Frame vs fixed end beam
Frame vs fixed end beam
(OP)
So I am checking a beam part of a two story, single bay frame, and the moment i am getting from the frame analysis is almost opposite as that of a fixed beam. Fixed beam, I am using WL2/12 at ends, and WL2/24 at center. From the frame analysis I am almost opposite that. Has anyone ever encountered that before?






RE: Frame vs fixed end beam
Ends of a beam in a frame are attached to columns that have some amount of flexibility - thus there is rotation at the ends of the beam and this dumps more moment into the center of the beam span.
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RE: Frame vs fixed end beam
I would have thought it would be a good gut check to just run a beam from a frame setup as a fixed end, and see if they were close.
im gonna check it with another program to see if I get similar reuslts.
RE: Frame vs fixed end beam
End Moments:
Zero rigidity (flexure) column: 0
Perfectly rigid column: WL2/12
So your end moment should fall between 0 and WL2/12, such as WL2/24, depending on the flexural rigidity of your column.
RE: Frame vs fixed end beam
Then replace them with really weak columns... Like 6" square columns. See how the moment at the mid-span of your beam moves much closer to WL^2/8?
That should give you a better feel for why the results are the way they are and how sensitive they are to the column size. There is no such thing, of course, as a perfectly pinned or perfectly fixed condition. This experiment just demonstrates it in a way that may be easier to grasp.
RE: Frame vs fixed end beam