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分析了主梁受弯、受剪和弯剪复合破坏3种主要的失效模式.推导了不同失效模式中含有不完全独立亦不完全相关的随机变量时失效模式间相关系数的计算公式.采用JC法计算了主梁不同失效模式的可靠指标及其敏感性因子.在此基础上,采用Ditlevsen窄界限公式计算了水工钢闸门主梁的体系可靠指标.结果表明所提出的失效模式间相关系数计算公式更具有一般性,它既可以考虑不同失效模式中含有相同随机变量时的相关性,也可以分析不同失效模式间包含相关随机变量的相关性.该公式为Ditlevsen窄界限公式计算结构体系可靠度提供了有益的补充.如果忽略了失效模式间的相关性,水工钢闸门主梁的体系可靠度水平将会被低估.Ditlevsen窄界限公式计算的主梁体系可靠度范围非常小,它完全可以满足一般情况下主梁体系可靠度计算精度的要求.
The main failure modes of the composite beams are analyzed, including composite failure of beams, shear and shear-bending, and the formulas for calculating the correlation coefficients of failure modes with different independent and incomplete random variables are derived. Method was used to calculate the reliability index and sensitivity factor of different failure modes of main girder.Based on this, the system reliability index of hydraulic steel gate main girder was calculated by using Ditlevsen narrow bound formula.The results show that the correlation coefficient between failure modes The calculation formula is more general, and it can consider the correlations between different failure modes with the same random variables, and also can analyze the correlations between different failure modes including the related random variables. The formula is based on the Ditlevsen narrow bound formula to calculate the reliability of the structural system Degree.If the ignorance of the correlation between failure modes, the system reliability level of hydraulic steel gate girder will be underestimated.Dislevsen Narrow Boundary Formula calculates the main girder system reliability range is very small, it is completely It can meet the requirement of reliability calculation of main girder system under normal circumstances.