Hysteretic response of steel element

[Amy87]

I am trying to model steel element in SAP2000 where one side of it will be fixed and at the other end an incremental force is applied. As a result I sbould get a hysteresis, or at least response total force-displacement (like in pushover analysis).
So I have several questions
- can I carry out pushover analysis without generating hinges, but generating nonlinear material properties of the element (no local nonlinearity, but global nonlinear behavior of the whole element)?
- does SAP2000 gives the opportunity to model nonlinear sross sections (fiber model)?
- any other suggestions how to solve this problem?

Please anyone who knows, help me.

 

[stressed]

You can define and assign nonlinear plastic fiber hinges to frame elements in SAP2000

 

[Amy87]

I know, but that is local plasticity.

 

[stressed]

Amy, please define what you mean by "local" plasticity. Local plasticity would account for example, for local yielding only at the edge of the top flange of a an I/Wide flange beam.. SAP2000 frame hinges do not provide that detail on local yielding. Frame plastic hinges are based on PMM and stress-strain

 

[JK7070]

I think what Amy87 means is "lumped" plasticity, also known as "local". You want to know if SAP can carry out a nonlinear analysis using a distributed plasticity model. The honest answer is I'm not sure but I didn't think so. Unless this has changed with the newer releases of SAP v15/v16. Please can someone confirm this.

The main difference between each plasticity model is that a moment curvature analysis needs to be completed and a hysteresis response needs to be defined for a "lumped" plasticity model. For a "distributed" plasticity model these are directly computed/defined by the material models.

Regards,
JK7070

 

[stressed]

JK, SAP2000's latest V16 version still uses "lumped" plasticity. There is no distributed plasticity option.

Perhaps I misunderstood you, but a hysteresis response does not need to be manually defined for a lumped plasticity model in SAP. If you choose Fiber hinge, this is directly computed and handled automatically based on material stress-strain.

My understanding is that the distributed plasticity analytical approach automatically divides the element into areas, an approach which could be simulated by assigning multiple "lumped" plastic hinges along the length. Distributed plasticity is computationally expensive whereas lumped hinges give you the option to specify how many or how few hinges are assigned. It's an interesting topic, and I'm open to being corrected, but it's my understanding that assigning multiple fiber hinges would be a near-identical approach to distributed plasticity. Please feel free to disagree if your understanding is different.