asdeasoft.net

Here you can find what those parameters mean:
https://opensees.berkeley.edu/wiki/inde ... _Material)

How to calibrate them?
Well, there is no specific rule. First, you have to understand what they mean in the numerical model (see the link above). Finally, you have to calibrate them according to what you want to simulate.
In your case, the shear behavior of an RC column.

$FprPos (You have considered 0.4 in your e-learning tutorial)
$A_Pinch (You have considered 0.1 in your e-learning tutorial)

They define the pinching of the hysteresis loop. You need some cyclic experimental tests to calibrate them. Otherwise use the values we used in our webinar.

$Lamda_S (You have considered 0 in your e-learning tutorial)
$Lamda_C (You have considered 0 in your e-learning tutorial)
$Lamda_A (You have considered 0 in your e-learning tutorial)
$Lamda_K (You have considered 0 in your e-learning tutorial)
$D_Plus (You have considered 0 in your e-learning tutorial)

They are necessary to define cyclic deterioration. In our tutorial we did not have any data to calibrate them, so we did not consider cyclic deterioration.

$Res_Pos (You have considered 1.05 in your e-learning tutorial)

It defines how large is the final residual strength

$theta_u_Plus (You have considered 100 in your e-learning tutorial)

It defines at what abscissa your residual strength drops to zero. In our case we did not want it to drop to zero, that's why we used a very large value

Dear STKO Team,
In this post only, you have posted a zip file containing excel for calculating ModiMKPinching parameters.

I have used it to determine the most of the parameters for my shear failure model of columns. But What is the value of Ko shall I consider ? In the excel, KRegularised is also given. What is that mean and what is its use ?

If I am using general value of elastic stiffness,Ko that is calculated in your excel than the time period of the structure is getting increased drastically. However, if I used the K,Regularized value than it remains the same.

So can you give some suggestion on which value of Ko shall I consider ?

Second thing is that, if I am keeping the Residual strength ratio (res) to the values calculated as per the excel given than the most of the time history analysis is getting failed whereas it doesn't fail if I keep Residual strength ratio (res) as 0.1.


Third, Since I am working in RCC building and so there will be no ductile tearing. So What value of Ultimate Rotation (theta_u) shall I use in my model.? With value of theta_u=1, analysis is running fine but still I have doubt that what value shall I use as it is not given in your excel.

Fourth and last, What if, in place of section aggregator, I use the same ModiMKPinching material in ZeroLength Element in Vx and Vy direction and assign it at the bottom of the column ? Will that also represent shear failure model ? Any difference in using ZeroLength Element?

Thanks in advance.

If I am using general value of elastic stiffness,Ko that is calculated in your excel than the time period of the structure is getting increased drastically. However, if I used the K,Regularized value than it remains the same.

K,Regularized is calculated exactly to provide the same response (regularized).
If you use a random value, if it is smaller than the flexural elastic stiffness of the beam, the period will of course increase

Second thing is that, if I am keeping the Residual strength ratio (res) to the values calculated as per the excel given than the most of the time history analysis is getting failed whereas it doesn't fail if I keep Residual strength ratio (res) as 0.1.


Third, Since I am working in RCC building and so there will be no ductile tearing. So What value of Ultimate Rotation (theta_u) shall I use in my model.? With value of theta_u=1, analysis is running fine but still I have doubt that what value shall I use as it is not given in your excel.

It depends on many factors... try to find some directives in literature or on national codes, then you can calibrate the hinge parameters

Fourth and last, What if, in place of section aggregator, I use the same ModiMKPinching material in ZeroLength Element in Vx and Vy direction and assign it at the bottom of the column ? Will that also represent shear failure model ? Any difference in using ZeroLength Element?

If you add it in the inner element with the sectionAggregator, it will consider shear deformation in the beam

Dear STKO Team,

I would be happy if you can elaborate your reply in little detail. Because in such short lines, it is difficult to understand what you are suggesting with respect to the question asked,

Thanks in advance.

K,Regularized is calculated exactly to provide the same response (regularized).
If you use a random value, if it is smaller than the flexural elastic stiffness of the beam, the period will of course increase

In the webinar about lumped plasticity, we explain this in detail.

It depends on many factors... try to find some directives in literature or on national codes, then you can calibrate the hinge parameters

Here I mean that we cannot suggest values that are good for any kind of situation. What I meant was:
1) Look into the literature or national codes for some moment-rotation (or shear-deformation) diagram, and try to reproduce it with the parameters of the OpenSees' material

If you add it in the inner element with the sectionAggregator, it will consider shear deformation in the beam

Force beam-column element can behave both as Euler-Bernoulli beam and Timoshenko beam. If you add the shear component to the section aggregator, it will behave as a Timoshenko (shear-deformable) beam.

Thank you so much STKO team.