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在用分段悬臂法施工的长跨度预应力混凝土桥梁中,各节段混凝土龄期之差自数天至半年以上,收缩徐变所引起的各施工阶段的挠度变化、应力损失及体系转换后的内力重分配等均为不容忽视的因素。但是在分析计算中采用何种徐变函数、关于徐变效应的结构分析采用何种理论和方法,国内外尚多分歧。本文以112m跨度的某双线铁路预应力混凝土3跨连续梁为例,对于各施工阶段的收缩徐变影响进行了分析计算,并对计算徐变系数的各种数学模式进行了比较和简略的讨论,选用了Z.P.Bazant教授于1980年提出的BP-2模式来计算各节段在各个时期的徐变和收缩值。徐变收缩对结构的影响则用有限单元逐步计算法计算。对计算结果进行了讨论,并对今后的改进提出了建议。
In the long-span prestressed concrete bridge constructed by the cantilever method, the difference of the concrete age of each segment varies from several days to more than half a year. The deflection, stress loss and system transition after each construction phase caused by shrinkage and creep The redistribution of internal forces are all factors that can not be ignored. However, what kind of creep function is used in the analysis and calculation? What theories and methods are used in the structural analysis of creep effect are still divided at home and abroad. In this paper, taking a 112m span double-track prestressed concrete 3-span continuous beam as an example, the influence of shrinkage and creep of each construction stage is analyzed and calculated, and various mathematical models for calculating creep coefficient are compared and simplified In the discussion, BP-2 mode proposed by Professor ZPBazant in 1980 was chosen to calculate the creep and shrinkage values of each segment in each period. The effect of creep shrinkage on the structure is calculated using the finite element step-by-step method. The calculation results are discussed, and suggestions for future improvements are proposed.