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tHe LOuVReS
As the glass louvres have an expansion coef cient different to
that of the steel framework, the studs supporting the rocker arms slide freely in the vertical supports holding them in place, without exceeding the threshold value of 2 mm corresponding to the maxi- mum movement the louvre pivoting mechanisms can handle.
A vertical series of special louvres able to cope with a movement of 7 mm is nevertheless to be found to the right of each C anchor.
tHe BRaCING CaBLeS
The horizontal forces acting on the louvres are taken up by hori- zontal cables with diagonal trusses to the walkways on the rst and second oors and to all roof consoles. On each of the three oors, triangulations (integrated into the walkways on the rst and second oors) take up any horizontal forces, directing them to the building’s structure.
tHe aCtuatORS
Numerous constraints govern the complex geometry of the double skin facade. One of the most important involves the requirement to avoid con icts between, rstly, the vertical rods connecting the louvres to the actuators responsible for their rotation, and, sec- ondly, the diagonal trusses of the bracing, as these two elements are both in the same plane.
Each set of four motors on top of the facade actuates three or four adjacent sets of louvres.
The louvres of the four facades are thus controlled by 256 actua- tors (18 x 4 = 72 for each north/south facade, and 14 x 4 = 56 for each east/west facade).