Q460高强钢焊接工字形截面简支梁整体稳定性能与设计方法研究

Design method and overall buckling behavior of simply-supported beams with Q460 high strength steel welded I-section

为研究Q460高强钢焊接工字形截面简支梁的整体稳定性能,对跨中无侧向支撑的3个双轴对称和6个单轴对称焊接工字形截面简支梁进行了整体弯扭屈曲试验。实测了试件的截面残余应力和初始几何缺陷,并分析其整体弯扭屈曲变形特征和稳定承载力。建立考虑残余应力和初始几何缺陷的有限元模型对简支梁受力进行了模拟,模拟结果与试验结果吻合良好,基于试验验证的有限元模型计算了大量不同截面尺寸和跨度的Q460高强钢焊接工字形截面简支梁的整体稳定承载力。将试验和有限元参数分析结果与GB 50017—2017《钢结构设计标准》、JGJ/T 483—2020《高强钢结构设计标准》、欧洲规范EN 1993-2005和美国规范ANSI/AISC 360-2016的简支梁整体稳定系数公式的计算结果进行比较,结果表明GB 50017—2017和ANSI/AISC 360-2016的计算结果偏于不安全,EN 1993-2005的计算结果过于保守,JGJ/T 483—2020的计算结果偏于安全且最为接近。最后,在JGJ/T 483—2020的简支梁整体稳定系数计算公式基础上引入增大系数,并根据截面高宽比的不同,取用不同的长细比指数对该公式予以修正,修正后的公式更适用于Q460高强钢焊接工字形截面简支梁的设计计算。

In order to investigate the overall buckling behavior of simply-supported beams with Q460 high strength steel welded I-section, three doubly symmetric and six singly symmetric welded I-section beams without lateral restrains at the mid-span were tested. The sectional residual stresses and the initial geometric imperfections in specimens were measured, and the flexural-torsional buckling deformation and overall buckling capacity were analyzed. The finite element analysis models considering residual stresses and initial geometric imperfections were also established and verified by experimental results, and extensive finite element analysis were carry out to calculate the overall buckling capacity of these beams with various sectional dimensions and different spans. The test results and finite element parametric analysis results were compared with the overall buckling curves from GB 50017—2017 ‘standard for design of steel structures’, JGJ/T 483—2020 ‘Standard for design of high strength steel structures’, EN 1993-2005 and ANSI/AISC360-2016. It is shown that the overall buckling design methods in GB 50017—2017 and ANSI/AISC 360-2016 are unconservative, the design methods in EN 1993-2005 are much more conservative, and the design methods in JGJ/T 483—2020 are conservative and more appropriate. Finally, the increasing coefficient was introduced based on the overall stability coefficient formula for simply-supported beam in JGJ/T 483—2020, and the slenderness ratio index was adjusted according to the difference in the aspect ratio of the section. The revised formula is more suitable for the design calculation of simply-supported beams with Q460 high strength steel welded I-section.