Seismosoft | Earthquake Engineering Solutions

Dear Seismosoft,

My name is Milena Ivanova, I am Ph. D. student in the faculty of Civil engineering of the University of Architecture, Civil Engineering and Geodesy – Sofia, Bulgaria. The subject of my work is reduction the effects of seismic action through passive energy dissipation devices. Numerical examples deal with models of existing buildings with supplemental damping (viscous or hysteretic damping). I am using Seismostruct computer software for the main purposes of my work.
I have a couple of questions. I would appreciate your answers of my questions very much. Please allow me to thank you in advance! The questions are:

1. How supplemental viscous damping element are implemented using elements with nonzero length and two nodes (link elements).

2. Could I model inherent damping of proportional type (Rayleigh),using of mass and stiffness proportional components modeled, by two nodes elements.

I would be grateful to you if you may send me some elementary examples easy for understanding which can be pointed out as some pattern. Again, thank you very much in advance!

Sincerely Yours,
Milena Ivanova

Milena, hi.

When assembling the global damping matrix of the structure, one 'adds' the various damping matrices for each element in the structure (which will be different from zero if additional damping has been defined for the elements).

The damping matrix for each of such elements is indeed typically defined as a proportion of the corresponding mass and/or stiffness matrix.

In the case of link elements, however, since these have no mass, the damping matrix can only be a proportion of the stiffness matrix.

Best,

Rui

Thank you for the response,

However, I still have some difficulties with modelling supplemental nonproportional viscous damping in a 2D frame structure. My purpose is to accopmlish diagonal braces with viscous dampers, for example. So could I ask some questions as: How can I model this problem in SeismoStuct? Which class elemts are appropriate- the dashpots or the links?
I would appreciate the receiving of such an example, containing supplemental damping for controlling dynamic and seismic structure performance, becouse I could not found such in the verification ones.

Thank you in advance!

Sincerely Yours,

Milena Ivanova

Hi Milena,

In order to achieve your goal (i.e. to model a diagonal brace with a viscous damper), I would most likely introduce, at one of the ends of your brace, a link element featuring a response curve whose hysteretic behaviour reproduces that of the damper in question (in SeismoStruct Manual/Help System both 'plst' and 'bl_kin' are indicated as possible candidates).

Personally, I do not have such an example at hand to send you, but perhaps some other user who is reading this discussion thread will?..

Best,

Rui