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预应力混凝土连续梁桥有几种不同的施工法。由于此种桥型施工方法的多样化,在内力计算上有与其他桥型不同的要求和内容。本文主要是介绍一种简便的方法来计算在施工过程中,由于连续梁体系的不断变化,由徐变引起的连续梁各截面的二次矩,以及由于体系转换由预应力产生的连续梁各截面的徐变二次矩。由此类推,也可用来计算由于支座沉陷及混凝土收缩引起的徐变二次矩。本文公式的推导是在建立结构各截面的变形协调微分方程式后,应用动态规划的数学模型,得出二次矩求解的递推公式,计算方便。文末所附计算实例说明考虑徐变影响后各支点截面(跨间截面亦同)的弯矩值比不考虑此影响的弯矩值约小15%左右,这个数值是不能忽略的。
There are several different methods of construction for prestressed concrete continuous girders. Due to the diversification of this kind of bridge construction method, there are different requirements and contents in internal force calculation compared with other bridge types. This paper mainly introduces a simple method to calculate the second moment of the continuous beam due to creep due to the continuous variation of the continuous beam system and the continuous beams produced by the prestress due to the system transformation Section of the second moment of creep. By analogy, it can also be used to calculate the second moment of creep caused by subsidence and shrinkage of concrete. The derivation of the formula in this paper is to use the mathematical model of dynamic programming after the deformation coordination differential equation of each section of the structure is established, and the recursion formula of solving the second moment is obtained, which is easy to calculate. The calculation example attached at the end of this article shows that the bending moment of each fulcrum section (cross-section) is about 15% less than the bending moment without considering this influence after considering the influence of creep. This value can not be neglected.