通过跨度60m圆形车辐式索桁架屋盖1:10缩尺模型的模态分析和模型试验,考察了拉索预应力、矢跨比及内外环直径比3个变化参数对结构自振特性的影响,对比分析了前四阶振型的试验结果与理论计算结果。试验和分析结果发现：结构第一、二阶振型为反对称上下振动,第三阶为内环扭转振动,第四阶为内环相对扭转振动；两者频率误差在10%以内,试验振型与理论振型基本吻合；前四阶振型的频率均在10Hz以上,表明车辐式索桁架结构为低频动力响应,自振频率较小且分布密集；预应力水平越高,振型频率越大,则结构刚度越大；矢高增加,结构频率随之减小,结构更容易发生侧向失稳；内外环直径比越大,结构扭转刚度相对会减小,容易发生扭转失稳。

Through the modal analysis and test of the 1:10 scale model of 60m circular spoke cable-trusses, the influence of 3 parameters of cable prestress, rise to span ratio and diameter ratio of inner and outer ring on the natural vibration characteristics of the structure were investigated. The results of test and theoretical of the first four order modal were compared and analyzed. It can be seen that: The first, second order vibration modes of the structure are antisymmetric upper and lower vibrations, the third order is the inner ring torsional vibration, and the fourth order is the relative torsional vibration of the inner ring. The frequency error is less than 10%, and the experimental mode of vibration is in agreement with the theoretical mode. The frequencies of the first four modes are all above 10Hz, indicating that the spoke cable truss structure is of low frequency dynamic response, and the natural frequency is small and the distribution is dense. When prestress level of the structure is higher, the modal frequency will increase, and the stiffness will also increase. With the increase of sagittal height, the structural frequency will decrease, and the structure is more prone to lateral instability. With the increase of the inner and outer ring diameter ratio, the torsion stiffness of structure will decrease and torsion instability will also occur.

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北京市科委科技新星计划（Z14110601814085）；住房和城乡建设部科学技术计划（2016-R2-043）。