钢管高强混凝土界面力学性能试验研究及黏结强度计算

Interface mechanical behavior test and bond strength calculation of high-strength concrete filled circular steel tube

为研究钢管高强混凝土界面力学性能,以混凝土强度和钢管黏结长度为变化参数,设计了4个钢管高强混凝土柱试件,对其进行推出试验。通过试验分析了试件的荷载-滑移曲线、钢管表面应变分布和界面黏结损伤规律,研究了界面黏结强度的计算方法。研究结果表明:加载端和自由端的荷载-滑移曲线与没有明显屈服点的钢材应力-应变曲线类似,界面黏结应力呈负指数分布;实测黏结强度大于名义黏结强度,随混凝土强度和黏结长度的增加而有所提高;黏结损伤发展在起滑点时刻较快,峰值荷载后缓慢而稳定;在分析实测黏结强度的基础上,根据现有黏结强度计算模型,指出了能够用于预测钢管高强混凝土界面黏结强度的计算方法。

In order to study the interface mechanical behavior of high-strength concrete filled circular steel tube( HCFST),four HCFST specimens,considering the main parameters of concrete strength and steel tube embedded length,were designed for push-out test. Through this test,the load-slip curves,bond strain distribution laws and bond damage laws for HCFST specimens were analyzed,and the bond strength calculation method was also researched. Test results show that the load-slip curves of load end and free end are both similar to the stress-strain curve of steel with no apparent yield point. The longitudinal strain of steel tube exhibits a negative exponential distribution. The measured bond strength is larger than the values of nominal bond strength,which may be slightly increased along with the increasing of concrete strength and steel tube embedded length. After start of sliding,bond damage develops rapidly,and then gradually slows after the peak loading. Based on the analysis of measured bond strength and bond strength calculation model,the calculation method for predicting the interfacial bond strength of high-strength concrete filled circular steel tube is presented.