水电站明钢管强度设计的应力分类法研究

为适应我国在压力钢管的管材、焊接和加工安装等方面的显著进步,以及与国际规范和工程经验相接轨的现实需求,文中系统研究了国内外明钢管强度设计普遍采用的应力分类法:从承载特性和力学机制角度阐明了明钢管结构计算模型与控制断面选取的依据,对比分析了国内外规范控制断面应力计算方法的异同,依据失效机理和控制断面应力构成提出了控制断面各部位管道应力分类的科学方法,推荐了各分类应力相应的安全度设置水平。研究表明:国内外规范的控制断面选取有差别,而应力计算方法基本相同;支承环近旁管壁边缘断面可不选为明钢管设计的控制断面;管道用钢量主要取决于跨中断面整体膜应力的允许值;采用本文推荐的应力分类和安全度设置水平,在满足强度安全要求下可有效地节省管道用钢量。

Stress classification based method for strength design of exposed steel penstocks in hydropower station

In order to adapt to the development on material, weld technology, fabrication and erection of the penstocks,and to consider the practical need on connection with international codes and engineering ex-perience,the stress classification method,commonly used in design of exposed steel penstocks,was investi-gated systemically. The philosophy under the selection of structural calculation model and key cross sections are illustrated from the standpoint of bearing capacity and mechanism. In addition,the differences and simi-larities of the stress calculation methods for key cross sections among the domestic and foreign codes were compared. The reasonable stress classification is suggested in terms of failure mechanism and the stress for-mation based on the failure mechanism and the stress constitution in key cross sections. The corresponding safety level for the classified stresses was then recommended. The conclusion is drawn that different key cross sections are claimed while no obvious difference among the stress results calculated by the domestic and foreign codes, and the section close to supporting ring may not to be chosen as key section and the steel consumption is mainly determined by the admissible value of integral membrane stress. Using the rec-ommended stress classification and safety level,material can be saved while ensuring structural safety.