円筒状海洋構造物の安定性に関する研究 （第２報） 周囲液体からの静液圧と一様なねじり荷重を受ける円筒殻の座屈

Abstract

This paper deals with the buckling problem of partially liquid-surrounded circular cylindrical shells under torsion to analyze systematically the stability of cylindrical offshore structures. A theoretical analysis is performed by means of the Galerkin method on the basis of the Donnell-type equation for shells, taking the effect of the axisymmetric deformation due to the static liquid pressure into consideration. Calculations are carried out for both simply supported and clamped shells and the torsional buckling loads ks are determined for various values of the shell geometric parameter Z, liquid pressure parameter px and liquid depth ratio l0.The main results obtained are as follows:(1) The torsional buckling load ratio ks decreases monotonously with an increase in the values of l0 and/or px. With an increase in px, the buckling wave number ratio β increases for small value of l0 and decreases for large value of l0.(2) The effects of the shell geometries Z on the torsional buckling load ratio ks are almost negligible for the simply supported shells.(3) The effects of the boundary conditions on the torsional buckling load ratio ks are almost negligible, especially in case of l0=1.0.(4) The effects of the surrounding liquid and the torsional load on the prebuckling and buckling deformation are clarified by means of the contour map representation.