Elegant glass bridge at Portuguese research centre benefits from the high performance of SentryGlas® ionoplast interlayer
A visual highlight of the Champalimaud Foundation´s recently-completed biomedical research facility in Lisbon, Portugal is the lightweight steel and glass bridge that connects its two buildings. The glass envelope encasing the bridge consists of curved panels of laminated glass made with SentryGlas® ionoplast interlayer, specified by the structural engineers Schlaich Bergermann und Partner and the specialist contractor Bellapart on the basis of its decreased deflection and superior post breakage behaviour as compared to laminates made with PVB. Moreover, the proximity of the research facility to the sea meant that the excellent weathering and durability performance of laminates made with SentryGlas® were further criteria for their selection.
The ‘Champalimaud Centre for the Unknown’ was designed by Charles Correa Associates of Mumbai, India, and comprises two buildings set in a large public area that accommodate treatment units, research laboratories, an auditorium and exhibition area as well as the offices of the Champalimaud Foundation itself. The buildings are connected by a 21-meter-(60-ft)-long steel and glass bridge, implemented by Schlaich Bergermann und Partner of Stuttgart, Germany, Prof. Schneider from TU Darmstadt, Germany and Bellapart of Olot, Spain. The curved glass envelope for the bridge consists of several laminated glass panels, each typically measuring 1950 x 1320 mm (78 x 52") and produced by the Spanish laminator Cricursa using a comparatively lightweight construction of 8 mm (5/16") tempered HST glass + 2.28 mm (90 mil) SentryGlas® interlayer + 8 mm (5/16") tempered HST glass.
The panels are held in place by four custom-designed clamp plates from Bellapart, located at the glass vertices, whilst vertical steel rings positioned at every two meters along the envelope are used for its support. Reduced glass thickness and weight Calculations by Schlaich Bergermann und Partner, carried out in partnership with Prof. Schneider of the TU Darmstadt, confirmed that in order to achieve a comparable rate of deflection in similarly-sized laminated glass panels using a PVB interlayer, glass thickness would need to be increased from 8 + 8 mm (5/16") to 12 + 12 mm (15/32"). Not only would this add significant weight to the installation, requiring a more substantial supporting structure, but it would also become difficult to achieve the required radius for the curved panels.
Familiar with SentryGlas® from previous projects, Bellapart repeated the glass load calculations for a laminated glass panel made with the ionoplast interlayer to ensure compliance with safety requirements, as Carles Teixidor, industrial engineer at Bellapart explains: “Our own calculations verified the low rate of deflection of the laminated glass panels with SentryGlas®, below L/100 in the 8 mm + 8 mm (5/16") construction, which is achieved despite exposure to quite high wind loads resulting from its geometry as well as its proximity to the sea.