部分積み時の非真球タンクの座屈強度に関する研究

－第２報：実スケールタンクの座屈強度に関する初期不整影響の検討－

抄録

This paper is the second of the two companion papers dealing with the buckling strength of a non-spherical tank in the partially filled condition, which is one of the severest loading conditions in terms of the buckling design of Moss-type LNG tanks. A method to estimate the reduction factor of the elastic buckling strength due to initial shape imperfection is proposed based on the Koiter’s initial post-buckling theory, and a simplified method to estimate the elastoplastic buckling strength is proposed in the first report. The reasonable accuracy of the estimated elastic and elastoplastic buckling strengths was demonstrated through a comparison with the results of scaled model tests and FE analyses of model-scale tanks.

In this paper, the applicability of the proposed estimation method is verified for actual scale tanks under axisymmetric load condition in the upright position and also under non-axisymmetric one in the heeled condition. For three types of actual scale tanks with different flatness, the characteristics of buckling mode and strength are examined. It is found that the concept of an equivalent toroidal shell analogy is applicable to the non-axisymmetric load conditions as well as to the axisymmetric cases. The reasonable accuracy of the estimated elastic and elastoplastic buckling strengths is demonstrated through a comparison with the FE analyses of actual scaled tanks.