Torsion on a monolithic RC T-Beam

[chritsar]

Assume a RC continuous two-span slab with pinned supports on all sides and a T-Beam acting as mid-support. The beam is supported by columns on each end (assume high flexural stiffness of columns).

Let's take two scenarios:
1) Slab span lengths and loading are equal, there is a force F acting with an eccentricity e[sub]y[/sub] on the beam (e.g. column sitting eccentrically on top)
2) Slab span lengths and/or loading highly unequal, one span has a much larger deflection than the other one

Would the beam need to be dimensioned for torsion in both scenarios?
Is the calculated torsion in scenario 1 (F x e[sub]y[/sub]) mitigated by plate in-plane forces resulting to less or no torsional stresses on the beam?
In scenario 2, can we assume rotation of the beam due to the largely different deflections, leading to a torsional stress because of the columns at each end? Is the calculated torsion mitigated by any factor as in scenario 1?

 

[human909]

Have a google of "compatibility torsion".

The torsional stresses in you beam would likely be relatively low because the torsional stiffness of the beam is low. Static equilibrium is provided mostly by bending moments in the slab rather than torsion in the beam.

 

[hokie66]

Is this a cast in place or precast T-beam? A section might help.

 

[chritsar]

This is about monolithic RC elements. I edited the title and original post to clarify.
The reference to compatibility torsion had me reading a lot, and it is there mostly explained.
This seems to be ignored by the European Code where I can't find a reference to it.

 

[human909]

The reference to compatibility torsion had me reading a lot, and it is there mostly explained.
This seems to be ignored by the European Code where I can't find a reference to it.

Glad it helped you.

The European Code doesn't ignore it. "Compatibility torsion" is a concept in static equilibrium. It exists whether it has a label or not.

I must say I had never heard of the term used either and it doesn't exist to my knowledge in my local code. The first time I had even hear the term used was from THIS forum. It wasn't a new concept for me, but it was the first time I've ever heard the concept given a label.