Cantilevered Beam with Through Beam Detail
Cantilevered Beam with Through Beam Detail
(OP)
First time poster to the forum and recent graduate.
I am still in the phase of questioning typical details in our office even though they have used for a while and nothing bad has happened.
We have a typical detail for cantilevered beam conditions that has girder interrupting the cantilevered beam. The goal of the detail is to engage some backspan and use the thru beam as a pinned support through which the cantilevered out beam rotates.


In my mind, this detail induces a non-neglible torsion about the girder. After discussion in the office, it was said that there is some torsion induced, but it is ignored. Is this a good/correct assumption? When can something like this not be ignored.
Thanks in advance,
S&T
I am still in the phase of questioning typical details in our office even though they have used for a while and nothing bad has happened.
We have a typical detail for cantilevered beam conditions that has girder interrupting the cantilevered beam. The goal of the detail is to engage some backspan and use the thru beam as a pinned support through which the cantilevered out beam rotates.


In my mind, this detail induces a non-neglible torsion about the girder. After discussion in the office, it was said that there is some torsion induced, but it is ignored. Is this a good/correct assumption? When can something like this not be ignored.
Thanks in advance,
S&T






RE: Cantilevered Beam with Through Beam Detail
With small stiffness the amount of torson (per unit of twist) is small. So the girder would tend to behave like a true pinned support for the cantilevered beam.
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RE: Cantilevered Beam with Through Beam Detail
Is there any concern for the connection of the through girder or beam back to it's supporting members?
Will a simple shear connection be able to "twist" the beam back to an upright position at the supports?
RE: Cantilevered Beam with Through Beam Detail
A beam which supports secondary beams or joists may feel torsion from the rotation of those members but does not need to be designed for torsion provided they are capable of carrying the load without reliance on rotational restraint from the carrying beam. In special cases, it may be wise to limit deflection, hence end rotation of the supported members.
BA
RE: Cantilevered Beam with Through Beam Detail
RE: Cantilevered Beam with Through Beam Detail
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Cantilevered Beam with Through Beam Detail
StructSU10 I share your concern. If that top flange of the thru beam or girder is close to buckling already from bending, it would seem like this tensile perpendicular load would be the icing on the cake to make it buckle.
S&T
RE: Cantilevered Beam with Through Beam Detail
S&T
RE: Cantilevered Beam with Through Beam Detail