Bridge Crane designs and ideas...38' span

[LD1]

Wow. My idea was to keep your current design of non moving 12' rails with the matching trucks you have, but instead of an underhung hoist (load on the bottom flange of the beam) on one big beam, use a top running design (hoist rides on top of and between two smaller beams).
The two beams do not move in relation to each other. Think IOI instead of a big I with an O hanging under it.


This design also leaves the bottom flanges of both beams available for smaller hoists for greater manipulation of a load. You can hang multiple hoists on a single beam but they are unable to bypass one another. With a main hoist on top and one on the bottom that can bypass the top, turning loads over becomes easier and safer.


This will help you by having smaller beams to lift into place. Two beams can have better torsional rigidity. Top running provides more room under the hook. A larger area of each beam is loaded.

I see what you are saying.

But I dont have enough rail to span 38' twice nor do I have a top running hoist.

What I do have is enough rail for the 12' spans, and 3 under-hung hoist. A 5-ton, a 1-ton, and a half ton. And I have a 5-ton and 1ton hoist.

And seeing what is out there in the used market, I think one large beam is gonna be cheaper than two smaller beams. ITs hard enough to find 38' of beam, let alone 2 of the same size.

 

[FarmWrench]

You still don't get it.

Your original post had a picture of three beams welded together. Drop the bottom beam and space the upper two just far enough apart to accept the hoist. You can't build a little car to run on top of two beams? You seemed determined to scab something together from Craig's list and your scrap pile so I went with that.

Where did I tell you to change direction? Where did I tell you to use the rail the long way? I didn't. I only tried to present an alternative to the three beam idea.

With the price of scrap where it is you should find a reasonable price on the real thing. Ask a demolition company as they know they would get very little sending one to scrap. Most current demo jobs were bid with higher scrap prices making a window of opportunity.

 

[Shield Arc]

Drop the bottom beam and space the upper two just far enough apart to accept the hoist. You can't build a little car to run on top of two beams?

That's how my steel supplier has their bridge cranes.
I have a set of V-groove wheels something like in this link. I thought about building a gantry crane. Mounting the V-groove wheel to the bottom of the 4-legs. Weld clips to the toes of angle iron, with the heel of the angle iron up, and bolt it to the shop floor for rails to run on. Don't see why LD1 couldnt build a cart with V-groove wheels mounted on the bottom, and angle iron on the top of the two span beams for rails for the cart to run on.
Value Brand Caster Wheel, 900 lb., 5 D x 2 In. 1NWG1 | Zoro.com

 

[Rustyiron]

The center posts are 8" x 8" x 1/2" wall square tubing.

phff, come on SA, cutting things a little close depending on that little piece of tin:laughing:

 

[farmer2009]

farmer2009 I gave you bad information! The center posts are 8" x 8" x 1/2" wall square tubing. You know how many times a day I walk right by those posts? And forgot what size they are.

Thanks. Post should be heavy enough. Amazing the little things we never pay attention to.

 

[LD1]

You still don't get it.

Your original post had a picture of three beams welded together. Drop the bottom beam and space the upper two just far enough apart to accept the hoist. You can't build a little car to run on top of two beams? You seemed determined to scab something together from Craig's list and your scrap pile so I went with that.

Where did I tell you to change direction? Where did I tell you to use the rail the long way? I didn't. I only tried to present an alternative to the three beam idea.

With the price of scrap where it is you should find a reasonable price on the real thing. Ask a demolition company as they know they would get very little sending one to scrap. Most current demo jobs were bid with higher scrap prices making a window of opportunity.

Oh I get it just fine.

When you mentioned two beams for the 38' span, I was assuming you meant them beams to be stationary, and a beam riding along them. NOT what I want,

this isnt Going to be a "scabbed" together piece. I have a pair of beams for the rails, rail track, columns, hoists, trolleys, etc. I only lack a main bridge beam. depending on whats out there, three beams as I picture is going to be stronger that twp in the method you describe.

Thanks for your input.

 

[flusher]

Relax safety police.

This is my own personal shop and no one for hire will be using the crane. No need for inspections or eng. stamp

Whatever beam I go with, I will run the calculations and assign a SWL. Dont need a freakin engineer to do some simple math for me.

