Liverpool Street, Darlinghurst

This project was an extremely sensitive site due to the constraints on retention of the heritage facade, structural configuration and the bulk excavation up to the internal face of the facade to a depth of 2 basements.

Mann Group has successfully won the contract through the smarts and innovation of the Mann Group team. A full structural redesign was tendered to the client, which ultimately secured the project with a full D & C package assigned to Mann Group as principal contractor.

Basically the construction constraints did not allow to install conventional structural steel facade retention system internally which was to secure the 16 meter (4 level) high boundary walls that where to be retained. This was due to the bulk excavation cut line ultimately commenced from the inner face of the internal line of the 4 boundary walls which went down some 9 meters (2.5 levels) below the ground floor slab.

The innovative solution that was offered by Mann Group was to utilise the existing structural steel roof as a diaphragm to support all the external walls. How this happened was a parallel webbed truss was constructed supporting the existing roof and orientated N/S mid way through the building bearing at the very northern and southern ends of the facade walls.

This truss spanned approximately 30m and was constructed prior to any demolition works starting.

Post completion of the truss and installation of 2 levels of whalers wrapping the perimeter internally, with all other associated structural upgrading works keeping in mind that all temporary steel support was installed strategically as not to foul with new slab construction.

Mann Group proceeded to remove all internal load bearing walls and slabs down to and including ground floor slab.

The structure built had successfully worked and was an extremely impressive design and build by the Mann Group team.

Accordingly the bulk and detail excavation and underpinning was conducted in rock utilising rock saw and minimal vibration techniques adopted to preserve the integrity and amenity of the adjoining neighbouring residents, hospitals and heritage component of the structure.

In addition to the positive points that the Mann Group solution offered, many more advantages where gained by not only Mann Group, but in fact the client as well.

Some points:

  • Zero (0) rain days, as the roof provided weather proofing
  • Dust and noise , as site was fully encapsulated
  • Zero obstructions for the new building to be built, as the original design was burden with sequencing, structural steel and staging.
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