Construction Demolition of the existing buildings commenced in November 2006 ; lateral support and bulk earthworks commenced during May 2007 and the project was essentially complete and ready for trading during the latter half of November 2010 . The Hotel was , however , completed and was fully occupied during the 2010 Soccer World Cup Tournament . There were some challenging structural obstacles that had to be overcome as noted in the Structural Engineer ’ s report below .
STRUCTURAL ENGINEER ’ S REPORT The structural system adopted for the various usages of the building was a 280mm thick posttension slab on a 8,5m x 10,0m column grid , with column heads and edge beams to the parking levels , 550mm thick 2-way coffered flat slab and edge beams to the retail levels and 350mm thick flat concrete slabs on a 8,5m x 7,8m column grid for the 8 floors of the hotel structure .
The use of deep tubular structural steel girders , spanning 22m over Tyrwhitt Mall , was the structural solution for the elevated retail bridge connecting the 2 phases of the Zone development .
A 15m deep basement excavation , abutting the Gautrain railway reserve in Oxford Road , posed a challenge as the tunnelling operations inside the reserve made it impossible for the Zone ’ s lateral support to be constructed using the conventional method of perimeter piling and ground anchoring . To solve this challenge a “ top down ” construction was proposed .
The lateral support piles along Oxford Road are designed to cantilever from basement P2 ( 6 m ) with an earth wedge of 8,000m 3 of unexcavated material left in position from basement P2 and P5 to maintain lateral support .
From level P2 , piles supporting the hotel structure were sunk to a founding level below P5 . Construction of the hotel proceeded conventionally upwards and thus maintained the tight programme dates for the hotel opening .
The remainder of the basement structure outside the area taken up by the 8,000m 3 earth wedge continued conventionally . Only once all the concrete structure had reached ground floor level and the lateral support reinstated , was it deemed safe to commence the “ top down construction ”, i . e . construction of the parking levels P3 , P4 and P5 with associated excavation of the earth wedge under the hotel was carried out from the top down under the P2 level with each slab being cast on the earth below in order to maintain lateral support to the existing piles below .
A major challenge in the construction of the underground parking link , at the first and second parking levels , was to maintain all the existing municipal services under Tyrwhitt Avenue operational at all times .
Sewer , storm water , water main , electrical H . V . cables and fibre optic cables were all temporarily diverted ( with council approval ) or hung from temporary structures during piling and the 7 m deep excavation across the full width of Tyrwhitt Avenue .
The Zone @ Rosebank 325