Seismosoft | Earthquake Engineering Solutions

Hi
I am using a link element with vsc_dmp in F1 direction and default lin_sym (with default values) for other DOFs,
I have connected two elastic steel members (UC350) to the two ends of the damper, at top of a chevron brace.
Although the link element is in series with elfrm element (UC350) the internal force of the steel members are almost double that of damper element
whereas it is expected to be the same. Please clarify,

Here are the specifications that I am using for the damper:

Kd= 200000 kN/m
C=400 kN.s/m
alfa=0.3
Pin tolerance = 0

Thanks

If the elements are connected in series, this is not reasonable.
Can you please employ a more stringent convergence criterion and (if posible) a force based convergence criterion?
Seismosoft Support

Thanks for your response,
I did changed the convergence criterion to force based with 0.001 tolerance
but the problem still exist. I appreciate your instruction

Thanks

This is not reasobable, because with a force-based criterion with 0.001 kN tolerance, the differences should be very small.
Can it be that you are comparing local against global forces, or forces at different axes?
Can you please check things again?
Seismosoft Support

I am comparing internal force of a link element (damper) of F1 DOF and axial force of the connected frame element (elastic) F(A) DOF.
I can send you my model. Or the elements internal actions history.

Thanks

I emailed my model to support@seismosoft.com.
the force in dampers are different than UC's connected to their ends (horizontal members)
it is obvious from early part of the record.

Thanks

The model that you sent is huge wih more than 1600 elements, and we cannot obviously check things. Note that you have defined element damping, which might be the reason for the discrepancies that you get. If this is not the case, please send us a more simplified model that reproduces the problem, so that we can check things easier.
Seismosoft Support

Hi

As you suggested, I have checked without global damping but this issue still exist.
The top of chevron braces is not supposed to be connected to the beam and it is intentional.
The difference between dampers load and corresponding connected frame elements is still significant
I sent you the simplified model. I do not know which axial force to refer to for designing the
chevron braces and the connecting members. I appreciate your advice.
Thanks

We checked again the small model that you have sent. It seems that there is a problem with the connection of the elements, the model cannot even run eigenvalue analysis. Check again the conectivity of the elements, this is probably the reason why the model does not converge.
Seismosoft Support

You have two or more nodes on the same coordinates that are connected to different elements. These elements are not connected to each other.
Seismosoft Support