Is structural damping effect considered in Bmodes program

Dear Dr. Jason

I am Daniel Kim in Texas A&M Uni. The meeting in ISOPE was very useful time to my research.

I am comparing the natural frequencies(NF) of tower obtained in the time domain simulation by FAST v7 to those obtained by Bmodes program.
The NFs are slightly different between FAST and Bmodes. I think that the damping of tower can be one reason for this. We can input tower damping ratio in FAST v7 program while we can’t in Bmodes. Does it mean that damping ratio is assumed to zero in Bmodes program?

Thank you for your time!!
Daniel Kim.

Dear Daniel,

I can’t confirm that this is the cause for the different natural frequencies between FAST and BModes that you are seeing, but as you noted, BModes does not consider any structural (material) damping in its solution.

Best regards,