Problem about bilinear material behavior ?

[yones]

hello ,

i want to define trilinear force-deformation behavior for material that use in SDOF system, so that Third line have Negative slope. i use Hysteretic Material with pinchX =1 , pinchY= 1 , damage1= 0.0 , damage2= 0.0 , beta= 0.0 , but after analysis force-deformation
diagram it 's not what I need. also i use combining two Steel01 materials in parallel (using parallel material), but in steel01 material slope of second line must be positive and negative value does not supported. how to solve this problem ?

please help.

[vesna]

hysteretic material should be the right one to use. What is there that you do not like in the response it gives you?

[yones]

vesna wrote:
> hysteretic material should be the right one to use. What is there that you
> do not like in the response it gives you?

hi vesna.

in hysteretic material parameters , i embed third point below second point (slope of third line is negative) but after analysis ,
i do not see such this behavior.

thank you for your reply.

[vesna]

I tested the material with the negative slope and works well for me. Did you displace your model enough to see the strength degradation?

[civil]

in first comment yones wrote: in steel01 material slope of second line must be positive and negative value does not supported. is that right?
b should be positive in steel01?

[fmk]

no .. b can be negative

[Eli]

Hi,
Is there any image for Bilinear.cpp material which is defined on following page?
http://opensees.berkeley.edu/OpenSees/a ... ource.html

[fmk]

as mentioned on another post, if it is not in arash's dissertation then no.

you could always write a script to generate an image given some input strain history.