中文摘要：

现行钢结构规范中没有给出HM,HW型钢梁在上翼缘承受均布荷载、下翼缘承受跨中集中荷载作用下整体稳定的计算方法.根据能量理论得到的结果,考虑屈曲前变形对弯扭屈曲影响,得出上述荷载作用下双轴对称HM,HW型钢梁的临界承裁能力计算公式,总结了荷载比例系数对临界弯矩的影响规律.采用有限元方法对该理论公式进行验证,在荷载比例小于3时,有限元解与理论解相差基本在5％以内.提出了这类荷载作用下钢梁的等效临界弯矩系数的计算公式.该公式最大误差不超过8％,平均误差在3％左右.

英文摘要：

The calculation methods of overall stability for HM and HW-shaped steel beams under uniform load on the upper flange and concentrated load on the lower flange are not included in current steel structure code.According to the results obtained with energy theory,with the impact of deformation before buckling on flexural-torsional buckling considered,the critical moment formula of biax-symmetrical HM and HW-beams was derived under the load mentioned above,and the effects of the load scale factor on critical moment were also summarized in this paper.The finite element method was used to verify the moment formula.When the load scale factor was less than 3,the result difference between the finite element method and the theoretical method was within 5 ％.In addition,the coefficient formula of equivalent critical bending moment for the steel beams under the same loading was put forward.The maximum error of this coefficient formula was less than 8％ and the average error was about 3 ％.