Single-point constraint object & Time-History

[evgin]

I am using a single-point constraint object in a load pattern (pattern Plain 10 {Series -time {0 10 10000} -values {0 1 1} -factor 1} { ) to impose displacement on some of the piles nodes. I have ground motion as well. Analysis is done without any warnings however when I monitor the moment diagram of pile which is surrounded by soil which is liquefiable, moments are very small. When I even increase the displacement constrain markedly, the moment is still small. It seems like SP command doesn’t work.


Should I change my analysis options like integrator or so, or for both types of loading ( i.e. ground motion, and SP) I can use the same options ?

Anyways, I don't know what is wrong and I would like to ask it here.

Thanks !

[etahmasebi]

If I understood your question well, in case you need the single point constraints to remain constant during your transient analysis, you have to use "loadConst" command after applying the single point constraint in order to make sure they don't change during the ground motion.
http://opensees.berkeley.edu/wiki/index ... st_Command

Also it is a good idea to define the "timeSeries" before the pattern and then assign the time series tag to the pattern. You can use a Path time series if you have a specific path to be applied.
http://opensees.berkeley.edu/wiki/index ... es_Command

[evgin]

Thanks for your hint ! I have one more question as well.

For my bridge when I am performing a dynamic analysis for it without pile I am getting reasonable results. However, when I add the piles and soil, I am getting very small demands. I try to make the section for piles as weak as I can but the response doesn't change at all. I tried different boundary conditions, load, etc etc, but no change.

Do you have any idea?

[etahmasebi]

Sorry, I haven't work with soil or pile modeling before. Maybe somebody who has more experience in this field can help. Just a general comment, make sure that the boundary conditions and assigned stiffness in the model with soil and pile are realistic.