Mobile Crane Outrigger Pad Design
Mobile Crane Outrigger Pad Design
(OP)
I'm designing a wood pad to support an outrigger(24" dia) load of about 120 kips. The soil is pretty weak, about 1000 psf bearing capacity (wood mill environment). This is my first time doing this type of design, and would appreciate any resource/help out there.
Thanks,
Kweku
Thanks,
Kweku






RE: Mobile Crane Outrigger Pad Design
RE: Mobile Crane Outrigger Pad Design
RE: Mobile Crane Outrigger Pad Design
RE: Mobile Crane Outrigger Pad Design
The sheathing serves only to stabilize the adjacent blocking and prevent rolling of members that have a high height to depth ratio.
So, to engage your 10'x12' nominal bearing area, you would need quite a bit of stacked material. I generally consider the "foot" of the outrigger to be capable of engaging its full footprint for the initial load transfer and let my loads transfer from there.
Going by this logic, you need quite a pile of blocking - so must you might not be able to get the outriggers to sit on top without walking the crane up by raising and lowering opposing legs.
Is the 1000 psf a general site condition or might their be some relief and higher capacity exactly where you need to set up?
Daniel
RE: Mobile Crane Outrigger Pad Design
Thanks for your input. The 1000 psf is part of Compliance Standard by the owner/client, to avoid the need for further testing (OSHA Regulations). The site being a timber mill with potential decayed organic material present, I guess the owner is being a little conservative for those two main reasons.
Thanks,
Kweku
RE: Mobile Crane Outrigger Pad Design
If the crane is stationary for a long period of time you can also bury a steel Wx in the ground to give a larger bearing area and get to good soil....or go the small micropile or jet grout column route (expensive)....or pour a concrete mat.
RE: Mobile Crane Outrigger Pad Design
RE: Mobile Crane Outrigger Pad Design