贺拥军 金志文 周绪红

摘   要：研究了拉索预应力折线型立体桁架拱中的拉索参激振动问题，使用ANSYS软件建立预应力拱有限元模型，分析了结构中拉索发生参激振动的可能性，采用非线性时程分析方法研究了结构在简谐加速度激励和地震作用下的动力响应，以及桁架拱拉索发生参激振动的诱发机制，考察了预拉力、激励幅值对拉索振动的影响. 研究结果表明：激励幅值一定，简谐激励频率与拱内侧拉索自振频率成2.05 ∶ 1关系时，将激发拉索的参激振动，拉索振幅较未发生参激振动时增加了约63倍，拱节点位移及杆件内力均有部分增加;地震波频率集中于拉索发生参激振动的频率范围时拉索有较大响应. 为保证预应力巨型网格结构在地震作用下的安全使用，需考虑拉索参激振动对结构的影响.

关键词：折线型立体桁架拱;拉索;参激振动;地震响应

中图分类号：TU393.3                           文献标志码：A

文章编号：1674—2974（2021）01—0117—09

Abstract：The parametric vibration of cables in the pretensioned folded line type 3D-trussed arch was studied and the finite element model of pretensioned arch structure was established to investigate the possibility of parametric vibration of cable by utilizing ANSYS. The nonlinear time-history analysis method was adopted to study the dynamic response  of the structures under different frequency harmonic load and seismic waves and to investigate the mechanism of parametric vibration of cable arch structure. The influence of parameters， such as the prestress and excitation amplitude， were investigated. The results indicated that the cable parametric vibration appeared when the ratio of the excitation frequency to the natural frequency of cable was 2.05 ∶ 1，the amplitude of cable increased by about 63 times and the response of some key nodes and members in the structure increased; the cable had a relatively large response when the frequency of the seismic wave concentrated on the frequency range in which the cable had a parametric vibration. The effect of cable parametric vibration on the structure response was necessary to be considered for ensuring the safety of the structure under earthquakes.

Key words：folded line type 3D-trussed arch;cable;parametric vibration;seismic response

近年来提出的预应力巨型网格结构[1-3]，是在网格结构中布置预应力高强拉索而形成的一种刚柔组合空间结构体系. 预应力的引入有效地改善了结构的静力性能及稳定性，从而进一步提高了结构的跨越能力. 预应力拉索作为结构主要受力构件，具有大柔度、小质量、小阻尼的特点，在地震作用下呈现高度非线性，当结构的振动频率与拉索频率满足一定关系时，激发拉索的大幅度剧烈振动，拉索可能发生参激振动，引起拉索及其锚固端的破坏……