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BEST
PR
O
JECTS
34
CONSTRUCTION WORLD
DECEMBER
2015
Careful planning and management of
façade cladding activities allowed
Murray & Roberts Western Cape
to gain 38 days on the construction
programme for Redefine Properties’ The
Towers project in Cape Town’s Central Busi-
ness District. An emphasis on innovation,
teamwork and safety characterised this
landmark project, which was completed in
August 2015.
Originally built in the 1970s, The Towers,
previously known as The Standard Bank
Building, consists of two towers, a 13 and
a 23 storey building complex, with a four
Building Contractors
A2
Project information
• Company entering: Murray & Roberts
Western Cape
• Project start date: 20 June 2013
• Project end date: 30 August 2015
• Client: Redefine
• Main contractor: Murray & Roberts
Western Cape
• Architect: Smuts & Boyes
• Principal agent: BFH de Jager Project
Managers
• Quantity surveyor: LDM Quantity
Surveyors
• Consulting engineer: Aurecon SA
• Subcontractor (façades): World
of Windows
• Project value: R370-million
(excluding VAT)
The Towers
storey building linking the two towers.
A planned upgrade of the complex to an
A-grade office building incorporated wrap-
ping the envelope in high performance
architectural glazing. It also involved adding
an additional 1 500 parking bays in the form
of a 13 storey parking structure between
the two towers, as well as upgrading of the
public square.
Construction commenced in April 2013,
with the parking structure columns being
constructed in the current basements. The
existing foundation of the seven storeys was
insufficient to cope with the loading of the
proposed 13 storey parking garage. New
foundations were required for the basement,
which continued to operate in the interim as
a three level parking garage for the tenants.
After construction of the founda-
tions for the new columns, a letterbox was
constructed in the existing slab above these
to facilitate the casting of the concrete for
the column. Once the first column on the
lower basement level was cast, the slab
above was back propped and a bigger aper-
ture was cut to extend the column through
the slab.
Concurrently with this operation the
existing four storey link building, situated
between the two towers and on top of the
old parking area where the columns were
being constructed, was being demolished.
The construction programme was
carefully coordinated to ensure that the
construction progressing from the basement
level upwards would simultaneously meet
with the demolition of the four storey link
building on the ground floor. Once this was
accomplished, the construction of the 14
storey garage began.
One of the interesting challenges
encountered on the project was main-
taining a column-free space in the existing
ground floor public square, with the top 10
levels of the parking structure cantilevering
13 metres over this square for a distance
of 50 metres. This was achieved with the
construction of a 55 metre span by 25 metre
high A-frame megatruss.
The truss is designed to span 50 metres,
carrying nine suspended floors by transfer-
ring the gravity load to the L-shaped shear
walls at the ends.
What is especially noteworthy is the
fact that an entirely separate, temporary
concrete structure was built, complete with
five piles, to support the A-frame until the
full frame was completed, whereafter the
temporary frame was demolished. This was
required due to the large magnitude of the
temporary loads, which would overload any
conventional back-propping system.
Once the A-frame was completed, the
tension ties and hangers were prestressed
to between 5 000 and 14 000 kN and
the bearing on the temporary columns
was released through a phased down-
ward-jacking process, using 8 000 kN flat-
jacks on top of the temporary columns.
Also entered Category
E