The use of a modularization system for the construction of this project was developed by BG&E in collaboration with Brookfield Multiplex to meet the very tight construction schedule and to cater for the significant spatial constraints on site. Various options were discussed and the final structural steel frame solution was identified as the most cost-effective while still satisfying the need for safety and within the provided crane maximum lifting capacity.
BG&E ALTERNATIVE DESIGN
BG&E’s strategy was to design the double-storey 10m high steel columns as free standing during construction so that the steelwork could be erected on multiple levels. In addition, Warren trusses were substituted for the original proposed Pratt trusses with the result of reducing the consumption of steel up to 10-15%.
BG&E also developed a modular construction system for the erection of the building’s 70m tall chimney where the tower structure could be broken into 1-storey, 5.5m tall modular sections built on-the-ground in a dedicated assembly bay and then lifted into final position. The advantage of the modular system was that all could be easily assembled on site and lifted in place in a very short period of time.
BG&E revised the design of the chimney steel bracing system using light steel sections acting perpendicular to the horizontal force, allowing the engagement of all the interior vertical columns. By using this design, the primary structural frame went from 90 tonnes to a more efficient 45 tonnes.
BG&E’s structural solution allowed for a faster and more efficient delivery of this project. The use of steel also reduced the requirements for false works and propping.
Steel framing members were craned off the trucks and erected into final position, eliminating the need for storage on site.
Due to the innovative design of the chimney tower, Brookfield Multiplex’s estimated 10 days per module was reduced to an average of 6 days.
The overall project from award to delivery took 1 year and 9 months to be completed, with 99% of the structure, including the chimney and all cladding, completed within a period of about 12 months, resulting in a substantial reduction of the estimated project cost.