Evaluation of Residual Strength of Offshore Structures

海上结构物剩余强度评估

• 批准号: 05452313
• 负责人: YAO Tetsuya
• 金额: $ 4.74万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05452313/
• 关键词: Offshore structure; Dent damage; Crack damage; Residual strength; Tubular member; Idealized structural unit method; Residual stress; Crack extension; 凹損; 三次元骨組構造; 亀裂

Residual strength of offshore structures which experienced denting damages, overall bending damages and cracked damages was investigated through a series of collapse tests and FEM shell analyzes on damaged tubular members. Based on the results, several improvements were made on the existing models of the Idealized Structural Unit Method (ISUM) for damaged tubular members.From the bending collapse tests and FEM analyzes on tubular specimens with denting damages, it has been found that a significant magnitude of residual stress is induced during indenting process and this results in a large reduction of member stiffness when dented region is loaded in tension. When the dented region is loaded in compression, a load carrying capacity is mostly reduced, while in tension it may be recovered up to the ultimate strength of intact members because of the decrease of dent depth under the action of tensile load. However, deformations and local strains are large compared to the intact condition. The ISUM was improved so as to consider the reduction of stiffness and the change in dent depth for the case of dented damage loaded in tension, and the validity was demonstrated through a comparison with tested and FEN results.Bending collapse tests, tensile collapse tests and the related FEM shell analyzes were performed on tubular specimens with a circumferential trough-thickness crack. The existing ISUM for cracked tubular members were also improved so that the effect of local yielding at crack tip can be considered in stiffness calculation.Using the improved ISUM,several examples including plane frames and space frames having damages were analyzed and the effects of damaged on the load-carrying capacity of structures were investigated.

通过对受损管状构件进行一系列倒塌试验和有限元壳分析，研究了遭受凹陷损伤、整体弯曲损伤和裂纹损伤的海上结构的剩余强度。在此基础上，对受损管构件理想化结构单元法（ISUM）的现有模型进行了一些改进。通过对具有凹陷损伤的管状试件的弯曲塌陷试验和有限元分析，发现显着的量级压痕过程中会产生残余应力，当压痕区域承受拉力时，会导致构件刚度大幅降低。凹陷区域受压缩时，承载能力大部分降低，而受拉时，由于在拉伸载荷作用下凹陷深度减小，凹陷区域可恢复至完整构件的极限强度。然而，与完整状态相比，变形和局部应变很大。对ISUM进行了改进，考虑了拉力载荷下凹陷损伤情况下刚度的降低和凹陷深度的变化，并通过与试验结果和FEN结果的比较证明了ISUM的有效性。弯曲塌陷试验、拉伸塌陷试验和相关的有限元壳分析是在具有周向槽厚度裂纹的管状样本上进行的。对现有的裂纹管构件ISUM进行了改进，在刚度计算中考虑了裂纹尖端局部屈服的影响。利用改进的ISUM，对存在损伤的平面框架和空间框架等算例进行了分析，并分析了损伤对结构的影响。对结构的承载能力进行了研究。