The ultimate resistance of steel H-section members under biaxial bending and compression has been discussed in the present paper. Finite element models taking account of geometrical and material nonlinearities are established and validated by previous laboratory test results. A series of parametric studies are then conducted considering different loading angles and a spectrum of flange width-to-thickness ratios, web width-to-thickness ratios and axial force ratios. An improved energy inflection method (EIM), which is verified by comparing the analytical results with numerical results, is proposed in order to determine the ultimate state of the members under biaxial bending. It is shown that the ultimate state determined by EIM occurs when the sectional stress distribution reaches the envelop line. Finally, a simple interaction formula is proposed to predict the ultimate capacity of the steel H-section columns subjected to biaxial bending and compression. It is verified that the interaction formula can provide a satisfactory prediction, in comparison against the European code which tends to offer a relatively conservative estimate. The proposed method is applicable to flange width-to-thickness ratios ranging from 8 to 28, web width-to-thickness ratios changing from 30 to 120, and axial force ratios varying from 0 to 0.4.

本文讨论了钢 H 型材在双轴弯曲和压缩下的极限抗力。考虑几何和材料非线性的有限元模型是通过先前的实验室测试结果建立和验证的。然后进行一系列参数研究，考虑不同的加载角度和翼缘宽厚比、腹板宽厚比和轴力比的范围。为了确定构件在双轴弯曲下的极限状态，提出了一种改进的能量弯曲法（EIM），通过比较分析结果与数值结果进行了验证。结果表明，当截面应力分布到达包络线时，由 EIM 确定的极限状态发生。最后，提出了一个简单的相互作用公式来预测承受双轴弯曲和压缩的钢 H 型截面柱的极限承载力。经验证，与倾向于提供相对保守估计的欧洲代码相比，交互公式可以提供令人满意的预测。该方法适用于翼缘宽厚比为8~28、腹板宽厚比为30~120、轴力比为0~0.4的情况。