Study on Load Carrying Capacity of Offshore Structure with Damaged Member

本文从实验和理论两方面研究了凹陷损伤对海上结构筒状支撑构件强度和刚度的影响。人们发现：1。凹痕部分伴随着残余应力，凹痕底部几乎是屈服的。凹痕的几何形状和残余的应变和应力都会影响管状支撑构件的强度和刚度。当一个凹痕是反对压缩力，最终的强度减少了一个凹痕。在达到极限强度后，凹痕开始变大，局部的壳变大，发生在凹痕底部的末端附近。当凹痕受到拉伸力时，由于凹痕，刚性降低。然而，随着载荷的增加，凹痕会被恢复，并且凹痕对全塑性强度的影响不大。在循环荷载作用下，在凹痕底部的末端容易产生裂纹。在轴向压缩弯管构件结构单元的基础上，提出了轴向拉伸弯管构件的理想结构单元。发现有必要作进一步的改进，如下所述。应考虑在压缩力作用下凹痕的生长和在拉伸力作用下凹痕的恢复。应考虑凹痕对刚度的影响，特别是当凹痕受拉伸作用时。应考虑凹痕处残余应力的影响。

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.