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DECEMBER • 2016
Construction
WORLD
50
Professional Services
C
PwC TOWER
The PwC façade is concave and twisting, and knowing
the history of high profile cases with problems caused
by concentrated solar reflections from buildings (notably
those at 20 Fenchurch Street in London – the ‘Walkie-
Talkie’ – where plastic fittings on a Jaguar on the street
melted in 2013), the Arup team identified this as a risk
and knew this was something that would need careful
study for the tower. At the time of design, no software
existed for calculating the intensities of solar reflections.
Arup therefore scripted its own calculation in parametric
software. Using this script, it was able to calculate the
magnitude of the solar concentrations in the open areas
surrounding the tower and provide feasible and practical
solutions to mitigate the impact of the solar reflections.
Solutions considered were sunshades on the façade,
randomly scattering façade panels and making spandrels
non-reflective. In the end, it was decided that the best
solution was to use a less reflective glass in the spandrels
that was further enhanced by acid etching. Landscape
shading addressed any remaining concentrations over limit.
The horizon of Midrand, north of Johannesburg,
is set to change forever with the construction
of the new high-rise head office for Pricewater-
houseCoopers (PwC). The R1,5-billion project will
be a focal point in the up and coming Waterfall City
development and comprises 45 000 m² of modern
offices, designed to house 3 500 PwC employees in
an efficient and optimally designed workplace.
It is set to become a structure of iconic proportion due to its
distinctive twisted form designed by LYT Architecture for Attacq
Waterfall Investment Company and their developer Atterbury, and
realised through close collaboration with Arup. The structure is
a concrete frame with post-tensioned (PT) floor plates and each
floor of the 28-storey office tower rotates 1,2 degrees relative to
the floor below.
The core of the building was constructed using a method called
slip forming, where the concrete is poured continuously within the
steel shutters, which moved up at a pace of 2,5 m a day.
The Arup façade engineers worked closely with the façade
contractors Geustyn & Horak on a new suite of extrusions
specifically for this project, which is the first curtain wall in South
Africa with twisted unitised panels.
Parametric modelling can be described as modelling a structure
or object in an n-dimensional space, where certain chosen
parameters of the structure are adjustable.
The biggest structural challenge was that the spiralling form of
the tower causes the gravity loads to create naturally a clockwise
torsional load on the building.
Project information
• Company entering: Arup
• Client: Attacq Waterfall Investment
Company
• Start date: October 2014
• End date: October 2017
• Main contractor: WBHO
• Architect: LYT Architecture
• Project manager: LYT Architecture
• Quantity surveyor: Brian Heineberg
and Associates
• Consulting engineer: Arup
• Steel contractor: Amsteele
• Façade contractor: Geustyn
& Horak
• Mechanical engineer: WSP
The building is designed to be a Leadership in Energy and
Environmental Design (LEED) Silver Green building and the
environmental impact due to construction activity is strictly
monitored. The building itself will comply with all latest
sustainable and energy-efficient requirements in terms of the air-
conditioning system, the light fittings and the selection of glass
used in the façade. As of 15 September 2016, there has been only
one hour of lost time due to injury over 2 260 000 total man hours
on this project.
Joint Winner