CorotTruss Recorder

[grahamo]

On my model the element recorder output file is empty. All my other recorders work fine. Is there a reason. I am using a corotational truss and here is the line of code that forms the recorder:

Code: Select all

recorder Element -file "$dataDir/$FileName/$ii/ElementForce$level Eq[expr $num+1].out" –time –ele $elemID axialForce stiff

Is there a reason that it would be empty? There should be forces applied to this element during the analysis.

Thanks.

[silvia]

try asking for either only axialForce or stiff, not both at the same time.

[grahamo]

I tried it with axialForce and stiff alone. But I still ended up with a blank output file. Any other ideas?

Thanks.

[silvia]

try removing the quotes.....
something's up....

[grahamo]

I removed the quotes from the recorder but I still end up with an empty file. The interesting thing is that the drift recorder is set up in the same way (with the quotes0 and it does return values. I know that there is force in the element since there is a large change in the displacement of the building if I remove the element.

This is a really perplexing problem... I hope that there is an answer. Let me know if I need to post anymore of my code that might have the bug. I did check and it is being applied to the correct element.

Thanks.

[silvia]

do you have the right element tag?

also, try using the regular truss in the element, see if that works, since we know the regular truss does work.

[grahamo]

I did pass it the right element tag. I have OpenSees output the element tag so that I can ensure that it is using the right one.

I changed it to a regular truss and it still came up with a blank file. I need to use the corotTruss element to avoid some potential convergence issues that may arise.

Here is some more information on my model that might help. I am designing a Buckling-restrained Braced Bay. I am using nonlinearBeamColumns to model the beams and the columns and the corotTruss to model the brace so that it doesn't buckle. I am using a hysteretic material for the brace as well. I am not sure if the material to element definition could be the problem with the recorder but I don't think that it is.

I couldn't find any examples of the element recorder used on trusses. That might help me as I compare it to the files that I written.

Thanks.

[grahamo]

Another idea is that I am creating the truss with the area and the material tag. Since I don't understand fully how the recorder formulates its response, is there a possibility that I need to define a section and then try to use the recorder?

[silvia]

if it didn't work with the truss, there is something wrong with your command/or model....
do you have the proper dash in front of the file.

also, why don't you copy a command from the examples manual and then modify it....

[grahamo]

Ok, I got it to work.

For other users, there is a difference between the dash and the minus sign on the ten key pad (even though they might appear the same). That is something to check when recorders don't work; make sure that the dash was used.

Thanks for all the help Silvia.

[silvia]

word of warning on that one: MSWord editors automatically change the right dash to the bad one!

[grahamo]

Something that I noticed in my recorder is that it resets the time and returns more results. In other words, after running from 0-10, for example, there are a few more values for from 0-10. Is that normal?

I think that the problem lies in the recorder is recording after that earthquake is done. (I am runnning multiple earthquakes in succession on the same building). Is there a command stop a recorder from recording? That would be very helpful. I couldn't find one in the manual.

Thanks.

[grahamo]

I got it.

If you use the remove recorders along with reset and wipeAnalysis, you don't have to rebuild the structure completely.