Backbone Curve Graph

03-Analytical/modelling capabilities
Kirkaguel
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Joined: 31 Dec 2018, 10:04

Backbone Curve Graph

Post by Kirkaguel » 13 Jan 2019, 03:35

Is there a way that we can see the backbone curve (whether bi-linear or trilinear) adopted for a non linear component i.e. plastic hinge in accordance with asce 41 guidelines?

One critical aspect of the backbone curve is the post peak stiffness assumption to capture cyclic degradation.

https://www.dropbox.com/h

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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Backbone Curve Graph

Post by seismosoft » 14 Jan 2019, 10:11

Since SeismoBuild is a fibre based program, this is not possible. Note however that in the next release a plastic hinge frame element with a multi-linear backbone curve will also be available.
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Ralazem
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Joined: 08 Feb 2019, 02:38

Re: Backbone Curve Graph

Post by Ralazem » 22 Mar 2019, 04:54

Is there another method to model the post peak stiffness assumption for cyclic degradation modelling?

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seismosoft
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Re: Backbone Curve Graph

Post by seismosoft » 22 Mar 2019, 17:07

Unfortunately, no.
In fiber modelling this is automatically taken care by the constitutive material models for concrete and steel.
There is no need for the user to calibrate it.

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Ralazem
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Re: Backbone Curve Graph

Post by Ralazem » 22 Jul 2019, 05:24

I am unable to obtain a degrading hysteteric behaviour under cyclic loading. What might be the cause?

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seismosoft
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Re: Backbone Curve Graph

Post by seismosoft » 22 Jul 2019, 13:09

There can be numerous reasons. For instance, relatively low loading level, presence of large transverse reinforcement that leads to large confinement factors for concrete, lack of adequate vertical loads, deactivation of 2nd order effects.
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Ralazem
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Re: Backbone Curve Graph

Post by Ralazem » 30 Jul 2019, 05:35

What do you mean by deactivation of 2nd order effects? How can I activate those?

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z.gronti
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Joined: 16 Oct 2013, 08:14

Re: Backbone Curve Graph

Post by z.gronti » 30 Jul 2019, 12:35

Dear Ralazem,

If you select the 'Include Geometric Non-linearities' check-box in the Analysis tab of the Project Settings, then the P-Delta effects will be taken into account.
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Ralazem
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Re: Backbone Curve Graph

Post by Ralazem » 31 Jul 2019, 02:46

oh, well, all of the items you have mentioned are taken into account in my model, yet my hysteretic curve does not display degradation. Is it a must to include link elements for degradation to be modeled?

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seismosoft
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Re: Backbone Curve Graph

Post by seismosoft » 01 Aug 2019, 06:06

You might want to activate performance criteria of code-based checks with residual strength upon reach of the criteria. Refer to the manual for Code based Checks and Performance Criteria for more details.The particular setting is the Strength Degradation Parameters, where you need to choose 'No Residual Strength' or Residual Strength equal to say 20%, instead of 'Keep Strength'.
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