柔性张拉构件补强下细长结构稳定性的基础性研究

Preliminary study on stiffening effect of flexible tensioned components to the stability of slender structures

为了分析膜、索等结构中柔性张拉构件在张力作用下对柱和拱的补强作用,基于静力平衡方程,在折线索上作用有集中荷载的情况下,提出虚拟弹簧刚度系数的概念并推导其计算式。在此基础上,分别得出一组和二组折线索-柱模型的屈曲控制方程,并采用非线性有限元分析进行对比。分析结果表明:有限元分析结果与理论分析结果吻合。补强效果中,折线索弹性刚度的贡献可以忽略,索张力起主要作用;随着折线索上荷载的增大,柱的屈曲荷载存在着先增后减的规律;折线索会起到类似铰接约束的作用,使得柱的屈曲模态发生迁移;与一组索补强效果相比,两组索补强下柱的屈曲荷载的最大值变化较小。最后,对曲线索-柱模型和曲线索-拱模型分别进行研究,分析结果表明,曲线索上集中荷载存在一个最优值,使得柱和拱的屈曲荷载取得最大值。

Flexible tensioned components such as membrane and cable may provide stiffening effect to column and arch. By using equations of static equilibrium,when concentrated loads are applied on polyline cables,a concept socalled stiffness of pseudo-spring is proposed and calculated. In addition,in-plane buckling control equations for columns stiffened by one pair and two pairs of polyline cables are derived and verified by nonlinear FEA respectively.It is found numerical results are in accordance with theoretical ones. Furthermore,it is tension rather than elastic stiffness of the polyline cables that contributes to stiffening effect. With concentrated loads on cables increasing,the critical loads of column will firstly increase then begin to decrease. The polyline cables can play a role similar to hinge constraint,and cause the transference of buckling modes of column. The critical loads of these two patterns of columns do not change so much. Finally,analysis on column and arch stiffened by curved cables shows that there are optimal concentrated loads on cables to obtain maximum critical loads.