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本文在总结国内外设计实践经验的基础上,系统讨论了下游坝面压力管道强度安全系数的概念和分类。根据不同的设计准则,强度安全系数可分为两大类:第一类是按钢衬与外包钢筋混凝土联合承载设计的整体安全系数;第二类是按钢衬和外包钢筋混凝土分别单独承担全部荷载的分部安全系数及其组合的总安全系数。这两类安全系数的共同点是,当外包混凝土出现径向裂缝后继续加载,以钢材达到屈服极限作为结构破坏的标志,在第一类安全系数中,由于结构分析方法不同或安全系数定义不同,又可分成以下三类:(1)对应等代厚度法的安全系数;(2)对应整体结构分析方法的安全系数;(3)对应按整体结构超载能力计算的安全系数。对各类安全系数,文中给出了相应的表达式,文章进一步指出,在进行结构整体强度验算时,采用结构优化设计方法,使钢衬和各层钢筋接近满应力状态,是提高结构安全度或节省钢材的有效途径。
Based on the summary of domestic and foreign design and practice experiences, this paper systematically discusses the concept and classification of the strength and safety factor of downstream dam pressure pipes. According to different design criteria, the strength and safety factor can be divided into two categories: The first category is based on steel lining and outsourcing of reinforced concrete joint bearing design of the overall safety factor; the second category is based on steel lining and outsourcing of reinforced concrete to bear all Sectional safety factor of loads and their combined total safety factor. The common factor of these two kinds of safety factors is that the concrete will continue to be loaded after the radial cracks occur and the steel reaches the yield limit as a sign of structural failure. In the first type of safety factor, due to different structural analysis methods or different safety factor definitions , And can be divided into the following three categories: (1) the safety factor corresponding to the equivalent thickness method; (2) the safety factor corresponding to the overall structural analysis method; and (3) the safety factor corresponding to the overall structural overload capacity. For all kinds of safety factors, the corresponding expressions are given in the paper. The article further points out that in the structural strength checking, the structural optimization design method is adopted to make the steel linings and all layers of steel bars close to full stress state, which is to improve the structural safety Or save an effective way of steel.