Structural glass engineering
Architects of prestigious buildings – whether in culture, politics or business – have always used glass as a design element. Yet today’s functional buildings tend to have shapes that go much further than pure expediency, and glass is therefore used more and more frequently as a structural support element. Historic, 19th-century examples include the greenhouses at Kew Gardens in London and at Laeken in Brussels: glass engineering of the highest standard and indeed over 130 years old. At the time flat glass was still rather a costly building material. The open greenhouses gave people an idea of state-of-the-art 19th-century engineering and of the owners’ wealth.
But the examples also show that glass helps to integrate a building skilfully into the surrounding landscape without disturbing its visual impact. Glass enlarges premises and provides a connection between the inside and the outside.
Glass has symbolic power
Inspired by this type of glass architecture, the renowned architect Frank Gehry recently designed an exhibition building for the Fondation Louis Vuitton in Paris which was opened in 2014 and shows how contemporary glass engineering can be realised at the highest level. Set within plenty of green space on the edge of the Bois de Boulogne, the twelve-part roof structure reminds us of two overlapping sails. Being a self-confessed sailing enthusiast, Gehry wanted to create the impression of a sailing boat moving ahead at full speed.
The total area occupied by glass – 13,300 square metres in all – consists of 3,600 panes, none of which are identical. The angle of the bend is different for each pane, ranging from flat to a 3-metre radius.
Moreover, the building material had to meet all the relevant safety engineering requirements, stipulated under French law. Gehry therefore decided to use laminated safety glass (LSG) in combination with a strong, highly rigid interlayer, 1.52 mm thick and made of SentryGlas® ionoplast from Kuraray Europe GmbH. The actual glass is prestressed, with panes that are six and eight millimetres in thickness. To meet the high standards of structural engineering, the LSG had to be freely shaped, using modified bending furnaces.
The 6-mm inner pane was given a reflective coat, with white ceramic screenprinting and 50% opacity – an important feature to protect the valuable exhibits from direct sunlight. Moreover, it creates a pleasant, non-glare lighting effect.
To ensure an undisturbed overall visual impact of the individual sails, the design engineers and the architect opted for an adhesive bond between the LSG and the frame and also as a filler for the wide expansion joints. They decided to use sealants from Dow Corning…
