内河船舶可靠性分析中的波浪弯矩统计与极值分布

Statistics and Extreme Value Distribution of Wave-induced Bending Moment for Reliability Analysis of Inland Waterway Ships

以内河A级航区波浪散布图与波浪谱为环境参数,基于三维势流水动力程序对43艘内河船舶进行波浪弯矩长期预报,获得样本船波浪弯矩长期Weibull概率分布的形状参数、尺度参数和10-8超越概率的预报值。将波浪弯矩预报值与静水弯矩进行对比,根据Turkstra载荷组合规则,确定船体梁总纵强度可靠性分析中的载荷组合形式。在此基础上采用序列统计法对波浪弯矩极值分布进行分析,极值分布近似服从Gumbel分布,即I型极值分布。

According to wave scatter diagram and wave spectrum of navigating zone A in inland river waters, the total 43 inland ships are calculated by the three dimensional wave loads calculation theory,then the shape parameters, scale parameters and predicted value under 10-8 exceeding probability of long-term Weibull distribution for wave-induced bending moment are obtained. The predicted value of wave-induced bending moment is compared with still water bending moment, and according to Turkstra＇s combination rule, the load combination is determined for reliability analysis of hull girder longitudinal strength. Then the extreme value distribution of the wave-induced bending moment is studied by the sequence statistics method. It＇s found that the distribution is obeying the Gumbel distribution which is also named the extreme value distribution of type I.