Gantry Crane Vertical Post Dimensions

I've got a 12" 'W' section I-Beam I'm planning on using for a gantry crane. Unfortunately, I'm having a tough time finding specs for the upright posts. Anybody have dimensions for square tube uprights for an 8k-10k lb. gantry?

Thanks!

This is something you really should have a proper engineer advise on, and they would (should) have some reluctance to stick their neck out without seeing design drawings and knowing how it's assembled/welded. Bracing can affect safe post size, as will whether this is stationary or will be on casters. Height of the post too, span of the top beam, etc.

I like overkill, so I'd use a solid 12" x 12" bloom for the upright.

Look at the Wallace crane website.

I like the Wallace crane underslung crane design quite a bit. But I'm thinking of reverse-engineering a more conventional design (Wallace doesn't list the A-Frame tube sizes fwiw). Certainly not asking for anyone to offer any legal or engineering advise here - just looking for what the spec is on a commercial unit so I can see what I'll be looking at in terms of materials.

For the formulas, look for Euler buckling of columns. Might be in Roark. This will give you the general theory. But there are lots of practical details, and a crane collapse is likely to make for a very bad day.

Understood. Of course, a perfectly engineered crane can fail because of poor construction, and a perfectly constructed crane can fail because of improper use.
A some point the end user in any industrial/heavy lift situation needs to assume some level of responsibility for their own safety.

Having said that, thanks for the formula reference. I've got a steel construction manual somewhere - If it's not in there, I'm always looking for an excuse to buy another reference book!

Why square? I would think round would be cheaper to buy and easier to calculate. It seems to me that square is stronger corner to corner rather then flat to flat.
Bill D

I'm not married to square tubing, it's just that most commercial units I see use square tubing. I'm assuming square tubing makes miter joints that much easier, which probably saves on fabrication costs for manufacturers more than the difference between round and square - but that's just a hypothesis on my part.
Regardless, I'm still curious what size/thickness are found on the vertical columns on the larger gantry cranes that folks here have in their shops - purely for academic purposes at this point. =]

My bad. I was thinking jib crane not gantry crane. I have seen pictures of a few gantry cranes with round uprights but most are square tube.
Bill D

Adjustable height will use larger posts to account for slop in the assembly.
Bil lD

No worries Bill!

So, for all the engineering types out there, what configuration would determine the effective length on a gantry's verticals? Pinned/Pinned, Fixed/Pinned, Fixed/Fixed, Free/Pinned, etc.? That seems to be the biggest single variable in the buckling calculation formulas.
FWIW, my gantry will be on 4-position lockable casters but would never be moved under anything but a very light load.

PS I'll probably be sticking with a fixed-height assembly.

There are several factors for the design, you should start with a bottom up approach. What is the target weight to lift/handle, add in a safety factor of 2-2.5. What is the thickness of the slab of concrete, what PSI rating is the concrete, what is beneath the concrete (fill, engineered fill, composite, etc), what is the distances to the edges of slabs, where is the re-bar located. This gets you started on your bearing/baseplate plate design for whatever column you want to support. Then you have pullout strength of anchoring systems. From the base plate you have to use statics and dynamics to determine the axial strength of the column to resist shear and buckling, statics for a loaded system with no movement, dynamics for a loaded system with movement. From the columns you go up to the vertical load bearing sections (span of rails) again you need to determine what shape and size for the "rails", almost as important as the capacity of the rails is the type of connection you will use to allow the transfer of load to the ground, AISC manual for that. You will need to use laterally supported rails to transfer the weight properly without buckling the flanges of the beam. Next is the transverse rail which the lifting system will move along, you will again need to determine the appropriate shape and size of beam/rail to use for this but there is extra consideration for off center loading and the forces imparted on the beam from swing in the load and twist when lifting. Are there any seismic considerations where the crane will be installed, that will need to be considered. Remember it isn't just the mass of the load being lifted, what speed will the designated hoist lift at. That will impart huge initial stress on the system as a whole. Lots of math to do, lots I am not mentioning here. You can chance it and "wing-it", buy a prefab system, or get a PE stamped engineer to design one for you. Just having a 12" wide flange beam means little, what is the Moment of Inertia of the cross section. That is what determines capacity.

Are you going to have a single upright or A frame uprights? What size hoist will you hang? Keep in mind failure will probably be in a dynamic mode rather than static. You are wheeling a load and one caster hits a hole in the floor or a dropped bolt and comes to a sudden stop. Or you hang a manual chain fall that isn't quite big enough, so you get a buddy thats larger than you to help you pull.

I made a 1 ton with A frame legs. I used 3" schedule 40 pipe. Iin 40 years of intermittent usage it hasn't made me nervous yet.

