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本文概述了1963～1971年期间,对英国许多桥梁进行混凝土的长期徐变和收缩变形的测定情况。混凝土标号大多是50N/mm~2(牛顿/毫米~2)*在实桥上收缩变形值一般约为200×10~(-6),而徐变系数约为2.0;此系数的定义是,在无限长时间内预应力有衰减情况下,预应力混凝土构件重心处的徐变终极值与弹性应变值之比。本文指出,水泥水化作用产生的早期热运动是导致混凝土浇注后不久立即发生开裂的最有可能的原因。研究结果表明,徐变与收缩变形通常随时间的对数而线性增长,也随季节的周期性变化而增长。本文还讨论了季节气候对变形计算的影响。
This article provides an overview of the long-term creep and shrinkage measurements of many bridges in Britain from 1963 to 1971. Concrete grades are mostly 50N / mm ~ 2 (Newton / mm ~ 2) * On the actual bridge shrinkage deformation value is generally about 200 × 10 -6, while the creep coefficient is about 2.0; The definition of this coefficient is, Under the condition of attenuating the prestress for an indefinite length of time, the ratio of the ultimate value of the creep at the center of gravity of the prestressed concrete member to the value of the elastic strain. This paper points out that the early thermal motion caused by the cement hydration is the most likely cause of cracking immediately after concrete pouring. The results show that the creep and shrinkage deformations usually increase linearly with the logarithm of time and also increase with the seasonal change of seasons. The paper also discusses the effect of seasonal climate on deformation calculation.