Moments and reactions in beam
Moments and reactions in beam
(OP)
I need to determine the reactions to the 20K load as shown on the attachment, as well as the bending moment.
Thanks.
Thanks.
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Moments and reactions in beam
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Moments and reactions in beamMoments and reactions in beam(OP)
I need to determine the reactions to the 20K load as shown on the attachment, as well as the bending moment.
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RE: Moments and reactions in beam
RE: Moments and reactions in beam
RE: Moments and reactions in beam
RE: Moments and reactions in beam
so you could say the reactions are ...
1) point loads in-line with the channel webs,
2) point loads at the fasteners (so there's a little flange bending happening),
3) distributed loads on the channel flanges.
i would expect to see some prying action ... the plate wants to react the load in-line with the channel webs, and the fasteners are preventing the plate from deflecting the way it's want to (which will amount to a fixed end).
RE: Moments and reactions in beam
For the direction of the force as shown, the plate will act more fixed due to the prying action on the bolts. Moment will be generated between the bearing point on the channel and the centerline of the bolt, with the lever arm somewhere between 1" and 1.75"
If the force is reversed, then the plate will act more like a simple beam, still with some moment, but not as much. The lever arm for any moment development will be from the centerline of the bolt to the outside edge of the channel - far less than an inch.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Moments and reactions in beam
You have not told us how wide, or how thick for that matter, your beam is. Perhaps this should be analyzed as a flat plate.
Can you find a copy of Roarks Equations for Stress and Strain?
Your supports look like channels. These could be long enough to twist under your load and affect the moments in your beam.
RE: Moments and reactions in beam
RE: Moments and reactions in beam
then how are the channels connected to the rest of the world ?
RE: Moments and reactions in beam
RE: Moments and reactions in beam
See the attached file.
Case #1. As a first approximation, you could consider the plate as a simply supported beam with a concentrated load of 20K at the center. That's figure 7 on my attachment.
Case #2. A more rigorous approach might be to consider the plate as "fixed at both ends", with a concentrated load at the center. The bolted connection of the plate to the channels could be considered a "fixed" connection. The maximum moment in this case would be PL/8, where P = 20 Kips, and L = beam length. Note - the the maximum moment for "fixed" is 1/2 the max moment for the simply supported case
RE: Moments and reactions in beam
I had consulted AISC, strength of materials books, PE Reference books, Roark's, etc., and am familiar with beam calculations. This problem, on the surface, was not quite as cut-and-dried as a simple beam or a fixed beam, due to several reaction points.
Anyway, I ultimately analyzed it as a fixed beam with supports at 14" (between the channel edge and the bolts).
RE: Moments and reactions in beam