405 Bourke Street is a new commercial development located in the heart of the Melbourne CBD. Designed by renowned architect Woods Bagot, the project features a 40 storey, 180 metre building combining office and retail spaces.
The tower is built in and around the constraints of the site. Existing car park structure, light easements, 399 Bourke Street building and the existing east retail and car park areas all provided constraints to the design as well as the constructability of the proposed tower.
The north-east portion of the tower cantilevers over the existing 399 Bourke Street via the use of three mega trusses. Each mega truss, approximately 28m long x 12m deep, consists of 1.3m x 1.3m steel sections with composite concrete filled tubular columns which form a distinctive feature of the building.
Extensive works and re-planning within the existing 399 Bourke retail zone were required with the design team to ensure the structural integrity of the existing structure was maintained and the client’s expectations realised.
Key technical challenges
- The primary tower structure consists of a composite slab and beam structure. Due to the long beam spans and thin slab, extensive analysis for footfall vibration was required to ensure the structure achieved code requirements and client expectations.
- Working with the existing structure and developing design solutions that strengthened rather than demolished.
- Extensive co-ordination with the mechanical engineer to develop a strategy that minimised beam penetrations and beam notches.
- Differential shortening analysis with consideration of mega truss, steel structure, concrete structure and existing structural elements
- Design of mega column and mega piles to resist the large concentrated truss loads. Specialised piling rigs were required to construct the 2100mm diameter mega piles required to resist the truss loads.
- Developing a strategy to resist the mega truss uplift forces with the use of special high strength reinforcement.
- To maximise the office floor column grids, HISTAR 460 HD columns were adopted in the design. Column cross sections are relatively small with thick web and flanges, as large as 140mm thick. HD Columns are fabricated and transported from Luxembourg.
Key technical innovations
- Design of mega column and mega piles to resist the large concentrated truss loads. Specialised piling rigs were required to construct the 2100mm diameter mega piles required to resist the truss loads.
- Developing a strategy to resist the mega truss uplift forces with the use of special high strength reinforcement.
- To maximise the office floor column grids, HISTAR 460 HD columns were adopted in the design. Column cross sections are relatively small with thick web and flanges, as large as 140mm thick. HD Columns are fabricated and transported from Luxembourg.
- 4-D Staged construction visualisation models were produced to show time-based, sometimes daily-resolution increments of construction to key stakeholders – complete with temporary works items such as protection decks, access equipment, partial construction – to provide contractors and client with up-to-date construction methodology and critical trade/builder inputs.
Project Metrics
Year Completed:
Expected completion 2021
Building Metrics:
Total NLA: 66,000m2
Levels: 40
Sectors:
Commerical
Retail
Project Metrics
Client:
Brookfield Foundry Landowner Pty Ltd
Architect:
Woods Bagot
Robert Bird Group Services:
Structural engineering
Civil engineering
Construction engineering
Exviz
Environmental performance
- 5 Star Greenstar
- 5 Star NABERs Energy and 4 Star NABERs Water ratings.