恒高温下钢管混凝土界面黏结性能试验研究

Experimental study on bond behavior of interface for concrete-filled steel tube under constant high temperature

钢管混凝土的界面黏结性能是钢管和混凝土之间共同受力与协调变形的基础。为探讨高温下钢管混凝土界面黏结破坏特点和平均黏结强度的主要影响因素,文中以恒温温度、长径比和径厚比等为主要研究参数,进行钢管混凝土试件恒高温下的推出滑移试验,得到钢管混凝土界面的温度-时间和荷载-滑移关系曲线。试验结果表明,在20℃~900℃研究范围内,恒温温度对圆钢管混凝土平均黏结强度有显著的影响,平均黏结强度随恒温温度的升高先减小后增加再减小,降低幅度最高达到90%;平均黏结强度随钢管长径比的增大而减小,降低幅度最高达50%;钢管径厚比对平均黏结强度影响很小,降低幅度在10%以内。

The bond behavior of interface for concrete filled steel tube （CFST） is the basis for coordination deformation and load bearing between the steel tube and the concrete. In order to investigate the bond failure and critical influence factors of average bond strength for CFST interface, CFST specimens were designed and push-out slip tests were conducted under constant high temperature, in which design parameters, such as temperature, ratio of length to diameter and ratio of diameter to thickness were considered. Temperature-time and load-relative slip curves of the specimens were gained. Test results show that constant temperature has significant influence on the average bond strength of CFST specimens when the temperature is between 20~C and 900~C. Average bond strength decreases with the temperature at first, then increases, and decreases at last with the highest reduction rate of 90%. While, the average bond strength decreases with the ratio of length to diameter of CFST specimens, with the highest reduction rate of 50%. It is shown that the ratio of diameter to thickness has minor influence on the average bond strength.