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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。
Rectangular CFST under asymmetrical bending and bending load is asymmetric, and the deformation axis is reversed with the change of load. According to the design of CFST post of Hongjiadu Hydropower Station in Guizhou Province, the thin-wall stiffening rectangle with large aspect ratio The properties of CFST under biaxial bending and bending load are analyzed theoretically. The deformation, the internal force at section and the deformation axis of the section under load are studied. At the same time, four rectangular thin-walled CFST members with aspect ratio of 2.4 were stiffened by bidirectional loading test. The results show that the torsional deformation of the cross-section rectangular CFST members can significantly affect the mechanical behavior of the members and reduce the bearing capacity of the members. The reduction of bearing capacity increases with the increase of the aspect ratio, The stiffener changes the buckling mode of the steel and increases the buckling capacity of the steel. The results of the final test are compared with those of the typical rectangular CFST design both at home and abroad. The results show that the existing codes conservatively calculate the bearing capacity of the CFRP members with large aspect ratio.