steel design working detail
The new orangery, in the grounds of Prague Castle, is a delicate tubular lattice of steel and glass, 100m in length. The enclosing envelope is formed of faceted frameless glass panels, suspended from a grid shell of tubular steel members. It replaces a glazed orangery, originating from the sixteenth century, of which only the rear brick wall remains. The new orangery is set against this rear wall but is not supported by it; a tubular steel prismatic truss beam runs above the wall to support the new grid shell.
The interior of the orangery is divided by two frameless glass walls into three sections, each approximately 27m long, with differing climatic control for propagating and displaying plants. The glass walls are set between paired steel 60.3mm-diameter chs columns, which support the prismatic truss beam, and between tubular steel cross-frames, which follow the profile of the steel grid shell and stabilise its edges. The prismatic beam components comprise high-tensile steel 88.9mm-diameter and 76.1mm-diameter chss whose ends taper to welded joints.
The grid shell is made up of a series of X-shaped frames consisting of four 60.3mm-diameter x 5mm chss welded together. They are of Grade 304 stainless steel with a bead-blasted finish. Their ends are fitted with solid stainless-steel machined nodes. They are connected together to form a grid which runs diagonally across the faceted glass enclosure. Each node connection consists of an upper and lower clamping arm, held together by a M16 bolt. The corners of four glass panels meet directly below the node connections and are bolted to them by 30mm stainless-steel arm supports. The panels, two layers of laminated 8mm toughened glass, are bonded with black silicone.
The grid shell members are bolted to a concrete plinth along the front edge and arch over to the prismatic truss beam along the rear wall.