Reports Clamping strip PC sheet
seal
Warsaw [4, 5]. The fixing and sealing deviate from standard solutions commonly used for such building elements (Fig. 3). The tests confirmed that it was correct to use the double set of seals to ensure the tightness of the covering, thermal movement of the sheets and appropriate tolerances for delivery and assembly of loadbearing and covering elements (Fig. 4).
4 Support structure for covering seal Aluminium purlin Fig. 3. Standard method of fixing and sealing the polycarbonate sheets 120 seal
Clamping strip PC sheet 25
seal 25
Aluminium purlin Fig. 4. The fixing and sealing method used for the covering at the Gdan´sk stadium
of modules with a fixed width of 800 mm. Aluminium supporting elements are mounted at this axial spacing. Around the circumference of the facility, the sheet length is determined by a division imposed by the geometrical system of the upper chord of the support girder and the varying distance between girders. This method of coverage made it necessary to build each of its elements individually. A sheet with a specific geometrical format may be mounted in only two places on the stadium structure. The polycarbonate sheets are mounted on two long edges – on aluminium purlins equipped with a set of seals. Along the shorter edges located at radial gutters, the sheets are seated on special elements only, i. e. so-called “parapets” equipped with seals in the sheet support zones. The method of fixing and sealing the sheets was developed following additional tests carried out by the Institute of Building Technology in
The purlins for the polycarbonate covering were made of individually designed aluminium sections with closed cross-sections and various depths ranging from a minimum of 25 mm to a maximum of 225 mm (Fig. 5) [7]. The individual fabrication options for the sections made it possible to select optimum depths for the sections to suit the spans between the support points on the girders and the distribution of loads. The sections were made of aluminium to EN AW-6060 (EN AW-AlMgSi) and PN EN 573-3:2009, and the supply conditions of T64 to PN-EN 515:1996. An extrusion method was employed to produce the sections. This production technology made it possible to supply loadbearing sections together with support elements for the plates and elements used for fixing seals. The small fall on the roof part of the covering meant it was necessary for purlin sections used in this part to be bent to enable rainwater to drain away from the polycarbonate sheets and directly into the radial gutters. The bending radius was 50 m in the section between circumferential gutters Nos. 1 and 2. The elements were bent cold in a fabrication plant using appropriate roller bending machines. Straight elements were used on the façade part. Gutter support elements were made from aluminium sheets in sections with a modular length of 800 mm. The metal gutter is merely a support element, which gives a basic shape to the rainwater drainage elements made from a modified PVC reinforced roof film. The elements of the aluminium structure carrying the external covering are fixed to the main steel roof structure with the help of support elements that allow adjustment of their positions with respect to one another. The adjustment made it possible to mount loadbearing elements for the covering in compliance with the fixed assembly spacing regardless of tolerances for the steel roof structure as built. The connection consists of two parts: a) Fixed part – in the form of steel support brackets welded to the main roof structure. The elements were used for profiling the support surface for the covering. The support plate of the bracket was equipped with elongated holes for adjusting the location of subsequent elements.
Fig. 5. Aluminium sections for roof purlins
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