The primary objective of the Smartstake project objective was to develop a trellising system that could be manufactured from steel, glass reinforced plastic (GRP) or concrete and be compatible to a conventional wood pole trellising system. Secondly the client also required simplified guidelines for adapting field implementations to local conditions. In a collaborative study with the client, the design and evaluation of the structural capacity of the profiles were contracted to SIMERA via Stellenbosch University Technology Centre (STC) as a Technology Innovation Agency (TIA) funded project for Ecostake.
The maximum load capacity of the conventional wood pole diameters and lengths used for trellising applications in South Africa were determined. The cross-sectional properties, including the thickness of the alternative steel, GRP and concrete profiles were determined using basic cross-sectional calculations and finite element analysis. The worst-case load condition in the trellising configurations considered was identified as winds load acting on the crop.
After extensive simulation and analytical loading comparisons and with associated design optimization a table which summarized the structural capacity of a profiles, relative to that of the equivalent wood poles, was generated. This table, along with a computational spreadsheet that could be used to determine the maximum wind loads that would act on a specific trellising configuration with a specific geometric location in South Africa, was supplied to the client. This enables the client to deliver a custom made trellising solution to the end user based on extensive engineering and simulation research.