扭转屈曲对十字截面轴心压杆承载力的影响

对于双轴对称十字形截面轴心压杆的设计方法，GB50017-2003《钢结构设计规范》在GBJ 17-88《钢结构设计规范》基础上增加了长细比不得小5.07b/t 的规定，相关文献指出根据该设计方法设计的构件截面偏大。对长细比不得小于5.07b/t 的规定进行了推导，从理论分析和有限元计算2 方面得出构件设计截面偏大的原因在于该设计方法要求材料必须足线弹性假定条件，进而分析得出了不同材料使用该设计方法时截面宽厚比需要满足的条件。最后，提出了考虑扭转屈曲时十字截面构件新的设计方法--等效设计强度设计，对比验证结果表明该方法简便、适用。

The Effect of Torsional Buckling on the Bearing Capacity of Axial Strut with Crisscross Section

In the national standard design code for steel structure（GB 50017—2003）,which is revised based on the former design code of 1988 edition,a new requirement is added that the slenderness ratio shall not less than 5.07 b/t（width/thickness） for the biaxial symmetry crisscross section axial strut.However,some literatures reported that the cross-section calculated by this method is too large.Theoretical analysis and finite element method calculation is performed on this requirement,which indicates that the cause for the larger cross section is due to the supposition condition required by this design method that the material must be linear elastic.The paper also obtains a number of width-thickness ratios that shall be satisfied for different materials when this design method is used.In the end a new design method-the equivalent design strength is proposed for crisscross section struts with consideration of torsional buckling,and comparison results show that this method is convenient and applicable.