question on stiffness damping coefficient

[zhangbaozai]

Dear All:


May I ask if anybody know a way to write the mass and stiffness matrix and corresponding mass proportional and stiffness proportional damping coefficient that is formed in OpenSees?

I created a 2DOF system and tried to see how the mass and stiffness matrices and how the mass proportional and stiffness proportional damping coefficients look like?

I used "print" command, but I can only see mass assigned at each node rather than the total mass matrix. Also, I can only see mass proportional damping coefficient, but I can not see stiffness proportional damping coefficient in the created text file from "print" command.

Thank you very much.


Sincerely,
Baozai

[selimgunay]

You can use the printA command to print the stiffness and mass matrices, but not directly the damping matrix. You actually input the Rayleigh damping coefficients yourself in the Rayleigh command.

[zhangbaozai]

[quote=selimgunay post_id=115128 time=1590624056 user_id=291338]
You can use the printA command to print the stiffness and mass matrices, but not directly the damping matrix. You actually input the Rayleigh damping coefficients yourself in the Rayleigh command.


Hi, Selimgunay,

Thank you for your response. I tried "printA 2.txt" but there is no file generated. I am using OpenSees 2.4.4, may I ask if this is due to the version of the OpenSees I used?

Yeah, I used the Rayleigh command to define the mass-proportional and stiffness-proportional damping coefficients. After I used "print 1.txt", I can see the mass-proportional coefficient after each node like below.
Rayleigh Factor: alphaM: 0.415153

I thought the stiffness-proportional damping coefficient will also be shown in the printed text file but I did not find it. So I just want to ask if this stiffness-proportional damping will be also shown in the text file or not.

Thank you.


Sincerely,
Baozai

[mhscott]

To get the matrices M, C, and K, read this: https://wp.me/pbejzW-FH

Also, you need to use the -file option, 'printA -file 2.txt'