Remember to add several hundred pounds to the load for the hoist, trolley and rigging. Many folks add a second lighter hoist as well. If these are manual hoists add another 100 pounds for the force pulling down on the lift chains.
Bill D

OK - lots of details to address here:
Shop floor appears to be >5" of concrete over crushed rock fill. No idea what psi - but I was able to roll my 10k lb Cinci #3 over it on pipes without issue and the floor under it now looks fine more than a year later. Basic design is either a 9' or 11' long 'W' section I-Beam (I have two sections to work with), 12"x30lb. 10' Tall non-adjustable vertical supports would be placed to leave approximately an 8.5' clear span. Basic design would support the I-beam on upside down 'Ts' with additional 45 deg. supports and 8" 4-position lockable casters (2.5k lb rated ea.) and perhaps some kind of screw jacks for additional support on heavy lifts. The base of the'T' section would 5-1/2' long. I would probably use a 1/2" top plate welded to the verticals and use bolts to secure the I-beam, but I want to size the columns before I settle on a particular attachment design.
I have verified commercial 10k lb gantry units that use this particular I-beam section profile in the span I'm looking at. The idea was to build the unit to 10k lb max specs but to rate the thing independently when finished. Understand that the heaviest thing I can imagine picking up in my shop currently is less than 6k lbs. Forseeable heavy tasks would involve things like tractor and forklift maintenance. I also have the technology on hand to test for deflection of the I-beam under load which would be how I would 'rate' the capacity of the finished product (eg put increasing loads on the unit an verify that the maximum deflection was not approached, inspect all welds, etc.).
I have no plans on rolling this thing with any kind of large load on it. My heavy hoisting rig would likely be one or two chainfalls using fixed attach points or a trolley as required.
This is going to be for a farm shop not a commercial setting so slow, steady, and careful will be the order of the day in terms of lift speeds.

Citxmech said:

OK - lots of details to address here:
Shop floor appears to be >5" of concrete over crushed rock fill. No idea what psi - but I was able to roll my 10k lb Cinci #3 over it on pipes without issue and the floor under it now looks fine more than a year later. Basic design is either a 9' or 11' long 'W' section I-Beam (I have two sections to work with), 12"x30lb. 10' Tall non-adjustable vertical supports would be placed to leave approximately an 8.5' clear span. Basic design would support the I-beam on upside down 'Ts' with additional 45 deg. supports and 8" 4-position lockable casters (2.5k lb rated ea.) and perhaps some kind of screw jacks for additional support on heavy lifts. The base of the'T' section would 5-1/2' long. I would probably use a 1/2" top plate welded to the verticals and use bolts to secure the I-beam, but I want to size the columns before I settle on a particular attachment design.
I have verified commercial 10k lb gantry units that use this particular I-beam section profile in the span I'm looking at. The idea was to build the unit to 10k lb max specs but to rate the thing independently when finished. Understand that the heaviest thing I can imagine picking up in my shop currently is less than 6k lbs. Forseeable heavy tasks would involve things like tractor and forklift maintenance. I also have the technology on hand to test for deflection of the I-beam under load which would be how I would 'rate' the capacity of the finished product (eg put increasing loads on the unit an verify that the maximum deflection was not approached, inspect all welds, etc.).
I have no plans on rolling this thing with any kind of large load on it. My heavy hoisting rig would likely be one or two chainfalls using fixed attach points or a trolley as required.
This is going to be for a farm shop not a commercial setting so slow, steady, and careful will be the order of the day in terms of lift speeds.

Click to expand...

There was a long thread a few months ago where someone had gone to great lengths to document their "build", try the fabrication section.

I'll see if I can find it. =]
...
Not seeing anything I haven't already read unfortunately (the 30 ton crane build sure is impressive however!). Before embarking on this project, I did do a pretty exhaustive search - not saying I couldn't have missed anything, but I didn't want to ask a question already answer 100 times. Column sizing information seems to be hard to come by for some reason.

Ok, maybe some confusion on my part. Are you planning on building a gantry crane (4 vertical beams permanently anchored to the ground with an overhead XY plane of movement for the hoist) or are you planning on building an (A-frame style lift, a structure mounted on 4 wheels with one central beam for support, lift travel in line only no perpendicular travel)?

Citxmech said:

No worries Bill!

So, for all the engineering types out there, what configuration would determine the effective length on a gantry's verticals? Pinned/Pinned, Fixed/Pinned, Fixed/Fixed, Free/Pinned, etc.? That seems to be the biggest single variable in the buckling calculation formulas.
FWIW, my gantry will be on 4-position lockable casters but would never be moved under anything but a very light load.

PS I'll probably be sticking with a fixed-height assembly.

Click to expand...

Unless it will be all welded, safest to assume that all joints are hinges. Build for a safety factor of at least four to one.

It looks to me like the huge 100 ton gantrys use the same basic a-frame leg design as the home shop type. Not the single vertical. leg design of the smaller units which max out around 5? tons
This one looks interesting as to how the top beam is installed. I think it is a double top beam. All the big ones tie the splayed a-frame feet together.
Bill D.

The festoon arrangement below is probably heavier duty then any crane I will ever own.

Hot Sale 200 Ton Double Girder Gantry Crane With Hook - Shenghua Heavy Crane Group - ecplaza.net