BSB Luxemburg

60,000 m³ birdcage scaffolding – know-how from the ashes

Financial centre Luxembourg: powerful banks and insurance companies. That is more or less the first association of an average European with the theme of the business location of Luxembourg. European media centre – the second. Iron and steel: well, not really. In the eyes of the observer, the coal and steel industry does not belong directly to the economic portfolio that would generally be linked with the Grand Duchy located at the heart of Europe. A mistake, since the iron and steel industry was a decisive factor in creating today’s wealth of the country. And now an unusual memorial will be erected in respect of this industry.

The last classic blast furnace was decommissioned in 1997 and signalled the end of an era. The furnaces A and B at the former Esch-Belval facility constituted the last two witnesses of this epoch and the state of Luxemburg had planned something quite special for them. The idea was to integrate the two furnaces into a modern, coherent concept bearing the name “Cité des Science”. Both monuments now form the core of the “City of Science”, which consists of 20 modern buildings divided into four quarters and located around the blast furnaces. EUR 68 million had been set aside by the Luxembourg State to implement this concept, thereby investing in Luxembourg as a science location and in this way redefining itself yet again. According to its own statements, the “Cité des Science” is one of the largest and most ambitious architectural and town development projects in Europe. The completion of the work was to be celebrated with a monumental light show. The architect, Jo Coenen from Maastricht, had 120 hectares available to develop the new town 20 kilometres to the south of Luxembourg City. “There, where the chimneys were once spinning out smoke, that’s where heads will now be spinning”, so the description in a Luxembourg press release. As many as 7,000 students will one day make up those heads.

As always, hard work and sweat are part of a good idea. The description of the two blast furnaces increasingly caused the planners some headaches in the budgeting phase. Both objects were so corroded at the commencement of planning that for commercial reasons only furnace A could be completely refurbished, whereas furnace B would merely remain as a silhouette. EUR 38 million was envisaged for the refurbishment of the two furnaces and for embedding them on the university grounds. In the future, the blast furnace A – as a contemporary witness – will comprehensibly demonstrate the classic production process for visitors and house the Centre for Industrial Heritage. The “Möllerei” will accommodate the “Maison du livre”, the university library.

The project reflects the European ideal. Not least of all because the scaffolding jobs required for the refurbishment were awarded in cooperation across national borders. The scaffolding partners Echo-Location s.a.r.l. from Luxembourg and BSB Franke & Wagner GmbH from Germany jointly won the contract to carry out the comprehensive assignment. The scaffolding concept was provided by BSB, the structural analysis – as so often in demanding projects – by Joachim Specht from Ingenieur- und Sachverständigen-Büro IBS Specht in Westphalian Schalksmühle.

The scaffolding work could be divided into two phases, in terms of both space and time. Building phase 1: blast furnace B, 2011 to 2012 and subsequently furnace A with a refurbishment period from 2012 to 2013. The scaffolding was provided to refurbish the furnaces and to remove the rust. Particularly rusty parts had to be replaced entirely. The colour concept of the Austrian designer Ingo Maurer envisaged coating large sections of the ovens with a grey colour, thereby protecting them against corrosion, while e.g. the boilers would be given a clear coat so as to preserve the rusty character of the monuments.

Blast furnaces are extremely angular objects with diverse anchorage and support possibilities. Large, smooth surfaces here are a luxury. Accordingly, the main task when building up the scaffolding was to get as near as possible to the object. The distance between the scaffold and the structure was planned so as to be minimal. In numbers, this meant a horizontal clearance of between 75 cm and 225 cm, depending on the structural circumstances. Vertically, the scaffolding needed to be as near as 15 cm to the surface of the object. The construction of all the floors had to be effected at the same height. Moreover, the entire scaffolding had to satisfy the requirements for enclosures using shrink film – and that up to a height of 95 metres. The formation of the outer contour of the scaffolding for this was planned by BSB with simple geometric shapes. In this way, the shrink process could be greatly simplified and an absolutely dust-tight and waterproof working environment created. Together with Echo-Location, BSB deployed large quantities of scaffolding material for the project which extended across almost the entire product range of the scaffolding manufacturer scafom-rux. BSB planned some 31,000 m² of facade scaffolding, partially as a birdcage system, just for the blast furnace B. Here, only the silhouette of the object was to remain. The second phase required even more remarkable amounts of scaffolding. Every corner of the object needed to be reached from the scaffolding: 25,000 m² of facade scaffolding and an additional 60,000 m³ of birdcage scaffolding were applied. Besides the scafom-rux modular scaffolding Ringscaff and Variant, the Schmölln-based company relied on the Super 65 facade scaffolding and, in particular, on the Super 100 facade system. This material with its convenient frame width is ideal for quickly creating a basic structure around a complex building.

This is an important precondition for the fitting of the shrink film and for gradually getting nearer to the structure of the building to be refurbished by using a number of different system-free components from the scafom-rux range. In particular, numerous special structures – mainly out of steel tubes and lattice girders with an installation height of 450 cm – were applied. This was again very important in view of the extremely advanced state of the corrosion in some sections of the furnace. Sometimes, the object was no longer able to take up the loads that resulted from the completely enclosed scaffolding.

Exemplary for particularly clever solutions was an electrically-driven suspended scaffolding (movable) which was assembled on the two top gas tubes of the furnace – and, of course, bearing a CE conformity marking. The fitting of stair towers supplemented the entire structure, from which all levels needed to be reached. Safety was always the uppermost priority throughout the project at Beval so the peripheral working platform was always free-standing and pre-assembled for 4 metres to protect the workers.

The scaffolding companies permanently applied two teams of respectively 12 staff members to assemble the scaffolding. These teams had 5 Geda 500 Z/ZP lifts and other 300 Z lifts at their disposal as well as winches for the vertical transportation of material. The assembly work was interrupted for 3 to 5 weeks in some sections to enable refurbishment work to be carried out. Other interruptions resulted from inclement weather conditions throughout the various seasons of the year. Snow, ice or strong wind and rain repeatedly took their toll in terms of time, particularly in view of the height of the object. Andreas Dölz: “Due to the tight deadlines defined in the building schedule, delays caused by weather for example had to be made up with one’s own compensation methods and documented.”

The scaffolding company from Schmölln with Jörg Franke and Siegfried Wagner always go into projects such as this with a good plan and very well prepared. Time delays could therefore be made up in the case of the Esch-Belval project. The inauguration ceremony was therefore able to begin punctually on 4 July 2014 with the two imposing blast furnaces at the heart of the “City of Science”.

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