高强钢焊接工字形截面压弯构件局部—整体相关屈曲

发布时间：2018-07-27 13:30

【摘要】：用高强度钢材做成的构件长细比不宜太大，而板件宽厚比较大，因此，局部和整体相关屈曲很重要。对工字形截面构件，腹板局部屈曲并不意味着承载能力的丧失，适当放宽腹板高厚比，并利用腹板屈曲后强度，可以达到提高承载力、节约材料的目的。本文采用有限元法分析了腹板高厚比超限的Q460钢焊接工字形截面压弯构件的极限承载力；研究了腹板高厚比、翼缘宽厚比、构件长细比和偏心率对其相关屈曲性能的影响；对部分构件在不添加残余应力或初始几何缺陷时进行重新计算，分析了初始缺陷的影响；提出了计算Q460钢压弯构件局部-整体相关屈曲极限承载力的修正公式。研究表明，文中有限元模型能很好地模拟腹板高厚比超限的工字形截面压弯构件非线性屈曲性能。腹板高厚比增大，构件极限承载力提高，腹板屈曲后强度保持能力增大，，构件延性增大。相反，翼缘宽厚比增大，极限承载力减小，腹板屈曲后强度保持能力减弱，延性降低。长细比增加，刚度明显减小，极限承载力降低，延性却增大。偏心率增大，弯曲变形起主导作用，跨中挠度急剧增加，而轴力的变化相对变缓。初始缺陷的存在对极限承载力降低作用显著。提出的修正公式计算结果与有限元结果吻合很好。
[Abstract]:The aspect ratio of the components made of high strength steel should not be too large, while the width and thickness of the plates should be large. Therefore, the local and global buckling is very important. For I-section members, the local buckling of web does not mean the loss of load-bearing capacity. By loosening the ratio of web height to thickness and utilizing the strength of web after buckling, the bearing capacity can be improved and the material can be saved. In this paper, the finite element method is used to analyze the ultimate bearing capacity of Q460 steel welded I-section compression and bending members whose web height / thickness ratio exceeds the limit, and the effects of web height to thickness ratio, flange width to thickness ratio, length to thickness ratio and eccentricity on the buckling performance of Q460 steel are studied. The effect of initial defects is analyzed by recalculating some members without adding residual stress or initial geometric defects, and a modified formula for calculating the ultimate load-bearing capacity of local and global buckling of Q460 steel compression and bending members is proposed. The results show that the finite element model in this paper can well simulate the nonlinear buckling behavior of I-shaped bending members with cross section. The ultimate bearing capacity of the members increases with the increase of the ratio of height to thickness of the web, the strength retention capacity of the web after buckling increases, and the ductility of the members increases. On the contrary, when the flange width to thickness ratio increases, the ultimate bearing capacity decreases, and the strength retention capacity and ductility decrease after buckling of the web. When the aspect ratio increases, the stiffness decreases, the ultimate bearing capacity decreases, but the ductility increases. With the increase of eccentricity, the bending deformation plays the leading role, the deflection in the span increases sharply, and the axial force changes relatively slowly. The existence of initial defects has a significant effect on the reduction of ultimate bearing capacity. The calculated results of the modified formula are in good agreement with the finite element results.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU392.1

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