Engineering Design Consultants
Jan112018
The Seismically Rated Hoist Challenge

Here at Eadon we regularly design and substantiate specialist mechanical lifting equipment, including high-integrity cranes for the nuclear sector.

A recent nuclear lifting project provided just the sort of challenge we enjoy, designing a high-integrity seismically rated hoist, supported from existing pre-cast anchor bolts weaker than the load they were required to carry! 

 typical Eadon desk with calc pad

The breakthrough came by realising that we needed to turn the usual approach to designing beams on its head. Increasing the stiffness of the support structure increased the impact factor from the suspended nuclear load, therefore, rather than making the beams stronger and stiffer, we counterintuitively needed to make the beams more flexible and ductile. By looking to the often sadly neglected E/R term in the elastic beam bending equation it was possible to quickly determine the optimum dimensions for a solid beam. These beams provided an elegantly simple solution to reducing the loading on the vulnerable bolts, by acting as tuned leaf-springs supporting a rigid runway beam to redistribute impact forces.

Response spectrum analysis was used to substantiate the structure against seismic loading and Beam Element Modelling enabled validation for fault and fatigue loads.

If you have an interesting engineering problem, or need to validate a complex structure for fatigue or seismic loading, call us on 0114 399 0400 or email us.

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