Australia 108

Structural Features

• The key structural system used in this 320m tower is a concrete core and outriggers to mega column and mega frame.
• Floors are flat plate two-way post-tensioned plates on a ring pattern of columns and mega columns. Lateral stability and acceleration control are a key design element, thus a liquid column damping system is provided on the 98th Level.
• Complex ‘StarBurst’ construction sees amenity zones cantilevering over 8m.
• Building façade access is by way of a main crane housed at the roof with supplementary systems housed under the ‘Star Burst’ zone.
• Carparks are concealed behind a pattern of cantilevered planters.
• Large diameter piles are used to support the structure; these are found more than 40m below ground level.

Key technical innovations

Change to coupled precast columns – quicker floor cycle times typically:

• Saving of 1 day per floor cycle.
• No puddle pouring of high-strength concrete on-site
• Full coupling of column reinforcement.
• Less reinforcement via removal of bar lapping.
• QA improvement of shrinkage and concrete grade characteristics.
• Advanced Grouting Technology (NMB couplers from Japan can achieve 150MPa strength).
• Improved axial shortening adjustments on-site1

Integration of temporary works and permanent works designs for Starburst levels:

• EXVIS visualization of construction sequence (useful for Client and Builder alike)1
• Steelwork used for both temporary and permanent design – less erection / clean-up, multi-use.
• Temporary worker protection screens at StarBurst edges which hang 10m outboard of structural floors.

Key Technical Challenges

Outrigger design using ultra high strength reinforcement (MACALLOY and SAS bars) embedded within core and columns.

Staged erection of outrigger to core walls: connection of high strength reinforcement through core and outrigger walls which are poured weeks apart.

StarBurst amenity area:

• 4 levels of floors cantilevering 8m outboard of main structure – 200m above ground level.
• Pools at edge of cantilevering structure creating large overturning forces on building; additional wind area.

Liquid Column Dampers:

• Large mass (circa 200,000-300,000L of water) some 300m above ground.
• Structural support of liquid columns via series of inter-connected walls and slabs.
• Wave formation in LCD’s generated via building movement.