三管梭形钢格构柱稳定极限承载力研究

Ultimate Load-carrying Capacity of 3-Pipe Shuttle-shape Steel Latticed Column

本文应用大挠度弹塑性有限元法对三管梭形钢格构柱进行了极限承载力分析。研究的重点放在梭形柱初始缺陷的分布形式和幅值大小对柱破坏模式的影响,同时分析了柱长度、柱长细比、分肢长细比、隔板数量和厚度对极限承载力的贡献以及对破坏机理的影响。分析结果表明,初始缺陷的分布形式和幅值大小对柱破坏形式起到决定性的作用;当梭形柱的初始缺陷分布形式与一阶弹性屈曲模态一致时,柱极限承载力最低。随着柱整体长细比的增加或隔板厚度的增加其破坏形式从“S”形向单波形转化,不过,随着柱单肢长细比的增加其破坏形式从单波形向“S”形转化,二阶效应是梭形柱破坏的主要原因。本文对广州新机场四根梭形柱进行了极限承载力有限元分析,初始缺陷分布取与一阶弹性屈曲模态相同,缺陷幅值大小取为L/500,其计算结果与足尺寸试验结果吻合良好。

The constitution of 3 pipe shuttle shape steel latticed column(SLC) is introduced, and the ultimate load behavior of this kind of columns is presented by employing an elastic plastic large displacement finite element analysis. Much more attention has been paid to the failure mechanism and influence of the initial geometric imperfection distribution forms and their amplitudes on the load carrying capacity of the column. The influences of some other parameters have also been taken into consideration including the column length, the slenderness ratio of the column and its single chords, the number of diaphragms and their thickness, etc. Conclusions have been drawn from the numerical results obtained that the column failure mechanism and associating load carrying capacity rely mainly on column length, its initial geometric imperfection distribution forms and their amplitudes. It is also found that the column failure mode switches from 'S'shape to single wave shape while the column slenderness ratio is or thickness of diaphragms increasing, and from single wave shape to'S'shape while the single chord slenderness ratio is increasing, and further, the second order effect is the main reason to cause the column failure. The FEM analysis results obtained for the columns used in engineering practice agree very well with those from the test, where it is assumed that the initial imperfection distribution is the same as the first elastic buckling mode with maximum magnitude of L/500.