“Investigating the Effect of Section Depth on the Strength of Deep Beams Strengthened with FRP Sheets”

behzad bolouki charzekhoon¹

1) Ph.D. Candidate

IOI Code : ABEB-ACABGH
Publication : 4th International Conference on Recent Advances in Engineering, Innovation and Technology - Belgium(eitconf.com)
Abstract :
    Existing concrete structures often require strengthening to withstand additional design loads, mitigate deterioration defects, enhance ductility, or address other structural deficiencies. In this context, Fiber-Reinforced Polymers (FRP)—composite materials consisting of high-strength fibers embedded in a polymer resin matrix—have emerged as an essential alternative to traditional materials and conventional retrofitting techniques. Due to their specific geometric proportions, reinforced concrete (RC) deep beams do not comply with the standard beam theory; hence, the ACI code recommends the strut-and-tie model (STM) for their design. While studies on continuous RC deep beams are limited, research concerning their retrofitting remains particularly scarce. In this study, six RC deep beams with shear span-to-depth ratios (a/d) of 0.5 and 1.0 were first designed using the strut-and-tie method. Subsequently, non-linear finite element analysis (NLFEA) was utilized to investigate each beam retrofitted with FRP sheets along two different configurations. Key influencing factors—such as the optimal FRP configuration, the effect of the shear span-to-depth ratio, the strengthening effectiveness of FRP strips across different beam depths, beam deflections, and crack patterns and widths—were comprehensively evaluated. The results demonstrate that for deep beams with a shear span-to-depth ratio of 0.5, FRP retrofitting has a minor effect, yielding only a 3% to 9% increase in capacity compared to the unstrengthened control specimens. Conversely, for beams with a shear span-to-depth ratio of 1.0, FRP retrofitting proved significantly effective, enhancing the structural capacity by 12% to 30%

Keywords : continuous rc deep beams frp composites structural retrofitting strut and tie model (stm) nonlinear finite element analysis (nlfea) shear span to depth ratio (a/h)2 1 introduction and research significance