RC JOINTS- Shear panel modelling

[Ralazem]

I have been extensively studying the RC Joints (example 1) verification files (Ch4 joint 1,2,3) regarding the modelling of RC joints as I intend to model other RC joints. I have read the seismostruct verification document and the original dissertation by Yu regarding the joints to see how the parameters are defined.

My question here is , how was the shear panel rotational spring modelled? In the dissertation, the author defines parameters to model the shear panel rotational spring as a takeda curve.

However , in the seismostruct verification files, the panel was modelled as an elfrm ( not link) element, and as rigid. Why is that so, and based on what was that decision made? Are there any references to indicate that the effect of the shear panel is negligible? That is the only discrepancy between the seismostruct verification file & the dissertation.

If I wanted to model it while taking into account the parameters of the shear panel, how would I incorporate with the other factors ( bar slip and shear) of the joint?

[seismosoft]

The elfrm elements (PANEL element class) model the volume of the beam column joint. The flexibility of the joint and the factors that affect it (e.g bar slip, shear deformations etc) are indeed modelled though the link elements and the Takeda response curve.
Seismosoft Support

[Ralazem]

This does not answer my question. I have gone through the link elements of these models very carefully, and while bar slip spring and interface shear spring were modelled, the shear panel interface was not included in your models and I am wondering why.

Considering this was one of the verification files I think there should have been a specific reason for deciding to not model it? The shear panel of the joint plays a huge role in the results.

[Ralazem]

In the Yu dissertation, there are 3 important things that were considered in the joint model:

1) Bar slip springs
2) interface shear spring
3) shear panel rotational spring

All the parameters were provided as well. The models provided by seismostruct only accounted for the first 2, and I need to know why the third was not considered, and if I were to add it on to the existing seismostruct verification models for this paper, how does it need to be applied in the relation to the other parameters?

Otherwise, what is the justification of not including it in the model?

[seismosoft]

Apparently the flexibility of the panel in shear was negligible with respect to the other two parameters. This is typically the case in beam-column joints of RC structures.
We are not sure how the shear panel rotational spring can be calibrated, a quite good reference though is Chapter 10 of ASCE 41.
Seismosoft Support

[Ralazem]

Can you provide any references or citations that confirm that theory please?

[seismosoft]

Apart from Chapter 10 of ASCE 41, I am afraid I do not have any other reference. However, the details provided there, should be probably enough.
In any case, is more like commonknowledge and not our 'theory' that the beam-column joints in RC buildings are generally very stiff with respect to other parts of the structure.
Seismosoft Support

[shahdhruviajay]

I modelled reinforced concrete simply supported beam and provide the bond spring at the two support . I also give point load at mid point of the beam. But i didnot get the accurate result . can you help me?
Thank you in advanced

[seismosoft]

Hello Shahdhruviajay,
Which type of element class are you using? How were the springs calibrated?
I suggest that you start from an simple elastic modelling gradually increasing the complexity and checking the results. This will help you identify the problem.
Seismosoft Support

[shahdhruviajay]

My element class is inelatic force based frame.
I am using ramberg osgood curve for kink element.
I will mail you on support@seismosoft.com my modelled and validation paper.