Lotschnitt

9 | Base of main rib, scale i:20.The L-shaped concrete ring beam has a bevel in the internal angle which forms the bearing perpendicular to the incoming timber rib. After correct positioning of the rib, the lateral 12 x 100 x 310 mm lugs are welded onto the embedded steel plate. The connection to the beam is via one M24 bolt and four screws. The larch wedges assist correct positioning. The wind girder anchor is provided on the vertical leg of the reinforced concrete beam; the detail is similar to the main rib connection except that two welded stiffeners are included and the two bolts pass through elongated holes. Two threaded bars are glued into the end of the rib to prevent shear failure of the timber.

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Only where greater forces are encountered, like in the wind girders, are the purlins fixed with Mi6 threaded bars passing right through the beams.

The supports for the main beams on the concrete ring beam are designed in such a way that all steel parts remain easily visible for inspection purposes and that any voids or joints formed remain open for good ventilation. Therefore, each main rib is fixed to the support by two 20 mm steel flats, one on each side, held in place by one M24 bolt and four screws. After correct positioning, these flats are welded onto the pre-aligned bearing plates embedded in the concrete. In the case of the wind girders, the upper part of each rib is also held by two stiffened 8 mm steel flats fixed with two nails and two M20 bolts, and welded onto steel plates anchored in the concrete. However, here the bolts pass through elongated holes as this fixing is only designed to take the thrust from the wind girder which is positioned further up the main beam and which would otherwise subject the rib to torsion because of the fixture at the base.

The above-mentioned joint at the crown of the dome consists of a 600 mm high x 500 mm dia. steel tube with a wall thickness of 15 mm. It is stiffened by two inner steel rings and X-bracing made from steel flats. Steel flats, 200 mm high, are welded on for the mounting and lateral positioning of the incoming ribs. For the wind girders, which are erected first, extra V-shaped shear protectors are welded on. The ends of the ribs and wind girders incorporate 10 mm steel flats that are connected to the ribs via flats let into slots in the ribs and two 20 mm dia. steel dowels per joint. Each rib or wind girder includes one 24 mm bolt welded onto this steel end plate which fits into a corresponding, pre-aligned hole in the steel tube of the crown hinge when erecting the member. The bolt is then tightened from inside the tube. The whole detail is designed in such a way that any condensation water which occurs can drain away and no hidden water traps are formed.

Large glassfibre-reinforced plastic sheets, 10 mm thick and with 100 x 100 mm strengthening ribs, form the covering to the dome. Each of these sheets covers one bay, i.e. the area bounded by two adjacent beams and purlins. The sheets are curved in both directions to match the curvature of the dome so that a smooth outer surface ensues and not a spherical polygon. They are fixed to the ribs by means of aluminium rails which hold the sheets down by means of bolts. There is a plastic extract dome at the crown, 3 m in diameter.

The structure has remained in unexpectedly good condition. After eight years an inspection revealed that all timber was free from defects or discolouration. All steel connections were also found to be unchanged. The occurrence of condensation water well above the level anticipated was noted but is not a cause for concern, merely leading to plans on how such large amounts of water at the supports can be drained off.

i | Site plan of whole complex, scale 1:4000. Left, the production building by Thomas Herzog, including the planned extensions.

2 | Architect's sketches showing the development of the "distinguishing feature".

2 | Architect's sketches showing the development of the "distinguishing feature".

3 I Plan of mezzanine floor, scale i:iooo. The roofs over the production bays are supported on the intermediate 5.40-m-wide H-frame blocks. The main axes of the loadbearing H-frames run north-south and the trussed roof beams are spaced at 6.60 m centres.

4 I Isometric view of supporting structure.

5 | Diagram showing deflected shape of structure under load (deflection graphically exaggerated: vertical scale = 75 x horizontal scale).

6 I View of production building from the west.

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