Architect and Builder Dec 2017 / Jan 2018 | Page 47

demolished to make way for six new suspended
concrete art display floors whilst carefully retaining
the delicate existing and deteriorated external
fabric of the silos, the other half of the internal
silos, the future open atrium, required an intricate
‘bite’ to be carved out in the shape of a huge corn
grain. What silo proportions remained above the
‘carved’ out atrium actually hung suspended in
the air and open to the skies above, but glazed for
weatherproofing. To achieve the ambitious atrium
carving, the original silos were re-sleeved with new
reinforced concrete rings, linked together through
the existing concrete rings at strategic positions,
to create a structural ‘portal frame’ spanning over
Zeitz Mocaa
20m of the atrium. The structural design modelling,
sequencing, as well as the geometry of the carving
was highly complex.
Structural Engineering – Silo Hotel
The rectangular Silo Hotel building, being
considerably taller at 67m (the tallest building
in South Africa at the time of completion in
1924), consisted of a structural steel frame,
clad in concrete with reinforced concrete slabs
and had no seismic resistance – being originally
designed as a grain elevator and storage building,
alongside the silos. To be converted to residential
use, City of Cape Town building regulations
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