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Sector
Commercial, Development
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Developer
Brookfield Multiplex
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Start date
October 2002
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Completion date
December 2004
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Net Lettable area
62,250
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Stage
Completed
The Project comprises two separate but inter-dependent buildings that formed part of the re-development of the whole city block known as World Square®. The Ernst & Young Centre is a commercial office tower with premium grade services with in excess of 62,000sqm of NLA rising forty-one stories above George Street. 50 Goulburn Street is a four level commercial building built over two levels of retail. Fitout over approximately 35,000sqm for the anchor tenant (Ernst & Young) was integrated with the base building, resulting in economies of scale and reduction of redundant work.
Construction difficulties faced by the project included working in and over an operating car park / loading dock and working with an existing structure that had been commenced fifteen (15) years earlier for a different building. This structure comprised 10 basement levels and above ground, approximately 13 levels of concrete core and floor stabs. The difficulties of working in and over existing, operating areas were addressed upfront by preparing and agreeing a construction agreement with other stake-holders on the World Square® site. This agreement set out staging of the various work areas and interfaces across the whole city block of World Square®.
The existing structure posed many challenges, including a lead-in demolition period of approximately six months before meaningful new construction could commence, had the most obvious sequence involving upfront demolition of all redundant structure been adopted. However, following detailed reviews and planning, a decision was made to proceed with what was called a “Jump-Start”, a sequence that involved the re-design of a floor at six storeys above street level as a 10kPa working deck from which the main two storey high transfer structure was erected. This process allowed the typical floors of the main tower to proceed at the same time as demolition of parts of the building and foundation, and re-construction of the lower levels. This construction technique took six months off the original programmes.
The existing structure included ten levels of car parking, loading dock and retail areas through which the main columns of the tower were strengthened to carry the higher loading to be imposed by the Ernst & Young tower. Foundations were enlarged and detailed geotechnical investigations carried out. However there was still a risk that settlement of the foundations supporting the tower would cause variance in levels through the existing, operating car park causing serviceability difficulties. The solution was to use a steel framed building thereby reducing the loads.
To fire-spray the structure of such a tower was cost prohibitive with the structure being fire-engineered to remove the need for fire-spray. This was done and the reviews intense, particularly considering the level of concern and uncertainty raised by the events of 11 September 2001. The tower structure and fire protection systems have high degrees of redundancy and addressed all issues raised by the authorities.