FOS for Jacking Points on a structure
FOS for Jacking Points on a structure
(OP)
I'm working on some jacking points for a pumphouse and I had a question about the FOS that should be used. I'm pretty green and haven't dealt with this yet. Basically the structure is going to be taken off the truck with jacks, and lowered onto the foundation.
I was wondering if anybody had any advice on this topic. Are jacking points to be designed similar to crane/lifting components (higher FOS)? Are these loads to be factored as any typical load (lesser FOS)?
I've dug around, asked around, and haven't been able to get a solid answer. If anybody has any info, or specific references where I should look to find this?
Thanks in advance.
I was wondering if anybody had any advice on this topic. Are jacking points to be designed similar to crane/lifting components (higher FOS)? Are these loads to be factored as any typical load (lesser FOS)?
I've dug around, asked around, and haven't been able to get a solid answer. If anybody has any info, or specific references where I should look to find this?
Thanks in advance.






RE: FOS for Jacking Points on a structure
Another thing is that you need to be as accurate as feasible with your solicitations; since dynamical, either a dynamical analyses or impact factors will need to be considered.
RE: FOS for Jacking Points on a structure
If it is not being used to lift over personnel then the jacking points just need to be designed for code factors. Just remember that it will probably not be the critical case as you only need to allow for the dead weight plus a dynamic factor.
Just make sure that there is a good allowance at the jacking points for abuse and misalignment as they will never get it perfectly right.
The high factor of safety on most construction equipment is due to the fact that this single factor allows for: materials and load factors, dynamic factors, and allowance for wear and tear since they are reused multiple times.
RE: FOS for Jacking Points on a structure
ASME B30.1 looks promising as far as outlining jacking procedures and design.
RE: FOS for Jacking Points on a structure
Good point about the 4 points of support though I would think it would depend on the stiffness of the frame. For a flexibly frame it would be more or less equal for a stiff frame it will be exactly as you say.
RE: FOS for Jacking Points on a structure
Very scary
RE: FOS for Jacking Points on a structure
Fighter airplanes are about 1.05:1
It all depends on how well you know your loads and the people putting it together. That's why it takes about 10 years to build a new airplane!!
I'd vote for around 2.5:1
RE: FOS for Jacking Points on a structure
RE: FOS for Jacking Points on a structure
I have designed a lot of jack and skid type jobs. The largest was a 3600 ton bridge.
Three point and four point comments are right on the money. They may use four jacks and pipe two together so you have a four point pick so to speak. Remember that the piped jacks will see the same pressure and thus distribute the load equally. Going this route you will get a flat plane that can pivot
Four point picks have more control but everything is independent. Good experienced crews are required. You need to absolutely specify differential elevations that are acceptable for the design of what ever you are picking. Forced differential elevations put the stress back into the picked object.
Also mind the center of gravity both spatial and in plane. If the vertical cog is high, to much differential lifting can make it go flop.
RE: FOS for Jacking Points on a structure
RE: FOS for Jacking Points on a structure