The construction technologies and methods of the ferris wheel structure should be specified according to the specific structure and site conditions. At present, there are three main construction methods of existing ferris wheels which can be summarized as following.
1. Ground assembly and integral hoisting method
The rim steel structure of the ferris wheel is processed and assembled in section in the factory. After being transported to the site, the rim is assembled into a whole and then connected with the internal rigid truss support or the flexible steel cable system. Finally, the whole wheel rim is hoisted in place. The London Eye exactly adopted this construction method. The steel tube truss of the rim was processed in the factory in three sections and shipped to the site for assembly as a whole. Then the steel cables inside the rim were installed and tensioned, and the prestress was introduced. Finally, the hoisting was carried out after the wheel structure and the supporting tower structure were formed into an integral one.
Ground assembly and overall hoisting method is conducive to the installation of steel structures, and the installation accuracy is easy to be ensured. However, the scale and weight of the ferris wheel structure are generally large, requiring a large construction site and strong lifting capacity.
2. Center rotation installation method
The center-rotating ferris wheel refers to the installation method to set up the work platform by the supporting tower after the tower and the wheel shaft are installed in place, or install the ferris wheel structure from the center to the outside circle by circle through the use of lifting system. It is widely applied to some medium and small ferris wheel installation projects.
3. Vertical rotation installation method
Vertical rotation installation method refers to the construction method that adopts temporary rigid spokes to drive segmented rim and cable rotating installation after the tower and the wheel shaft are installed in place. This method is divided into one-side rotation installation and two-side rotation installation, which is suitable for the flexible ferris wheel structure system with the centripetal force provided by the steel cable.
The vertical rotation installation method can avoid a large number of high-altitude operations and has low risk; however, it requires a larger traction power system and a good braking system, especially the two-sided rotation installation method requiring special treatment on the central axis of the ferris wheel.