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钢-混组合梁徐变效应分析是设计中的重点和难点。在该领域目前急需适合于计算机程序编制并易于用计算机推广的计算方法和完善的计算软件。为了便于运用计算机求解钢-混组合梁的徐变效应,本文以初应变法原理为基础,在应用初应变对钢-混组合梁徐变效应求解中引入混凝土等效弹性模量,而在换算截面时又将调节混凝土弹性模量改为调节截面一定高度处的变宽点宽度和截面特性的方法,推导出了钢-混组合梁非线性分布的徐变初应变和徐变荷载向量的通用解析表达式。作者将推导的结果用于钢-混组合梁有限元程序的编制,并用编制的程序对静定和超静定钢-混组合梁的徐变效应进行了分析。分析结果表明,钢-混组合梁的徐变效应折减程度将小于混凝土弹性模量折减幅度,按平截面假定计算的预应力钢-混组合梁徐变效应经过折减后仍然较大,建议在设计和施工中采取合理措施减小该类型结构的徐变损失。
Creep effect analysis of steel-concrete composite beam is the key and difficult point in the design. There is an urgent need in the art for computational methods and sophisticated calculation software suitable for computer program development and for easy computer promotion. In order to facilitate the computer to solve the creep effect of steel-concrete composite beam, based on the principle of the initial strain method, the equivalent elastic modulus of concrete is introduced into the creep effect of steel-concrete composite beam by using the initial strain. In the section, the method of adjusting the elastic modulus of concrete is changed to the width of widening point and the characteristic of cross section at a certain height of the section. The general expressions of creep initial strain and creep load vector of the nonlinear distribution of steel- formula. The author applies the result to the finite element program of steel-concrete composite beam and analyzes the creep effect of the statically determinate and the statically determinate steel-concrete composite beam by using the program. The results show that the degree of reduction of the creep effect of the composite beam is smaller than that of the concrete. The creep effect of the prestressed steel-concrete composite beam is still large after the reduction, It is suggested that reasonable measures be taken in the design and construction to reduce the creep loss of this type of structure.