参数随机性对水电站压力钢管结构安全有重要影响,目前压力钢管可靠度分析主要依据基本部位的构件可靠度进行,未能从系统可靠度角度全面把握压力钢管的整体安全性.文中考虑明钢管各基本部位之间的相关性,提出了由4个基本部位构成的串联系统,采用二阶界限法分析典型明钢管工程实例的系统可靠度,识别明钢管系统失效的控制部位,并研究了随机变量对明钢管系统可靠度的影响.研究表明:按现行规范设计的平直管道和倾斜管道,支承环及其近旁管壁是明钢管系统失效的控制部位;随机变量均值对明钢管系统可靠度的影响显著,需在设计、施工和运行各环节中严格控制均值波动范围,提高结构的整体安全性.
Parameter randomness has an important m~ue~ the reliability analysis of the penstocks at present is mainly based on the component reliability of the primary parts, havin~ no full reflection of the integral safety of the penstocks from the system reliability point of view. In this paper, a series system consisting of four classical parts is proposed by considering the correlation between basic parts, and the system reliability of the typical engineering examples of the exposed penstocks is analyzed to identify a part which will control the system failure using the second-order bounds based system reliability method. Then analysis of the impact of random parameters upon the system reliability is carried out. The analysis results suggest that the supporting ring and nearby pipe wall are the control parts of the system failure of the exposed penstocks designed in terms of the present specifications- The impact of mean values of the random parameters on the system reliability is significant, so the parameter fluctuation range should be controlled strictly in structural design, construction and operation to improve the integral safety of penstocks.