The glazed elements are fixed to a reticulated bolt which via stainless steel spiders fixing is fixed directly to the structure. The spider fixing can either be fixed directly to a steel structure or to a vertical glass fin. There is often no aluminium grid behind the glass with the only external visible support being the flush fitting reticulated stainless steel glass bolts.
THE PIRELLI HQ PROJECTSuspended bolted façade, fitted with upper glass blocks
(west elevation 2500 m2)
The west elevation of Pirelli Headquarters , with its suspended bolted façade, represents one of the main architectural landmarks in Italy due to its technology and size. The whole system is suspended from a steel beam with a single span 40 m in length. In addition the steel structure of the façade consists of 11 laser cut tubular beams (diameter 150 mm) set horizontally. Each one is circa 40 m long and 2,5 deep, these are anchored similarly to upper beam and remain suspended by means of tubes 100 mm diameter at 3 metre centres, alternating with 60 mm diameter tubes also at 3 m centres. The steelwork was cut using lasers with a maximum tolerance 0.2 mm and welded using robotic technology. This use of the most up-to-date industrial methods meant the maximum deviation tolerance would be 0.5 mm. Even thought not specifically requested by the Design Team, the welding was subjected to non destructive testing. All steelwork has been sandblasted and has a coating of oven baked paint fixings and “spider” clamps for the glazing are in stainless steel. The load bearing steel beam has been pre-stressed to ensure that it has a zero deflection when supporting the glazing. To allow glazing installation the glass load had to be simulated by use o a threaded rod attached to every mullion, which could be regulated as installation progressed to ensure an even loading. The average size of the glazed modules is 1500mm x 3840mm. The glazing is laminated with an external sheet 12 mm thick, toughened with Heat Soak Test, laminated to an 8 mm heat strengthened inner pane, it is fixed to the structure by 6 no. “spider” fittings. This system was thoroughly tested to ensure that if the glass broke, and there was a wind blowing, glass fragments would not fall causing a hazard to persons below (the height of the façade is 40m).
bolted façade Pirelli Headquarters