multiple support excitation

[Olympia]

Dear all,

I would like to ask if there is an option in OpenSees for multiple support excitation in terms of accerelation input instead of displacements.

Thanks a lot,
Olympia

[vesna]

Yes, there is such option but it is not very exact. To get displacements from accelerations OpenSees uses trapesoidal rule and does not include line correction.

[Olympia]

Thanks a lot Vesna for your reply!!
So does it mean that I can excite my structure using as input different accelerograms at different nodes (for example 3 different accelerograms, one at the base of each of the 3 bridge piers, asychronous motion) but the results may not be exact?
So it is better to excite in terms of displacements?

Regards,
Olympia

[vesna]

Yes, you can use 3 acceleration records and get not so exact results or you can use displacement records and get exact results.