...Amstetten, has reinforced its panels with extra waling, says an official. The firm has supplied 78 automatic climbing formwork units to the job.
At least four floors below the top of the core, Eversendai’s steel erectors are putting up the diagrid. The main diagrids will include 2,124 structural elements, with another 384 roughly 50-cm-dia steel tubes around the atrium, according to RMJM.
Under its approximately $55-million subcontract, Eversendai is welding one- story-deep, X-shaped steel modules together to build up the diagrids. A crew of over 60 welders is at work, says Willats. Welding, to reduce the size of joints, is being used much more extensively than in a typical U.K. project, he adds.
Horizontal beams of the perimeter diagrids and the 80-cm-deep girders of the composite floors are bolted to the nodes.
Because of the ever-changing geometry, “we have to make individual jigs for every diagrid,” says P. Baskaran, Eversendai’s project manager.
Building Information Model
Eversendai is fabricating modules at plants in Sharjah and Dubai with steel mainly from Europe. The firm is using Finland’s Tekla Structures steel-building information modeling software to transfer member geometry from the detailing phase straight to fabrication and, finally, to set out diagrids for erection.
The subcontractor is building up the diagrid’s heavier pieces from steel plate, which is up to 8 cm thick. Lighter elements for higher up the building are standard rectangular hollow sections. Diagrids are sprayed with a three-hour fire-protection coating during fabrication.
It took until last September before Eversendai’s erectors were at “full speed,” finishing one floor every five and a half days, says Baskaran. Since starting in June last year, workers were stalled by the concrete core’s initially slow rise and their own learning curve, he adds.
The steel erectors’ ascent over the past couple of months was also close to a snail’s pace because of the three structurally complicated mechanical levels above floor 16, says Willats. Eversendai has now cleared those heavily structured floors and is moving at a fuller tilt again, using extra shifts, he adds.
While steel erection was beginning, engineers with Austria-based Waagner-Biro Stahlbau A.G., Vienna, were working out how to enclose the oddly shaped building. The roughly $45-million cladding contract includes the facade’s 6,500-sq-m portion of sunscreen mesh, which will flow decoratively down the east side from the 19th-floor swimming pool. The plan is for the “splash” of stainless steel to also cover the adjacent exhibition grandstand.
To ease the logistics, Waagner-Biro said no to the architect’s idea of having the cladding built up with triangular...