analysis and design the compatibility torsion on the concrete beams
analysis and design the compatibility torsion on the concrete beams
(OP)
Dear Experts
in case of design concrete slab-beam system , shall we ignore the compatibility torsion on the beams by put the torsional stiffness equal to zero (torsional modifier factor=.0001 in etab software ) and design only on the equilibrium torsion ?.
in case of design concrete slab-beam system , shall we ignore the compatibility torsion on the beams by put the torsional stiffness equal to zero (torsional modifier factor=.0001 in etab software ) and design only on the equilibrium torsion ?.
Thank you





RE: analysis and design the compatibility torsion on the concrete beams
RE: analysis and design the compatibility torsion on the concrete beams
Thank you
RE: analysis and design the compatibility torsion on the concrete beams
RE: analysis and design the compatibility torsion on the concrete beams
Also the other question is in case of external beam which is supported slab/beam ,if i will put the torsional modification factor = zero in the sap model and in the site during construction the top reinforcement of the slab/beam which is supported be the external beam take the sufficient development length to transfer the end moment to this external beam , the external beam in that case will be fail or the redistribution will be happened before failure.
Thank you
RE: analysis and design the compatibility torsion on the concrete beams
Even if you have no top reinforcement at the end, the beam will still attract torsion until the concrete cracks in torsion thus relieving the stresses. Just because you have told the beam it has no torsional stiffness does not mean that it has none in practice. That is why design codes require minimum torsion reinforcement, especially in edge beams, even in cases where you have ignored compatibility torsion. So that the beam will not fail in torsion and is able to redistribute its effects.
RE: analysis and design the compatibility torsion on the concrete beams
This is not direct torsional stiffness, but this the torsional modification factor , anyhow i make a lot of experimental models and i sure for the direct torsion (like cantilever slab from the beam without back span ) it has been taken into consideration.
The thing is that the failure in torsion is brittle failure ( happen suddenly), and I don't know if the minimum torsion reinforcement is sufficient to over come on the comparability torsion till the redistribution happened or not .
Thank you
RE: analysis and design the compatibility torsion on the concrete beams
Design codes suggest that it is sufficient.