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在后张预应力混凝土中,无粘结预应力作为一项专门技术具有节省材料、减少人工、缩短工期、简化施工程序等项优点,特别是在采用大跨度双向预应力连续平板、密肋板和井式梁升板的多层工业厂房结构中,无粘结预应力技术可以带来明显的经济效益。目前,国内外在无粘结预应力混凝土结构的设计中仍基本使用经验统计的方法,或借用有粘结预应力混凝土的方法,对一些尚不清楚的问题采用偏于安全的措施处理。由于各国的试验研究角度不同,对试验结果统计的方法不同,所得经验公式和计算值的差别很大。随着计算机在结构设计上的广泛应用,工程建设对结构设计计算方法的合理性、准确性提出了更高的要求。设计人员也要求有更多的尽可能准确且力学概念清楚、适用性强、使用简便的计算分析方法(理论的或半理论、半经验的方法),代替以往完全由统计分析得到的经验方法,使设计更准确地建立在结构实际受力和变形状态之上。近年来,先进的现代化试验设备逐渐应用于研究工作,使构件和结构的力学试验更逼近于真实情况,使许多力学和数学模型得到试验的证实,这为满足上述要求,使钢筋混凝土结构理论向一门独立的力学学科方向发展创造了良好的物质条件。无粘结预应力混凝土作为钢筋混凝土的一个分支,应该有一套与钢筋混凝土结构基本理论相衔接的分析方法,本刊发表的有关无粘结预应力结构设计的文章,在这方面作了有益的探索。
In post-tensioned prestressed concrete, unbonded prestressing as a specialized technology has the advantages of saving material, reducing labor, shortening the construction period, simplifying construction procedures, etc., especially in the use of large-span two-way prestressed continuous slabs and dense ribbed plates. In the structure of a multi-story industrial building with a well beam riser, the unbonded prestressed technology can bring significant economic benefits. Currently, at home and abroad, in the design of unbonded prestressed concrete structures, empirical statistics methods are still basically used, or methods using bonded prestressed concrete are used, and some unclear problems are treated with partial safety measures. Due to the different angles of the experimental research in different countries, the statistical methods for the test results are different, and the empirical formulas obtained and the calculated values are quite different. With the wide application of computers in the structural design, engineering construction puts forward higher requirements on the rationality and accuracy of structural design calculation methods. Designers also require more analytical methods (theoretical or semi-theoretical, semi-empirical methods) that are as accurate as possible and have clear mechanical concepts, strong applicability, and easy to use, instead of empirical methods that were completely obtained from statistical analysis in the past. Make the design more accurately based on the actual stress and deformation of the structure. In recent years, advanced modern test equipment has gradually been applied to research work, making the mechanical testing of components and structures closer to real conditions, and many mechanical and mathematical models have been confirmed by experiments. This meets the above requirements and makes the theory of reinforced concrete structures The development of an independent discipline of mechanics has created good material conditions. As a branch of reinforced concrete, unbonded prestressed concrete should have a set of analytical methods that are linked to the basic theory of reinforced concrete structures. The article published in this journal on the design of unbonded prestressed structures has been useful in this area. explore.