作　　者： ; ; ; ;

机构地区： 湖南大学土木工程学院建筑安全与节能教育部重点实验室

出　　处： 《安全与环境学报》 2014年第3期67-71,共5页

摘　　要： 采用高温抗压试验炉和长期加载装置进行了有约束应力作用下混凝土经历升温、降温、冷却及长期静置全过程后的轴压力学性能试验,研究了持荷时间和温度等级对高温全过程混凝土变形特性与高温全过程及长期静置作用后混凝土残余强度、弹性模量和应力-应变关系的影响规律。结果表明:约束应力使混凝土产生明显的残余压缩变形,长期静置对高温后混凝土抗压强度和弹性模量有显著影响;长期静置过程中持荷时间和温度等级对混凝土轴向变形有一定影响;全过程作用后混凝土抗压强度和弹性模量显著降低;长期荷载作用下有约束应力高温全过程后混凝土破坏突然,明显变脆。 This paper presents an experimental study on the mechanical behaviors of concrete under sustained axial stress after exposure to heating, cooling and long-term loading. The tests were conducted by using a specially-built electrical furnace and a long-term loading device. The paper mainly focuses on the effects of temperature rating and long-term loading on the creep property and mechanical behavior of fire-damaged concrete after the whole period of heating, cooling and long-term loading. The test results show that the concrete prism specimens after exposure to high temperatures tend to suffer remarkable residual compressive deformations and high temperature-induced expansion deformation. The sustained loading during the whole testing period led to significant effects on the residual compressive strength and modulus of elasticity of concrete after exposure to high temperatures. In addition, the axial creep deformation of fire-damaged concrete can also be found during the long-term loading test. With the increase of temperature and long-term loading time, the axial deformation of concrete can be found to increase, while the residual compressive strength and elasticity of modulus decrease. The residual compressive strength and modulus of elasticity of fire-damaged concrete can be found to decrease significantly compared with those at room temperature. It can also be found that the variation of residual compressive strength of fire-damaged concrete with three-month loading is characterized by an initial stage of strength loss, a stage of strength recovery and a stage of decrease in strength. However, the residual compressive strength of fire-damaged concrete with six-month loading sharply decreased with the increase of temperature. After exposure to high temperatures and long-term loading, the concrete specimens with sustained restrained stress were loaded to fail in a brittle mode. Therefore, it can be concluded that the tested results can serve as a useful reference for reasonably assessing the mechanical behaviors

关 键 词： 工程结构 混凝土 残余强度 残余弹性模量 高温后 长期静置

领　　域： [建筑科学]