Architect and Builder September/October 2015 | Page 26

Around the atrium, several
pause areas and
breakaway zones where
staff and visitors can
interact animate the space

Also facing Bram Fischer Drive is a ‘jelly
bean’ shaped portion of the building which is
clad out in active glass louvres that open and
close automatically to shade the energy from the
late afternoon sun whilst leaving uninterrupted
views for most of the day, Again steel plays a
vital role in the support of these glass louvres as
tubular steel arms cantilever out from the slab
behind to support a curvilinear tubular member
that supports the glass louvres and mechanical
actuators. The grand glass façades on this face
too take their ‘strength’ from tubular support
steelwork resulting in a wonderfully transparent
‘arrivals event’.

24

Entering the building the visitor is immediately
greeted by a grand volumetric atrium space
with a wonderfully elegant tubular strutted arch
structure supporting air inflated ETFE cushions.
The strutted arch spans order of 24 metres and
its form is ideal for resisting the more dominant
uplift wind forces of such a structure whilst
being quite slender in form as a result of the very
light in mass ETFE cushions. The atrium space
is further complemented by beautifully detailed
structural steel staircases that feed people up
to the various floors.
On the north and south of the building very
carefully detailed steel shading structures hang
from the roof above providing shading (primarily
on the north) as well as doubling up as primary
cleaning access walkways. Again steel was
up to the task and loading of such walkways.
Despite this the shading structures remain
proportionally elegant in nature.
The design process was again one of
teamwork with the Professional Team, including
Pure Consulting - the Structural Engineers
- working seamlessly with the structural
steelwork contractors, Tass Engineering and
Nancy Engineering, along with the external
‘skin’ contractors in the successful delivery of
a beautiful end result.
The fabricator for the two roofs, Tass
Engineering, participated in many design
workshops to resolve connections together and
craneage and access had to be carefully worked
out so that the atrium roof could be erected with
cranes standing on the ground floor slab below
albeit with props by Main Contractor under the
outriggers. The cantilever roof on the west was
successfully rigged from Bram Fischer Drive
using conventional methods.
Multichoice City