The structure of the outdoor big observation wheel has a different structural form from other buildings, and its characteristics, the natural vibration, also have its own uniqueness. The modal analysis studying the Ferris wheel can intuitively reflect whether the structure quality and stiffness matrix are reasonable and whether the structure layout form is appropriate, so as to avoid the risk that the resonance may generate when the structures are under dynamic load.
First, the selection of the cross-section of the spoke cable is very important. The spoke cable of the flexible big observation wheel is the main component of the roulette mechanism. The vertical and lateral loads acting on the rim must be transmitted to the bushing through the spoke cable, and then transmitted to the next nodes and foundation through the bearing and the axis. The change of cross-section will directly affect the internal force distribution of the whole structure and the rigidity of the whole structure. If the cross-section is too small, the rigidity of the structure will be reduced, and the deformation will be too large; if the cross-section is too large, the weight of the structure will increase and it will not be beautiful.
Secondly, the big observation wheel is a flexible structure, and its prestress is a prerequisite for satisfying its own stiffness and bearing capacity. The prestress will produce a lot of pressure in the rim, thereby increasing the overall stiffness of the rim and having slight deformation when it is subjected to external loads, which will impact significantly on the structures’ natural vibration.
After the prestress is applied, the simple small deformation conditions are no longer applicable to the formation of the stiffness matrix and considering the nonlinearity of the structure, and the large deformation with geometric stiffness should be analyzed. The main factors that affect the structure's natural vibration characteristics are the diameter of the wheel structure, boundary conditions, and structural defects.