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Re: Max load for I-beam
Re: Max load for I-beam -- Mark Kent	Post Reply	Top of thread	Forum

Posted by: sblack ® 07/18/2005, 09:20:25 Author Profile Mail author Edit

Hey, I am pretty new to this, but I have just completed a similar project. I used a deflection equation for my analysis. (5/384) * W(L^3) EI This is the maximum deflection at center equation. You need to know your weight(W), length(L), modulus of elasticity(E), and your moment of interia(I). You know your length, the modulus of elasticity (if steel) is about 29,000,000. I am not sure yet on the moment of interia, I will research. Try to determine weight or you can just plug in numbers and see what your deflection would be. Shane

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Re: Max load for I-beam
Re: Re: Max load for I-beam -- sblack	Post Reply	Top of thread	Forum

Posted by: Mark Kent ® 07/18/2005, 16:54:24 Author Profile Mail author Edit

Thanks Shane, I have done some comparisons of similar I beams, and conservatively the beam should weigh about 17kg/meter. if we use the weight of 50kg total weight, it should be safe. i have no idea of interia. Thanks Mark

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Re: Max load for I-beam
Re: Re: Max load for I-beam -- Mark Kent	Post Reply	Top of thread	Forum

Posted by: zekeman ® 07/19/2005, 10:59:48 Author Profile Mail author Edit

What are the loads on this beam? Is it just the weight of the beam or otherwise?

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Re: Max load for I-beam
Re: Re: Max load for I-beam -- zekeman	Post Reply	Top of thread	Forum

Posted by: Mark Kent ® 07/19/2005, 18:41:43 Author Profile Mail author Edit

It is for a gantry in a workshop. I would like to move about two ton on this beam if possible. Thanks for your help. Mark

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Re: Max load for I-beam
Re: Re: Max load for I-beam -- Mark Kent	Post Reply	Top of thread	Forum

Posted by: zekeman ® 07/21/2005, 16:15:51 Author Profile Mail author Edit

Worst case, the central loading causes a max moment of FL/4=4000*122/4=122000 lb in The corresponding stress,s is s=FL/4(c/I) where c is the 1/2 width of the crosssection and I is the moment of inertia For your beam I get c/I=1/4 so the stress is in excess of 30,000 psi, which is way too high for mild steel. You need to get a huskier beam or reduce the load by at least 2 and then also check to see whether the max deflection is acceptable.

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Re: Max load for I-beam
Re: Re: Max load for I-beam -- zekeman	Post Reply	Top of thread	Forum

Posted by: wen101 ® 08/22/2005, 15:03:46 Author Profile Mail author Edit

Hi- I have a related beam question. I am interested in replacing a load bearing wooden beam in my house with steel, and I want to determine the dimensions needed to satisfy the load. What I am looking for is a conversion of wood dimensions to steel I-beam, as I have no way of knowing what the load is on the wood beams. Any suggestions? Perhaps a recommended book, or a retail point of contact? The details are as follows: I'm looking at a beam that is composed of two boards, together yielding dimensions of 3" x 9" x 93", and supported at points up to 12" in from each end. My desire is cut down on the 9" dimensions by using steel or another material, so as to increase the headroom in these doorways. Thanks, William

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