Designing and building the commercial offices for one of the world’s largest bankers was no small feat for fitzpatrick + partners and Multiplex. The development process for the project was a complex one, which saw the initial design for a residential building change to a commercial project for a sole occupier, due to changes in market forces.
Multiplex Developments’ brief was for a project of “an innovative methodology, for the creation of a well mannered yet landmark building, within the King Street Wharf precinct” says Jeremy Deale, project architect at fitzpatrick + partners.
Obviously, this posed some challenges for the architect. Firstly, the conversion of the existing residential envelope and basement proved problematic in order to meet the development criteria. But these restrictions forced the architects to think outside the square. For example, due to the existing basement parking, the architects could not design a series of internal atrium columns within the basement without serious compromise to achievable parking numbers.
The solution? “A five-storey hanging column suspended off the seventh level diagrid was developed by Arup Structural Engineers in association with Robert Bird Group, which created structural tolerances to be co-ordinated into the design. These tolerances, along with variable deflection around the building, created a unique façade curtain wall in accommodating structural movement within a refined glazing solution designed around the diagrid,” Deale says.
“Most of the basement and ground level structure for the previous residential project was complete at the time of project commencement, presenting the design team with the immense challenge of structural load distribution for the new commercial building through five levels of basement parking, which included a bus layover facility.”
Other challenges, according to Tina Tang, project director at Multiplex Developments, included:
- materials handling with three cranes, three hoists and over 3,000 tonnes of steel
- construction methodology was complex to avoid deflections in the structure due to the difficult nature of the diagrid design
- having over 400 penetrations through the façade, as the structure braces the floor’s edge beam and meant very detailed construction around each of the building node points or penetrations
Achieving a Green Star rated building meant developing the awareness and skills of the subcontractors, and also prompted Multiplex to look at alternative products. For example, it reduced PVC by over 60 per cent by using non-PVC products where it could. Changes were also made to the design to accommodate specific products, such as changing the drainage to siphonic drainage. Concrete was also changed to a ‘green’ mix.
One of the main points of innovation at the project is the structural diagrid system, which is placed on the outside of the building. It provides a visually unique exterior, but also differentiates the building from others at King Street Wharf and the CBD of Sydney. Deale says, “This sculptural play of structure bridges the gap between the commercial buildings of the CBD and the more playful architectural response of the retail and food/beverage outlets to the King Street Wharf precinct.”
The diagrid itself posed further challenges, according to Tang, including integrating the it with the façade. As it is positioned external to the façade, with only a 150 mm gap between the diagrid and the glass face, close monitoring, management and co-ordinating the installation, sequencing and the accuracy of the steel and structure was required.
Deale says having a builder involved during the concept stage and committed to design quality is vital in achieving a sense of design ownership and a high quality, sustainable design outcome. “Multiplex, acknowledging the prominence of the building, has been very collaborative with respect to achieving a quality outcome and has been proactive in working through design options with fitzpatrick + partners and the consultant team.”
For Tang, issues between the builder and architect were resolved “through a disciplined process agreed by all parties at the outset, which involved many meetings, workshops and dialogue. This ensured everyone knew what the key objectives were early on and what was required to achieve these. The results of maintaining such a disciplined, collaborative process can be seen in the building design and construction.”
