高温后钢纤维加强混凝土有效导热系数计算方法  

Calculation Method of Effective Thermal Conductivity of Steel Fiber Reinforced Concrete after High Temperature

作　　者：朱德 韩阳[1] 段君峰[1,2] 沈雷 姚秀鹏 曹茂森 ZHU De;HAN Yang;DUAN Junfeng;SHEN Lei;YAO Xiupeng;CAO Maosen(School of Civil Engineering,Henan University of Technology,Zhengzhou 450001,China;Architectural Engineering Institute,Zhengzhou University of Industry Technology,Zhengzhou 451150,China;Department of Engineering Mechanics,Hohai University,Nanjing 210098,China)

机构地区：[1]河南工业大学土木工程学院,郑州450001 [2]郑州工业应用技术学院建筑工程学院,郑州451150 [3]河海大学工程力学系,南京210098

出　　处：《硅酸盐通报》2021年第5期1510-1519,共10页Bulletin of the Chinese Ceramic Society

基　　金：中国博士后科学基金特别资助(2020T130170);国家自然科学基金(51908195,50678060)。

摘　　要：钢纤维加强混凝土(SFRC)的导热系数是结构抗火性能模拟的重要参数,快速准确获得其高温前后导热系数具有重要意义。因此提出一种SFRC导热系数细观多尺度计算方法,其特点是考虑高温下混凝土材料细观热开裂行为(裂缝热阻效应),而非利用细观组分导热系数随温度变化关系进行计算。通过试验获得砂浆、高强混凝土与钢纤维体积分数分别为1%和2%的SFRC在高温(20℃、60℃、150℃、300℃、450℃和600℃)前后的孔隙率和导热系数,以验证所提方法。结果表明:当界面热阻系数随温度线性增加时,模型与试验结果吻合较好;当温度达到600℃时,由界面热阻效应引起的砂浆、高强混凝土,以及纤维体积分数为1%和2%的SFRC的导热系数的降低分别约占50%、36%、7%和12%;当高强混凝土的界面热阻系数取0.4,SFRC的界面热阻系数取1.0时,高导热系数颗粒的添加对复合材料的有效导热系数没有增益作用。The thermal conductivity of steel fiber reinforced concrete(SFRC)is a primary property for structure fire resistance performance analysis.It is of great significance to estimate the thermal conductivity at/after high temperature quickly and accurately.For this demand,a multi-scale method for thermal conductivity of SFRC was proposed,featuring with the thermal cracking behavior at high temperature,namely the interfacial thermal resistance(ITR),rather than the temperature-dependent decreasing law of components thermal conductivity.Afterward,the experiments on the thermal conductivity and porosity of mortar,high strength concrete,and SFRC with 1% and 2%(volume fraction)fiber heated up to various temperatures(20℃,60℃,150℃,300℃,450℃,600℃)were performed to validate the proposed model.The results show that the numerical predictions satisfy the experimental data very well when the ITR coefficient is assumed to linearly increases with heating temperatures.When the temperature reaches 600℃,the decreases of thermal conductivity of mortar,high strength concrete and SFRC with fiber(volume fraction 1% to 2%)caused by ITR effect are about 50%,36%,7% and 12%,respectively.When the ITR coefficient of high strength concrete is 0.4 and the ITR coefficient of SFRC is 1.0,the addition of particles with good thermal conductivity has no help to increase the effective thermal conductivity of composite materials.

关 键 词：钢纤维加强混凝土 高温 有效导热系数 热开裂 界面热阻 

分 类 号：TU528.58[建筑科学—建筑技术科学]