force-deflection curve

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imancivil
Posts: 55
Joined: Mon Feb 11, 2008 11:15 pm
Location: Kerman

force-deflection curve

Post by imancivil »

Hi all,

I want to use unidirectional element with nonlinear generalized force-deflection capability that can be used in any analysis. The element is defined by a generalized force-deflection curve.
How can I define an optional force-deflection curve?

Thanks.
susan
Posts: 110
Joined: Sun Mar 02, 2008 12:10 am

Post by susan »

Dear iman,

You raise an interesting question. i have the same question about this. Although I know in ANSYS it is possible to define a specific force-deflection curve for elements, but in opensees i don't know.

Can anyone help us?

Thanks!
silvia
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Location: Degenkolb Engineers
Contact:

Post by silvia »

why not use the truss element where you define the section response via the uniaxial section?
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
imancivil
Posts: 55
Joined: Mon Feb 11, 2008 11:15 pm
Location: Kerman

Post by imancivil »

Daer silvia & susan,

thanks a lot for your consideration. i think i could not mention my purpose clearly.
i have the force-deflection (F-D) curve for the a specific element:

D=-100mm at F=-250 KN
D=-60mm at F=-360 KN
D=-36mm at F=-460 KN
D=-24mm at F=-550 KN
D=-16mm at F=-800 KN
D=-8mm at F=-1100 KN
D=-5mm at F=-2140 KN
D=0mm at F=0 KN
D=0.458mm at F=2525.76 KN
D=2mm at F=2525.76 KN

(F<0 are compression forces and F>0 are tension forces)

how can i apply this behavior to element?

thnx
Iman Mansouri
PhD Candidate
University of Kerman
silvia
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Post by silvia »

use the hysteretic material for the section, defining A=1, the section stiffness becomes the force-deformation behavior, right?
otherwise, use a zero-length element.....
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
imancivil
Posts: 55
Joined: Mon Feb 11, 2008 11:15 pm
Location: Kerman

Post by imancivil »

Dear silvia,

Thanks for your help. :)
Iman Mansouri
PhD Candidate
University of Kerman
esi_opensees
Posts: 93
Joined: Mon Apr 14, 2008 10:53 pm

Post by esi_opensees »

Dear silvia,

would you please tell me why A=1? the area may be greater,equal or less than 1.
silvia
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Joined: Tue Jan 11, 2005 7:44 am
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Post by silvia »

to make the stress equal to the force....
i may be wrong...
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
imancivil
Posts: 55
Joined: Mon Feb 11, 2008 11:15 pm
Location: Kerman

Post by imancivil »

i agree with silvia; because first we define the properties analysis (section, material,…) for a single element and capture the force-deflection curve; we repeat this step for all the types of elements; then in the next step we apply the data which obtained from the curve on the whole of structure. A=1 causes the stress = force, right?
Iman Mansouri
PhD Candidate
University of Kerman
esi_opensees
Posts: 93
Joined: Mon Apr 14, 2008 10:53 pm

Post by esi_opensees »

Dear silvia&iman

According to your notions when we applying the behavior of material (Hysteretic material) for entire of structure the value of area is independent (each value is correct). isn’t it?
silvia
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Joined: Tue Jan 11, 2005 7:44 am
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Post by silvia »

you've got to work throught the modeling with someone in person with pen and paper in front of you.
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
esi_opensees
Posts: 93
Joined: Mon Apr 14, 2008 10:53 pm

Post by esi_opensees »

you ridicule me? :cry: i only told my opinions... :(
silvia
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Joined: Tue Jan 11, 2005 7:44 am
Location: Degenkolb Engineers
Contact:

Post by silvia »

no, it is really difficult to work through this via this forum.
i was making the recommendation i give everyone who is trying to figure out how to define a model.
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
esi_opensees
Posts: 93
Joined: Mon Apr 14, 2008 10:53 pm

Post by esi_opensees »

thanks, you are very kind.
:)

now, would you plz tell me the imancivil's opinion is true or false?

tnx.
silvia
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Joined: Tue Jan 11, 2005 7:44 am
Location: Degenkolb Engineers
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Post by silvia »

for uniaxial response, yes, where stress=force/area
Silvia Mazzoni, PhD
Structural Consultant
Degenkolb Engineers
235 Montgomery Street, Suite 500
San Francisco, CA. 94104
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