Fiber numbering and recorder limits

[cchisari]

Dear all,

I have reinforced concrete structure, where the members are modelled as forceBeamColumn with fiberSec section. I would like to output stress-strain relationships for EACH fibre (say N) and for EACH Gauss point (say M). As I can understand, I should create NxM recorders, but apparently there is a limit for the number of recorders. Furthermore, I cannot understand how to iterate over the number of fibres, and how are they numbered, i.e. I would like to know, given a fiberSec section, how many fibres have been defined. So, my questions are:

- What is the limit for the number of recorders, and how can I set it?
- How can I retrieve the number of fibres in a section in any part of the tcl model, i.e. without storing it when I build the section?
- What is the meaning of 'matArg1' in the command output 'fiber $fiberNum $matArg1 ..' (http://opensees.berkeley.edu/wiki/index ... er_Section)?
- How are they numbered (referring to fibreNum of the previously mentioned command)?

Thank you for any help.

Corrado

[selimgunay]

Please check the fiber, patch and layer commands.

[cchisari]

Dear selimgunay,

Thank you for your response. I cannot find any answer to my questions from the documentation, except for (maybe) setMaxOpenFiles command to set the maximum limit for the recorders, which I have not tried yet. The commands you suggested do not explain i) how the fibers are numbered, ii) how to output the number of fibers in a section, iii) what the meaning of "matArg1" is.

To make question ii) clearer, I would like to know if there exists a command similar to getNodeTags, but referring to fibers, something like "getNumberOfFibers $sectID". Alternatively, if there is a workaround for this.

Any other suggestions?

Corrado

[EricsonEncinaZ]

2. I think there is no such a command for fibers as you are asking.
3. Don't know. May be it is more useful something like "recorder Element -file filename.out –time -ele 1 section 1 fiber $y $z <$matID> stressStrain", I think you can also change stressStrain for either stress or strain, depending on what you want.

Since you are working with fiber sections (it assumes plane section remain plane), you can post-process and build the strain profile by either taking the strains at both ends or requesting section deformation (axial strain and curvature), then by using the constitutive material relationships you can get the stress for any part of your section. This is clearly quite useful if you have a monotonic problem, but it won't consider material degradation under cyclic displacements.

[selimgunay]

I think you don't essentially need the information of the total number of fibers and how they are numbered, because you can record the stress and strain information of a fiber with the following command.

recorder Element -file Element1.out -time -ele 1 3 section 1 fiber 0.10 0.10 stressStrain

matArg1 represents the material tag of the material assigned to that fiber.