This study investigates the flexural shear strength of ultra high performance concrete I-girder. The effect of aspect ratio on the flexural - shear strength of UHPC was analyzed using finite element analysis. The UHPC I-type girder was modeled using 3D shell elements and analyzed using geometric and material nonlinear analysis. The boundary condition is simple support condition and a displacement load is applied to the center of the upper flange. The results shows that shear strength decreased as the aspect ratio increased and the bending-shear failure of UHPC I-girder does not occur even at larger moment than ordinary concrete due to the cross-linking action of steel fiber.

철근콘크리트 슬라브의 휨강도 보강을 위해 제안된 섬유보강폴리머(Fiber Reinforced Polymer, FRP)와 초 고거동 콘크리트(Ultra High Performance Concrete, UHPC)의 합성구조의 파괴 시 거동을 살펴 본 결과, 과다한 휨 보강으로 인한 전단파괴와 보강된 FRP의 탈착에 의한 파괴가 발생하였다. 전단강도와 휨 강도의 크기를 고려한 설계 기준을 제시하여 휨 보강 한도를 제한하고, 전단 철근을 추가하여 탈착에 의한 파괴를 보강하였다. 휨 강도의 보강을 제한 하고 부착 철근이 보강된 슬라브의 실험 결과, 휨에 의한 연성파괴가 유도되었다.

In the present study, exfoliated graphite nanoplatelets (xGnP) with different particle sizes were coated onto polyacrylonitrile-based carbon fibers by a direct coating method. The flexural properties, interlaminar shear strength, and the morphology of the xGnP-coated carbon fiber/phenolic matrix composites were investigated in terms of their longitudinal flexural strength and modulus, interlaminar shear strength, and by optical and scanning electron microscopic observations. The results were compared with a phenolic matrix composite counterpart prepared without xGnP. The flexural properties and interlaminar shear strength of the xGnP-coated carbon fiber/phenolic matrix composites were found to be higher than those of the uncoated composite. The flexural and interlaminar shear strengths were affected by the particle size of the xGnP, while the particle size had no significant effect on the flexural modulus. It seems that the interfacial contacts between the xGnP-coated carbon fibers and the phenolic matrix play a role in enhancing the flexural strength as well as the interlaminar shear strength of the composites.

In this study, flexural strength properties of SC shear walls were investigated through static pushover test. Failure modes and stiffness characteristics of SC shear walls under lateral loads were inspected by analyzing the experimental results. Main failures of unstiffened SC shear walls were found to be the type of bending shear failure due to the unbonding of the steel plate at the concrete interface. The ductility capacity of SC structures was also confirmed to be improved, which is considered to be a confining effect on steel plates in the longitudinal behavior of SC shear walls.

This study investigates the mechanical properties of SFRC reinforced by mixing different steel fibers with compressive strength of 70 MPa. In this study, The fiber aspect ratio consist of 60 and 80 and tensile strength is 1,100 MPa used. Cylindrical specimens with a ∅150×300 mm were made fo compression test, and prismatic specimens with a 150×150×550 mm were made fo flexural and direct shear tests. Test results show that the superior compression performance was observed in SFRC with Mixing different steel fibers.

High-rise buildings in recent years are increasing demand for high strength. However, the higher the floor, the greater the weight of the building, resulting in structural problems. In this study, the shear span ratio was equal to 1.5, and the effect of the web width (100 mm, 150 mm) on the shear strength of I-type flexural members was evaluated.

Ultra high strength concrete was introduced into architectural members. The current ultra high strength concrete can achieve compressive strengths up to 200 MPa and tensile strengths up to 20 MPa. In this study, the flexural and shear strengths in precast structural beams using ultra high strength concrete are evaluated and compared with reinforced concrete beams. This paper also provide a design flexural strength formula for the developed members.

본 논문에서는 리모델링 공사에 있어 요구되는 노후화된 부재의 내력평가 및 보강설계를 위한 기본 자료를 구축하기 위하여 기존 공동주택의 해체공사시 채취한 철근콘크리트 보 부재에 대한 구조실험을 통하여 노후화된 부재의 내력특성을 분석하고자 한다. 이를 위하여 기존 재건축 아파트 현장에서 총 10개의 보 부재를 채취하고, 각각의 기하학적 특성에 따라 정적 휨 또는 전단내력 실험을 실시하였다. 본 실험결과에 의하면 모든 부재에서 계산치 이상의 실험 내력값을 얻을 수 있었으나, 콘크리트 타설불량 및 심각한 균열이 관측된 일부 실험체에서는 취성적인 파괴와 더불어 낮은 내력값을 나타내었다. 따라서 이러한 심각한 균열/손상 등은 리모델링 공사에 앞서 적절히 보수․보강되어야 할 것으로 판단된다.

휨철근 대체재로 FRP Bar를 사용한 콘크리트 보에 대하여 휨보강근비의 변화에 따른 콘크리트의 전단강도를 일련의 콘크리트 보 실험을 통하여 조사하였다. 실험 결과, 콘크리트의 전단강도는 RC보의 경우보다는 낮은 값으로 나타났지만, 휨보강근비가 증가함에 따라 전단강도도 증가하는 것으로 분석되었다. 문헌에 제안된 식과 실험결과의 회귀분석을 이용하여 FRP Bar의 종류 및 휨보강근비를 고려한 전단강도보정계수를 제안하였다.