The Use of Structural Aluminum for the Design of Large Span Roofs: the Case of the 'Cubierta de Oviedo'

摘要

The architectural artwork "Cubierta de Oviedo" is located in the Buenavista building complex, it being the movable roof of the City of Oviedo (Asturie, Spain) conference centre. The original design and realization was by the archistar Santiago Calatrava (2004-11). The structure is made in steel. Since the testing of the structure, it was not possible to open the roof. From this occurrence, the idea to design the cubierta in structural aluminum seemed to be a challenge, due to the lowest weight of aluminum as respect to steel. In this perspective, the study focuses on the design of the main beam, spanning 134m total length, with 110m cantilever length, in the most unfavorable condition of open roof. The more appropriate aluminum alloy 7075 has been selected, according to the required mechanical properties. Considering the large height (4.20m) of the cross section, which is a special welded box section, for connecting the component elements, the Friction Stir Welding innovative technique is examined and proposed. The EC9 design codes for aluminum structures is applied with some adaptations due to the peculiarities of the structure. A comparison of steel and aluminum solutions is then presented, in terms of internal forces, mechanical efficiency, deformability, weight and costs, it evidencing the advantages of aluminum for large span roofs.