基于温度-应力试验的混凝土早龄期应变分离及热膨胀系数计算

Strain separation and thermal coefficient calculation of early age concrete based on thermal stress test

针对采用标准试验方法难以测试早龄期混凝土热膨胀系数、难以分离温度应变与自生体积应变问题,本文利用温度-应力试验的特点,引入第一零应力时间作为有效应变测试的起测点;建立了以等效龄期作为时间尺度并考虑温度影响的混凝土自生体积应变的数学模型,实现了自生体积应变与温度应变的分离;提出分两阶段考虑早龄期混凝土的热膨胀系数,在升温阶段和降温阶段混凝土的热膨胀系数均为常数。

Thermal coefficient of concrete at early age is difficult to be measured by standard test method and thermal strain and autogenous strain are hard to be separated from total strain. In order to solve these problems, the advantage of the characters of thermal stress test was taken in this paper and some results can be concluded. Age at which first zero stress has been reached （tz.~） was introduced as the starting point for effective strain. Based on concept of equivalent age, numerical model for autogenous strain under practical temperature history was established and the separation of thermal deformation and autogenous strain were achieved. Thermal coefficient should be concerned at heating stage and cooling stage separately, and concrete thermal coefficient is constant at specific stage.