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Commercial The Finsbury Circus Facade is being retained. The three separate buildings will be combined into one. “As well as However, marrying a new frame to an old steel He says strengthening was needed to the columns knitting together the structural works on the project, Mr Fuller says. overloaded columns.in the form of additional plates to supplementframed structure is the most challenging aspect of old and new, The first major part of the work was to provide Mr Dobbins adds that using steel has brought steel has also temporary support for the existing Finsbury Circus more flexibility to the project. “As well as knitting and Eldon Street facades and retained listed together old and new, steel has also allowed the allowed the structure behind. The retained structure was braced floor build to be more compact with all services floor build to be with steelwork to ensure stability was maintained accommodated between the beams.” during demolition. Running parallel with the Finsbury Circus more compact Steelwork contractor Bourne Steel commenced building, Eldon Street originally consisted of two with all services steel erection in June 2006. Overall Bourne will erect separate buildings. The facade of the listed building 1,500t of structural steel in approximately 3,700 at 26-31 Eldon Street is to be replicated on the accommodated individual pieces, with 100t used on the Finsbury adjoining new structure with a Portland stone facade between the Circus segment. to match the existing facade. A new central bay beams.” comments: “Although the Finsbury Circus frontage the development.entrance hall will provide access from this side ofRod Potts, Bourne Steel’s Divisional Manager is being retained, some major works have been The new build section along Eldon Street and undertaken to raise the existing floor height.” abutting the Finsbury Circus structure is a traditional The idea is to have a regimented 3.43m floor steel column and beam structure consisting of eight- height throughout the project to match the existing storeys and a steel-framed roof which will be glass storey heights. To bring the retained Finsbury Circus clad. Set around a trapezoidal 11m x 18m atrium the building into line with the new structure the screed new structure has a predominant grid plan of 6m x has been removed from the existing concrete floors 4m with 415mm deep fabricated beams with 250mm to reduce their levels while a number of supporting deep penetrations. beams has also been reduced. Mr Potts explains that Bourne’s contract also Bourne’s In the centre of the retained structure there were includes erecting steel decking for the new build contract involved a series of fireplaces and chimneys which began at section, and building a novel arrangement to allow basement level. These have been removed and their cherry pickers to stand on the decking without building a novel large supporting beams which measured 700mm causing any damage. arrangement deep have been replaced and reduced. “We’ve made five sets of supporting frames from to allow cherry necessary to have such large supporting beams,” and prevent any damage to the decking,” he says.305UCs which constrain the wheels of the picker“Once the chimneys were removed it wasn’t pickers to stand Mr Potts explains. “The chimneys went back two “We only have three pickers but making five frames on the decking reduced to that the floor height is increased,” he frame.”means we can always move a picker to a sparebays and the first beam of two on each floor is being without causing adds. The cherry-pickers have initially erected any damage. Because these beams are connected to the steelwork up to the second storey by working at retained facade it was impossible to remove them basement and ground level. As Mr Potts explains, so Bourne Steel is inserting channels either side of the frames will be used on the second level to allow the beams and then cutting away approximately erection up to the fourth storey, with the process 300mm off the bottom flange. The second repeated on the fourth level and the sixth floor. supporting beam on each floor is being replaced Importantly, Mr Dobbins adds the new structure, with a new slimmer beam measuring 280mm deep although basically a free-standing building, takes that is being raised up into the depth of the slab. all of the lateral stability for the entire project. This The other major element connected to this called for some intricate foundation works as the part of the project has seen the original floorplan new piles had to avoid existing pad foundations. demolished down to the sixth storey and a new Two artesian wells were also discovered under seventh floor and roof added. This will then marry the demolished section and these had to be capped into the overall floorplan of the new building. The with new piled foundations - mostly steel ground original roof of this building housed a small plant beams - built over them. Bourne erected raking room, and this will be moved to a new section of the columns around the perimeter of the site at lower Eldon Street building. basement level to avoid transfers which would have Barry Dobbins, Regional Director of Waterman otherwise impacted on the below ground headroom. says this part of the project called for some lengthy The project is scheduled for completion by surveying and analytical calculation of the structure September 2007, when central London will acquire a to ensure the load capacity of the existing columns modern office block built around and incorporating and floor plate would cope with an extra floor. restored listed features. 18 NSC October 2006


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