Thanks Wesley and Josh for your promt responses. I should have shared a bit more information. This reactor is supported by four channel beams which are then supported by the 12 B 16.5 beams, which is where im having problems with. Example: A 12 B 16.5 beam has three piont loads acting on it and a dead load which yields reactions of 4.832 and 4.269 kips at the ends and a maximum moment of 7.947 kip-ft (the calculations are correct). It is only braced at the ends and the beam is 5' 6" long.
From: "Josh Comfort" <jcomfort@ggbse.com>
Reply-To: <seaint@seaint.org>
To: <seaint@seaint.org>
Subject: RE: Maximum Moments in Beams
Date: Tue, 17 Jul 2007 08:01:42 -0700
It appears to me that unless you have a very short span your maximum moment might be calculated wrong if the beam is carrying a 13k load.Can you give us more information, i.e. beam span, tributary area, basic loading...?Josh Comfort, P.E.
Golden, Graper & Burton, Inc.
1500 W. Fourth Ave., Suite 509
Spokane, WA 99204
(509)624-3224 (509)624-3225 Fax-----Original Message-----
From: Mauricio Castro [mailto:rico355@hotmail.com]
Sent: Tuesday, July 17, 2007 7:27 AM
To: seaint@seaint.org
Subject: Maximum Moments in BeamsI am currently revising the structure of the floor of a building to make sure that the old beams will manage to carry an increase in dead load of about 7/5 of the current load. I calculated the new maximum moments and compared them to the maximum moments allowed by the beam (Using my 13th edition AISC steel construction manual).I am getting maximum moments of about 8 kip-ft and according to the manual these beams (12 B 16.5 which are supposed to be W12x16) should resist moments up to 75.4 kip-ft. This is a noticeable difference which makes me thing that either the beam highly safe or the calculations wrong. I haven't considered safety factors yet, but even then, the safety factor would be too high. The floor is the top floor and practically only carries the weight of a reactor (around 13kips) and unfortunately the only plans are the layouts of the beams.Does this difference in maximum moments sound right?Mauricio CastroCivil Engineering StudentLSU
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