梁腹板在弯、剪及局压复合应力作用下的屈曲分析

前钢结构设计规范(GBJ17-88)中有关梁腹板局部稳定的计算公式来源于无限弹性完善板假定,一方面与构件的实际工作状况有一定出入,导致计算结果有时会偏于不安全;另一方面又与有关钢梁在弯曲正应力作用下的强度计算公式(考虑截面部分进入塑性)不相协调。针对《钢结构设计规范》(GB50017-2003)中变动较大的该部分设计内容,本文考虑不同的几何参数及弯、剪、局压多种应力组合工况对梁腹板屈曲临界应力的影响,对修订后的梁腹板横向加劲区格在复合应力作用下的临界应力相关公式进行了大量的有限元分析与计算;重点考察了梁腹板的弹塑性屈曲性态及规范(GB50017-2003)中相关公式所具有的设计安全度。在此基础上,提出相关的设计建议,供规范修订及进一步的研究参考。

BUCKLING ANALYSIS OF BEAM WEBS SUBJECTED TO COMBINED BENDING,SHEAR AND PATCH LOADING

The computational formula for the local stability of beam webs is based on the assumption of infiniteelastic perfect plates in the former Code for Design of Steel Structures(GBJ1788).This assumption contradicts to the stress states of realistic structure members,which sometimes leads to nonconservative results,and it is also incompatible with the strength formula of beams under bending stresses(considering partial plasticity of the section).These issues are studied in this paper.Considering the effects of various geometric parameters and stress combinations on the buckling critical stress of webs,the revised local buckling correlative formula for transversely stiffened web panels under combined stresses is verified by using the finite element method.The elastoplastic buckling states of beamwebs are examined emphatically,and the design safety degree of the correlative formula in the new version of the Code for Design of Steel Structures(GB500172003)is validated.Conclusions and suggestions for design are provided,which may be useful for code revisions and further studies.