混凝土桥梁收缩徐变计算的有限元方法与应用

将桥梁规范附录四中给出的混凝土徐变系数表达式用指数函数进行拟合,从而得到了徐变计算的递推公式。利用混凝土收缩应变规律推导出由收缩应变增量产生的单元等效结点力增量,并以此为基础,绘出了用初应变法进行节段施工混凝土桥梁的收缩徐变计算的有限元列式,编制了有限元程序。最后,以三跨等截面混凝土连续梁和长沙湘江北大桥主跨210m的混凝土斜拉桥为例进行了收缩徐变分析,且利用12年实桥现场观测结果验证了其理论分析结果。

Finite element method and application for the shrinkage and creep of concrete bridges

In this paper,authors have deduced the recursion formulas for the creep calculation of concrete by substituting the exponent functions for the creep coefficient expression of concrete listed in appendix 4 of the bridge criterion. They also have deduced the equivalent node force increment caused by the shrinkage strain increment in the elements using the rule of the shrinkage strain of concrete. Based on these facts,a group of finite element formulas are deduced by the way of the primary strain method, which can be successfully applied to concrete bridges constructed by the method of sections, the finite element program is programmed, and the results from the program calculating are validated. The shrinkage and creep calculations of two bridges are made and compared with the measuring outcomes in the real bridges through 12 years of these bridges. One bridge is a continuous beam bridge which consists of three spans and the sections are equal in size,the other is Changsha Xiang River Bridge which is a concrete bridge and the main span is 210m. It is concluded that the formulas and the program are correct and feasible.