中文摘要：

矩形钢管混凝土在双向压弯荷载作用下截面受力不对称，随着荷载的变化变形轴发生扭转，本文结合贵州洪家渡水电站钢管混凝土厂房柱的设计，对大长宽比的薄壁加劲矩形钢管混凝土构件在双向压弯荷载作用下的性能进行了理论分析，研究了构件的变形、截面内力和截面变形轴随荷载的变化。同时对截面长宽比为2．4的4根带有加劲肋的矩形薄壁钢管混凝土构件进行了双向加载试验研究。结果表明：双向加载的矩形钢管混凝土构件截面变形轴扭转会显著影响构件的受力性能、降低构件的承载力；随着截面长宽比的增加，承载力降低幅度增大；薄壁板件的加劲肋改变了钢板的屈曲模态，提高了钢板的屈曲承载力。最后试验结果和国内外典型矩形钢管混凝土设计规程的计算结果进行对比，对比结果表明：现有规程偏于保守地计算了大宽厚比矩形钢管混凝土双向压弯构件的承载力。

英文摘要：

For rectangular composite columns under biaxial bending moment and axial load, the stress distribution is not symmetric across the section. With the increase of load, its neutral axis turns. The behavior of composite column in the Hongjiadu Electric Power Station with large height-to-breadth ratios and thinner steel plate is studied. A total of four specimens were designed and tested. The behavior of the specimens, including deformation, stress distribution and rotation of neutral axis, was studied. The results showed that the rotation of neutral axis influenced the bearing capacity and could cause decrease of beating capacity. With the increase of height-to-breadth ratio, the decrease of hearing capacity rises. The stiffener changed the buckling modes of steel plate, thus increasing the buckling bearing capacity. The experimental results were also used to evaluate the accuracy of typical design codes, and the results show that the experimental results are evidently higher than those calculation results according to different design codes.