3D tubular mesh as a girder for bridge design

The following paper will present a spatial tubular solution adopted for the design proposed for the new Langensandbrücke in Luzern-Switzerland. The image of the city of Luzern is linked to those of its famous covered bridges and the layout of the structure was conceived as a modern interpretation of wooden structure covering the renowned Kapellbrücke. Therefore the occasion to propose a main structure composed by a couple of truss girders formed by a number of inclined steel rings of different diameters able to hold inside a cycle track and the pavement for pedestrians and to support centrally the 5 lanes road on a total span of 80m. To support the simple even if non conventional conceptual design an accurate finite element analysis was performed on the structure to assess its stress state, its stiffness under design loads and its overall reliability. The design proposed reveals a strong symbolic value with non conventional structural solutions.