question about Hysteretic material

[dynaforce]

Hi dear all.

I want to use Hysteretic materail for flexural members (Beam).
Hysteretic material can uses 'stress-strain' or 'force-deformation (Moment-Rotation)' options
My question is that Input parameter is only value (ex 123). there is no Unit(kNm or N/mm^2)
How can Opensees distinguish between 'stress-strain' and 'Moment-Rotation'

Thanks.

[nbazaraa]

For unit system, you can adapt a consistent system of units by your own, for example you can use Newton, mm, Sec, kg but should be used for the whole project. All arguments you put should be unit less, i.e if the input is elastic modulus E of steel and you are using Newton-mm, you just type 200000.

Regarding the tangent stiffness, it is recommended to use stress, strain and elastic modulus as input for beam sections and stiffness & force for spring elements.

[dynaforce]

Thank you for your answering my question.
The focus of my question is that Input parameter of 'hysteretic material' is only numerical value.
i.e yield stress = 235Mpa (in Stress-strain relationship), yield moment = 446940000 Nmm (in Moment-rotation)
there is no input unit system (Mpa, Nmm). Only numerical value there is (235, 446940000)
I wonder that how can Opensees distinguish between the two??

[fmckenna]

OpenSees is unitless .. it is thus you who distinguishes between them .. as for stress-strain or force-deformation it depends on the usage of the material, e.g. if in a zero-length element it is force-deformation, if a fiber in a section it is stress-strain

[dynaforce]

thank you.
thank you very much.
I Understand. thanks to you.