Re: Torsion in Concrete Beam

Torsion in interior beams are not required for equilibrium. What I have done in the past is design the interior beam for threshold torsion only. In the computer model, assign the torsional stiffness modifier to a low number. This will cause moments to redistribute to positive moments. At the first occurence of a torsional crack, the moments will redistribute to the midspans.

I am curious as to what other engineers do in this regard. In order for the beam to torque, it has drag the slab with it and yield the slab reinforcing.

~Anantha

On Thu, Aug 6, 2009 at 3:49 PM, Jeremy White <admin@structuralae.com> wrote:

I am beyond the torsion threshold specified in ACI 11.6.1.

My interpretation is that if you are less than the torsion threshold then you can "double dip" on your stirrups.  If you are beyond that (and you can't redistribute load) then you have to provide additional provisions for torsion resistance.  Does this sound correct?

- Jeremy

Quoting David Topete <d.topete73@gmail.com>:

The typical stirrup configuration doesn't provide adequate torsional
resistance?  Interesting.

On Thu, Aug 6, 2009 at 11:47 AM, Jeremy White <admin@structuralae.com>wrote:

Is it common to have to add torsional reinforcing to an interior (not
spandrel) concrete beam?

I have an interior beam/girder with one adjacent span almost 2 times the
other adjacent span which is apparently introducing torsion into the beam.
 The torsion is high enough that according to ACI I will need to provide
torsional reinforcing.  I didn't think torsional reinforcing on an interior
beam was common.

- Jeremy

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