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Rational Constitutive Laws to Describe Creep and Shrinkage of Concrete at Elevated Temperatures

描述高温下混凝土蠕变和收缩的有理本构定律

基本信息

批准号：
01550436
负责人：
MIHASHI Hirozo
金额：
$ 1.6万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550436/
关键词：
Shrinkage Moisture Migration Creep Atmospheric Temperature double power law Thin Wall Cylinder Specimen Moisture Content Hygral Gradient 温度勾配アコ-スティックエミッション

项目摘要

Since the late of 1950's, the development of prestressed concrete nuclear reactor containment vessels has demanded the knowledge of mechanical behavior of concrete at high temperatures. Mathematical models for creep and shrinkage of concrete at temperatures over. 100^ﾟC have been asked particularly for finite element analysis of the safety in nuclear reactor structures. For this purpose, numerous experimental studied have been tried and various mathematical models have been proposed as the constitutive laws for the finite element analysis. Most of them, however, have failed to simulate the experimental results. The influence of moisture content and movement on the mechanical properties such as Young's modulus, shrinkage and creep behavior is significant even under 100^ﾟC as well as over 100^ﾟC. Therefore, it is very important to study the moisture migration in concrete for understanding the mechanical properties of concrete at elevated temperatures.In this project, the following result … More s are obtained:(1). Cylindrical specimens of mortar and concrete were tested under several temperature atmosphere to study the moisture migration process and changes of mechanical properties such as modulus of elasticity, compressive strength, tensile strength and so on. Moreover, these results of moisture migration were analyzed by a finite element method as a nonlinear diffusion process and the obtained material parameters were discussed.(2). By means of thin wall cylinder specimens, the moisture migration process and shrinkage of hardened cement paste at elevated temperatures were studied. It was shown that the the relationship between shrinkage and water loss had some changing points and this tendency became more clear as the temperature increased.(3). Coefficients of the double power law for creep of concrete are influenced by the moisture content in the concrete. In order to develop a generic constitutive law to describe rationally the creep of concrete, these coefficients should be given as functions of the moisture content. Less

自20世纪50年代末S以来，预应力核反应堆安全壳的发展对混凝土高温力学性能提出了更高的要求。温度过高时混凝土徐变和收缩的数学模型。核反应堆结构安全性的有限元分析特别要求ﾟC。为此，人们进行了大量的实验研究，并提出了各种数学模型作为有限元分析的本构关系。然而，他们中的大多数都未能模拟实验结果。即使在100^ﾟC和100^ﾟC以上的温度下，水分的含量和运动对混凝土的杨氏模量、收缩和徐变等力学性能的影响也是显著的。因此，研究混凝土中的水分迁移对于了解混凝土在高温下的力学性能是非常重要的。获得更多的S：(1)。通过对砂浆和混凝土的圆柱形试件在不同温度气氛下的试验，研究了水分的迁移过程以及弹性模数、抗压强度、抗拉强度等力学性能的变化。此外，将水分迁移的结果作为一个非线性扩散过程进行了有限元分析，并对得到的材料参数进行了讨论。通过薄壁圆筒试件，研究了硬化水泥浆体在高温下的水分迁移过程和收缩。结果表明，干缩率与失水率之间的关系存在一定的变化点，并且随着温度的升高，这种变化趋势越来越明显。混凝土的徐变双幂定律系数受混凝土含水率的影响。为了建立一个通用的本构关系来合理地描述混凝土的徐变，这些系数应该作为含水率的函数给出。较少