Behaviour of concrete corbels reinforced with GFRP bent bars
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Date
2023-06-05
Authors
Borgohain, Ankit
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Abstract
Steel-reinforced concrete (RC) corbels are one of the significant components in the precast buildings and superstructure of bridges, and they are used for load transfer from girders or slabs to columns. In North America, such elements are exposed to harsh weather, which makes them more susceptible to corrosion problems. This study focused on the behaviour and performance of reinforced concrete corbels using non-corrodible glass fibre reinforced polymer (GFRP). The study involved constructing and testing fourteen large-scale concrete double-sided corbel specimens to failure. Twelve out of the fourteen corbels were reinforced with GFRP bent bars, and the remaining two were reinforced with steel reinforcement as control specimens. Four out of the twelve GFRP-RC corbels were cast using high-strength concrete (HSC), while the remaining eight were constructed using normal-strength concrete (NSC). The corbel was tapered with cross-sectional dimensions of 450 mm deep × 300 mm wide at the corbel-column interface and 300 deep × 300 mm wide at the free edge. The overall length of each corbel, measured from the corbel-column interface, was 600 mm. All corbels were tested in an inverted position under displacement-controlled monotonic loading. The test variables were the shear span-to-depth ratio, main reinforcement ratio, crack-control horizontal reinforcement ratio, and concrete strength. The test results were presented in terms of the cracking and ultimate capacities, deflection and strains in reinforcement and were compared to predicted values by relevant Canadian Standards and American Codes.
The test results indicated the formation of the strut-and-tie-model (STM) and showed that increasing the concrete strength and main reinforcement ratio increased the stiffness and load-carrying capacity of the corbel to a large extent. Increasing the shear span-to-depth ratio and decreasing the crack-control horizontal reinforcement ratio led to a significant decrease in the load-carrying capacity of the corbel. Overall, this study contributes to a better understanding of the behaviour and performance of the non-corrodible GFRP reinforcement in concrete corbels. The results can lead to the development of design guidelines and standards for corbels, especially in North America, where harsh weather makes such components more susceptible to corrosion problems.
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Keywords
Corbels, Glass Fiber-Reinforced Polymer (GFRP), High-Strength Concrete (HSC), Shear Capacity, Strut-and-Tie model (STM), strut failure, Analytical model, Secondary Horizontal crack-control reinforcement, Shear span-to-depth ratio (a/d)