大开口船舶的扭转极限状态

给出利用下限定理计算扭转极限状态下船体剖面上塑性剪流分布的方法，以及相应的线性规划问题，根据扭转极限状态下剖面剪应力的分布可计算剖面的极限转矩，对3艘不同尺度的大开口集装箱船用该方法进行了计算，所得极限转矩与主要船级社规范公式计算的波浪转矩设计值进行了比较，从而得到船体在扭转方面安全性的粗略的定性估计，计算结果表明，对大型和超大型集装箱船，扭转方面的安全性必须引起重视，该方法可在大开口船舶计与扭转失效模式的结构可靠性分析中作为计算船体极限转矩的工具。

Limit State of Torsion of Ship Hulls with Large Hatch Openings

Limit state of torsion of ship hulls with large hatch openings was studied. A method to determine the distribution of the plastic shear flow on the hull cross section in the limit state by using the lower bound theorem was presented together with the corresponding linear programming problem. The limit torsional moment of the hull cross section is obtained based on the distribution of the shear stress in the limit state. Three typical container ships of different sizes with large hatch openings were calculated. The calculated limit torsional moments were compared with the design values of wave torque calculated by using the equations given by main Classification Societies in their rules. A rough estimate of the safety margin was obtained. The results show that for large container ships, it is necessary to pay attention to the safety in respect of torsion. The proposed method can serve as an effective tool in structural reliability analysis of ships with large hatch openings when the failure mode of torsion is taken into account.