高温后方钢管高强混凝土界面黏结性能试验研究

为研究高温后方钢管高强混凝土的黏结性能，以混凝土强度、温度、锚固长度为变化参数，完成了17个方钢管高强混凝土试件的高温后静力推出试验。通过试验获取了各试件的荷载-滑移曲线及特征点参数，分析了各变化参数对黏结强度的影响；并基于试验分析，提出了高温后方钢管高强混凝土黏结滑移的本构关系。结果表明：加载端和自由端的荷载-滑移曲线形状相似；方钢管高强混凝土黏结强度与锚固长度成反比，并随恒定温度的升高呈现先增大后减小的变化趋势；试件黏结损伤的发展随历经恒定温度的升高而发展较迟且缓慢；界面黏结耗能能力总体上随混凝土强度的提高而增强、随历经温度的升高而下降的变化趋势；方钢管的应变与应力沿其长度方向均呈指数分布，由自由端向加载端减小。

Study on interface bond behavior of high strength concrete filled square steel tube after high temperatures

In order to reveal the bond-slip behavior of high strength concrete filled square steel tube (HSCFST) experiencing high temperatures, a total of 17 high strength concrete filled square steel tube specimens were designed for push out test and the load-slip curves of the whole process and parameters of feature points were obtained from the experiments. The parameters of concrete strength, temperature and bond length were considered to research their influences on bond strength of HSCFST. Based on test mechanism analysis, the bond-slip constitutive formula of HSCFST experiencing high temperatures was put forward. Test results show that the shape of load-slip curves at the loading ends and free ends are similar. The bond strength of HSCFST is proportional to the anchoring length, and increases first and then decreases partly with the increase of the constant temperature. The bond damage of specimens with lower constant temperature develops earlier and faster than the specimens with higher constant temperature. The energy dissipation capacity of the bonding interface is generally enhanced with the increase of concrete strength, but is roughly a downward trend with increasing temperature. The strain and stress of square steel tube presents exponential distribution, and decreases from free end to load end.