半潜式海洋平台疲劳影响因素分析

Fatigue influencing factor analysis of semi-submersible offshore platform

在海洋结构物疲劳评估时,频域谱分析法将交变应力峰值分布简单认为是窄带分布,不符合宽带海况特征,疲劳结果往往偏保守。全时域法虽然计算精度高,但整个过程过于耗时,很难应用在实际工程中。本文考虑到时域法和频域法在疲劳评估时各自的缺陷,给出一种时域-频域混合法,运用此方法对某半潜式海洋平台关键节点进行疲劳计算,并分析不同因素对疲劳损伤的影响。结果表明,不同浪向角和短期海况对半潜式海洋平台的疲劳损伤贡献度不同,贡献度大小与评估区域位置有关。所得结论为半潜式海洋平台的疲劳评估提供一定依据和参考。

In the fatigue assessment of marine structures,the frequency domain spectral method simply considers the peak distribution of alternating stresses as narrow-band distribution,which does not conform to the characteristics of broadband sea state,and the fatigue results are often conservative.Although the full time domain method has high calculation accuracy,the whole process is too time-consuming and difficult to be applied in practical engineering.The paper gives a hybrid time-frequency domain method considering the defects of the time domain method and frequency domain method in fatigue assessment.This method is used to calculate the fatigue damage of hotspots of a semi-submersible offshore platform and to analyze the effects of different factors on fatigue damage.The results show that:different wave angles and short-term sea states contribute differently to the fatigue damage of semi-submersible offshore platforms,and the magnitude of the contribution is related to the location of the evaluation area.The conclusions obtained provide a certain basis and reference for the fatigue assessment of semi-submersible platforms.