矩形钢管混凝土双向压弯构件的理论与试验研究

Experimental and Theoretical Analysis of Concrete-filled RHS Under Bi-axial Bending Moment

对9根方形、矩形钢管混凝土在轴压、单向压弯及双向压弯受力状态下的力学性能进行了研究。构件的主要变化参数为加载角度和截面长宽比。试验结果表明:在受力过程中构件存在扭转,构件绕弱轴的跨中挠度和绕强轴的跨中挠度比值随着荷载的增加而增大,说明在受力过程中构件绕弱轴的刚度不断降低。编制了数值分析程序,采用纤维模型法分析矩形钢管混凝土在双向压弯受力状态下的力学性能,分析过程中考虑了截面变形轴扭转对构件力学性能的影响,理论分析结果和试验结果吻合良好。利用所编制的数值分析程序,分析了在不同加载角度和截面长宽比下变形轴扭转对构件力学性能的影响。分析结果表明:加载角度为45°时,扭转对构件承载力的降低幅度最大,达到20%以上;随着截面长宽比的增加,截面变形轴扭转会明显降低构件的承载力,截面长宽比越大,承载力的降低幅度也越大。

Total of 9 specimens were tested under the state of axial loading condition, uni-eccentric loading condition and bieccentric loading condition. The main parameters are load angle and height-to-breadth ratio. The results showes that the rigid rotation of the specimen appeared, and the ratio of deflection along minor axis deflection to deflection along major axis become larger with the increase of load. A nonlinear program is produced to analyze the behavior of the specimen under bi-axial load, and the effect of cross-sectional neutral axis rotation is considered. The calculated results are compared with the experimental results and other experimental results, and they agreed well with each other. For rectangular composite columns, the rotation of the neutral axis will decrease the rigidity and bearing capacity. With the increase of height-to-breadth ratio, the decrease ratio of bearing capacity will become larger. For rectangular composite columns with load angle 45°, whose height-to-breadth ratio is larger than 1.0, the decrease ratio of bearing capacity is the largest.