Architect and Builder November/December 2018 | Page 69

Mobilisation and Erection Challenges
While continuing with the main concrete superstructure,
structural steel erection had to overlap with the concrete
works in order to keep to the very challenging and
demanding programme. This entailed back-propping of
the newly constructed lower ground concrete floors down
to the B3 level, to allow access for multiple construction
laydown zones and mobile cranes in excess of 80 tonnes,
and in some instances 220 tonnes, to be positioned on
the concrete floors for assembly of the compression
ring, tubular space frame roof trusses, rigging sub-grids,
catwalks, stage mechanics support structure and the
placement of the raking steel beam structures to facilitate
the final finished bond-dek seating structures.
Erection Methodology and Sequence
of Arenana Roof and Seating
The steel contractor developed his Erection Methodology
and Sequence to suit the main contractors concrete
programme, concrete pour sequence, striving for minimum
radius of lifting weights, maximum permissible slab loads
using the minimum amount of back propping to determine
the most economical choice of cranes to lift the Main
Roof assemblies.
24/7 with labour and surrounding main contractor plant,
tower cranes, etc.
What made this project exceptional was the teamwork
required between the steel contractor, main contractor
and engineers which all had to work in harmony, trusting
each other views and coming up with the best plans to
execute such a complex roof and sub-structures of over
1500 tons in this short period of time, with a client which
gave their backing in all circumstances during the process
to ensure the end goal achieved to open to the public on
time and produce revenue.
Client/Developer: Sun International
Architect: LYT Architecture
Quantity Surveyor: MLC
Structural Engineer: WSP
Steelwork Contractor: CADCON
Steel Erector: On Par
Cladding Contractor: Chartwell Roofing
Corrosion Protection/Paint: Dram Industrial Coatings
Main Contractor: WBHO
Photography: Sun International
Main Challenges - Fabrication and Erection
Planning had to be done from shop detailing stage, to
ensure complete assemblies fit on site and erection
weights being considered taking into account the crane/
lifting philosophy followed to limit erection costs and back
propping as far as possible.
The steel fabricator designed temporary workshop
jigging, which was detailed in X-steel and built to make
sure when the complete gutters girders, hammerhead
structures and roof trusses built, it would fit 100% on site.
In essence, the complete roof assemblies built in
workshop, and bolted spliced where the assemblies
suited best the transport route from Centurion to Menlyn,
whilst also considering each assembly maximum lifting
weights. Weights were pre-determined in Tekla and
indicated on the Erection Methodology, also indicating
maximum crane lifting radius. This ensured that slabs and
cranes were not overloaded on slabs where activity was
Steel Awards
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