Unable to adjust damping of structure

Hello everyone,

I am trying to find out how to impose a damping factor to my structure. It’s a model of a simple bridge to which I apply a sudden force and then use a time step analysis to see how the bridge vibrates. When I plot the resulting acceleration in a node in the middle of the bridge, I can see that there is some damping present, but I don’t know what causes it or how I can change it.

I’ve tried adding the ‘Earthquake’ task and adjust the settings in the ‘Damping’ tab, but this has no effect. I’ve also added damper-springs onto the bridge which are attached to masses (which represent pedestrians), but this also has no effect. The only way I can affect it seems to be by changing the self-weight (in kN/m³) of the materials I’m using, which is what I did in the images below with some extremely high (left) and low values (right).

My end goal is to be able to impose a damping factor (which is directly related to the logarithmic decrement) as an input parameter to my model, and also be able to see this value reflected in the output results. Any help is greatly appreciated. The file I’m using can be found here: https://we.tl/t-AmzoEucbEV

Kind regards


A reason for the damping of your system could be the numerical damping in ASE. Please have a look at this post from last year.

Further information about damping can be found within the DYNA Manual.

SSD / TEDDY > Help > User Manuals > All Manuals… > dyna > chapter 3.11 MODD - Modal Damping
SSD / TEDDY > Help > User Manuals > All Manuals… > dyna > chapter 3.5 GRP - Selection of Element Groups

And you could have a look at the related dyna examples.

TEDDY > File > Examples > dyna > english > …
TEDDY > File > Examples > ase > english > dynamics > …

Best regards
Frederik Höller
Your SOFiSTiK Support Team

1 Like

Thank you very much for your help, Frederik. I looked further into the information you referred to and this has helped me to solve the problem.

Kind regards