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Re: I beam

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Posted By<" ">P Doyle on May 10, 2002 at 11:56:57:

In Reply to: I beam posted byrusty on April 30, 2002 at 19:18:22:

: What size I beam would it take to span 40 feet and hold a 1000lb load in the middle? thanks

Moment governs
M = PL/4, L = 40', P = 1k, M = 10 k-ft = 120 k-in
Fb = 0.66 * 36ksi = 22ksi for most old beams laying around.
Need a Section Modulous, S > M/Fb = 5.6 ci
Try a W8x10
This will want to wobble in the middle.
If you positively can't stop the wobble with cables you need 3x
heavier beam or try some horizontal truss with wood srrewed with TEK screws.

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Subject: Re: Re: I beam

Comments:: : What size I beam would it take to span 40 feet and hold a 1000lb load in the middle? thanks : Moment governs : M = PL/4, L = 40', P = 1k, M = 10 k-ft = 120 k-in : Fb = 0.66 * 36ksi = 22ksi for most old beams laying around. : Need a Section Modulous, S > M/Fb = 5.6 ci : Try a W8x10 : This will want to wobble in the middle. : If you positively can't stop the wobble with cables you need 3x : heavier beam or try some horizontal truss with wood srrewed with TEK screws.

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