The Stele is an 85 metres high obelisk, made of reinforced concrete for the first 9 metres and of steel with welded plates for the upper 76 metres.
An experimental campaign was carried out at PoliMi’s Wind tunnel in order to define wind loads to consider in the structural design and possible interventions aimed at mitigating the dynamic effects due to wind action.
The design and construction of a “sectional” stiff model with constant section – representative of the aerodynamic properties of a suitable portion of the stele – allowed the testing in “rigid” and “free motion” conditions in order to define the aerodynamic static properties, the dynamic responses of the structure due to vortex shedding phenomena and investigate the possible dynamic instability of the model due to wind-structure interaction.
The results of the experiments in the wind tunnel underlined the pressing need to increase the damping of the structure in order to avoid critical speed of galloping and vortex shedding among the design speeds.