热力耦合途径下再生保温混凝土的细观力学性能

Meso-scale Response of Recycled Aggregate Thermal Insulation Concrete Based on Coupled Thermo-mechanical Modeling

结合再生保温混凝土(RATIC)的表征非均质特性,基于Monte Carlo方法,借助MATLAB软件生成了RATIC二维多边形随机骨料模型,并利用ABAQUS有限元分析软件对热力耦合途径下的RATIC进行了单轴受压损伤模拟。首先对不同温度下RATIC的热传导行为进行模拟分析,基于温度场模拟结果,利用混凝土塑性损伤本构模型分别探究100、200、300、400、500、600、700、800℃下各细观组分的热膨胀系数、热传导率和比热容等热工参数以及泊松比、强度和弹性模量等力学参数的差异性对RATIC细观力学性能的影响,并进一步对比分析了模拟和试验条件下RATIC在不同受火温度下的单轴受压破坏形态。结果表明:当受火温度超过400℃时,温度应力对RATIC强度产生了削弱作用,800℃时,试件内部产生了最大的温度应力3.309 MPa;高温下单轴受压的RATIC试件损伤首先出现于界面过渡区,然后向砂浆基体发展,其主要集中于试件的自由端,且随着受火温度和加载时间的提高,损伤均呈现出逐渐加剧的趋势,细观损伤模型可以较好地模拟高温下RATIC的单轴受压力学性能和破坏形态。

Based on the meso-scale heterogeneity of recycled aggregate thermal insulation concrete(RATIC),MATLAB software was used to generate a 2-D polygonal random aggregate model of RATIC by Monte Carlo method,and then the finite element analysis software ABAQUS was used to simulate the uniaxial compression mechanical properties of meso-scale RATIC based on coupled thermo-mechanical modeling.Firstly,the heat conduction behavior of RATIC at different temperatures was simulated.According to the simulation results,the effects of meso-scale constituents at different temperatures(100,200,300,400,500,600,700 and 800℃),such as the thermal parameters(conductivity,specific heat and thermal expansion coefficient)and the mechanical parameters(strength,elastic model and Poisson′s ratio),on the meso-scale RATIC mechanical properties were explored.Furthermore,a comparative analysis was conducted to study the uniaxial compression failure modes at different fire temperatures of RATIC under simulated and experimental conditions.The results show that the temperature stress weakens the strength of RATIC when the temperature exceeds 400℃.And at 800℃,there is a maximum temperature stress of 3.309 MPa generated inside the specimen.The high temperature damage of RATIC specimens under uniaxial compression first appears in the interfacial transition zone,and then develops to the mortar.It is mainly concentrated on the free end of the specimen,and with the increase of the fire temperature and loading time,the damage shows a gradual increase trend.The results indicate that the meso-scale model can be well used to simulate the uniaxial compression mechanical properties and failure patterns of RATIC at high temperature.