. For both reinforcement types, it was found that experimental deflections exceeded theoretical predictions, with GFRP-reinforced slabs presenting the largest divergence. The study emphasizes the importance of experimental verification in establishing realistic assessment of serviceability for RC slabs reinforced by alternative reinforcement materials.
Reinforced concrete (RC) slabs serve as one of the most important elements of any building structure. They act as primary load distribution components transferring imposed loads to various beams, columns, and supporting walls. The structural performance of these slabs is determined primarily by flexural behaviour, which governs serviceability aspects like deflection control, crack development, and stiffness characteristics. Excessive deflections or cracking may pose challenges to function, durability and comfort even when sufficient strength is given, thus making serviceability performance an important design consideration for slab elements. Although reinforced concrete slabs have always been incorporated with high-yield steel deformed (HYSD) bars because of its high flexible behavior and elasticity, reliable performance most especially under service and ultimate loading conditions has been the traditional application of HYSD in reinforced concrete slabs. Steel reinforced slabs possess good stiffness and a predictable load-deflection behavior supported by design guidelines under codal provisions; however, steel reinforcement is susceptible to corrosion under very harsh environmental conditions like coastal areas, industrial zones, and areas with exposure to chemicals and moisture. Corrosion causes loss of cross-sectional area, deterioration of bond, and reduced service life. Thus, the development of alternative reinforcement materials not so vulnerable to the incidence of deterioration has been greatly motivated. GFRP bars are increasing as a popular alternative to normal steel reinforcement because of their better internal tensile strength, resistance to corrosion, and lightweight. The most important advantage offered by GFRP reinforcement is its durability and degradation through environmental exposure. However, GFRP bars have a significantly lower modulus of elasticity than steel bars, which brings differential flexural response behaviour. Notably, GFRP concrete slabs tend to exhibit greater deflection and lower stiffness under service loads compared to steel-reinforced slabs, thus making serviceability behavior crucial in the design criterion. A lot of work has been done on the study of flexural behavior of reinforced concrete beams reinforced with steel and GFRP bars, but the experimental work relating to slab elements was relatively limited. Slabs differ from beams concerning a twodimensional load-transfer method, boundary condition, and
Key Words: Reinforced concrete slabs; Flexural behaviour; HYSD reinforcement; Glass Fibre Reinforced Polymer (GFRP); Load–deflection response; Serviceability performance
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