Need A Simple Beam Selection Program??
Need A Simple Beam Selection Program??
(OP)
Anyone know of a simple calculator, table, or "cheat sheet" for sizing beams? This would be for simple point loading on beams supported on both ends. I'm in construction and had to recently choose a 10' long beam that would be supported at each end and point loaded in the center with 5,500 Lbs. It was to be used for rigging up some equipment with a chainfall. I have a person to call for help with this, but it would be nice to be able to do it myself. He advised me to go with a W8x31 for that application. Anyone have a simple guide or reference for someone who is not well-schooled in structural steel?






RE: Need A Simple Beam Selection Program??
In light of that, you may find some text books and information to help you become better able to size beams. Schaum's outlines may help. If you purchase the AISC manual, you will find many charts and tables but you'll need to understand which apply and when, and why others are inappropriate. There's enough that goes into beam design that one simple chart that could capture all the necessary conditions and assumptions wouldn't be very simple.
You mentioned you had to size a beam (unless I misunderstood). How close was your answer to your advisor's?
I think you should start reading up on steel beam design if you are truly insterested in doing it yourself, but keep in mind it's not something you can learn overnight.
RE: Need A Simple Beam Selection Program??
So find out what I you need and it will be easy to just use the AISC.
RE: Need A Simple Beam Selection Program??
I also have a 1-page sheet on beams from an unknown reference. That sheet works through a problem similar to mine. It shows an equation for the moment on a point loaded beam supported at each end as M=1/4*L*W. Plugging in my 120 in and 5,500 Lbs, the Moment comes to 165,000 in-lb. It then identifies a "safe stress" as 20,000 psi and divides by this number to get the "Minimum modulus". In my case, I came up with 8.25.
I didn't question my advisor, but it seems to me that his choice of W8x31 is overkill, since it looks like that beam has a modulus of 27.4. Would not a W8x17 have worked just fine? He may have thrown in a safety factor.
Again, my needs for structural knowledge are very limited and are generally just for small rigging jobs such as this. That's why I am wondering if there is a "simple" reference that shows some typical beam sizes and how much they can carry at various spans?
RE: Need A Simple Beam Selection Program??
That said - Archoneng.com has a very good steel beam design program for about $40 or $50.
Always be careful about providing lateral bracing as required!!! Also, working around construction - be leary of load numbers provided by others - sometimes correct - often way too low!!!
RE: Need A Simple Beam Selection Program??
I suppose it will be no comfort to know that bending equations have gotten quite a bit more complex since the AISC 7th.
What you'll find though, as far as diagrams and charts, is that the AISC is probably the easiest you'll get that covers what needs to be covered. Even then you'll still need to know what went into those charts to know if you can use them in your case.
RE: Need A Simple Beam Selection Program??
RE: Need A Simple Beam Selection Program??
Then, buy yourself a new steel manual as I don't think you can get a W8x17 anymore.
RE: Need A Simple Beam Selection Program??
Please consider this thread closed.
RE: Need A Simple Beam Selection Program??
The "designer" also needs to consider the unbraced length, web crippling and yielding, and flange buckling. If the rigger wraps a chain or cable around the beam in order to hold the hoist, the highly concentrated load could damage the beam even though the bending stress is OK.
RE: Need A Simple Beam Selection Program??
Try this calculator
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regards
desertfox
RE: Need A Simple Beam Selection Program??
The higher size may be a result of an allowable bending stress of less than 20,000psi assuming your unbraced length is 10 ft. It seems unlikely that deflection would be an issue in a use such as this, but should be checked nonetheless.
RE: Need A Simple Beam Selection Program??
Be aware that OSHA may require higher factors of safety than used in normal steel structural design. Also see ASME B30.20.
RE: Need A Simple Beam Selection Program??
The issue here is buckling.
For rigging beams this is an exceptionally bad situation for buckling as there is nowhere along the length that is properly restrained.
This situation is much more complex than you realise and I would stay within your expertise (as your PE licence dictates) and let the structural engineer take his small fee (and the liability).