基于ANSYS的混凝土内湿度场计算方法

摘要

In order to calculate the humidity field of concrete using the temperature field module in finite element program,a comparison between thermal field and humidity field was made of their differences in the differential equations,initial and boundary conditions,etc.Based on the temperature field module in ANSYS,a finite element method was proposed to calculate the humidity field in concrete.From the aspect of self-desiccation and desiccation,this method was verified against the existing test results of the relative humidity in concrete.The values of parameters for ANSYS analysis such as the coefficients of the internal moisture consumption function,moisture diffusion coefficients,and surface factors which affect the humidity field in concrete were analyzed.The results show that the relative humidity,diffusion coefficients,self-desiccation formula,and the coefficient of moisture transfer in surface used in the humidity field calculation can be replaced by the temperature,thermal diffusivity,adiabatic heating function,and the heat transfer coefficient used in the temperature field calculation.Using the temperature field module to analyze the humidity field in concrete,the maximum error between the calculated results and the existing test results is 7.3％,which meets the engineering requirements.The serf-desiccation formula obtained from the experimental results can be applied to the moisture field calculation of the concrete with a water cement ratio ranging from 0.28 to 0.68.%为利用通用有限元程序温度场模块计算混凝土内部湿度场,对比了温度场和湿度场的微分方程、初始及边界条件,提出了有限元程序ANSYS温度场模块计算混凝土湿度场的有限元方法,并基于既有混凝土内相对湿度测试试验结果,从自干燥效应和干燥效应两方面对该方法进行了验证,分析了影响湿度场分布的内部水分自耗函数、湿度扩散系数和表面水分转移系数的参数取值,得到了水分自耗率公式.研究结果表明:湿度场计算中的相对湿度、湿度扩散系数、湿度自降低项和表面水分转移系数可分别用温度场计算中的温度、导温系数、绝热升温函数和换热系数表示;用温度场模块分析混凝土的湿度场结果与既有试验结果的最大误差为7.3％,满足工程要求;获得的水分自耗率公式可适用于水灰比为0.28 ～ 0.68的混凝土湿度场计算.