Trolley beam sizing

[LAA]

Does anyone know a calculation or a set of tables or standards to figure the minimum size and weight of I-Beam that should be used for a trolley beam to prevent lateral buckling of the beam? The distance of unsupported span and the intended load rating are known, need to run a trolley beam 36 feet in length but due to overhead height restrictions and other impediments in the ceiling of the building will need to space a total of 3 support mounts 18 feet apart, 0 -- 18 -- 36 -- need a 2 ton working load but will have to get an initial certification test to 4 tons. Due to the limited overhead space I can't do what I would normally do which would be to use a beam that was 5 times as strong as needed so as to ensure it was idiot proof. I will have room above the beam to weld a strongback doubler, just really restricted on how low the beam can hang. Thanks.

 

[Puddles]

This chart may help you. I got it from a bridge crane site years ago.

 

[PJH]

Puddles - I have to ask what will probably turn out to be a stupid question:

Why is the data duplicated all through the second chart? I'm sure I'm overlooking something. . . ?

Thank you for all of the good and interesting advice that you give on this site.

Paul

 

[Puddles]

Who knows what / how those engineers types think! :lol:

 

[sflem849]

(quoted from post at 09:55:37 07/22/12) Who knows what / how those engineers types think! :lol:

There aren't two different types of steel? weight/lb? No footnotes on the tables?

 

[Puddles]

Here is another chart I just scanned from my Ryerson Data Book.
[u:d2c306f4e2][b:d2c306f4e2]Caution! [/b:d2c306f4e2][/u:d2c306f4e2]These capacities are for uniformly loaded beams. For point loaded beams as in use for a trolley to run on, you will have to cut these capacities in half. Also these numbers seem high to me, so I would think there is no safety factor calculated in the capacities at all! Where the first chart I would think there is a 3/1 or even 5/1 safety factor.

 

[dpendzic]

AS per the AISC manual--the lateral force assumed on a crane rail shall be 20% of the vertical loads.
it appears that a W10 x 45 could span 18 ft without the top flange buckling with a reduced load of 122000 ft lbs for grade 50 ksi steel.

 

[Puddles]

If height of beam is a problem, a guy can go with a wide flange, and buy a wide flange trolley. Northern Tool has them, but only 1 1/2-tons.

Height of an S-shape for my span beam was really going to kill my head room. So I ripped and S-shape and welded it to a wide flange for my bridge crane.

 

[jrh009]

(quoted from post at 06:24:05 07/22/12) Does anyone know a calculation or a set of tables or standards to figure the minimum size and weight of I-Beam that should be used for a trolley beam to prevent lateral buckling of the beam? The distance of unsupported span and the intended load rating are known, need to run a trolley beam 36 feet in length but due to overhead height restrictions and other impediments in the ceiling of the building will need to space a total of 3 support mounts 18 feet apart, 0 -- 18 -- 36 -- need a 2 ton working load but will have to get an initial certification test to 4 tons. Due to the limited overhead space I can't do what I would normally do which would be to use a beam that was 5 times as strong as needed so as to ensure it was idiot proof. I will have room above the beam to weld a strongback doubler, just really restricted on how low the beam can hang. Thanks.

This is not a question that should be answered in a forum. There are serious consequences if bad advice is taken. None of the information presented here to date addresses your question that would permit a certified safe installation. I do this for a living as a Professional Engineer.

It's not only the beam sizing but the reactions to the building frame itself are critically important in a retrofit instance as lateral loads can easily cause instability. Lateral deflections have a serious effect on joint capacities and building stability.

Professional advice will likely save you money and may possibly prevent an accident and injury.

 

[sflem849]

(quoted from post at 17:58:44 07/23/12)

(quoted from post at 06:24:05 07/22/12) Does anyone know a calculation or a set of tables or standards to figure the minimum size and weight of I-Beam that should be used for a trolley beam to prevent lateral buckling of the beam? The distance of unsupported span and the intended load rating are known, need to run a trolley beam 36 feet in length but due to overhead height restrictions and other impediments in the ceiling of the building will need to space a total of 3 support mounts 18 feet apart, 0 -- 18 -- 36 -- need a 2 ton working load but will have to get an initial certification test to 4 tons. Due to the limited overhead space I can't do what I would normally do which would be to use a beam that was 5 times as strong as needed so as to ensure it was idiot proof. I will have room above the beam to weld a strongback doubler, just really restricted on how low the beam can hang. Thanks.

This is not a question that should be answered in a forum. There are serious consequences if bad advice is taken. None of the information presented here to date addresses your question that would permit a certified safe installation. I do this for a living as a Professional Engineer.

It's not only the beam sizing but the reactions to the building frame itself are critically important in a retrofit instance as lateral loads can easily cause instability. Lateral deflections have a serious effect on joint capacities and building stability.

Professional advice will likely save you money and may possibly prevent an accident and injury.

What do you know about taking the haymow out of a dairy style barn and making it clear span?

 

[LAA]

There was plenty of information presented here that permits a safe installation, I'm talking 2 tons, 4,000 lbs. - you don't have all the details so you automatically assume that non-engineers don't look at the big picture and use their heads. The ''buildings frame'' is a lower hull compartment on a ship 15'' half flange beam girders on 8 foot spacing with 4''X 6''X 1/2'' angle iron struts, 3/8'' double wall ABS decking and sheathing, you could not tear the walls and ceiling out with a D-8 if you could get it down there. If you want to talk safety I will tell you something I know to be a fact, you as an engineer would design a beam hoist arrangement to spec for the customers intended use and load limit, I as a non-engineer but a long time supervisor of men would design a beam hoist arrangement that king Kong could not tear down because I know it will be mis-used and abused.

 

[Puddles]

LAA sounds like you have a handle on things, so this isn't so much for you, but others who might be thinking of installing a beam with a trolley. The structural engineer friend who helped me with my bridge crane explained how these beams fail like this to me. Take a yard stick support it at each end vertically. Take your finger and push down in the center of the yard stick. What happened? The yard stick will bend to one side or the other, it will not go straight down. That is why these beams need to be laterally supported as much as possible! The next best thing to do is go with a wider flange. The flange of the beam is where the strength is, not the web! The flange keeps the beam from bending to one side or the other. That is why I went with a wide flange beam for my span beam. The strongest part of my bridge crane, (according to the engineer) is the center of the span beam.

Here is a great way to up the capacity of a beam, if need be.

 

[LAA]

Puddles -- I appreciate the drawing and the earlier help, I am glad we have ''H'' or ''W'' style wide flange beams for the span instead of ''I'' beams after seeing this drawing. Believe me, I did not mean to imply that I knew more than a structural engineer, just that when you work in remote locations without any of that type of support available you tend to just over build everything to make sure, kind of like hammers, big is good, bigger is better. Thanks.

 

[Puddles]

LAA I knew exactly what you were saying, been there done that! :wink: When I was working it was always required by the city, county, state, or federal government to have an engineer on site. Now they did not have to be PEs just had to have an engineering degree. The company I worked for must have had at least 75 field engineers, and a whole engineering department at the main office, if we ever had any questions, they were only a phone call away. And most of them would do anything for a job site visit, anything to get out of the office! :lol:

 

[KF]

We have a commercial 2 ton rated trolley crane here. The trolley beam is 27 ft. unsupported span with a trolley on the bottom flange. The beam is a S shape 18 x 70. It is large for two reasons. One to prevent twisting under load and the most important is that the flange required to hold two tons safely on a trolley must be of substantial thickness and rigidity. A beam just to support a load of 2 tons would be much smaller, but to support a trolley on the lower flange is quite another thing.