The design creates a tower structure that addresses multiple scales, from silhouette to surface, similar to the nearby Sydney Opera House.
At the macro scale, the team designed the 814-foot-high tower to be the tallest building in Sydney, with a distinct profile on the skyline.
At the micro scale, the tower is situated within an active pedestrian zone in the city center. It complements and promotes the busy pedestrian laneway network while touching the ground as lightly as possible, despite the building’s size. Both scales help create a new city landmark and welcoming destination for residents and visitors to work, eat, shop and pass through.
Project Designer for HOK
To maximize space on the ground plane, the design pushes the tower bulk to the ceiling of the buildable envelope, lifting the first full floor plate 80 feet above the lobby.
This gesture creates a porous, multilevel ground plane and lobby, accommodating grade changes on site. More importantly, it encourages pedestrian movement through the site and draws natural light into otherwise cavernous laneway spaces.
To create a flexible office plan, the design creates an offset core to the south of the building, preserving coveted harbor and Sydney Opera House views to the north.
An external structural shell supports office flexibility through a 39-foot, column-free band on the north side of the floor plan. The exterior structural grid also protects the north facade from direct solar exposure.
Given the narrow footprint of the tower in the North-South direction, the size of the core walls must be increased beyond the thickness required by strength, in order to limit the deflection of the upper floors of the tower during wind events.
While the core and outrigger system has the required strength to resist the design seismic and wind events without the presence of the perimeter diagonal tie members, the addition of the tie members increases the lateral stiffness of the tower, reducing the amount that the core must be oversized to comply with the lateral movement limits.
As the diagonal tie members are not required for gravity or lateral strength, they do not need to be fire proofed, and the cross section can be kept minimal. The presence of the perimeter tie members has the following benefits:
• Tower stiffness increased by 20% without
thickening the core walls
• Required Core wall thickness reduced from approximately 1.1 meters to 0.9 meters
• Torsional behavior of the tower reduced
• Approximately 2,000 cubic meters of concrete saved
The project brief requested that all teams work with artists on their proposals. HOK elected to collaborate with James Carpenter Design Associates to distinguish the architecture through integrated art.