热湿传导模型在早龄期混凝土非结构性裂缝分析中的应用

为了更加准确的分析混凝土结构早龄期非结构性裂缝的产生机理,提出了混凝土三维有限元热湿传导数值计算模型.该模型考虑了水泥水化放热引起的混凝土温度变化、表面干燥失水而造成的混凝土湿度非均匀分布和热传导与湿度扩散之间的耦合作用;采用考虑水化度的混凝土弹性模量和抗拉强度计算公式来表征早龄期时温度变化对其力学性能的影响,同时在应力分析中采用Bazant的双幂函数徐变模型.算例分析表明,该模型能很好地预测实际条件下混凝土温度、湿度变化和相应产生的应力,具有一定的工程应用价值.

Analysis of non-structural cracks at early ages by coupled heat and humidity transmission model in the concrete

In this paper, a three-dimensional finite element model for the analysis of concrete structure is introduced. The numerical model takes into account both the time-dependent thermal variations due to hydration heat and non-uniform moisture distribution during drying, and the coupling effect between the heat transfer and the moisture diffusion. Calcula-tion of the temperature and internal relative humidity variations of concrete structure is followed by determination of stres-ses due to thermal gradients, differential drying shrinkage, and average drying shrinkage. The mechanical properties of concrete at early ages, determined from numerous experimental studies, are taken into consideration to improve the accu-racy of the numerical results. The validity of the proposed procedure is verified by comparing the measured data with the numerical results for concrete aqueduct.