含冗余拉索的棱柱型张拉整体结构成形过程分析

Analysis on forming process of prismatic tensegrity structures with redundant cables

为有效指导张拉整体结构的施工成形,对其成形过程进行仿真分析,并预测其所需经历的施工平衡状态.定义了一类带有冗余拉索的棱柱型张拉整体结构,采用解析方法研究其自应力模态、刚度等力学特性随相位角的变化规律.基于此类结构的拓扑关系,提出了设置临时吊点并分批次张拉2组斜索的成形方案,采用简化的动力松弛法对其成形过程进行逆向追踪.结果表明,通过控制杆件的轴向刚度模拟主动索的移除、被动索的松弛或张紧,可确保结构拓扑不因拉索退出工作而发生变化,算法稳定性好.将动力松弛法与反分析思想相结合可准确预测张拉整体结构成形过程的中间状态,并给出节点坐标、杆件内力等各项结构参数,为此类结构的施工成形提供理论依据.

To effectively guide the erection of the tensegrity structures, the forming process was simulated, and the intermediate equilibrium states were predicted. A kind of prismatic tensegrity structures with redundant cables was defined. The change rules of its mechanical properties including self-stress states and structural stiffness with the change of the twist angle were investigated analytically. Based on the topology of this kind of structures, a reasonable forming scheme was proposed in which some temporary lifting points were set and two groups of vertical cables were tensioned in batches. A simplified dynamic relaxation method was employed to track the forming process inversely. The results show that when the removal of the active cables and the relaxation or tension of the passive cables are simulated by controlling the axial stiffness of the members, the structural topology keeps invariant regardless of the withdrawal of the slack cables, and the stability of the algorithm is good. Combining with the inverse analysis, the dynamic relaxation method can accurately predict the intermediate states in the erection of tensegrity structures, and determine the key structural parameters such as the nodal coordinates and the internal forces of members, which provides a theoretical basis for the construction of such structures.