Q460高强钢焊接工字形截面单伸臂梁整体稳定性能与设计方法研究

为研究Q460高强钢焊接工字形截面单伸臂梁的整体稳定性能以及完善规范中关于此类构件的设计方法，进行了6根集中荷载作用下Q460高强钢焊接工字形截面单伸臂梁的整体稳定性能试验，测量了试件的初始几何缺陷和截面残余应力。试验结果表明：当单伸臂梁整体失稳的控制梁段位于简支跨时，单伸臂梁的整体稳定承载力随伸臂长度比的增大而减小，截面高宽比较伸臂长度比对单伸臂梁整体稳定承载力的影响更大。在试验基础上，运用有限元程序创建考虑初始几何缺陷和残余应力的有限元模型对试验进行模拟，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，分析荷载形式、荷载比例、简支跨长度、伸臂跨长度和截面高宽比等因素对Q460高强钢焊接工字形截面单伸臂梁整体稳定承载力的影响规律。基于特征值屈曲分析结果，回归出单伸臂梁的弹性屈曲临界弯矩计算公式，并通过对试验结果和有限元参数分析结果的回归提出了Q460高强钢焊接工字形截面单伸臂梁的极限弯矩计算公式。

DESIGN METHOD AND GLOBAL BUCKLING BEHAVIOUR OF Q460 HIGH STRENGTH STEEL WELDED I-SECTION OVERHANGING BEAMS

To investigate the global buckling behaviour of welded I-section overhanging beams of Q460 high strength steel and to develop the global buckling design method for such beams in the code, six overhanging beams were totally tested under concentrated loads. The initial geometric imperfections and the residual stresses were all measured. The test results show that when the dominative stability segment of specimens is located in the simply supported span, the global buckling capacity of the specimens decreases with the increase of the overhanging’s length-to-span ratio and the height-to-width ratio of the cross section has a greater effect on the global buckling capacity of the overhanging beam than that of overhanging’s length-to-span ratio. By the grounds of the test, the finite element model considering initial geometric imperfections and residual stresses was developed. The model was validated against test results, and a good agreement was obtained. According to the validated finite element model, parametric studies were carried out to analyze the effects of the loading form, of the loading ratio, of the simply supported span length, of the overhanging length and, of the height-to-width ratio on the global buckling capacity of welded I-section overhanging beams of Q460 high strength steel. Based on the results of eigenvalue buckling analysis, the calculated formulas of elastic critical moment for the overhanging beam were obtained by regression. Furthermore, the calculated formulas of ultimate moment for the Q460 high strength steel welded I-section overhanging beam was proposed through the regression results of test and finite element parametric analysis.