Credit: Tristan Cuisinier
It is called "Galéo" because it resembles a large upright pebble, its skin being composed of a well-ventilated double skin that contributes to temperature control of the offices. The inner concrete skin in which large windows are formed, forms the walls and roof and delimits the internal boundary of a buffer space inside which maintenance gratings are installed. The outer skin delimiting the external boundary of the buffer space is composed of some 700 silk screen printed glass scales and controls the quality of ambient light and the general appearance of the building, noble and opaline like the works of the famous glassmaster Émile Gallé.
Aurélie Bareille, CSTB supervisor for the ATEx file, explains that the project is exceptional firstly due to the large developed point-fixed structural glazing area to cover 8 floors and the roof of the ovoid1. It is also exceptional due to the through nature of the fasteners that support two large glass panes. The transparent glass panes are offset from each other in the horizontal plane, while overlapping in the vertical plane, creating lateral views that resemble those of the "Renaissance" hotel on Avenue de Wagram in Paris2: "The secondary frame is composed of stainless steel tubes fixed at the bottom and top by steel brackets forming part of the primary structure. Each of these tubes supports not only one but two 3.50 m high HST laminated glass scales through four fasteners with built in ball joints."
At the same time, CSTB implemented a test campaign based on the experimental protocol for point-fixed structural glazing3. In simple terms, the objective was to evaluate the deformation and strength of glazing and the different components of the structure under wind loads, and determine the allowable radii of curvature for ball joints.
1- The operation includes 4,000 m² of point-fixed structural glazing (AEG)
2- See the June 2009 webzine
3- Experimental protocol described in CSTB booklet No.35.74