Enex 100 Retail and Office Tower
100 St Georges Terrace, Perth



Pivot / ISPT Group

Project Manager

Johnson Group


Hames Sharley


Brookfield Multiplex



Year Completed



Civil & Structural Consultants

Unique Design Elements

  • Reuse of Existing Diaphragm Walls & Piles
  • Utilisations of Shear Friction around Existing Piles and new footing collars
  • Large Floor Plate using Precast Beams and Hollowcore Planks

Enex 100 Retail and Office Tower
100 St Georges Terrace, Perth

This was a $250M development at 100 St George’s Terrace Perth that extended between St Georges Terrace and Hay St in the centre of the City.

This project comprises a 30 storey tower fronting St Georges Terrace with 4 basement carpark levels. The development extends through to the Hay Street Mall where there are 5 levels of retail and a double basement so that trucks can service the Hay Street Mall.

BPA engineering were engaged initially by The Pivot Group as Structural Consultants for the project. We worked very closely with Ralph and Beattie Bosworth in providing detailed sketches that showed all structural works including retention of existing fascades, establishing the extent of existing diaphragm walls and piles that were on the site from a previously aborted development and incorporating them into the new building, extent and capacity of an existing slab at the Hay Street end of the site and incorporating that into the new development.

After costings were established BPA engineering were assigned across to the Builder to complete the documentation and oversee the construction works. This involved 4 basement levels built up against existing Heritage buildings on two sides with restrictions on anchoring into adjacent properties. A 30 level office tower was built at the St Georges Terrace end of the site with retail linking through to Hay St over 5 levels.

Existing pile infrastructure where possible was upgraded by providing footing collars on the existing piles.

The existing diaphragm walls which extended around 50% of the site and were built for entirely different floor levels were incorporated into the new development by providing deep slab edge downturns that supported the walls laterally at a level that suited the reinforcement that was in the walls.

The fascade itself was investigated in detail by a specialist contractor (after advice from BPA) and this was repaired to overcome extensive deterioration. The System for removal of all the temporary bracing from behind the fascade and tying it back into the new building was all part of BPA’s work.


Master Builders Best Commercial Project Over $50m – 2010