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001 to nullify beam's torsional stiffness.In this way, the torsional stresses (if arising due to compatibility of deformation i.e compatibility torsion ) are transferred via alternate load path (i.e redistribution of torsional moments occurred), considering that beam is unable to provide torsional restraint and in other condition if torsional stresses in beam is required to satisfy equilibrium of structure (where redistribution is not possible) then torsional stresses in beams remains independent of whatever value of "J" you have selected as equilibrium equations are necessarily satisfied independent of stiffness as "Compatibility is optional and equilibrium is essential". Whereas the torsional constant, ETABS asks in " analysis property modification factors" is simply the torsional moment of inertia (J) used to determine torsional stiffness of a member (JG/L) i.e something else.Īs long as its value is concerned,then in building structures it is a general practice to use a negligible value like.

I don't know the origin of document,you have uploaded for calculating torsional constant,but the methodology given therein is incorrect.As "Tcr" and "Tu" given therein are indeed threshold torsional strength and ultimate torsional stresses respectively, and are both design properties not analysis properties. The Beam part of a cantilever slab has to transfer the moment through torsion as no other load path is available in this case, and redistribution is not possible.

In these cases you can run the analysis by reducing tosion stiffness of beam so that beam does not fail in shear+torsion in ETABS. Only minium torsion reinforcement is required in this case. The beam that transfers load from a slab which is supported on four /three sides don't need all the torsion reinforcement reported by ETABS, as it can redistribute the stressed in the form of flexure and shear in beam and slab. Stirrups are also able to arrest the cracks due to torsion.īut the important point is to ascertain the importance of torsion reinforcement in a beam.

It is a common practice to add torsion reinforcement in flexural reinforcement, and divide it over the depth of beam: top bottom and middle. What do you mean by interpret ETABS have clearly defined the symbols/acronyms that they use in design report.