Your problems will start when you or your heirs try to sell your property including the shop with your DIY crane. The buyer's mortgage entity will insist on a detailed inspection and will be looking for the engineering design package, the building permits and the periodic inspection reports for that bridge crane. Stuff like that can slow down or kill the escrow.

Good luck and be careful out there.

 

[LD1]

No intentions on ever selling. And if I do, it wont be hard to take the crane down. But I doubt I will have to worry about any of that. This is rural ohio, not CA or NY. We dont have any building inspections or anything like that here.

Had no issues selling my last house that had I-beams spanning across the garage with trolleys as well as supporting the upstairs floor loads.

 

[LD1]

Another question for the masses as I cannot find a formula or program to do what I want.

How to calculate stacked beams?

Example: I currently have 35' of W6x12 beam on my rack. Obviously it is too weak to make a span.

If I were to use W12x65 that is listed on c-list (nice 12" wide flanges so not much worry about buckling), I could safely lift 5550# @ 7200psi stress and 0.68" deflection.

IF I were to attach the W6x12 beam under it for the trolley to ride on, how to caclulate the new load capacity? I would end up with 18" of total depth, and 77# per foot total, but obviously the metal isnt distributed like a W18x76 (close) beam is. Which a W18x76 by itself would yield 9230# capacity @ 0.45 deflection.

I am guessing The W12x65 w/ W6x12 under it is going to be somewhere between those two. But would like a way or program to work it out and havent found a formula yet. Would like to try various scenarios as I come across beams, or look back at beams I previously ruled out as they were too small.

 

[CNC Dan]

Another question for the masses as I cannot find a formula or program to do what I want.

How to calculate stacked beams?

Example: I currently have 35' of W6x12 beam on my rack. Obviously it is too weak to make a span.

If I were to use W12x65 that is listed on c-list (nice 12" wide flanges so not much worry about buckling), I could safely lift 5550# @ 7200psi stress and 0.68" deflection.

IF I were to attach the W6x12 beam under it for the trolley to ride on, how to caclulate the new load capacity? I would end up with 18" of total depth, and 77# per foot total, but obviously the metal isnt distributed like a W18x76 (close) beam is. Which a W18x76 by itself would yield 9230# capacity @ 0.45 deflection.

I am guessing The W12x65 w/ W6x12 under it is going to be somewhere between those two. But would like a way or program to work it out and havent found a formula yet. Would like to try various scenarios as I come across beams, or look back at beams I previously ruled out as they were too small.

I think you just add the rigidty( moment of inertia) of both. See if you can find an online calculator that will do rectangles, and see what you get for a solid square, and then a rectangle the same size as two of the squares, and see if the moment of inertia is double.

 

[Tractor Seabee]

Trying to plan out and decide how I want to build my bridge crane in the shop.

Thoughts, Opinions, Am I crazy?

Quote from your OP.

You asked for it; here it is.

Thoughts: you have many posts with exactly that.

Opinion: After all this dialog you have created you are still trying to figure this out. That should convince you that you are out of your league and need a proper engineered design as several of us have stated.

Are you crazy: No, just not in the world of reality.

No response is necessary, I answered your questions.

Ron

 

[LD1]

Double would be placing them side by side I think.

IE: two identical beams rated to carry 2k. Side by side you would be good for 4k. But stacking has a different effect.

Doing as you suggest,

2x2 solid chunk of solid steel has an i4 of 1.33 in both directions

2x4 solid chunk of solid steel has an i4 of 10.66 and 2.66 in the 2" direction.

So they double if width is doubled. but go up by a factor of 8 if stacked. Since in the equation, the height gets cubed.

My issue though is trying to use different sizes.

IE: a W12x65 beam with a 533 i4 stacked on top of a W6x12 beam with an i4 of 22.1.

I know stacking them will have a greater effect than side x side (just adding the moments), but how much greater is what I am trying to figure. So in other words, lets say you have a pair of 2x2 square tubes. And weld them together. If laid flat where its only 2" high, you will be twice as strong as a single. simply additive. But place them so they are 4" in the vertical it is going to be alot more than double the strength.

 

[LD1]

Quote from your OP.

You asked for it; here it is.

Thoughts: you have many posts with exactly that.

