Incremental Launching of a Wide Span Glazed Roof

The main characteristics of this glazed roof were illustrated in Ref. [1]. In this paper the incremental launching erection method, which is unusual for wide span glazed structures, is described. This technique was applied earlier [2] but not for a glass dome structure. The glazed roof features a sub square plan with side dimensions of 58,52 m and 58,42 m and is composed of two orthogonal groups of tubular steel arches laid at typical centers of 4,238 m which support a secondary structure on 1,413 m by 1,413 m square grids bearing the stratified glass panes (Fig. 1). The edge arches, parallel to the sides, are supported by short struts hinged at both ends, while the orthogonal ones are pin-connected to supports, capable of resisting the vertical and horizontal components of the relevant thrusts. The dome is supported by four existing contour buildings, which were designed by other consultants as independent seismic resistant structures with a very wide, ultimate relative top displacement of ±300 mm (height of the building/100). In order to overcome the problem posed by such support conditions and to avoid any kind of coupling with the existing structures, the glazed roof was designed as a unit fixed to one of the above said buildings and sliding on the top of the three other ones. To equilibrate the horizontal thrusts, the contour supporting structure was designed as a horizontal frame with three sides composed of a steel truss resting on sliding bearings and the fourth one of a post-tensioned concrete beam anchored to one of the existing buildings.