Seismic Analysis of a High Integrity Nuclear Crane
Eadon Consulting were approached by SCX, a specialist crane supplier, to assist with the optioneering phase of a project which looked at the design and supply of a high integrity nuclear crane. With a number of different options for the cranes layout being developed, Eadon Consulting were asked to carry out simple hand calculations looking at the seismic performance of the different options.
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Following this initial work Eadon Consulting were then contracted to carry out a response spectrum analysis of the finalised crane structure as well as checking the mechanical components. A full beam element model of the crane was first created using ANSYS V12. This was subjected to a modal analysis and subsequently a seismic response spectrum analysis. The crane had to comply with the requirements of BS2573: Rules for the design of cranes, as well as JSP 467. The various beam moments and stresses were extracted to ensure that none of the elements would fail under seismic loading.
One of the main challenges on the project was the long span of the main beams. The design of these had to be developed to ensure that they did not buckle during a seismic event. However it had to be possible to fully inspect all welding of the beams to ensure that it was acceptable for a nuclear environment. This resulted in special beam section being developed that had good buckling strength but with minimal welding.
The hoisting mechanism was also checked under various fault load cases to ensure that it was satisfactory. These included snagged loads as well as ledge loads and rope failure.
The project was successful with the feasibility of the crane structure having been proven and the whole project is now awaiting HAZOP 2 review.