Mercedes Benz, nuova ABC
Photos: D. Domenicali
The headquarters for the largest Mercedes Benz dealership in Italy, “Nuova ABC” designed by TECHN-ARCH ENGINEERING, has recently been constructed within the “Tecno Città” district in Rome.
The building, intended to be an architectural symbol of the technical evolution of Mercedes, is a modern glass envelope in contrast to the three historic towers in the immediate vicinity.
The main characteristic of the development is the visual contrast between the curved façades of the Showrooms, the horizontal façades of the offices and the vertical façades of the Stair cores and car ramp.
The potential of the Focchi design and engineering dept. with its sophisticated and individual approach to every section of the project by their use of 3-D modelling, allowed for the design team to preview the "Panorami" structural façade, to ensure the regularity of the trapezoidal and triangular glazing .
The initial geometrical and structural data consisted of:
Spatial coordinates of the roof nodesStructural nodal characteristics
The architect required a "mushroom" façade, fully glazed. The lower portion of the façade was to be curved, with variable radiuses on each side, and the height ranging from 3000 mm to 6000 mm. The upper part, bending outward, was to be continuously inclined, but the upper and lower levels of this inclined plane were variable. The polyhedral plan was required to connect with the lower vertical façades with fully glazed corners.
The following solution was adopted:
The static analysis of deflection when under load resulted in a "broken" solution for the mullions. Vertically the "Panorami" was reinforced by an additional structural aluminium mullion anchored and fixed at floor level, whilst the fixing to the lower spheres of the roof frame was "floating" to allow for any movement in the façade. Diagonal steel connections "hang" from the highest "spheres" of the roof level frame and are pinned at their lower level to allow for thermal movement. As the polyhedral surface would imply vertical dihedrals between the upper mullions, a bespoke version of "Quadra" was adopted, involving the glazing to be structurally bonded on mullions designed on purpose for this application.
The design of fixing brackets was complicated by the need of transferring the concentrated load to the local supports of the three-dimensional roof structure. In particular, due to the variable rotation around the theoretical plan corner axis imposed to the upper "Quadra" mullion by the 3-D model dihedral, the fixing system allowed the mullion a free rotation during installation, until the theoretical position was assumed.
The profiles were automatically shaped by the 3-D software, programmed on purpose for this project. The "puzzle" installation method, therefore, did not need any site measurement or complicated lining.
The surfaces were to be connected three-dimensionally, following the alignment of corner spheres of the roof frame. The design of the corner glazing was performed by adopting a repetitive programme. Where the panes resulted in a curvature which was not acceptable for the design solution, these were broken at the curve of the pane and the edges of the new panes were ground then re-assembled to provide an acceptable flat pane. Where necessary the aluminium frame elements were welded to conform to the angular structure of the new panes.
Copings and intermediate flashings deserve a mention too. Their shape was automatically designed and formed by our use of bespoke software, allowing us to use complex cutting angles and welded edges to allow an effective sealed joint.
The adopted cladding system is the same of typical façades, but due to the complete transparency, all fixing bracings and ironmongery is stainless steel.