Jib Crane

[dik]

I'm looking for a 'generic' solution for a jib crane support. The actual jib crane has a maximum reach of about 20' and a maximum service load of 2000 pounds. The existing concrete floor slab is sawcut away, a small pit is excavated and a 'blob' foundation is cast into the void. The top of the foundation is cast flush with the top of the slab and the jib crane bolted to the foundation. Soil is generally dense, non-cohesive. I've designed a few of these, but an wondering if there's a generic solution out there (nice to have a reference).

The gravity loads are resisted by the soil and the overturning is resisted by the soil at the base, active soil pressure on one side and the concrete slab at the top on the opposite side. The effects of any soil friction on the sides has been neglected, but the generic solution could include this (although I wouldn't include this component in the final design).

Can anyone suggest a website, spreadsheet or a text that has a generic solution for this?

 

[RiBeneke]

I would do the stability calculation in a spreadsheet of my own, as normal structural analysis software does not always have the load and stability factors in the right places.

Then use foundation design software for the footing, and structural steel design for the steel part.

 

[dik]

RiBeneke:
Can you outline the stability calcs a bit. For overall stability, I assume the bearing value as uniform at the outside edge and neglect the effect of the active soil and slab. For pressure distribution, I assume a regular triangular distribution going from 0 to max bearing, the full width of the footing and a triangular load active soil pressure on one side and a point load balancing this on the opposite side generated by the slab.