본 연구는 ACI 등 규정에 없는 FRP 보강 콘크리트의 복보강에 대한 설계흐름도를 제시하였으며, 단보강과 복보강을 비교, 분석하였다. 다양한 파라미터 연구를 통해서 각각 단보강일 때의 이점과 복보강일 때의 이점을 분석하였다. 콘크리트의 단면이 작을수록 보강량이 클수록 복보강의 휨성능이 유리하며, 반대의 경우는 단보강이 유리한 것으로 나타났다. 콘크리트의 단면을 크게 하는 것이 FRP 보강량을 크게 하는 것보다 효과가 좋으며, 콘크리트 단면 중에서 콘크리트 높이를 크게 하는 것이 효과가 우수하게 나타났다. 콘크리트의 설계기준강도가 클수록, FRP의 탄성계수가 작을수록 단보강이 유리하며, 반대의 경우는 복보강이 유리한 것으로 나타났다.

A typical low and medium-sized neighborhood living facility in reinforced concrete building secures a high floor and pursues an efficient module plan(long span). Accordingly, research on the development of new hybrid beams that can innovatively reduce labor costs such as on-site installation and assembly while securing strength and rigidity is ongoing. In order to verify the structural performance of the U-flanged truss composite beam with newly developed shape, Experiments with various variables are required. Based on the results, this study is to evaluate the strength of U-flanged truss hybrid beam through the flexural strength of the Korea Design Code and experimental values. It was evaluated that nominal flexural strength was 110% to 135% higher than the experimental value.

The U-flanged truss hybrid beam is a new composite beam made by pouring concrete into the U-flanged truss beam. In this study, an experimental study was performed to verify the shear capacity of U-flanged truss hybrid beams with the newly developed end reinforcement details. For all specimens, the maximum shear strength was determined by shear failure of concrete in the loading point The detail reinforced with stirrups at the end zone can exhibit the greatest shear strength, but the method of reinforcing the end zone using vertical steel plates, which is a relatively easy method to manufacture, is considered to be the most effective detail in terms of shear strength and ductility. Also, in the case of U-flanged truss hybrid beams reinforced with vertical steel plates at the end zone, the shear strength can be evaluated on the safety side by using the Korea Design Standard formula.

In this paper, we present the result of analytical investigation pertaining to the structural behavior of steel-concrete composite plate girder with arch-type web stiffener. In the arch-type web stiffener located in the compression side of web, infill concrete is cast to strengthen the arch-type stiffener and also to exert resisting force against compression force. This type of composite steel-concrete plate girder bridge is built and is in service. To understand the behavior thoroughly, analytical parametric study was conducted by using the finite element method. As a result it was found that the effect of arch-type stiffener with infill concrete is considerable for the design of such type composite girder bridge.