Timeline – Durban Sugar Terminal
- 4th June 2020
- 2 Comments
Welcome back to the FGG Architects “Timeline” Series.
In this post we’ll be looking at the second project featured in our timeline for the SAIA-KZN Exhibition – Segregation & Integration exhibition.
The 1960s was a decade with a number of prominent projects for the firm. This included the headquarters of Standard Bank in the Durban CBD, the first houses in La Lucia and most significantly the Durban Bulk Sugar Terminal.
Sugar farming is synonymous with KwaZulu-Natal and it has had a significant effect on the economy and culture of the country. The sugar terminal project was born from the local sugar industry’s determination to increase the exports of South African sugar and compete in the world sugar markets on an equal footing with other major sugar exporting countries.
Globally there was a trend toward the transport of raw materials and a shift towards bulk shipping in many ports, due to the economic benefits of this method in comparison to packaged products, like bagged sugar.
Each of the three silos were built at different times, in 1963 the initial project budget was R4 million to construct the first silo and associated facilities, including railway infrastructure, conveyors and gantries, wharf side installations, administration building, public relations building and gardens. This first phase of the terminal was completed in 1965.
As you can imagine, there was a large engineering aspect to the project and this was handled by Sir Eric Millbourn in association with Moreland Engineering Consultants.
Even with only the first silo completed, the terminal was one of the largest of its type in the world at the time and became a distinctive feature on the Durban skyline. Something that would become even more prominent as the remaining two silos were built. The second silo being the largest of the three.
Before the relocation of the airport in 2010, the three lumps of sugar were a landmark passed by countless travellers when visiting the city by air.
The buildings’ architectural appearance is as a result of a combination of carefully considered functional and economical engineering factors. Ultimately these considerations resulted in a silo constructed in reinforced concrete with a cross-sectional shape that conformed as closely as practicable to the profile of the sugar pile housed within.
Due to the limited space available along the harbour’s edge, the sugar pile needed to be of considerable height and retained by the walls of the silo. The structure is a three pinned tied arch, which utilises the weight of two concrete arch segments to counteract the internal pressure of the sugar pile, tied together by the structural floor of the building.
Interestingly, at the time of design, several arch profiles were analysed and their construction costs estimated to establish the most economical design to achieve the best approach to proceed with. Ultimately it was a design consisting of hyperbolic paraboloids that would go ahead.
The silos feature a central hinge along the crown (top) beam, with the two edge (bottom) beams resting on roller bearings atop the pile caps. This allows for the silos to expand and contract to accommodate the sugar pile within. Together with expansion joints at 12 metre intervals, between which each arch is structurally independent of its neighbour, it creates a superstructure that is effectively articulated both in section and in length.
The greater terminal compound also features a complex network of gantries and conveyors that work tirelessly to transport the raw sugar from the purpose-built railway sidings and road network into the silo.
Beneath the sugar stored within the silo are a series of louvred hoppers, which allow for the controlled extraction of the product from any part of the silo by gravity flow. These hoppers discharge the sugar into a conveyor tunnel running under the length of the floor. This terminates at the eastern end of the silo into a junction pit. From the pit the material is moved up to the top of a tower that automatically weighs it on its way back down to a wharf side conveyor gantry.
At this point it is moved to a series of travelling outloaders which run on rails alongside the water’s edge. These outloaders utilise telescopic chutes fitted with sugar throwers to distribute the sugar evenly into the ship’s hold.
In many ways these buildings represent a bygone era. At the time of writing this post, the sugar industry in South Africa has felt the impact of a steady global decline in the consumption of sugar. Despite this, these silos remain operational and are a critical cog in South Africa’s R14 billion sugar industry.
We hope that you enjoyed our second timeline article. If you have any questions or would like to get in touch, you can drop a comment below or get in touch.
Next week we’ll be looking back to the 1970s when we take a closer look at the Umlazi Beer Hall, one of only three recipients of the national award for architecture in 1977.