New Zealand Commercial Design Trends Series NZ Commercial Design Trends Vol. 34/02C | Page 20

Over 3500m 3 of concrete and masonry and 250
tonnes of reinforcing steel were removed in all.
Stephen Cummings of McKee Fehl Constructors
says sequencing of the structural changes had to
be carefully developed to ensure the stability of the
buildings wasn’t compromised during the works.
“For example, the creation of the atrium required
major and lengthy structural demolition, including
the removal of a full shearwall from ground to level
5 that was the main spine of the north building,”
says Cummings.
However, this work couldn’t start until a com-
pletely new structural system had been installed
in key locations. The new structural system was
achieved with sprayed concrete shearwalls to
the north building, along with installing Buckling
Restraint Braces (BRBs) into the existing structure.
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“The use of BRBs allowed for the majority of the
seismic structure to be located at the edges of the
floors, resulting in open, uncluttered office space.”
The BRB is a contemporary seismic device with
an outer sheath of steel and an inner steel member
set in concrete that functions as a structural
damper, yielding and absorbing energy.
“Installing the BRBs into the existing structure
was our greatest challenge,” says Cummings. “The
connection details through the existing beams and
columns required scanning, hammer drilling and
then templating for the bracket installation.
“Every connection ended up being different, and
there was very little tolerance for installing the final
BRB. We also had to contend with the usual inner-
city issues of no storage space and limited access.”
Transpower’s interior design was by Jasmax, with
Previous pages:A grouping
of adjacent inner-city buildings
with an open a