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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.
In order to analyze the generation mechanism of the early age non-structural cracks in concrete structures more accurately, a numerical calculation model of the three-dimensional finite element heat and moisture transmission in concrete is proposed.The model considers the temperature change of concrete caused by the hydration of cement hydration, Which is caused by the non-uniform distribution of humidity and the coupling between heat conduction and humidity diffusion. The formula of elastic modulus and tensile strength of concrete considering the degree of hydration is used to characterize the influence of temperature change on the mechanical properties of the concrete at early age. At the same time, Bazant’s bivariate function creep model is adopted in the stress analysis.Examples show that the model can predict the concrete temperature and humidity changes and the corresponding stress under the actual conditions, and has certain engineering application value.