strain recorder

[clazela]

I would like to obtain the maximum strain of a column, at each step of a pushover, considering firstly all the fibers of concrete cover and, secondly, all the fibers of concrete core, without specifying the the coordinates of all the fibers. I have used the following recorder commands:

set recTag60 [recorder EnvelopeElement -file "Core.out" -time -eleRange 5 10 section fiber $IDconcCore strain]\n');
set recTag70 [recorder EnvelopeElement -xml "CoreXML.out" -time -eleRange 5 10 section fiber $IDconcCore strain]\n');
set recTag80 [recorder EnvelopeElement -file "Cover.out" -time -eleRange 5 10 section fiber $IDconcCover strain]\n');
set recTag90 [recorder EnvelopeElement -xml "CoverXML.out" -time -eleRange 5 10 section fiber $IDconcCover strain]\n');

where IDconcCore coresponds to the tag of the material assigned for the cover and the $IDconcCover is the tag of the material used for the cover.

If I don't put "section" and "fiber" the output is empty.

When I check the xml output, the material tag is the same for both the cases; it means that I am recordering values related to only one material.

May I have some suggestions?

[fmk]

read the bottom of the section command in the manual .. you need to proviide a fiber location as well as the tag .. at the moment you are just getting
the fibers that are numbered: $IDconcCore and IDconcCover .. you want the fibers at a location with a specified tag.

http://opensees.berkeley.edu/wiki/index ... er_Section

[clazela]

Thanks for your reply...

Now I cannot figure out why I am obtaining something as follow: I am asking concrete strains as you have suggested, but even if I ask for specific coordinates, when I check the xml output, the coordinates shown are different.
I am working with circular sections, thus the subdivision is in wedges and rings, so in the recorders the coordinates defined were those correspondent to the center of each portion...

[mhscott]

The recorder finds the fiber whose centroid is closest to the given coordinates, not necessarily at the given coordinates

[clazela]

I knew this so I tried to get the correct fibers information doing as explained in the following.
What I am looking for - I have to extract the strains related to the unconfined concrete fibers in most external ring.
What I have done - I have created a loop that compute the y and z coordinates of the points located in the middle of each external portion of circular sector, considering the entire turn. The turn was subdivided according to the number of wedges considered in the definition of the section.
Output – The input coordinates result different from the output ones and not close enough to think that it is considering the closest centroid, but for instance they are even diametrically opposite.
In order to check better, I have plotted the coordinates of input and of output and it seems that the most are located in the correct position, along the turn, but some of them are totally wrong. The disagreement between and output is cancelled in most of the cases cause I am considering the entire turn, but the impossibility of capture fibers of which I need information about becomes an issue…
Could I have a piece of advice?

[fmk]

if you need to, add the fibers individually one at a time yourself at the locations you specify. you can then use the order instead of the coordinates to get the fiber you want.