Concrete structures of spent nuclear fuel interim storage facility should maintain their shielding ability and structural integrity during normal, off-normal and accident conditions. The concrete structures may deteriorate if the interim storage facility operates for more than several decades. Even if deterioration occurs, the concrete structures must maintain its unique functions (shielding and structural integrity). Therefore, it is necessary to establish an analysis methodology that can evaluate whether the deteriorated concrete structure maintains its integrity under not only normal or off-normal condition but also accident condition. In accident conditions such as tip over and aircraft collision, both static material properties and dynamic properties of the concrete are required to evaluate the structural integrity of the concrete structures. Unlike the calculated damage results for the static deformation of the concrete structure, it is very difficult to accurately estimate the damage values of the degraded concrete structures where an aircraft collides at a high strain rate. Therefore, the present authors have a plan to establish a database of the dynamic material properties of deteriorated concrete and implement to a Finite Element Analysis model. Prior to that, dynamic increase factors described in a few technical specifications were investigated. The dynamic increase factor represents the ratio of the dynamic to static strength and is normally reported as function of strain rate. In ACI-349, only the strain rate is used as a variable in the empirical formula obtained from the test results of specified concrete strengths of 28 to 42 MPa. The maximum value of dynamic increase factor is limited to 1.25 in the axial direction and 1.10 in the shear direction. On the other hand, in the case of the CEB model, static strength is included as variables in addition to the strain rate, and a constitutive equation in which the slope changes from the strain rate of 30 /s is proposed. As plotting the two dynamic increase factor models, in the case of ACI, it is drawn as a single line, but in the case of CEB, it is plotted as multiple lines depending on the static strength. The test methods and specimen sizes of the previously performed tests, which measured the concrete dynamic properties, were also investigated. When the strain rate is less than 10 /s, hydraulic or drop hammer machines were generally used and the length of the specimens was more than twice the diameter in most cases. However, in the case of Split Hopkinson Pressure Bar tests, the small size specimens are preferred to minimize the inertia effect, so the specimens were small and the length was less than twice the diameter. We will construct the dynamic properties DB with our planned deteriorate concrete specimen test, and also include the dynamic property data already built in the previous studies.

손상된 콘크리트 구조물은 적절한 보수 및 보강을 통해 성능과 기능을 회복시켜야 한다. 장기간 공기 중에 노출된 콘크리트는 동결융화 작용으로 균열 및 박리를 일으켜 내부 철근의 부식을 유발하게 되는 주요 요인이 된다. 본 연구에서는 동 결융해 손상을 입은 콘크리트 교각의 FRP 보강의 연성에너지 증가 효과를 분석하였다. 보강 FRP 재료와 보강 높이, 보강 겹수 에 따라 동결융해 손상 콘크리트의 푸쉬오버 매개변수 해석을 수행하여 모멘트 곡률의 연성에너지를 비교 분석하였다. FRP 보 강 높이는 소성 힌지 이상의 높이 보강은 비효율적이며, 동결융해 손상이 커질수록 FRP 보강으로 인한 연성에너지 증가량은 커 지는 것을 확인하였다. 보강으로 인한 연성에너지 증가를 위해서는 고강도 FRP 재료보다는 높은 탄성계수를 갖는 FRP 재료가 효율적으로 나타났다. 또한 각 FRP 재료의 특성에 따라 일정 보강 겹수 이상에서 보강 효과가 나타나는 것을 확인하여 FRP 보 강으로 인한 손상된 콘크리트 교각의 연성에너지를 비교 분석하였다.

When RC members are subjected to chemical attack such as aggressive substances, the surfaces of member are seriously degraded. In this paper, an experimental study is executed to investigate the characteristics of flexural behavior of surface degraded reinforced concrete member. According to results, it is seemed that the surface degradation affect the load capacity, fracture energy, neutral axis depth and rigidity of RC members.