Modellation of TMD for a cable-stayed bridge (in SAP2000)

[leonardo04]

In order to avoid the excessive vibration in a steel cable-stayed bridge due to pedestrian load in resonance I tryed to put a tuned mass damper in the middle of the deck. I found problem modelling it.
I've drawn a point in the middle of the deck with a certain mass assigned, linked to the deck with a Nlink element-Damper giving stiffness properties in the only axial direction and fixing all the others directions. I tryed with both the linear and non linear properties of the link.
I used a Linear analysis with direct integration starting from the stiffness obtained from a previous non linear case(to take into account the cable non linearity) but the TMD doesn't work: there's no damping given by TMD. It works only starting from stiffness zero conditions. I can't understand why. Is there anybody can explain me how to do?
Thank you.

 

[DanCivil]

at first I would suggest to check the mass source (Define - Define mass source). It is important that "additionall masses" are used.

Afterwards it should be checked if there is any kind of displacment of the joint and the link element.


Perhaps you could place the sdb-file here, this would simplify the procedure to help you.

good luck,
best regards,
Daniel