African Design Magazine June 2016 | Page 36

African project
PwC Tower – South Africa
boundaries of design. Our advanced parametric modelling software and systems enables
us to explore many options in our search to establish the optimal solution for complex
building designs such as the PwC Tower project.”
Arup façade engineer Rudolf le Roux describes parametric modelling as ‘modelling a
structure or object in an n-dimensional space, where certain chosen parameters of the
structure are adjustable’. In other words it makes it possible to explore the impact of any
of the input parameters on the design and cost of a structure.

Building design
“The biggest structural challenge was that the twist causes the gravity loads to naturally
create a clockwise torsional load on the building,” explains Lawson. “The obvious solution
to this would have been a very thick core wall, but because we were able to quickly asses
a number of different structural geometries, we were able to optimise the solution. Our
final scheme incorporated structural columns on the façade of the building that slope in
a counter clockwise direction around the core, balancing the gravity loads on the corner
columns and reducing the torsion on the core of the tower. This meant that the stresses
on the core wall decreased by a factor of four; therefore we could use a 450mm thick wall
which is not much thicker than a typical straight tower of that height would have needed.”
Le Roux continues, “We also utilised parametric modelling for the design of the façade
for the PwC building. Various solutions were on the drawing board at the conceptual
stage with factors such as glass utilisation, aesthetic integration with the structure and
integration of blinds with a sloping, slanting façade. Building a concave, twisted façade
out of straight aluminium profiles and flat glass was a challenge made possible through
parametric modelling.
“What we really enjoyed was that we could sit down with the architect and make
real-time adjustments to things like the column spacing and angles that they could
see instantly in 3D. It makes collaboration easy, and results in far less exchange of
correspondence back and forth,” explains le Roux.

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PwC head office, Waterfall, Gauteng. © LYT Architecture