Client: Kumba Iron Ore – Sishen Mine
Project: DMS Primary Crusher Replacement Project – Workshop Building upgrade in crane capacity from 120T SWL to 140T SWL
Year: 2021
The DMS Primary & Secondary Crushing Plant Building was originally designed and constructed in 1978 to accommodate 120T/15T SWL, 15T & 35T SWL Electric Overhead Traveling cranes and has been in service to date. In 2021 Sishen Mine endeavoured to replace the existing ageing Nordberg Gyratory Crusher which has reached the end of its service life. The new crusher’s bottom shell assembly has a mass of 137.89T which exceeds the capacity of the existing 120T/15T SWL Electric Overhead Travelling crane. The 120T/15T SWL EOT Crane needed to be upgraded to a 140T/40T SWL EOT Crane and Euler Structural Engineering was appointed to assess the building in order to determine whether the structure is suitable to function under Serviceability Limit States (SLS), Ultimate Limit States (ULS) and Fatigue Limit States (FLS) loading conditions under the anticipated loading from the crane and extended life of mine:
Fatigue Limit States (FLS) analysis – The fatigue effects due to the cummulative cyclic loading of the 120T/15T SWL crane installed for the past 42 years (1978 to 2021), as well as the remaining 15 years life of mine (2020 to 2035) with the proposed new 140T/40T SWL crane installed, was investigated. It was determined that all structural elements have adequate fatigue resistance and that the design will be adequate to continue safe operation at the required service levels for the remaining life of mine.
Serviceability Limit States (SLS) analysis – The building and crane support structure was assessed to determine whether the deflections of the structures are within the limits specified by the relevant codes and standards. The building foundations was analyzed for soil capacity, uplift, overturning & sliding. All structural steel elements were found to conform to the serviceability requirements of SANS10162-1:2011 & Anglo-American Specification 114001. The foundations were able to provide adequate resistance against sliding, uplift and overturning.
Ultimate Limit States (ULS) analysis – A 3D Software Model was developed and the maximum stress levels assessed at Ultimate Limit States (ULS). This provided an indication of whether all structural elements, including all connections have adequate strength to resist the forces induced by the higher 140T/40T crane wheel loads. In addition, the civil concrete foundations were also assessed for shear and bending moment resistance. Significant structural modifications were required to the crane support steelwork.
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