Construction World November 2023

Erection of the steel framework structure underway on one section.

Columns being erected using the innovative conveyor system.

An aerial view showing the steel framework with some of the solar panels already installed.

“Smaller quantities of concrete are collected by dumpers from the readymix trucks at road level and brought to the base of the conveyor belt.” Concrete is shovelled onto the conveyors and further guided into the column boxes from a receiving platform on the scaffold. To transfer the load of the new installations right through to the original foundations of the centre, the concrete columns have to be drilled and doweled into the existing column heads. This requires an intricate methodology of first scanning and then opening up the concrete roof slabs to ensure that no post-tensioned cables in the slab are compromised during the process. “The wind loads on the roof top structure are also high, creating significant challenges and we mitigate this by ensuring that our dowels have a pull-out strength of 12 tonnes each – or 120 kN,” he says. The HVAC aspect of the project also has its complexity, as it requires demolition, strengthening and new construction over existing Eastgate Shopping Centre tenants, and this has to be accomplished without interrupting trading activities. The existing structure will not bear the load of the seven new 10 tonne HVAC chillers which are to be installed, and Muller explains that interlinking stub columns will create a grid to support these chillers. “We will cast the stubs in a similar process to the solar panel columns, ensuring that the load is correctly transferred to existing columns,” he says. “Beams will then be systematically cast, working in a direction of priority for the HVAC specialists, so they can start their installations on the network of support steelwork and grating that we provide.” Framing the HVAC area is a perimeter louvre closure some 3,5 metres high, to conceal the installation from view. All this work is to be safely conducted at height, given that the HVAC rooms are 8,5 metres above ground on one side, and 20 metres on the other. Rainwater harvesting is the third aspect of the project, and will allow Eastgate

Shopping Centre to make better use of rainwater – as well as groundwater – to reduce its reliance on municipal supply. The centre already has a buffer tank to offset the impact of water outages, but the new facility will harvest and treat rainwater for tenants’ and shoppers’ use. “At the heart of the new facility are two segmented steel tanks measuring 4,6 metres high and capable of containing about 200,000 litres of water,” he says. “It will be fed from rainwater runoff and by groundwater resources under the centre.” There is also a filtration and treatment system to ensure the water’s potability. Adding to the stringent health and safety demands, the water tank is being built close to an LPG gas installation, limiting the use of certain electrical equipment.  The solar domes are designed to protect shoppers and their parked vehicles from sun and rain, while still allowing sufficient cooling air movement under the dome.

29 CONSTRUCTION WORLD NOVEMBER 2023