Building Taller with Existing Structures: Sydney Greenland Centre, Sydney

Session: G: Construction Award

Jason LangerAlex WuProject image

Jason Langer
Group Managing Director, Robert Bird Group
Sydney

Alex Wu
Project Director, Greenland Group

The project brief saw the existing 29-level commercial tower - built in the 1960’s - partially demolished, however 26 levels of primary steel structure were retained, modified and adaptively incorporated into a new 70-level residential tower. The City of Sydney Council had granted the developer relaxed tower setbacks in exchange for the developer’s commitment to retain the existing tower primary structural frame. The unique feat of both engineering and construction was to ensure temporary structural adequacy and stability was achieved at each of the more than 50 unique steps making up the partial demolition, retention and re-construction sequence. Failure at any step, risked catastrophic consequences. The challenge of maintaining temporary stability was ever-present; from the initial erection of scaffolding and cranes, through removal of the façade, removal of floor slab diaphragms, removal of critical lateral stability systems, and finally removal of significant basement structure, down to foundation level. Many of the removed structural elements generated critical global stability risks for the tower, that had to be overcome via engineering and construction solutions. The project also faced other unique project risks, including knowledge gaps associated with the existing structure, structure condition risks, and fifty-five years of un-documented modifications to the building.

The Sydney Greenland Centre presents an exceptional answer to the question of whether a tall building can be adaptively re-used, and if so, how to build it. The unique structural engineering and construction challenge of adding 45 levels to an existing 26-storey building - a modification unforeseen by the original design - has been proven to be possible.

The key advancements made on this project are understanding risks and developing solutions for the unique engineering and construction challenges that apply to adaptive re-use of tall buildings. This transferable knowledge can enable redevelopment and densification of our cities, whilst improving sustainability outcomes. This project demonstrates that tall buildings can indeed be recycled, adaptively re-used, and enjoy an extended life contributing to the future success of our urban habitats.

View Building Information on CTBUH.org