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洋结构物管状支撑构件强度和刚度的影响。已经发现：1.凹陷部分伴随着残余应力，凹陷底部几乎屈服.凹陷的几何形状以及残余应变和应力都会影响管状支撑构件的强度和刚度。当凹痕抵抗压缩力时，极限强度因凹痕而降低。达到极限强度后，凹痕变得拥挤，并且在凹痕底部末端附近发生局部壳buclilinc，l。4.当凹痕受到张力时，由于凹痕，刚性降低。但随着载荷的增加，凹坑会逐渐恢复，而凹坑对全塑性强度的影响不大.在循环荷载作用下，凹坑底部的端部容易产生裂纹，本文提出了凹坑受轴拉构件的理想结构单元，并对凹坑受轴压构件的单元进行了改进。人们发现，如下文所述，有必要进一步改进。应考虑压痕在压缩力作用下的扩展和压痕在拉伸力作用下的恢复.特别是当凹坑受拉力作用时，应考虑凹坑对刚度的影响.应考虑凹陷部分残余应力的影响。

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.