Crystal and cloud: Musée des Confluences by Coop Himmelb(l)au
Architect: Wolf D. Prix / Coop Himmelb(l)au
Location: 86, quai Perrache, Lyon 69002, France
This special location is also reflected in the long, triangular shape of the building. The museum, which was erected on supports, rises above a plot of land measuring around 21,000 m². With dimensions of 180 metres in length, 90 metres in width and up to 37 metres in height, the building offers about 30,000 m² of usable space and a gross floor space of about 46,000 m². Visitors can meander, like a river, among both closed-off and open exhibition spaces and can access new currents of knowledge by means of countless passages, ramps and levels.
The steel-and-glass façade of the city’s new trademark was constructed by the German company Josef Gartner GmbH. The complex shape of the building, designed by the Viennese architects surrounding Wolf D. Prix of Coop Himmelb(l)au, consists of a crystal and a cloud. In order to build such free architectural shapes, Gartner’s engineers had to overcome several statics-related and structural problems and develop entirely new solutions.
The architects and Gartner engineers worked together to make a 30-metre-high funnel of steel and glass for the entryway and optimize the nodes of the steel construction. Using a 3D computer model, every single one of the 160 nodes was individually designed, into each of which six steel struts made of rectangular hollow profiles flow together. The direction and axis of each splice plate were determined for each node at the computer; this enabled both the correct cutting of the hollow profiles and a more elegant design for the nodes themselves.
The 30-metre-high funnel required the manufacture of spherically formed panes, which pushed the designers to the edge of what is technically possible. Until now, curvatures with radii of under 500 millimetres existed only for the cockpit windows of jet planes. The museum’s extra-large panes, which have an edge length of up to 4.5 metres, underwent a complex manufacturing process and were curved while warm in order to achieve the desired shape. Only then could the edges be sanded to the exact measurements so they would fit to the millimetre.
The steel construction of the ‘crystal’ in the entrance area comprises 32 differently inclined surfaces which Gartner created from about 650 tonnes of steel. In order to avoid gaping joints in the complex geometry, parts of the primary and secondary steel structure were connected with screws inserted in profile. The upper plate was set back a few millimetres before being welded to the pipe. The steel components are force-locked so that the high pressure will be transferred only over the wall of the pipe. A strictly controlled prestress sequence ensures a homogeneous distribution of tension at the junction points in a cross-section of pipe. After painting the pipe walls, these joints are no longer visible on the completed structure.
Furthermore, Gartner developed a new technique for connection and assembly: rods with two-sided ball joints which balance out installation tolerances in all directions. Many trips with special transport were required to get the building components from Gundelfingen an der Donau to the construction site: the largest steel pieces were up to 4.5 metres wide and 20 metres long.