Robot Structural Analysis Forum
Welcome to Autodesk’s Robot Structural Analysis Forums. Share your knowledge, ask questions, and explore popular Robot Structural Analysis topics.
cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Seimic (again)

1 REPLY 1
SOLVED
Reply
Message 1 of 2
tony.ridley
393 Views, 1 Reply

Seimic (again)

Hi guys,

 

I understand it's important to hit say 90% mass participation in the modal case to properly run seismic analysis. 

 

In order to define AS1170.4 in Robot you first need to define a modal case.  If I input a user defined base shear, Robot will try to match the CQC reaction to the user defined shear.  This seems to be regardless of the mass participation in the preceeding modal case. 

 

So - does this modal case need to hit 90% mass, or is the seismic case using the "correct" mass by scaling to hit a pre-defined value?

 

Cheers,

Tony

1 REPLY 1
Message 2 of 2
Pawel.Pulak
in reply to: tony.ridley

Hi Tony,

modal case needs to hit 90% mass.

Using only the scaling to pre-defined base shear will result in overestimating the influence of some vibration modes while neglecting the influence of other vibration modes (not found by modal analysis because of not reaching 90% mass).

 

---------------------------------------------
If this post answers your question please click "Accept as Solution". It will help everyone to find answer more quickly!

 

Regards,


Pawel Pulak
Technical Account Specialist

Can't find what you're looking for? Ask the community or share your knowledge.

Post to forums  

Autodesk Design & Make Report