受约束混凝土早龄期温湿度应力计算

Calculation of moisture-temperature induced stress in early-age restrained concrete

为了探讨受混凝土受约束构件在干缩和温度变化影响下的早龄期应力变化规律及开裂风险,以受约束混凝土棱柱体构件为例,建立了混凝土受约束构件在湿度场和温度变化作用下早龄期收缩应力解析计算方法。采用松弛徐变系数法对混凝土徐变的影响作了修正,应用该模型对不同环境湿度、不同单日温度变化和不同约束三种情况的混凝土构件应力应变进行了计算分析。结果表明:约束度越大,应力越大,开裂风险越大;当环境湿度与混凝土内部湿度接近时,环境湿度对混凝土的应力应变影响最明显;单日温度骤降对4 d龄期内的混凝土应力应变影响较为明显。因此,内外约束和环境湿度是影响构件早龄期应力变化的主要影响因素。

This study aimed to explore the change law of early-age stress and crack risk of concrete-constrained com- ponents under dry shrinkage and temperature. With a restrained concrete prism component as an example, a calculation method for the early-age shrinkage stress of the restrained concrete components under the action of moisture field and temperature was developed. Relaxation and creepage coefficient were applied to revise the effect of concrete creepage. The model was adopted for the calculation and analysis of the stress and strain of concrete compo- nents under different environmental humidity, temperature changes within a single day, and constraints. Results show that a high degree of restraint led to large stress and risk of cracking. When the moisture of the environment was close to the intemal humidity of concrete, the greatest effects on the stress and strain of concrete were ob- served. A sudden decrease in temperature within a single day apparently affected the stress and strain of concrete lying within the age of 4 days. Therefore, the inside and outside constraint conditions and environmental humidity were the main factors affecting stress changes in early age.