29 / 64
27
CONSTRUCTION WORLD
MARCH
2015
sarily round, from which would hang the
viewing platform and hoisting structure. So,
introduce a Toblerone profile compression
ring at lower and upper levels of the roof.
Attach the upper parts of the columns to
the compression ring in a manner that would
allow them to rotate in plan, make them
also Toblerone in profile with curved upper
ends (like those shoulder parts). Make the
lower columns out of big tubes, whose final
length and shape of the ‘dog’s leg’, which
kink near their tops, and would be finalised
on site after erecting the roof (on tempo-
rary supports) based on the positions of the
bases now drilled and welded into position.
Excellent use of steel
The detailing and fabrication of a tubular
structure like this takes a special team.
Spiral Engineering, the steel contractors
on this project, is one of a few companies
with the skill and dedication to build such a
complicated structure.
Project team
• Developer:
The University of the
Witwatersrand School of Geosciences
• Architect:
Krynauw Nel Associates
• Structural engineer:
Peter Fellows
Consulting
• Quantity surveyor:
Crane QS
• Project manager:
Craig Harrison PM
• Main contractor:
Omni Struct Nkosi
• Steelwork contractor:
Spiral
Engineering
• Detailer:
KRU Detailing
• Cladding:
Cupric Tectonics
• Painter:
Mzekizeki Painters
The original brief:
• The structure must protect the fossil
bearing deposits from elements –
particularly rain and falling debris and
must prolong working hours on site for
the scientists.
• The structure must act first and foremost
as a platform for research.
• The structure must be able to
accommodate tourism, or group visits of
up to 48 people, but must separate these
visitors from the research activity.
• The structure must be able to lift rocks
weighing around one metric ton
PROJECT PROFILE – STEEL CONSTRUCTION
The proposed structure was to have no concrete
footings), and removable, should it ever be
required – leaving minimal traces. It was clear
that some steel structures would be the answer.
The accuracy of the detailing and the dimen-
sional accuracy of the fabrication was
tested during a trial assembly on temporary
supports (thus emulating the actual erection
procedure) at a local rugby ground.
Erection
To reach the site, one has to cover the 7,5 km
farm track road, which runs partly through
a river bed. Special trucks with limited
capacity were used on the farm. After four
unsuccessful tries, finally a 30 ton all-ter-
rain crane made it to site and had a long
enough radius and capacity to reach without
damaging the trees and the bush.
Once the roof structure was erected
on the temporary scaffolds and the upper
columns were hung, only then could the final
site-made dog’s leg kinks be done, leaving
the beetle standing on its own legs.
and move these rocks to a vehicle
loading point.
• The structure must not have a significant
foundation and be as close to free
standing as possible.
• The structure must not make contact
with the ground within the anticipated
10 year excavation goals. The structure
must be, due to the nature of the
environment, temporary as it will
almost certainly be there for many
decades it must be permanent in
nature (thus a temporary-permanent
structural design).
• Due to the sensitivity of the environment
the structure sits within, it must be
as near as possible ‘invisible’ within
the environment.
• Due to the importance of the fossils it
protects and the projected tourism and
VIP visitations, the structure must be
impressive when one is within it and
reflect the importance South Africa holds
for these World Heritage objects.
• The structure must tell in its architecture
the story of the site and the discoveries
made there.
• The structure must be fire and
animal resistant.
• The structure must be low maintenance.
• The structure must be flexible for
placement when on site.
• The structure must allow for expansion
of the excavation in the future.
• The structure must be, where possible,
manufactured in South Africa and use
environmentally friendly materials
where possible.