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Title |
A Study on the Thermal Crack Control of the In-Ground LNG Storage Tank as Super Massive Structures
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Keywords |
단열온도 상승시험 ; 관통균열지수 ; 표면균열지수 ; 선행냉각 ; 석회석 미분말 adiabatic temperature rising test ; through crack index ; surface crack index ; pre-cooling ; limestone powder |
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Abstract |
In this study, thermal stress analysis are carried out considering material properties, curing condition, ambient temperature, and casting date of the mass concrete placed in bottom slab and side wall of the in-ground type LNG tank as a super massive structure. Also, based on the numerical results, cracking possibility is predicted and counter measures to prevent the cracking are proposed. For the tasks, two optimum mix proportions were selected. From the results of the thermal stress analysis, the through crack index of 1.2 was satisfied for separately caste concrete lots except for the bottom slab caste in 2 separate sequences. For the double caste bottom slab, it is necessary introduce counter measures such as pre-cooling prior to the site construction. Also, another crack preventive measure is to lower the initial casting temperature by 25oC or less to satisfy 1.2 through crack index criterion. In the 1st and 2nd caste bottom slab, the surface crack index was over 1.2. Therefore, the surface cracks can be controlled by implementing the curing conditions proposed in this study. Since the side wall’s surface crack index was over 1.0, it is safe to assume that the counter preventive measures can control width and number of cracks.
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