The Floating Roof

The Floating Roof

Novartis, the multinational pharmaceutical giant, has its headquarters in Basel, Switzerland, a 50-acre campus with numerous buildings that are at the center of the company’s global empire. The campus has a master plan designed in 2001 by Vittorio Magnano Lampugnani, and includes a decidedly non-conformist Frank Gehry building amidst its many more rectilinear structures.

The Main Gate, or Reception Building for this vast enterprise is a stunning glass-walled structure designed by architect Marco Serra who, since 2003, has worked directly for Novartis and is responsible for the Novartis Campus Master Planning. (Since 2014, he is also the Global Novartis Chief Architect.) The walls are entirely glass, with no other hidden structural supports The “front desk” has no glass partition separating visitors from the reception staff and the interior, either (although a glass partition comes up at night when no one is on the desk). The design intended to create a sense of clarity and openness.

But what kind of a roof can you put up that can be supported only by glass? Composite, of course.

The glass wall panels are not flat panes, but rather, shallow U-shapes. The large “bottom” of the U forms the façade surface. The two legs of the U are oriented toward the interior of the building, fins that give the panel structural stability and rigidity. They are joined across the top by a steel band to help resist in-plane loads. Vertical loads are transferred to the glass panes near the fins. Tension rods between the fins are anchored to the underside of the roof to secure it against uplift.

The roof is rectangular in plan, but the elevation is a tapered shape reminiscent of an airplane wing. Three sides come to a tapered edge. The fourth side is cut off to expose the wing profile and emphasize its shape. The entire roof was made in four sections, fabricated off-site and then transported to the campus for installation. Fully assembled, it measures 21.6 x 18.5m (71 x61 ft).

The roof is a sandwich system of glass fiber reinforced polymer (GFRP), constructed using a concept we have seen employed, to a more limited degree, in the CabinCube, and rather extensively in the Fiberspan Bridge at Wolftrap. The roof is composed of long, narrow strips of PUR foam, CNC-milled to the proper shape, and then hand-laminated with glass fiber fabric on all surfaces. Each strip thereby becomes a small box-beam, its vertical faces forming the webs of the beam. They were then lined up side by side on an adjustable scaffold, and their vertical faces joined with resin. The laminated strips were joined into blocks, and finally, laminated together with a GFRP face sheet into a large panel. At this point, the panel was upside down relative to its final orientation in the roof. FRP plates were attached to help flip the panel over, and then the other face was laminated. They got a UV resistant top coat that also enhances the waterproofing of the roof. This was done for each of the four large roof sections.

The four pieces were then trucked to the site (stacked up two high), assembled on scaffolding, and laminated together. Finally, the glass façade was installed under the roof, and the scaffolding removed.

The effect is not only of transparency – being able to see clear through the building – but also of weightlessness of the floating canopy. It is a bold corporate statement (perhaps rather at odds with the security function of the building) and a very neat visual achievement.  If could only have been achieved using a very light, strong material like GFRP.

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