New Steel Methodology Delivers Safe Outcome Ahead Of Schedule
A steel-intensive approach has allowed an innovative parallel beam flooring system to further speed construction of Brisbane’s new 480 Queen Street office tower allowing a new floor to be added each week along with the more traditional benefits derived from using offsite fabrication alleviating onsite congestion, providing better safety and logistical efficiencies.
The building is targeted to be the only premium grade, 6-star Green Star rated tower of the three new office towers currently under development in Brisbane. It comprises approximately 4000 tonnes of steel made up of approximately 2500 tonnes of universal sections, 500 tonnes of fabricated beams and 1000 tonnes of tubular columns.
Associate Buildings project engineer at Aurecon, Aaron Toscan said this is the first steel building of this size in Brisbane. It also utilises a steel system that has never been used here before on a building of such large scale.
He said that the floor construction uses parallel continuous primary floor beams with continuous secondary beams above supporting a steel formwork supported concrete slab.
“Given the multiple layers of structure, particular attention has to be paid to diaphragm action to transfer column restraint actions as well as wind and earthquake loads to the lateral resisting core,” he said.
He said for the parallel beam flooring system, beams are placed in two separate layers like a bearer and joist arrangement allowing all building services to ‘weave’ in and out with zero beam penetrations.
“By eliminating beam penetrations the control of fire spray coverage is also simplified both during and after construction. The approach allows construction to speed up from fabrication to installation with every process significantly quicker.
Assistant Project Manager at Grocon, Cameron Starkey said cycle times for the three zones, which make up the 3355sqm campus floor plates (floors 6 to 14) are achieving five-day turnarounds.
“Although comparable to conventional concrete cycle times, material time benefit is realised by eliminating formwork support frames and back propping allowing services and finishes trades onto the open decks sooner than conventional construction methods,” he said.
“While steel construction is delivering time benefits, it is also proving to be a safer method of construction with no Lost Time Injuries (LTIs) occurring on the project to date which is particularly pleasing for Grocon as safety is a core value for our company.
“This improved safety can be attributed to the meccano style installation method, simplified structural connections and significantly reduced formwork back-propping.”
Key steel supplier on the project, OneSteel provided a processing and delivery offer to cut and drill all long product and plate materials required for the project.
Business Development Manager, Queensland at OneSteel Metalcentre, Frank Van De Weyer said approximately 2500 tonnes has been processed in Brisbane, individually marked and made ready for loading for transportation to site.
“Material was pre-ordered from mill rolling to reduce waste and enable efficient nesting with delivery to site to match the specific order defined by the site erection methodology,” he said.
OneSteel Metalcentre has now successfully fulfilled all project requirements ahead of schedule.
*This is an abbreviated version of an article that was first published in the December 2014 issue of Steel Australia. The full version of this article can be downloaded at http://steel.org.au/media/File/Steel_Aust_Dec_2014_p1618.pdf