The polycarbonate pyramids are formed from 6mm thick, flat sheets, three pyramids being made from each sheet. The chords are made from laminated timber. Short lengths are connected together at the cast aluminium nodes, to which the pyramids are attached, using glued joints. At the top of the pyramids, stainless steel discs are glued in two places to either side of the polycarbonate and to these is bolted a bent stainless steel plate, from which a rod with a rubber block cast on it projects radially. The rubber block has a push with the outer aluminium nodes; it is fixed by an outer cover plate with a screw fitting to the rod.
Although free to rotate radially, the cross-pin is fixed in the building's long direction so that wind forces in this direction are transferred to the 'ladders', which act as frames; the 'ladders' are connected to each other at the apex and mid-point on each side of the building. The cross-members of the 'ladder' are attached to the radial members with bolts. To prevent buckling, the inner radial edges of the pyramids, adjacent to joints, are stiffened by aluminium channels each side of the polycarbonate; the channels are bolted together through the polycarbonate, using slotted holes to allow differential thermal movement, and do not carry any axial load. The joint between the arch units is made watertight by an internal and external strip of transparent PVC.
The structural design is influenced by the need to allow for thermal movement of the polycarbonate. As the inner edges of the pyramids increase in length their radius of curvature also increases. This movement is largely unrestricted because of the pinned joints used, only secondary moments occurring in the elements.
Notes:
cross-pin n. поперечный штифт
curvature n. кривизна
disc n. диск
push n. толкатель, кнопка
PVC поливинилхлорид