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Following an EU-wide tender by the stadium operating company, the extensive works on the final development phase of the legendary Fritz Walter Stadium, on Kaiserslautern’s Betzenberg hill, began in December 2004. The existing football arena is being upgraded to meet FIFA specifications in time for the 2006 World Cup. The turn-key contract for these works went to the “SEK” (Stadium Extension Kaiserslautern) consortium, a JV of Hochtief Construction AG, Mainz and Rheinland-Pfalz / Saarland, and “Sportstätten Heberger-Bau GmbH” of Schifferstadt.
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This final phase of construction involves, firstly, removing the roof from the western grandstand and demolishing the north-eastern and south-eastern corners with their standing-room terraces. These are being replaced by a modern 7-storey media tower and a VIP loggia tower. Once it has been extended, the western grandstand will be given a new and hugely cantilevering roof. Although the southern grandstand is to keep its 300 t roof, this will have to be lifted 4.00 m to the height of the adjoining roofs, in a spectacular operation made necessary by the fact that this entire block is being raised. By the time the first World Cup match at Betzenberg kicks off on 13.06.2006, the stadium will be able to seat 48,500 fans – around 8000 more than before the alterations.
The construction work is having to be carried out without any interruption to regular operations at the stadium. This means that access to the grandstands has to be kept clear, and that the spectator zones have to be kept safe from the building work. What is more, all storage areas anywhere near the stadium have to be vacated during every match, to make space for outside broadcast vans. These extremely tough site-logistics requirements also have to be taken into account by the Doka Formwork Experts when it comes to materials-scheduling. “All in all, they haven’t exactly made things easy for us here”, as Hochtief-project manager Werner Bär points out.
Doka will be supplying nearly 3000 m² of wall formwork, almost 1800 m² of floor-slab formwork and more than 510 lin.m of folding platforms and Climbing formwork MF 240.
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The formwork and concreting operations together constitute the major part of the stadium-extension works. For this reason, the JV prepared these works in great detail, obtaining comprehensive offers from all leading suppliers. Ultimately, it was the Doka Formwork Experts at the Bonn/Frankfurt Branch and the Applications Technology Dept. in Maisach who presented the most convincing offer. Another factor in the equation: Their many years’ experience in the stadium-building field, on e.g. the Allianz Arena in Munich, the Olympic Stadium in Berlin, the Veltins Arena in Gelsenkirchen, and the LTU Arena in Düsseldorf.
Doka framed formwork Framax Xlife is being used on the foundations of the main piers for the extension of the southern and western grandstands. The viscoplastic surfacing on the form-face of this formwork makes it ideal for use in these rough conditions. Each block foundation for the stairwells contains around 187 m³ of concrete, cast in a single pouring cycle. 12.00 m long rock anchors reach deep into the supporting subgrade to provide the extra anchoring called for by structural design considerations. On these, the up to 25.50 m tall, pier-shaped wall sections, each measuring 1.20 x 3.70 m or 0.80 x 7.76 m, are then erected in in-situ concrete – also in a single pour for the first casting section of up to 10.50 m in height. The first section is followed by three to four further cycles, each of up to 4.50 m in height. The formwork used here is stood safely on platforms from the Doka climbing formwork MF 240 range. The top edges of the wall piers are terraced in readiness for the seating rows. Cantilevering, reinforced-concrete-composite stepped beams follow on from the top projections of the wall piers, ending at a height of 33.10 m above the ground. This will make it possible for the fans to enjoy a good view of the game even from the very back row.
On the stadium side, a crosswall links the individual piers of the western grandstand. The resulting stairwells, with outside dimensions of 7.76 x 10.80 m, have a number of special features: At a height of 16.60 m, the grandstand piers have a projecting shoulder which cantilevers out by as much as 2.20 m, with special steel fittings protruding from the sides of the walls. These are used for holding the diagonal supports for the reinforced-concrete composite stepped beams and their wind bracing. These constraint points also had to be allowed for by the formwork.
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With its absorbent 3-ply formwork sheeting, the series Doka wall formwork FF20 exactly fulfils the architects’ demands for the fair-faced concrete walls. Moreover, the FF20 system’s appearance – with its tidy joints, equally neat tie-hole pattern and slightly wooden texture – fits in very well indeed with the tongue-and-groove board formed concrete surfaces of the rest of the stadium.
Practically all the areas of wall that will be exposed to view are thus being formed with Doka wall formwork FF20. Despite the tight shell construction period of only 7 months, the commissioning quantity on the site is relatively low – only around 2300 m². This is a result of the high degree of utilisation of the FF20 formwork. Thanks to their built-in stacking flanges, the elements can be used for anything from low upturn beams to stairwell walls, and even for the very highest wall piers. This reduces the non-utilisation rate, making the formwork highly economical.
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Staxo load-bearing towers from Doka are in use here to provide fast, safe support for slabs at heights of 7.85 m and above. The supports for certain areas of these slabs had to be stood on an inclined surface. Here, the forming operations were carried out using a combination of Dokaflex and lengthened floor props Eurex 60. The Eurex 60 props are very easy to brace, by linking them to one another using their built-in scaffold tube connections. “The same superstructure is used here every time, using the new ‘Doka H20 top’ beams with the blue ends. This makes the job a lot easier for my people, as in this way they don’t have to be adapting to changing situations all the time”, explained foreman Alexander Lehr from JV partner Heberger.
For the stairwells, which project outwards by 3.90 m at a height of 19.50 m, the Doka “Ready-to-Use” Service pre-assembled 104 m² of custom tables with an integral edge floor-beam, on a project-specific basis that was exactly tailored to the dimensions of the structure. Again, these were supported by Staxo load-bearing towers.
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As early as in the bidding stage, Doka adviser Frank Hennig Richter presented Doka’s “on-site acceptance inspection service”. This entails both qualified Doka staff and authorised site personnel jointly inspecting the rented formwork equipment on the site after the building work is finished. This “on-site acceptance inspection” enables formwork rentals to be wound up quickly, with complete certainty regarding the costs, and in a dispute-free manner. It pays for itself in that the rental can be wound up “on the spot” and that the information on any missing or damaged items is available straight away. This ensures a high degree of transparency, and the site can be regarded as completed ahead of time from the formwork equipment point of view.
“Hochtief” Contractors’ Supervisor Wolfgang Schumak reckons that to successfully complete a job of this size in so short a time, it is vital to motivate and communicate properly with the site crew. Which is why plain talking comes naturally to him – for both criticism and praise. He sums up his experience with the Doka Formwork Experts like this: “We had some pretty high expectations, and were not once disappointed – and whenever we needed them, Doka were always there to help.”
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| Cantilevering, reinforced-concrete-composite stepped beams follow on from the top projections of the wall piers, reaching a height of 33.10 m above the ground. |
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