Moment Connection on Each Side of Supporting Beam
Moment Connection on Each Side of Supporting Beam
(OP)
When you are providing a moment connection for a cantilever beam that is supported by a main supporting beam, what is the reason for providing a beam with a moment connection on the other side of the main supporting beam, in the same location as the cantilever, even though the additional moment connection could be a simple shear connection?
Is it simply to provide resisting moment on the opposite side as to bring the resultant moment at that location closer to zero and minimize torque at the main supporting beam?
Is it simply to provide resisting moment on the opposite side as to bring the resultant moment at that location closer to zero and minimize torque at the main supporting beam?






RE: Moment Connection on Each Side of Supporting Beam
BA
RE: Moment Connection on Each Side of Supporting Beam
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/
RE: Moment Connection on Each Side of Supporting Beam
Wide flanges have very little torsional stiffness.
Slabs on top of the system could perhaps resist thee cantilever bending moment but how to get the resultant forces up into the slab?
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RE: Moment Connection on Each Side of Supporting Beam
I don't think I understand your question. Maybe I should clarify mine.
I have a main beam (B1) that is simply supported on each end. A beam (B2) is cantilevered off of one side of the main beam (B1) to pick up a hanging load that couldn't be located directly below the main beam (B1). This cantilevered beam (B2) will just be welded all around to the main beam (B1). I've included another beam (B3) at the same location along the main beam (B1), but on the other side of the main beam (B1). This beam (B3) will also be welded all around to the main beam (B1) and then frame into a secondary main beam (B4) a few feet away with a shear connection to create a bridge walkway, mainly made up of the 2 main beams (B1 & B4). The question was why is it necessary to create a moment connection where the (B3) beam is at the same location as the (B2) beam along the main beam (B1).
RE: Moment Connection on Each Side of Supporting Beam
If there is any unbalance (of torque) that results in the ends of the girder seeing any torque.....be advised: simple shear connection won't transfer that load. (I make that point because you say the "main beam" is "simply supported".)
RE: Moment Connection on Each Side of Supporting Beam
RE: Moment Connection on Each Side of Supporting Beam
RE: Moment Connection on Each Side of Supporting Beam
BA
RE: Moment Connection on Each Side of Supporting Beam
If that's the case, yeah, that works. You will get a bit of compatibility torque at the ends.....probably not much though (depending on displacement).
But to answer your question: it has to be (i.e. fixed on both sides) to balance out the torque.
RE: Moment Connection on Each Side of Supporting Beam
And thanks BAretired and TehMightyEngineer for understanding without the additional explanation!
RE: Moment Connection on Each Side of Supporting Beam
The connection from B3 to B4 can be a simple shear connection.
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