Connection load transfer
Connection load transfer
(OP)
Hi Guys
I have a question and seems I get a lot of uncertain answers from other engineers not on this forum.
So if I could ask please try not to be vague.
If you design a beam member as pinned supported at both the ends and you use a fixed connection and not just a normal pinned would that moment be transferred to the underlying support or will the beam resist the moment as it was meant to do and the connection is mere a formality to connect the beam so it does not hang in the air.
I do understand you will have a little bit of a moment on the support at the bottom as the support is not always loaded eccentrically right in the middle.
I have a question and seems I get a lot of uncertain answers from other engineers not on this forum.
So if I could ask please try not to be vague.
If you design a beam member as pinned supported at both the ends and you use a fixed connection and not just a normal pinned would that moment be transferred to the underlying support or will the beam resist the moment as it was meant to do and the connection is mere a formality to connect the beam so it does not hang in the air.
I do understand you will have a little bit of a moment on the support at the bottom as the support is not always loaded eccentrically right in the middle.






RE: Connection load transfer
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RE: Connection load transfer
If you for example use a fixed support like a moment end plate going into a column, then that is a different situation. This is definitely a fixed support and should be analysed as such.
I hope this was some help, your problem sounded a bit more complicated than I might have interpreted.
RE: Connection load transfer
The way I see it the beam should be able to resist that moment without transferring it into the fixed connection.
But that is the question does it transfer the load anyway into the connection and then into the support although there is almost no movement and the beam would be able to resist the moment without the need of a fixed connection.
RE: Connection load transfer
The connections and members should not only be design against imposed load (for example momenets, shear forces etc), but against the deformations that are calculated by the analysis.
For example, a pinned connection means that a rotation will take place at the end of the pinned member. Will the connection be adequate to safely carry that rotation? Furthermore, connections are classified to nominally pinned, semi-rigid and rigid. So, during the connection design, one must also confirm that the assumed member dof-releases in the analysis are valid.
Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis
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RE: Connection load transfer
RE: Connection load transfer
There is no such thing as an infinitely rigid connection or beam.
And in any case, the stiffness of the beam has no affect on the end moment of a fixed end support.
It is always wL^2/8 at the end - the term doesn't include EI in the derivation of the end moment.
If you get a very short beam, with very high depth, then deep beam theory would kick in and the analysis would be different - but with that kind of beam, a "fixed end" wouldn't probably make sense either.
Again - why the question? What is this for?
RE: Connection load transfer
Or
if the beam is stiff enough (not stiffness as in EI) but strong enough that there won’t be any deflection movement in the beam, so that it won’t transfer the moment to the fixed connection cause the beam handles it like a simply supported beam which has no moment on the edges only it is fixed.
So basically like I said if you design a beam as simply supported but now on site you make a fixed connection to a column that was not designed to handle the fixed moment will it transfer that moment?
RE: Connection load transfer
You have your simply supported beam, max bending moment would be in the middle, of let’s say 30KNm now you designed your beam according to that and your deflections is like 1mm.
So if you make the connection a fixed end connections you would normally now have a moment on the connections and the supports on either side but the design would yield a much smaller beam that only needs to handle for arguments sake 10KNm and on the fixed connections the other 10KNm on either side of the supports which gives you your total of 30KNm.
What if the beam can handle the 30KNm moment with ease will the moment still be transferred to the connections and ultimately to the supports or will the load be transferred to the fixed connection as if it was a simply support?
RE: Connection load transfer
RE: Connection load transfer
RE: Connection load transfer
How much moment? This depends ratio of column stiffness to beam stiffness. "stiffness attracts force" If you have a massive beam framing into a tooth pick the beam will take the majority of the moment (remember the moment distribution method, among others?). So if the beam is 'infinitely rigid' compared to the column (not sure how to design that, but...) I suppose the only moment transferred would be the eccentric shear at the end of the beam.
Also while I have a feeling your referring to concrete, take a look at "Type 2 Connections" or "Wind Only Moment Connections" or "Flexible Moment Connections"(all for steel structures).
EIT
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