I want to simulate Absorbing Boundary Conditions for Seismic
Analysis in ABAQUS.
How should damping be assigned to the boundaries?
After that, should also be assigned them the support?
Which menu of software should be used?
you have to go to ---- interaction module -- special tab --- spring/dashpot --- create ----
then if you want to connect to the ground use second option : connect point to ground ----- select points that you want to connect spring or dashpot ---- ok --- in new menu you must select degree of freedom and import stiffness of spring or coefficient of dashpot .
· Spring stiffness. Enter the force per relative displacement for springs.
· Dashpot coefficient. Enter the force per relative velocity for dashpots.
good luck
If you are referring to ground response analysis, i.e. your medium is soil, you need to use some linear viscous elements to resemble your elastic half-space.
Damping coefficients are as follows,
C=rho.Vs.A
in which rho and Vs are, respectively, mass density and shear wave velocity of the half-space and A is the tributary area of the used damper (it depends on damper placements).
First node of the dampers should be fully fixed and the other node should be connected to the soil medium.
Note that in this technique, ground motion should be imposed as an equivalent force rather than acceleration.
I think you can find further info in the following webpage (the page is devoted to OpenSees bu the same can also be done in Abaqus).
http://opensees.berkeley.edu/wiki/index.php/Dynamic_2D_Effective_Stress_Analysis_of_Slope
It depends If you are working in the frequency domain or in time domain. There is two options PML (which is only available in 1D and 3D in the Frequency domain) and the infinite element which I know exists in ABAQUS but you should consult the documentation to see the different optins available.
Thank you very much for the guidance. I've studied theories relevant to them But I do not know how to model in abaqus.
If you can help me more about this issue, I appreciate you.
Unfortunately I did not work Abaqus. I have a good experience with ANSYS and Comsol though.
you can use ABAQUS to
create a spring between two points (ground and supports) and assigning degree of freedom to the spring also assigning the stiffness of the spring, if you need assigning viscous damping you should assign Dashpot coefficient.....good luck
you have to go to ---- interaction module -- special tab --- spring/dashpot --- create ----
then if you want to connect to the ground use second option : connect point to ground ----- select points that you want to connect spring or dashpot ---- ok --- in new menu you must select degree of freedom and import stiffness of spring or coefficient of dashpot .
· Spring stiffness. Enter the force per relative displacement for springs.
· Dashpot coefficient. Enter the force per relative velocity for dashpots.
good luck
you have to go to ---- interaction module -- special tab --- spring/dashpot --- create ----
then if you want to connect to the ground use second option : connect point to ground ----- select points that you want to connect spring or dashpot ---- ok --- in new menu you must select degree of freedom and import stiffness of spring or coefficient of dashpot .
· Spring stiffness. Enter the force per relative displacement for springs.
· Dashpot coefficient. Enter the force per relative velocity for dashpots.
good luck
for dashpot coefficient :
C=density*Vs*A
Vs = soil shear velocity.
A = effective surface of point that dashpot connect to it
how can i simulate dashpot for a boundary ? what you say is for one node.
what range is dashpot coefficient?
MIDAS GTS software provides a robust framework for conducting dynamic 2D equivalent linear analysis. A rigid bedrock at the base of the model can easily be simulated using fixed conditions. However, i am trying to define an elastic bedrock (compliant base), and it does not seem like a trivial task. For example, QUAD4M software implements a transmitting boundary option at the base so that the need to define a rigid bedrock was eliminated. This was done using Lysmer and Kuhlemeyer (1969) damping method to absorb artificial wave reflections.
I wonder if someone has some experience with how this can be done manually in MIDAS GTS or just a general advice on it.
Thank you.
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