基于构件直接分析法的高强钢压弯构件平面内稳定研究

Study on the in-plane stability of high-strength steel members under combined axial compression and bending based on member direct analysis method

基于构件直接分析法,建立了横向荷载作用下两端简支初弯曲压弯构件平面内稳定的通用分析过程,得到了挠度的一般表达式和二阶弯矩的一般表达式。以全跨均布荷载、跨中集中荷载作用下初弯曲压弯构件为研究对象,采用数形结合法确定了最大二阶弯矩的位置,得到了对应的最大二阶弯矩、C_(mx)系数的表达式,基于边缘屈服准则确定了轴压力-弯矩相关方程。对比了C_(mx)系数与《钢结构设计标准》(GB 50017—2017)中的等效弯矩系数,并通过数值算例验证了分析结果的正确性。结果表明:对于横向荷载作用下两端简支初弯曲压弯构件的平面内失稳,不需要采用等效弯矩概念和等效弯矩系数进行内力的确定,GB 50017—2017中的等效弯矩系数未实现等效的效果;当采用《高强钢结构设计标准》(JGJ/T 483—2020)设计压弯构件的平面内稳定时,建议采用C_(mx)系数代替GB 50017—2017中的等效弯矩系数。

Based on the member direct analysis method,the general analysis process of in-plane stability of simply supported initial bending members under combined axial compression and bending was established,and the general expressions of deflection and second-order moment were obtained.Taking the initial bending members under combined axial compression and full-span uniform load or mid-span concentrated load as the research object,the position of the maximum second-order moment was determined by the combination of expressions and figures,and the corresponding expressions of the maximum second-order moment and C_(mx)factor were obtained.Based on the first yield criterion,the axial force-moment correlation equation was proposed.C_(mx)factor was compared with the equivalent moment factor in the Standard for Design of Steel Structure(GB 50017—2017),and the correctness of the analysis results was verified by numerical examples.The results show that for the in-plane stability of simply supported initial bending members under combined axial compression and bending,it is not necessary to use the concept of equivalent moment and the equivalent moment factor to determine the internal force,and the equivalent moment factor in GB 50017—2017 does not achieve the equivalent effect.When the in-plane stability of simply supported initial bending members under combined axial compression and bending is designed according to the Standard for Design of High Strength Steel Structure(JGJ/T 483—2020),it is recommended to use C_(mx)factor instead of the equivalent moment factor in GB 50017—2017.