大跨空间结构风致动力稳定分析

Wind-induced dynamic stability analysis of large-span space structure

研究大跨空间结构在随机数值风场作用下的动力稳定性能,并与静力全过程进行对比分析。以空间网架结构为例应用Abaqus对结构进行特征值分析,应用改进的弧长法对结构在非线性和带有初始缺陷的条件下进行全过程稳定分析,初步判定结构的失稳极限荷载,最后通过逐步增量动力分析对每个风荷载强度指标进行结构的弹塑性时程分析,并且利用Budiansky-Roth(B-R)准则判定结构的动力失稳极限荷载。结果表明:考虑非线性后的结构屈曲荷载因子降低了10%,当考虑脉动风的影响时,结构的极限承载力降低了29%。材料非线性和几何非线性对网架结构动力稳定性能有较大的影响,并且此类结构用静力方法分析它的极限承载力是偏不安全的,因此,网架结构在进行风荷载稳定性设计时必须进行动力稳定分析。

The dynamic stability of large-span space structure under static random numerical wind field was studied and then compared with that of the static whole process analysis. By taking a space-truss structure as an example, the eigenvalue analysis of the structure was conducted by Abaqus. The whole process stability of the structure under the conditions of nonlinear and initial defects was then analyzed by using the improved arc-length method. Therefore the instability ultimate load of the structure could be preliminarily determined. Finally, the elastic-plastic time-history analysis of the structure under each wind load was conducted by incremental dynamic method and the dynamic instability ultimate load of the structure was determined by Budiansky-Roth （B-R） criteria. The results showed that buckling load factor decreased 10% under nonlinear condition and ultimate load decreased 29% when fluctuating wind was considered. Both material nonlinearity and geometric nonlinearity had great impact on the dynamic stability of structure, and the analysis of such problems by static methods tends to unsafe. The stability analysis of space-truss structure under wind load must be carried out by dynamic method.