I Beam for structural support

[Rock knocker]

And based on THAT, you would need a w16x40 to get the stress and deflection down to an acceptable level

That's kind of what i thought he would end up at, something at least 36#/ft. And it will need a number of web-stiffeners, and the connections should be given careful consideration.

The roof load is what kills. If you could find a way to convert them to trusses as someone else mentioned....it would take a MUCH smaller beam to 30' clearspan for only using a 1-ton hoist. You could actually drop that down to a w10x15 beam for the hoist.

I don't know the answer here, but an engineer may want to upsize the trolley beam even more to account for movement of the trolley, any extra safety margins due to the fact the entire assembly is now an overhead-lifting device and deflection primarily normal to the beam in a horizontal plane.

But none of this is meant to argue with you LD, you clearly show the ability to understand the issue(s) and come up with a fine first-order quantitative answer. It is meant to show that someone with a understanding of the standards is needed here. A 30' clearspan is huge. I used to build POS Butler buildings for a POS steel-erector, and some of the building steel we needed to put in to header-off normal rather modest building elements could shock you.

 

[LD1]

Supporting the roof is the biggest killer here. Cause there are too many unknowns associated with that. Snow load? What was it designed for? Wind forces? etc. Sizing a beam for a given load on a trolley is easy. But 30' clearspan supporting a good portion of the roof...... cannot be done online with any degree of accuracy.

 

[Rock knocker]

I'll accept your answer in full, LD.

The OP needs to look downward too. He has taken four point loads down to two. Are the existing foundations strong enough? Are they even on foundations? He mentioned that the existing building is a pole barn. They do some weird things with those sometimes, including burying ground contact posts with no concrete foundation

 

[Shield Arc]

In this situation I wouldn't even look at an I-beam / S-shape. They will get very tall before getting any real load capacity! I would look at wide flanges, and rip an S-shape and weld it to the bottom of the wide flange for the trolley to run on. That is what a structural engineer suggested to me for my 24-foot span bridge crane.

 

[Rock knocker]

Your shop is close to putting MARCO to shame

 

[LD1]

Does that for real have a SWL of 80 tons??? Cause it dont look anywhere near stout enough. Heck, our 15ton crane at work is massive in comparison. The two beams it rides on (above and not suspended) are 36" depth and span 30'. The hoist itself is on beams at least as big as the one you have labled 80T, AND there are TWO of them AND only spanning 15'.

Not saying it wouldnt do it, just skeptical is all.

 

[Shield Arc]

Your shop is close to putting MARCO to shame

OK, I'll bit, what is MARCO?

Does that for real have a SWL of 80 tons???

No! Those were two beams in a spreader bar I used to set precast utility vaults on an aircraft carrier pier I worked on.

 

[LD1]

No! Those were two beams in a spreader bar I used to set precast utility vaults on an aircraft carrier pier I worked on.

Thats kinda what I figured. Scrap re-used from something else. I just was unsure how to ask (and almost didnt) for fear of starting a pizzing match:mur:

Have you calculated or know what IS a SWL for that?

Doing what you did makes it a bit harder to figure...with adding a cut section to the bottom.

 

[Shield Arc]

Have you calculated or know what IS a SWL for that?

According to my engineer buddy, center of the span beam which is a W 12x87 is the strongest point of the crane, with a SWL of 2-tons, with a 5 to 1 safety factor. The weakest point is between posts in the center of one of the rails which are S 12x31.8, SWL of 1-ton.

I designed the crane, but my buddy approved everything but the welding. He said if I couldn't handle that he'd kick my ***. :laughing:

 

[LD1]

I trust him not to double check everything but that does make sense. That main beam is huge compared to the two carrier beams. He's saying that those are the weakest links, and just looking at it, is probabally right.

But the welds.......:laughing: