## General Mechanical

#### How to apply an earthquake excitation on a structure in ansys workbench

• Rana Nasser
Subscriber
Hi everyone!

I need to know how to apply the earthquake in acceleration time history form on a strusture at the base level, thanks all
• peteroznewman
Subscriber

Hi Rana,

Take a look at this blog post.

Regards,

Peter

• Rana Nasser
Subscriber
Peter, thank you so much!!
• Rana Nasser
Subscriber

Hi !

I've tried to apply the suggested procedures in the plog post and the other article that peter graciously attached in his last comment, but I still have a big problem!

My problem is that one of the structural elements material is a mohr-coloumb material and i can't do a modal analysis for the structure because of the non linearity of this material, so I can't use the EMM or the other 3 methods to apply the base excitation at the foundation level of my structure. Is there any updates on the EMM or any othre way that could help me to solve this problem?

• Rana Nasser
Subscriber

Is there any advice on how to apply the earthquake base excitation on a structure without using mode superposition?!

I'm trying to do this using APDL commands in transient  analysis , but I cant find the right code to do it. is there any insights please!!

• sk_cheah
Subscriber

Hi Rana,

You could try to do a full transient dynamic analysis with large mass method. This method uses a large point mass coupled rigidly to the mount points. Force load is applied to the mass point such that the force divided by the mass is equal to the desired acceleration.

Kind regards,
Jason

• Rana Nasser
Subscriber

Hi Jason,

Thanks so much for your response, Could you please attach an Apdl command file for any LMM dynamic analysis?

• sk_cheah
Subscriber

Hi Rana,

There are quite a few transient dynamic analysis in the VM page. Instead of applying force at one of the response DOF, you'll apply the force F on a large mass that's say 1000x of your total mass that represents the foundation. You can use MASS21 keyopt(3)=0 as the foundation with fixed rotational dof to avoid the model spinning in space.

Kind regards,
Jason