충전강관구조용 초고강도 콘크리트의 열특성 및 충전성 평가를 위한 연구

The number of high-rise buildings is increasing because of the necessity of efficient land with the rise of land price as well as the symbolic value of such buildings, and the trend is expected to continue in the future. Such a trend resulted in composite structures, and one of them that complies with the trend is structure that uses concrete-filled steel pipes. Concrete-filled steel pipe structure is a rational type of structure that maximizes performance by combining the strong points of steel frame and concrete. In the structure, the confining effect of steel pipes increases the bearing power of infilled concrete and the strengthening of local bucking of steel pipes by infilled concrete increases the bearing power of members, and these result in the reduction of cross-sectional area and high transformation capacity. Moreover, the structure is economically efficient and widely applicable that it is used from super-high buildings to residential, business and apartment buildings. It enables the construction of multi-story buildings with long spans using columns of small cross-sectional area. In case of diaphragm, however, it is difficult to confirm the compactness of the closed inside of steel pipes. The present study examined the properties of super-high strength concrete over 80㎫ by comparing it with 40㎫ concrete through heat conductivity and length change tests based on a mixture ratio satisfying the mixture goal presented in the guideline for the design and construction of concrete-filled steel pipe structure, and evaluated the performance of super-high strength concrete according to the shape and size of the aperture ratio of diaphragm.