Abstract:Through the modal analysis and test of the 1:10 down-scale model test of 60 m circular spoke cable-trusses, the influences of three parameters including the cable prestress, rise to span ratio, as well as the diameter ratio of inner and outer ring on the natural vibration characteristics of the structure were investigated. The results obtained from test and theoretical formulation of the first four order modal were compared and analyzed. It can be seen that:The first and the 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 good agreement with the theoretical mode. The frequencies of the first four modes are all larger than 10 Hz, 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.