2019
SAISC Steel Awards
This year a wide range of stakeholders in the built environment actively participated in
the SAISC Steel Awards and have started to recognise the pivotal importance of steel.
Durban Christian Centre
OVERALL WINNER, SAFAL STEEL INNOVATION CATEGORY
The ‘Jesus Dome’ roof structure at the Durban Christian
Centre was a well-known feature roof on the N2 coming
into Durban. The auditorium burnt to the ground in a fire
in 2016. The rebuild was commissioned in 2017.
The client wished to retain the memory of the original
dome into the future, however this is a shape that belies
the modern understanding for acoustic performance.
To produce a world-class auditorium the architects
instead conceived memory of the dome up into the air
and a tri-bifurcated arch was conceived. Simple, smooth
extruded box shapes rising over a sheeted, duo-pitched
and acoustically attenuated free-spanning roof structure.
On plan confined onto a hexagonal concrete ring beam
squeezed to focus on the stage.
There seemed little purpose, other than feature, for the
arches if they were not to be used to hang the roof below.
So, two possible schemes were followed in parallel. One
with no arches – the roof structure truss grillage made
deep enough to free span, and a second with the arches
used to hang the primary apex girder so economising on
the truss grillage. This gave cost comparisons to the client
in respect of the spend to achieve the arches over a more
conventional structure.
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Taking it to the Ground
Steel arches need pouncing points, which for this
structure, were some 15m off the ground. Off shutter
concrete prisms seemed to fulfill the need in every way.
The primary arch buttresses needed to be slimmed to
allow access on a restricted footprint so this arch was tied;
the primary girder running under the primary arch forms
the arch tie, interconnected in a bold move through large
welded steel elbows set into the 2.5m wide reinforced
concrete buttresses. The secondary arch buttresses were
free to sweep to ground along the steel arch thrust lines,
or thereabouts. For the balance of the roof structure, a
chunky concrete ring beam sits atop 7m high concrete
columns and ties into the double story structures at front
and back of house.
Making the Geometry Work
The arches are, as a trio, wedged from a single sphere,
with the origin deep below the floor slab. Each arch is the
rind of a perfect slim slice through the origin of the sphere
and as such, in radial section, is very slightly trapezoidal –
this variation was so small that the shape could easily
be rationalised to rectangular allowing the designers and
Steel Awards