| General Post Office Melbourne |
| December 2004 | |
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The redevelopment of the historic Melbourne GPO is an exciting project currently in progress. The nineteenth century structure is preserved in the facades facing the Bourke Street Mall and Elizabeth Street, while the interior will reflect a grand, belle epoque atmosphere enhancing the fashionable boutiques and shop tenancies planned for the site. A new 6-level building housing restaurants, shops and offices, will connect with the original GPO. Whilst connecting foot traffic and services with its historic partner, the new building is structurally separate so as not to impact the structural integrity of the orginal structure.
Also the structural rigidity was obtained by providing a precast moment frame at the Elizabeth Street end of the building. The use of hollowcore planks allowed the relocation of the air-conditioning plant to below the ground floor permitting the drilling of 200 mm diameter holes in the planks on a 1200mm grid. |
The new building, which will have all-glass exteriors, was originally conceived as in-situ construction due to the architectural requirement of cantilevers on three sides and the lack of wall panels to provide structural ridigity. However, the builders (St. Hilliers) and consulting engineers (Arup) in conjunction with Hollow Core Concrete Pty. Ltd. Decided prior to the commencement of the project that there would be considerable advantages to the use of pre-cast components, and asked the precast manufacturers to suggest appropriate construction techniques. The project team agreed to proceed down this path, and the company has provided the majority of the precast components required for the project, including precast columns, beams, hollow core planks, solid cantilevered planks and lift panels for the new building as well as the stair panels and stair flights for the original building. 
The builder cites speed of construction and the rapid access avaiable to following trades as the major advantages for using precast components. Overall, some six weeks in time were saved and this could have been higher but for unavoidable design requirements. There are other advantages to this method of construction. As the architectural design calls for angled, cantilevered terrace and floor sections facing both Elizabeth Street and Little Bourke Street, the solution was found in the use of solid cantilver sections cantilevering from the precast beams.