Two twin aluminium domes have been erected within the thermo-electrical power plant of the Italian Electrical Department (ENEL) in Torreveldaliga Nord near Civitavecchia (Italy).

They are two reticular space structures shaped as geodetical domes (with 144 m diameter and 50 m high) made of aluminium alloy tubes and stainless spherical nodes, according to the MERO system. The two domes are the largest built in Europe and surely ones of the largest in the World. Their function is for coal storage, according to the requirements of the thermo-electrical power plant.

The aluminium alloy 6082 T6 has been selected in order to obtain both a mechanical strength comparable with the one of steel and a corrosion resistance compatible with the aggressive environment, being the plant located close to the Tirreno sea cost.

The design of the domes has been done following the Eurocode 9, also considering the “design assisted by test” approach. In fact, a series of tests has been planned in order to qualify the structural behaviour of each material, component and substructure. The global behaviour has been analysed by means of sophisticated numerical models and wind tunnel tests have been also done, being the wind load effect more severe than the earthquake for this type of structure, also thanks to the lightness of the structural material.

During erection, very comprehensive quality control and qualification tests have been planned. The final proof tests on the whole structure, both static and dynamic, confirmed the satisfactory behaviour of the domes in good agreement with the numerical prediction.

This challenging application demonstrates once again that aluminium alloys are excellent structural materials with a strength-to-weight ratio more than twice the one of steel and in addition the good corrosion resistance allows avoiding any protective coating. Non negligible economical advantages have been obtained for the structure itself, the foundation dimensions and, last but not least, the maintenance cost. The two aluminium domes represent a clear example in which this aluminium solution can be competitive versus a steel one.