base excitation

[partla]

Hi,
I’m modeling a geotechnical problem and want to dynamic analyze. Is there any way to base excitation? As I know while using Uniform excitation it’s assigned to all the free DOF’s. But I want to simulate base excitation (propagation of waves from bed rock).
I’ll be happy hearing from you.

[vesna]

Uniform excitation pattern will do it.

[partla]

Thanks dear vesna

[mnazari]

How about if we define two nodes at base connecting with a zero length element, modeling a rotational spring. Using uniform excitation pattern, which of these nodes base acceleration is applied?

[fmk]

have you looked at the geotech exampes in the wiki. a number of these examples demonstrate an approach for doing what you want, e.g.
http://opensees.berkeley.edu/wiki/index ... Definition