防撓矩形板の最終強度解析 (第3報)

船体外板の崩壊強度の推定

抄録

It is important to estimate the ultimate bending moment of a ship hull girder, because it is the real resistant value to the maximum wave bending moment. The ultimate bending moment of the cross-section of a hull girder was calculated by the in-plane strength of stiffened plates. Therefore, it is necessary to calculate the ultimate strength of stiffened plates. The author's 1st and 2 nd reports presented an approximate analytical method which was in good. agreement with experimental results. In the design stage, however, it is difficult to determine the initial imperfections of the real ship structures.
This paper estimates the initial imperfections of ship structures and studies the ultimate strength of typical stiffened plates used for the longitudinal stiffening of ships. Initial deflection, residual stress and water pressure are the main influences on the ultimate strength of a hull. Two approximate formulas are developed for calculating the ultimate strength of stiffened plates from the elastic buckling stress and the yielding stress. One is a formula for long rectangular plates and the other is a formula for one way stiffened plates. These formulas are in good agreement with past experimental results and have confirmed efficiency in designing ship hull structures.