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selimgunay wrote: ↑Mon Aug 24, 2020 12:23 pm If you are using an elastic response

uniaxialMaterial Elastic $matTag $GA

If inelastic (using Steel01 for example to represent bilinear relationship)

uniaxialMaterial Steel01 $matTag $Fy $GA $b

Fy is the shear capacity, GA is the multiplication of shear modulus and shear area, b is the ratio of slope after yield to GA. You can have it negative to represent brittle failure

Thanks for your reply.
Can I understand it in this way, when using uniaxialMaterial command:
For shear, we use GA to describe the relation between F and gamma;
For torsion, we use GJ to describe the relation between T and theta;

As for Fy, does it mean the shear force when the section starts to yields?
Hope you can help me confirm it.

Another is for the A in GA, do we need to use the whole area or the effective area and why? Thanks.

mhscott wrote: ↑Mon Aug 24, 2020 12:04 pm Use a uniaxialMaterial to define the section shear force-shear deformation relationship, then add it to the fiber section using 'Vy' in the aggregator. I don't have a specific example on hand, but you can search the message board as this is not an uncommon question.

Thanks, it is very helpful,

Hi, everybody,
I am using the section Aggregator command to add the Shear force-deformation to the existing fiber section, but I am confused about how to define the Shear force-deformation relation for the uniaxialMaterial, anybody can help or provide some reference about it? Thanks a lot.

What if I do the static analysis and transient analysis? Will ''-mass 0.86'' be regarded as the dead load or should I define the dead load again by using load pattern command.

Also if I didn't turn the PDelta effect and didn't define the dead load by using load pattern command when doing the transient analysis, will the results be different? Thanks.

Basically, I want to know how the mode shapes were normalized in OpenSEES. If anyone knows it, please tell me. Many thanks.

Hello, everyone,

I am now doing the modal analysis for a tall building using OpenSEES, from the eigenvalue analysis I can get the natural frequencies, but I don't know how to get the generalized mass and generalized stiffness for each mode. So does anyone know how to get them from OpenSEES? Thanks.

So can I interpret it in this way that the ''-mass 0.86'' in the command, element nonlinearBeamColumn 1 1 2 7 1 1 -mass 0.86, will only be used in the modal analysis (eigenvalue analysis), and when you want to apply the dead load to the model using load pattern command, even ''-mass 0.86'' includes the dead load, it will not affect the dead load you applied to the building, so they are two independent process? Thanks.

Hello everyone:

I am trying to build a model of a tall frame building to carry out the mosal analysis, and I use the command below to define the mass density of the beam:

element nonlinearBeamColumn 1 1 2 7 1 1 -mass 0.86;

The ''-mass 0.86'' includes the Self Weight of the beam, Slab Dead Loads and Superposed Dead Loads.

My question is during the modal analysis process, you need to apply the Dead Loads and Live Loads to the building, how does the OpenSEES deal with the mass density ''-mass 0.86'' ? Does it ccalculate the Dead Loads from "element nonlinearBeamColumn 1 1 2 7 1 1 -mass 0.86;" automatically or should I apply the Dead Loads again when I apply the loads?

Thanks.