447 Collins St – Linking of Towers via Skybridge

Rob DiBlasi
4D Workshop, Melbourne

447 Collins Street is a significant mixed-use precinct development comprising commercial office, 5-star hotel, luxury apartments, basement car parking and extensive public realm landscaping in an iconic building form. Commercial office space is located in the West Tower, and a hotel is in the East Tower. Podium levels and the ground plane accommodate office and hotel front-of-house and amenities, retail and public realm. Luxury apartments are located on the upper levels of the east and west towers, and link across to create the arch form, via a skybridge above level 34. The architectural form includes features such as a receding south façade, stepping West Tower façade, and the East Tower’s lean of 12 meters towards Collins Street.

This presentation explored the unique design considerations for 447 Collins Street due to its complex form, and focuses on the linking of East and West Towers via the skybridge.

Each tower experiences permanent lateral deflections in different directions due its unique geometry. The architectural aspiration was to maintain an uninterrupted façade across connecting towers. The skybridge structure has been utilized to link the towers and avoid expansion joints.

Design considerations include individual tower movement during construction and construction tolerance, skybridge and link structure design and detailing, consequential design effects on stability elements, and skybridge construction methodology.
The linking of towers can be carried out successfully to create a unique continuous and homogenous architectural form. Internal linking forces can be significant and may affect design, detailing and construction.