Opinion: After all this dialog you have created you are still trying to figure this out. That should convince you that you are out of your league and need a proper engineered design as several of us have stated.

Are you crazy: No, just not in the world of reality.

No response is necessary, I answered your questions.

Ron

Appreciate your input and concern. But 2 things are certain

1. I AM going to build this
2. I AM NOT hiring an engineer to crunch numbers and formulas that I am more than capable of. Just seeking assistance in finding the appropriate formula for stacking beams.

In a perfect world, I would just buy a new beam to suit my specs. (which would likely be cheaper than an engineer). But when shopping the used market, that perfect beam isnt always available.

The W12x65 I mentioned will safely carry 5500# with a comfortable 5:1 SF. Why would I want to hire someone just to tell me that?

Concern is the W12x65 is a 12" wide beam. (good for resisting top flange buckling). But would like to add a smaller beam under it better suited for a trolley to ride on. I would like to know how much additional capacity this "may" give the beam. Worst case scenario I just call it 5500# max capacity. And thats fine. But I think we all "know" adding that beam under adds strength. Just trying to solve for = how much.

 

[Streetcar]

Ld
How would the two beam attach to each other? Bolted , continuous weld, intermittent weld
This would affect the strength

 

[LD1]

Ld
How would the two beam attach to each other? Bolted , continuous weld, intermittent weld
This would affect the strength

I have the ability to do any. But I have yet to find any programs or calculations, let alone worry about connection type.

 

[Streetcar]

Search moment of inertia.
This is what gives the beam its strength
width increases strength in linear function . Increase in height is squared assuming the beams are rigidly connected
If I knew where my steel Manuel was located to get base numbers ,the calculation is relatively easy

 

[CNC Dan]

Double would be placing them side by side I think.

IE: two identical beams rated to carry 2k. Side by side you would be good for 4k. But stacking has a different effect.

Doing as you suggest,

2x2 solid chunk of solid steel has an i4 of 1.33 in both directions

2x4 solid chunk of solid steel has an i4 of 10.66 and 2.66 in the 2" direction.

So they double if width is doubled. but go up by a factor of 8 if stacked. Since in the equation, the height gets cubed.

My issue though is trying to use different sizes.

IE: a W12x65 beam with a 533 i4 stacked on top of a W6x12 beam with an i4 of 22.1.

I know stacking them will have a greater effect than side x side (just adding the moments), but how much greater is what I am trying to figure. So in other words, lets say you have a pair of 2x2 square tubes. And weld them together. If laid flat where its only 2" high, you will be twice as strong as a single. simply additive. But place them so they are 4" in the vertical it is going to be alot more than double the strength.

OK. Now we're getting somewhere.
If you look at The Machinery's handbook, you can find out how to figure out the I^4 of any shape, by breaking it down into smaler parts. And figure out the neutral axis too.

I think that's the key, knowing how far away the steel is from the neutral axis so you can calculate how much it contributes to the overall moment of inertia.

You could do that with your beams.
But I can't help thinking that there must be someplace online that can give you the I^4 of any shape you give it.

 

[Streetcar]

Ld
Is there an 18 deep beam in your table with similar flange to the small beam. If yes the two beams welded together would be a slightly stronger beam

 

[CNC Dan]

There was this program called "beam boy" that would calculate all sorts of data related to beams and deflection and loading. I can't remember if you could give it custom shapes. You might try looking into that.

For Android smartphones there is an app called epic FEM, but doesn't allow custom shapes far as I know.

 

[LD1]

Ld
Is there an 18 deep beam in your table with similar flange to the small beam. If yes the two beams welded together would be a slightly stronger beam

I wish. The 6x12 has a 4" flange that is 0.280" thick. The lightest 18" beam 6" x 0.425" flange. And that light 18" beam has a smaller moment than teh w12x65 I would be starting with. So that dont work out.

There was this program called "beam boy" that would calculate all sorts of data related to beams and deflection and loading. I can't remember if you could give it custom shapes. You might try looking into that.

For Android smartphones there is an app called epic FEM, but doesn't allow custom shapes far as I know.

Beam boy dont allow custom shapes. (I use beam boy alot). Also tried a couple more beam tools I downloaded, but dont allow custom shapes.

I'm even drawing a blank on the moment calculations by breaking down into individual shapes.