工字形截面钢偏心压杆的弯扭屈曲可以发生在弹性阶段、弹塑性阶段以及截面出现屈服区的阶段。关于弹性阶段和弹塑性阶段弯扭屈曲临界力的计算,我们曾经在1972年作过分析和实验验证。在弹塑性阶段,当杆截面受压较大的翼缘应力超过比例极限时,把该翼缘的厚度δ按相应的切线模量E_i折减为δE_t/E,就可以按弹性杆来分析。当 The flexural-torsional buckling of an I-section steel eccentric pressurizing bar can occur in the elastic stage, the elasto-plastic stage, and the appearance of a yield zone in the section. The calculations of the bending-torsional buckling critical force in the elastic stage and elasto-plastic stage have been analyzed and experimentally verified in 1972. In the elasto-plastic stage, when the stress of the flange subjected to large pressure in the cross section exceeds the proportional limit, the thickness δ of the flange is reduced to δE_t/E according to the corresponding tangent modulus E_i, which can be analyzed by the elastic rod. when