Australis Nathan Building
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Australis Nathan Building

November 18, 2015
Project Name: Australis Nathan Building, Britomart, Auckland CBD
Client: Cooper & Company
Architect:  Peddlethorpe
Engineer:  Holmes Consulting Group
Main Contractor:  Hawkins Construction
Description: The existing 5,500m2 building comprising two adjoining structures, Australis House and Arthur H. Nathan were the last remaining vacancy in the Britomart precinct awaiting an anchor tenant. Tiffany & Co were secured so Cooper & Company got underway with the upgrade of the prime building.

This project involved three main aspects, being; temporary works to support the floor lowering process and removal of five existing columns; new Concrete foundations and plant room; seismic strengthening to each floor and at Parapet/roof level along with a new Mezzanine level.

Part of the floor area in the Tiffany tenancy required 5 existing hardwood columns to be removed from the new ground floor level to underside of level one. New portal frames were introduced to replace the columns The welded beams were installed within the floor space of level one. Once the new portal frames were installed the existing columns from level one above were hydraulically jacked up to transfer the dead load from upper levels into the new transfer portal frame. New concrete foundations where poured on the existing basement slab support the portal frame.

The existing steel beam/Kauri joist floor was 1.2m above the existing street pavement level. Tiffany & Co required the floor to be coincident with street level which meant the floor had to be lowered. 622m2 of flooring was lowered in 3 phases by simply being hung from the upper levels. This process was one of the existing and creative aspects of the project. Seitech work closely with the structural design engineers, Holmes Consulting Group to get all of the temporary works and permanent structure once lowered to meet the brief.

The seismic upgrade was a mix of a new diaphragm floor at each of the mid floors, which involved drilling and grouting 1500 threaded rods into the 500 thick brick walls where an equal angle was fixed to both the wall and a new plywood overlay; and new SHS and PFC elements around the perimeter of the structure at both roof level and parapet level.

A new 250m2 Board/deck at Mezzanine floor level along with a 90m2 plant room was created in the existing gable roof space.

Australis Nathan Building

Contracting, Construction & Strengthening Project