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Re: Load Capacity of Steel Beam

From: info@builderswebsource.com
Category: Structural
Remote Name: 63.198.181.43
Date: 01 Feb 2002
Time: 09:12 PM

Comments

We didn't hear back from you regarding our clarifications, so we took your assumptions at face value as follows:

1) Clear span = 20' 2) LL = 300 PLF, TL = 450 PLF - uniform load 3) Steel I Beam (S 10x35) = 5" x 10" A36 STD FLANGE

Assuming a lateral bracing at each 5' interval, this beam has a LL deflection of L/949 and TL deflection of L/587. Shear, cross section and deflection are well within acceptable limits, assuming no other point loads.

Now, we also tested this beam under 3-times the load (700 PLF LL and 1050 PLF DL). At this loading, the beam is just under "critical". However, due to the long span of 20 feet, even though the deflection is less than SPAN/360 for LL and SPAN/240 for TL, the total deflection is approximately 0.91 inches, which is a bouncy beam!

Generally, it is recommended to keep total deflection to less than 0.3 inches. The less the better and the stiffer the floor will feel.

Always have a licensed structural engineer verify your conditions and make a recommendation based on all available data. The above example is for illustrative purposes only.

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