太阳辐射作用下钢管膨胀混凝土界面性能试验与分析

EXPERIMENT AND ANALYSIS ON INTERFACIAL PERFORMANCE OF CONCRETE FILLED STEEL TUBES UNDER SOLAR RADIATION

太阳辐射作用是影响钢管混凝土截面非线性温度分布进而造成其界面脱粘的重要环境因素,而采用核心膨胀混凝土是钢管混凝土界面性能优化的重要方法。设计了8种不同膨胀剂掺量钢管混凝土试件,采用太阳辐射模拟器对其进行太阳辐射作用下的界面性能试验研究,分析了钢管和混凝土的温度和应变时程以及沿光照方向的截面温度梯度模式,结合热传导理论和有限元法,探究了混凝土自应力对太阳辐射作用下钢管混凝土截面温度应力、光照作用所引起的界面径向应力变化、界面间隙部位和大小变化的影响。研究结果表明:混凝土自应力可有效地改善太阳辐射作用下钢管混凝土的界面受力性能,避免其截面不同部位由于较大的温度应力梯度所引起的界面脱粘;同时,混凝土自应力对太阳辐射作用下的钢管混凝土界面间隙产生部位及其大小变化有一定影响。

Solar radiation is an important environmental factor which affects the nonlinear temperature distribution of concrete filled steel tubular （CFST） sections and then causes interfacial debonding, while the use of a core expansive concrete is a significant method for optimizing the interfacial performance of CFST elements. In this paper, eight CFST specimens with different expansion agent dosages were designed, their interfacial performances under solar radiation were investigated using a solar radiation simulator, and the temperature and strain time-histories of the steel tube and core concrete and the sectional temperature gradient mode along the direction of the incoming light were analyzed. Then the impacts of concrete self-stress on the sectional temperature stress, the sectional radial stress caused by radiation effect, and the position and size of the interface gap under solar radiation were investigated using heat transfer theory and a finite element method. The results show that the concrete self-stress can effectively improve the interracial mechanical performance of CFST under solar radiation and help avoid interface debonding caused by large temperature stress gradients at the different sectional positions; it also exerts a definite influence on the interracial gap positions and size of CFST under solar radiation.