The project contains a number of highly bespoke details tuned to the complex geometries and design challenges, including the multi-stay connection at the top of the masts and column bases formed of spherically machined plates and rotational bearings, which allow the new design to accommodate differential movements between the new and existing structures. An area of complexity centred on the temporary modes of the stadium. For typical stadium conversions an additional tier can be built behind the existing building and a new roof constructed over the existing roof, with little interaction between old works and new. This was not the case with Etihad as the roof profile and supports at the end stands extended further back behind the seating and the new upper tier would therefore project through the existing roof profile. The ‘interim roof’ solution involved cutting and removing the existing back of the roof, acknowledging that this meant cutting into roof rafters which had significant locked-in forces from the dead loading of the roof. Significant and complex temporary works were required for the project, with the remodelling of the existing roof completed in the first closed season alongside temporary propping to allow work to proceed above the existing roof. The existing roof was removed in the second closed season to reveal the new terrace behind. The new design respects the geometry of the existing stadium and, whilst the expanded South Stand is significantly larger than the previous one, blends into the original design. Examples of innovation include bespoke designed solutions such as spherical bearings, cable protection frames, an upper MEWP platform, intermediate roof propping, tie bar installation lifting beams to include remote release features and hidden bolted splices in the rafters. The availability of a CTL 1600 crane, the largest crane of its type in the country, significantly influenced the lifting methodology as it permitted much larger lifts, speeded up construction and reduced the need for working at height splicing components. In terms of sustainability the project focussed on re-use and recycling, rather than demolition. The team worked exceptionally hard to retain the existing cable net that supports the stadium roof. Much of the original building was retained during construction and existing components from the building’s façade reused. Steel and aluminium crowd ‘flood gates’ were cleaned, repaired and repainted and the existing lower tier terracing was re-used following careful detailing of the connections to the new building. The client also received a masterplan design which enables the stadium capacity to be expanded further to the absolute limit of the existing cable net, and then only at that point does the roof need to be completely replaced. A risk assessment considered potential fire loadings throughout the building and established specific design criteria. Intumescent paint was used extensively to enable steel to be exposed to view and corrosion protection is to a high standard and specification. The extension, completed within 16 months, was opened on the 16 August 2015 in front of a record crowd of 54,331 people. JUDGES’ COMMENT This is a complex project which added 6,000 seats above the roof at one end of an existing stadium. The work tested all facets of steelwork construction to their limits, including design, fabrication and construction. A stunning testimony to all concerned and to the capabilities of steelwork which merges seamlessly into the existing structure.
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