高温后不同类型混凝土力学性能试验研究

Experimental research on mechanical properties of different type of concrete after high temperature

对高温后C40和C50普通混凝土以及C80高性能混凝土的力学性能进行了试验研究,描述了试验现象,探讨了火灾温度、恒温时间、试件尺寸、冷却方式和混凝土类型等因素对高温后混凝土力学性能的影响,提出了高温后不同类型混凝土的轴心抗压强度、弹性模量、峰值应变等经验计算公式和高温后混凝土轴压应力-应变关系曲线表达式。试验研究表明,随着火灾温度的升高和恒温时间的增加,高温后混凝土立方体抗压强度、轴心抗压强度、弹性模量等整体上呈降低趋势,而峰值应变逐渐增加;在火灾温度、恒温时间恒定时,试件尺寸越大越不利,喷水冷却不如自然冷却,高性能混凝土不如普通混凝土。

The present paper aims mental research on the mechanical to introduce the authors＇ experiproperties of C40, C50 ordinary concrete and C80 high-performance concrete （HPC） when high temperature is applied to it. For this purpose, the authors have given a detailed review of experimental phenomena and the influences of the significant parameters, such as peak temperature, exposure time, different size of specimens, cooling regimes and different types of concrete on the mechanical properties of concrete after high temperature were provided. And then, the paper has given a formula for stress-strain relationship of normal and high-performance concrete when high temperature is applied to it. Next, some empirical calculation formulas for axial compressive strength, elastic modulus and peak strain were proposed. The results of the authors＇ research indicate that ： with the exposure of temperature with the exposure time increases, cube compressive strength, axial compressive strength and the elastic modulus of concrete tend to decrease as a whole while peak strain for concrete tends to increase. On the condition that the peak temperature and temperature exposure time are the same, the loss of compressive strength proves greater for big specimen size than for small ones, greater for water cooling than for furnace cooling and greater for high-performance concrete than for ordinary concrete.