Torsional stiffness of RC beam-column elements

[ryanchinaski offline]

Hi there - I'm hoping somebody might help me with this.
I'm currently doing some analyses in SeismoStruct on RC walls subjected to torsion.
The walls are U-shaped and I'm modelling using to the Wide-Column Model (with rigid links).
While I can change the properties of the rigid links (modeled as elastic frame elements), I would like to vary the torsional stiffness of the vertical elements (beam-column elements) representing the web and flange/s of the wall - is it possible to vary the shear modulus in Seismotruct (or poisons ratio for example) for RC beam-column elements? The manual states this is automatically calculated using the classic formula, but it seems odd to me that you cannot vary the poisons ratio at all. My only other option I think would be to vary the value for J (torsional constant), which I believe would only be possible by changing the sectional geometry of the wall (i.e. thickness) - which I would not like to have to do.

Any help would be much appreciated!

Thanks,

[seismosoft offline]

Hello ryanchinaski,
As you correctly pointed out it is not possible to change the poisson ratio in SeismoStruct.
An alternative would be to adopt elastic frame elements and change the EI2, EI3 and GJ parameters, though we are not sure if this would fit your model (e.g. you might need to model inelasticity in the core).
Seismosoft Support