CENTER MASS RIGIDITY on ETABs

[andtangh]

Dear All,


Anybody can explain about what is the unit table output "center mass rigidity" at column " Mass X or Mass Y"on ETABs?
I was thinking why when I change the global unit kN-m to kN-mm it just different about 1000x, has it actually to be same or else?
And if we need the mass in unit tons, how to obtain from ETABs?


Thanks,

Andreas

[miquan]

At first, you are view the results from modal analysis.
So all values are non dimensional.

Actually, for more understanding, you should read "Dynamics of Structure" books.
You should read exactly about how to normalize the eigen vector.

Matrix of eigen vector is normalized follow matrix of mass. So result by MassX (mass) multiply XCM (eigen vector) is a constant.

You can check two results below.