疲劳和腐蚀损伤下海上浮体极限强度时变可靠性

Time-variant Reliability of Ultimate Strength of Floating Structures under Fatigue and Corrosion Deterioration

以腐蚀和疲劳裂纹作为影响浮体结构极限强度随时间退化的主要因素,应用简化的逐步破坏方法进行弯曲和扭转载荷作用下超大型浮体主体结构时变极限强度研究。同时开展目标海域浮体的长期波浪载荷预报和极值载荷分析,应用蒙特卡洛方法模拟波浪长期极值载荷时变特性,最后基于异交率模型建立考虑强度退化和载荷随机过程的时变可靠性计算方法。研究结果表明,在腐蚀与疲劳裂纹影响下,浮体极限强度时变可靠性下降较快,时变可靠度下降曲线与指数分布模型符合较好。

A series of complex-type floating structures with characteristics of long-term serviceability and large scale have derived from the research of very large floating structures(VLFS).In order to evaluate the bending and torsional ultimate strength reliability of complex-type floating structures,fatigue crack,and corrosion are selected as the main factors influencing ultimate strength degradation.Time-variant bending and torsional ultimate strength are calculated based on the simplified progressive collapse analysis.Long-term extreme wave-induced loads and their time-variant characteristics are analyzed.Finally,the time-variant reliability calculation method considering strength degradation and loads random process is established based on the out-crossing model.Results show that severe corrosion deterioration and fatigue make time-variant ultimate strength reliability decrease with time growth.The time-variant ultimate strength reliability decreasing curve matches well with that of the exponential distribution model.