Study on Load Carrying Capacity of Offshore Structure with Damaged Member

本文从试验和理论两方面研究了凹陷损伤对海洋结构管状支撑构件强度和刚度的影响。结果表明：1.凹坑零件存在残馀应力，凹坑底部几乎屈服。凹坑的几何形状和残余应变和应力都会影响管状支撑构件的强度和刚度。当凹坑受到压力时，极限强度就会降低一个凹坑。在达到极限强度后，凹陷变成乌鸦和局部贝壳，L发生在凹陷底部附近。当凹陷受到拉力时，由于凹陷，刚性降低。然而，随着载荷的增加，凹坑会被恢复，而全塑性强度不会受到牙体的影响。在循环荷载作用下，凹坑底部容易产生裂纹，在此基础上提出了一种理想的轴向拉伸凹槽结构单元，并对该单元进行了改进。现已发现有必要进一步改进，如下所示。应考虑压痕在压力下的增长和在拉力下凹痕的恢复。应考虑凹陷对刚性的影响，特别是当凹陷受拉力作用时。应考虑凹陷部分的残余应力的影响。

In this study, the influences of denting damage on strength and rigidity of tubular bracing members in offshore structures have been investigated both experimentally and theoretically. it has been found that :1. A dented part is accompanied by residual stresses, and the bottom of a dent is almost yielded.2. Both geometry of a dent and the residual strains and stresses affect the strength -and rigidity of a tubular bracing member.3. When a dent is objected to compressive force, the ultimate strength is reduced by a dent. After the ultimate strength has been attained, the dent becomes to crow and local shell buclilinc, l takes place near the end of a dent bottom.4. When a dent is subjected to tensile force, the rigidity decreases due to a dent. However, a dent is recovered with the increase of load, and the fully plastic strength is not so much affected by a dent.5. Under a cyclic loading, a crack easily initiates at the end of the dent bottom.The idealized structural unit for a dented tubular member under axial tension is developed improvinal the unit for a dented tubular member under axial compression. It has been found that further improvements are necessary as indicated below.1. Growth of a dent under compressive force and recovery of a dent under tensile force should be considered.2. The influence of a dent on rigidity should be considered especially when a dent is under tensile force.3. The influence of residual stresses at a dented part should be considered.