Wind Resistant Design of a Very Large Observation Wheel

From an aerodynamic point of view, very large observation wheels are complex structures. Several parts are slender with bluff cross sections, and therefore wind–structure interaction effects can influence their dynamic behaviour. Vortex-induced vibrations (VIVs), wake-effects, galloping instability, wind–rain interactions and buffeting response must be considered and studied during the design of substructures such as the A-frames and spoke cables. Both wind-tunnel tests and numerical tools can be used to assess the expected vibration levels and eventually to design appropriate countermeasures. In this paper, the Ain Dubai observation wheel is taken as a test case to present a procedure that can be applied to verify and validate the design of such structures when considering the effects of natural wind. For the A-frame, which turned out to be prone to VIVs during wind-tunnel tests on a scaled model, tuned mass dampers are studied as mitigation devices; for the spoke cables, several parameters affecting their aerodynamics were investigated in a wind tunnel on a full-scale model: inclination angle, structural damping and LED equipment. The characterization of these effects allowed both the performance of the cable damping system to be assessed, and configurations that could not perform adequately to be discarded.