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EducationConference report slender, reinforced concrete columns until the new structure was erected. “Stability is the key to this building,” says Mr Abood. Although the new steel frame provides essential bracing for the columns supporting the lecture theatre, the concrete structure is also essential to the stability of the new steel frame. “The architect really wanted The Hub to be a building with open spaces,” explains whitbybird director Martin Burden. “When you go through the entrance, you should be able to see all the way through. But because the architect didn’t want any walls anywhere, it has been very difficult to brace.” There is only one possible location where bracing could go in, at the end of the building, where the three walls around the main lift have been braced with steel. Beneath these walls – at basement level – is a new 840mm steel transfer beam, which takes the load onto the original pile caps. With no structural walls in the rest of the building, the only way to prevent the twist that would occur without bracing at the other end is to “grab” the four columns that support the lecture theatre, and now fall within the structure of the Hub’s main building. All the steelwork had to be down to the lower ground floor level, leaving the “You can’t concentrate the loads, so we’ve designed lifted from the street over foundations and basement, which houses a car connections that wrap around the columns,” says Mr the recently completed nine park. The new three-storey Hub building has been Burden, “We want the load to go smoothly into the storey building built around a steel frame installed by steelwork columns without exerting any additional moments.” contractor Graham Wood Structural that makes use The old columns are cruciform in plan, and are of these original foundations. “By taking advantage extremely heavily reinforced. Fortunately, whitbybird of steel as a lightweight material we have managed has all the original reinforcement details for the to add an extra storey without having to strengthen original buildings, so could design connections that “By taking advantage of explains Ali Abood, could avoid damaging any essential re-bar.“We designed a series of plates that are resin-the foundations,” steel as a lightweight design engineer with anchored to the existing columns,” explains Mr material we have structural consultant Burden. “Each plate is pre-drilled, but there are extra whitbybird. holes in case the hole lines up with the main steel. If managed to add an Although the weight it is in line with a link, that’s OK. They can cut through extra storey without of the steelwork is that. not a crucial factor “The connections have been designed so that the having to strengthen in the loads being new steel is not clamping onto the columns, but the foundations” transferred into the ‘cuddling’ or grabbing them,” he continues. old foundations, When it came to erecting the steel, Graham Wood concrete in the Holorib composite floors is. The Structural fixed the connections plates first, and designer specified lightweight aggregate for the worked out from there, as there was absolutely no 130mm thick slabs to ensure the weight stayed within room for error on these connections. The open plan Pavilion makes allowable limits. The steelwork was procured while the demolition use of vierendeel trusses and The structural steel frame of the Hub building sticks was underway. Even though whitbybird had access to exposed circular columns mainly to the 7m x 7m grid of the original concrete the original design drawings, the design team could frame, so that the columns will bear directly onto the not be sure that they would find the as-built structure existing basement frame where possible. Beam and to be the same. The new steelwork connects to the column sizes vary, but at first floor level most of the existing campus buildings in 16 different places – main columns are 203 x 203 sections, and the beams including the four lecture theatre columns – so it was 254 x 254 universal column sections. essential the steelwork fitted exactly. Adding an extra storey takes the height of the “The whole building is surrounded by existing new building to the underside of the University’s buildings and we have to get that building to be an main lecture theatre, with the soffit of the lecture exact fit,” explains Mr Abood. “When we started theatre providing the roof for part of the Hub. Like exposing things, plus or minus one millimetre could many similar facilities, the theatre was designed make a difference, so anything that was not as we with columns supporting the weight of the building, planned it – even by a millimetre – we had to look at with the raked seating cantilevered over the rear again. Individual resin anchored plates were fabricated for the set of columns. In the original design, the beams of “As we demolished, we had to confirm every bit, so connections between the new the old lab building provided horizontal support for there was a lot of pressure to get the information to steel and the existing lecture these columns. Once they had been demolished the the construction guys. To the credit of the steelwork theatre columns contractor had to provide temporary props to these contractor, everything fitted.” 18 NSC February 2006


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