Aluminium domes of the Enel plant in Civitavecchia, Italy
Department of Structural Engineering, University of Naples “Federico II”, Italy
Two aluminium domes have been erected within the thermo-electrical power plant of the Italian Electrical Department (ENEL) in Torreveldaliga Nord near Civitavecchia, Italy. The two reticular space structures are 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 for sure one 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 structural steel and a corrosion resistance compatible with the aggressive environment, since the plant is located close to the Tirreno sea cost. The design of the domes has been done following 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. The wind load effect is more severe than the earthquake for this type of structure, which is partly due 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 that the satisfactory behaviour of the domes is 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 that of steel. In addition, the good corrosion resistance allows avoiding any protective coating. Considerable 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 of an aluminium solution that can compete with a steel solution.
Key words: Dome, space truss, large span, aluminium, coal storage, power plant