Repurposing, not rebuilding
The original structure at 55 Southbank Boulevard was a six-storey commercial building completed in 1989.
Being so close to Melbourne's arts and cultural precinct and land in the area at a premium, WSP was engaged to design a new concept using cross-laminated timber to add ten storeys to the existing building which represents 13,000 m2 of new space.
The height of the extension was limited by the capacity of the existing piles and installing new piles would not have been possible within the existing building. WSP investigated using concrete slabs, composite deck slabs and CLT floors for the extension. The CLT option was selected because it allowed 10 additional storeys without exceeding the pile capacity whereas feasibility studies ¬-showed only a six-storey extension was possible using concrete slabs.
Alongside our structures team and a cross-laminated timber specialist, we created a Future Ready solution where additional levels were well supported with the existing building columns and core walls were strengthened to accommodate the additional load from the extension, involving the use of CLT walls between all the hotel rooms. WSP designed a composite slab transfer deck at the first hotel level to transfer the vertical loads from the walls to the existing concrete columns.
A taller building also means higher lateral loads on the The completed 55 Southbank building existing building. WSP designed two new steel cores extending to the top of the CLT extension, incorporated an existing concrete wall in the stability system and designed strengthening of the existing concrete core walls to allow for this load. A new raft was designed under the steel core to transfer the new loads to the existing piles, avoiding new piles.
In order to achieve uninterrupted views from all corners of the hotel, we designed steel beams and columns around the curved section to support the cross laminated timber floor panels and larger wall spacing.
We designed steel beams and columns around the curved section to support the cross laminated timber floor panels and enable larger wall spacing to allow for an uninterrupted view from all corners of the hotel.
The completed 55 Southbank building
Saving time, money and carbon emissions
There were multiple complexities to the Future Ready design and construction of this project that our team had to factor in, including the construction occurring while the floors below were occupied, the existing utilities and services in the building and avoiding adding additional foundation piles.
By using prefabricated cross-laminated timber and adapting an existing building using Circular Economy principles, time and money were saved as well as minimising the environmental impacts associated with demolition and rebuilding.
The building opened in August 2020, with part of the building becoming the Adina Apartment Hotel Melbourne Southbank.
More information, see this recording