Crane Loading
Crane Loading
(OP)
Hi I am just curious about the loading from the footprint of a crane (track dimensions: 11m x 1.5m). When discussing the spreading of the loading from this crane through regular fill would it be standard to take it as a wheel load with a 30 degree spread angle against depth. Or because the dimesions are so large would it be more accurate to take it as an area load (udl) therefore the pressure will remain constant with depth?
Any advice is welcome
Thanks
Any advice is welcome
Thanks






RE: Crane Loading
Yes, I've typically taken the wheel load as spreading out at 30 degrees for the soil pressure. I use actual track dimensions or calculated wheel contact areas.
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: Crane Loading
A few cautions and general rules of thumb about crawler crane track load distributions (since they came up):
- Most crawler cranes are designed so that about half the track width bears on hard surfaces. When used on soft surfaces, the crane sinks in to engage the full width of the track
- In the situation mentioned by TME with a heavy pick over the front, you'll often end up with a triangular distribution over some portion of the track length, but not the full length (often 1/2L to 2/3L)
- If the crane has a large counterweight and the boom is in tight with no load on the hook, the crane is unbalanced in the opposite direction. This happens alot while the crane is mobilizing around a site, and can have nearly as pronounced an effect for track loads
- When a crane is swinging over the side, you can typically count on a uniform load in each track, but different percentages of the weight in the two tracks -- 80% and 20% isn't unheard of
Crawlers with variable-position counterweights or super lift trailers perform better in this regard -- I've heard that you can get close to uniform loading with those, but not quite.Also, I apply similar considerations for RT and Hydro cranes on tires or outriggers -- but I won't get into those here.
RE: Crane Loading
https://www.youtube.com/watch?v=xz71eVreMDc
RE: Crane Loading
*** If the crane has a large counterweight and the boom is in tight with no load on the hook, the crane is unbalanced in the opposite direction. This happens alot while the crane is mobilizing around a site, and can have nearly as pronounced an effect for track loads
It is imperative that this load condition be checked. This is many times the controlling load case for heavy lifts. Large crawlers that are fitted with backstay, loaded up with counterweight, and boomed up tight and unloaded generate very high ground bearing pressures with the triangular load distribution opposite of what you see when loaded.
RE: Crane Loading
Dave
Thaidavid
RE: Crane Loading
RE: Crane Loading
I was thinking about the cranes used along the pier at NUCOR, in Decatur, Alabama. These do set up on outriggers. @Joe Grant didn't specify his crane usage in his post, so I offered my thoughts on speculation. Apparently these were off the mark for his application.
Thaidavid
RE: Crane Loading
Do you happen to have a photo of the mentioned crane? I've not seen one like that. Sounds a little like a dock-side "whirly-bird" crane, but all of those I've seen have either been on rail or on wheels.
RE: Crane Loading
Dave
Thaidavid