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Re: Jib Cranes

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Jim ---

I can tell you that jib crane foundations as designed by the mfr. - in my
experience - often need frequent releveling due to soil settlements. 
About one out of every three or four will need base plate adjustments as
soon as the first proof load is lifted.  Proceed cautiously, and specify
that the warrentee period for such adjustments is appropriate.  My
preference is a conservative flag pole (caisson) type foundation.

I know of no reliable references to address this type of foundation
shortcoming.

Russ Nester
rnester(--nospam--at)juno.com

____________________________________
On Mon, 20 Mar 2000 14:54:05 -0500 James_F_Fulton(--nospam--at)RohmHaas.Com (James F
Fulton) writes:
> Any OSHA/ANSI/other references that address design requirements such 
> as 
> design impact factor or safety factor against overturning. One 
> reason I ask 
> is that in a standard design I've got from a manufacturer for a jib 
> crane 
> supported by a concrete footing, it turns out that for the max lift 
> span of 
> 20 ft. and 2000 lb. max allowable lifted load (static), the heel 
> uplifts 
> somewhat. The calculated bearing pressure at 1500 psf is still well 
> within 
> allowable and Overturning safety factor is 2.20.  Thanks for any 
> info.
> 
> Jim Fulton
> 

Russ Nester
rnester(--nospam--at)juno.com