Seismosoft | Earthquake Engineering Solutions

Hi everyone,

I am doing a analysis on a frame with semi-rigid connections, and to modelling the behaviour of the connection I introduce link elements on the frame. My problem is that when I am doing a eignvalue analysis its gave me the same fundamental period that for the same frame with no link elements, i.e with strength connections. I don't know why this is happening, anyone can help me ?

Ana Santos

Dear Ana,

I have carried out a search in this Forum using the terms "eigenvalue link elements" and found a number of relevant posts on the topic, which I would suggest you to consult as well.

In any case, if the K0 values in your springs are relatively high (as they typically are), then the elastic response of your frame will not change in siginficant fashion, and your eigenvalues will be the same, with the differences in response being instead more evident when one carries out an inelastic analysis (i.e. pushover or nonlinear dynamic analysis).

If, instead, your K0 values are very low, and you are still obtaining the same eigenvalue results, then it could be that your link elements are not properly connected to the frame elements. (on the other hand, if your K0 values are very low, then the model could give rise to eigenvalue analysis problems, which, again, will not be very informative - as I mentioned above, it is with inelastic analysis that the impact of link elements introduction become more apparent)

Best,

Rui