中文摘要：

为了研究高温后方钢管高强混凝土短柱的受力性能,以温度及混凝土强度为变化参数,设计了15个试件进行高温后的静力加载试验,观察了高温后试件的外观变化和破坏形态,分析了其荷载—轴向位移曲线,研究了各个参数对高温后方钢管高强混凝土短柱的力学性能的影响,并探讨了引入材料强度折减系数后已有规范对构件承载力计算的可行性。研究结果表明：高温后方钢管高强混凝土轴压短柱破坏模式为剪切破坏和腰鼓破坏两种,温度低时倾向于发生剪切破坏,温度较高时易发生腰鼓破坏;温度在400℃以下时试件的承载力和轴压刚度变化不大,超过400℃时承载力和轴压刚度迅速降低,温度从常温升至200℃、400℃、600℃、800℃时,试件承载力分别为常温试件的101%、105%、76%、54%,其轴压刚度分别为常温试件的97%、96%、62%、51%;极限承载力随混凝土强度等级的提高而增大,混凝土等级从C60提高至C70及C80时,平均极限承载力分别提高7%和12%。延性系数随温度的升高经历先减小后增大的变化过程,温度为400℃时延性系为常温试件的92%,800℃时为123%,混凝土强度对试件的延性系数影响并无明显规律。引入折减系数后我国规程DBJ 13-51-2003及日本规程AIJ（1997）的计算值与试验值吻合较好。

英文摘要：

In order to study the mechanical behavior of high strength concrete filled square steel tube（ HSST） after high temperature,a total of 15 HSST columns were investigated experimentally under static axial compression by considering two parameters of temperature and concrete strength. Themechanical failure process and modes were observed,the load-displacement curves with characteristic point parameters were obtained and the influence of factors on the mechanical behavior of the HSST specimens was analyzed. The possibilities of using present specifications to calculate the ultimate bearing capacity of HSST with the introduction of material strength reduction factor were discussed. The results show that the failure modes of HSST after high temperature mainly contain two modes,the shear failure mode and the waist drum failure mode,and that shear failure mode is more likely to occur when the temperature is low. The waist drum failure mode appears when the temperature is over 400 ℃. The bearing capacity and axial compressive stiffness of the specimens change little when the temperature is below 400 ℃,and they drop rapidly when the temperature surpassed400 ℃. When the temperature raises from room temperature to 200 ℃,400 ℃,600 ℃ and 800 ℃,the bearing capacity is respectively 101%,105%,76% and 54% of that of the room temperature specimens,and the axial compressive stiffness is 97%,96%,62% and 51% of that of the room temperature specimens. The bearing capacity increases with the increase of the concrete strength,and when the concrete grade increases from C60 to C70 and C80,the average ultimate bearing capacity is increased by 7% and 12% respectively. The ductility factor decreases,and then recovers with the increase of temperature. The ductility factor is 92% of that of room temperature specimens when the temperature is 400 ℃,and the value raises to 123% when the temperature increases to800 ℃. There is no obvious effect of concrete strength on ductility factor. The results also indicate that the calcula