Exploring the Bond, Flexure, and Shear Behaviour of Bundled Bars in Concrete Structures

Bundled bars, also known as bundled reinforcement, involve grouping multiple steel bars together to form a single unit, which is then embedded within concrete structures. We aim to comprehensively understand the behavior of bundled bars in reinforced concrete structures. This study investigates the behavior of bundled reinforcement bars in concrete beams, aiming to assess their influence on structural performance. A series of experiments were conducted, including pullout tests on bundled bars and flexural and shear tests on concrete beams with and without stirrups. The study evaluated various parameters such as peak load, displacement, ductility, stiffness, and energy absorption capacity for different bundling configurations. Results indicate that bundling enhances the peak load capacity and energy absorption of beams, with minimal impact on displacement and stiffness. However, beams without stirrups exhibit higher stiffness compared to those with stirrups, suggesting a trade-off between shear capacity and structural rigidity. Overall, the findings provide insights into the behavior of bundled reinforcement bars in concrete structures, informing design practices for enhanced structural performance and resilience. Contrary to IS code recommendations, findings from this study indicate that such recommendations are not essential and could even be counterproductive.