I beam specifications

BD gave you a good example of what happens when someone cheats the engineer.

From looking thru my book, all the sizes mentioned in this thread are not even close to my SWAG as you didn"t even give enough info to make a close SWAG. Please get an engineer involved.

T_Bone

Ex. W10 x 20 = W Shape designation 10 = 10" web 20 = 20lbs per foot. That is how the shapes and sizes are described.

Do yourself a favor, take the all existing conditions, proposed new construction and have a licensed professional engineer check the span as it will be built. If you need a low profile beam with a shorter web, wider flange for height considerations mention that, but a conventional shape should work. Detail this for the engineer, provide the maximum live loads you would impose on the span, besides any building structure loads, include weights of rigging, like a chainfall or motorized hoist. If you are going to use the member for a specialized hoist, you may want to check the shape you plan to use, against what it requires, say like a trolley arrangement, even a beam clamp, just to be sure and make sure the engineer gets the same information. When said and done, clearly label both sides of the member with it's maximum load so that there is no mistake about what can and cannot be hoisted.

Some people balk at this, that is fine, do as you like, but for what an engineer would charge for this straight forward analysis, calculations etc. and having concise knowledge of the load capacity including the safety margin built in, I think it's well worth it, why guess or create something that could be a danger to you or someone else years down the road.

Your building insurance won't be worth a flip if you collapse the roof due to an undersized beam. Get it in writing from a structural engineer and then if something happens, the insurance will pay, just another consideration.

Charles

I was looking for similar information recently, and thought I would be able to simply look up the information I needed in an engineering specifications reference book or online, the way I do to check the requirements for a wooden beam, floor joist or stringer dimensions, etc. Turns out it's not so easy. My research revealed one thing I wasn't previously aware of: Google has a question answering service in which you pay for that kind of information. The answer to that kind of structural engineering question, with all the calculations shown, seemed to cost about $50. Apparently people were happy with that price because several added $10 tips.

All the best, Stan

An 8 inch deep web is much too shallow for a 24 foot span.

I've designed wide flange beams as headers for garage doors, and from experience know that it takes a W10x22 beam to span 20 feet.

This size just barely supports a roof with 40 psf dead+live load and an 18 foot tributary width. There is no capacity left for additional live loads such as hoists.

The stiffness of a beam is proportional to the cube of the depth, but only linear with the width of the flange. For equal weights, a 12 inch beam is 3 times the stiffness of an 8 inch beam.

A (very rough) rule of thumb is that steel wide flange beams offer optimum span to depth ratio of 16 to 24. By this rule it is going to take at least a 12 inch deep beam to span 24 feet for just the structural load. A 14 inch deep beam is better.

An accurate analysis requires knowing climate conditions, roof construction, and the nature of the additional live load proposed.

As other posters have mentioned, 24 feet is a rather long clear span and it takes a pretty serious beam or truss to do it for any kind of significant load.