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Hello, everyone,

I am using the uniaxialMaterial BoucWen to simulate the material degradation, but when I was doing the static analysis, I saw the following warning in the calculation, anyone knows how to solve it? Thanks.

WARNING: BoucWenMaterial::setTrialStrain() -- did not find the root z_{i+1}, after 20 iterations and norm: 8.71013e-08

mhscott wrote: ↑Sat Mar 19, 2022 11:07 am HystereticMaterial is often used for steel to capture stiffness and strength degradation. There should be many examples online.

Thanks a lot for your reply. HystereticMaterial is very useful to model the stiffness and strength degradation. But I don't know how the following parameters influence the degradation:


$damage1 damage due to ductility: D1(mu-1)
$damage2 damage due to energy: D2(Eii/Eult)
$beta power used to determine the degraded unloading stiffness based on ductility, mu-beta (optional, default=0.0)


I don't know if you can provide some references about how these three parameters change the stiffness and strength. It would be better if there are some theoretical equations to quantify their influence. Any suggestions about these three parameters are appreciated.

Hello, everyone,

I am looking for a stress-strain model for the steel material that can consider the stiffness degradation and strength degradation and also this material model can be used in the fiber section. Are there any recommendations for it and which one is the best option for the steel material and the fiber section? Also are there any references or examples to help determine the model parameters for the steel material? Any suggestions are appreciated. Thanks.

Hello, everyone,

I have a question about using the following codes to do linear static analysis in OpenSees. The model is linear elastic and if static load of magnitude 5e6 is applied to the model, the output of target displacement is 300mm.

For the load vector, staticload, in the following code:

If "set staticload {5e6 5e6 5e6 5e6 5e6}" was used, the output from OpenSees of the target displacement is {300 600 900 1200 1500} mm, which is understandable;

What I am confused is if "set staticload {0 5e6 0 5e6 5e6}" was used, the output of the target displacement should be {0 300 300 600 900} mm, but it is {0 600 0 1200 1500} mm from the output of OpenSees.

Anyone can help explain why and how to change the code to get the displacement {0 300 300 600 900} mm when "set staticload {0 5e6 0 5e6 5e6}" was used? Thanks a lot.



#####################################################
set i 0

set staticload {0 5e6 0 5e6 5e6}

while {$i < 5} {

set y60 [lindex $staticload $i]

pattern Plain 1 Linear -fact 1 {
load 1098 0.0 $y60 0.0 0.0 0.0 0.0;
}

wipeAnalysis;

constraints Transformation
numberer RCM
system BandGeneral
test NormDispIncr 1e-3 200
algorithm NewtonLineSearch;
integrator LoadControl 1;
analysis Static;
analyze 1;

remove loadPattern 1;

incr i

}

Ashok wrote: ↑Sat Nov 28, 2020 5:47 pm Hi,
I am not sure about STKO, but see if this helps.
https://portwooddigital.com/2020/08/27/ ... -marplots/
This is a article written by Prof. Scott.

Thanks, it is very helpful.

I am trying to STKO's new diagram plot feature, so I just built a fixed beam to test the results. But when I fix all DOFs of node 1 and node 2, the OpenSees can not output any results. Does anyone know how to deal with it?

fix 1 1 1 1 1 1 1;
fix 2 1 1 1 1 1 1;

https://opensees.berkeley.edu/wiki/inde ... nFig01.png

Hello, everyone,

For the bearing element in the link, there is a relation between Fy-dy, anyone knows any references about how to determine the parameters $mu $alpha and $eta? Thanks.

Just tried FullGeneral, no WARNING. But it is really time-consuming.

For the output files, I designate them to different directories for each analysis.

There are some procedures shared by different analysis, which will be used by the two windows at the same time, I don't know if this will affect the results. Thanks.

dispBeamColumn needs more elements to make the results accurate enough, and FullGeneral costs more time, are there any better solutions for it? Thanks.

Hello, everyone,

As described in the code below, before the transient analysis, the static analysis was carried out, the problem is when using rayleigh damping, everything goes well with the settings in the codes, but when switched to modal damping, the following WARNING will appear,

WARNING - ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element: 1(dW: << 95.0218, dW0: 1.60825e+36)

so can anyone help solve this issue? Thanks.

Codes:
--------------------------------------------------------
analysis Static;
analyze 1;
loadConst -time 0.0
wipeAnalysis;

# Apply dynamics loads

source procDynamicLoad.tcl

set N 6;
eigen $N
modalDamping 0.01;

constraints Transformation;
numberer RCM;
system UmfPack -lvalueFact 50;
test NormDispIncr 1.0e-3 200;
algorithm NewtonLineSearch;
integrator Newmark 0.5 0.25;
analysis Transient;
analyze 10 0.04;
--------------------------------------------------------

Hello, everyone,

For the parametric study, I need to run two OpenSees windows to use most of the computer memory. I am wondering if it works when the two OpenSees windows are from the exact same one OpenSees.exe in the computer (say just double-click the OpenSees.exe twice and then there will be two OpenSees windows on the screen), and you run different analysis in each window. Will the running in the two windows influence each and what are the maximum windows you can open from a single OpenSees.exe? Thanks.

selimgunay wrote: ↑Mon Aug 24, 2020 3:36 pm You can find a derivation and some references here:

http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

Awesome, many thanks.

selimgunay wrote: ↑Mon Aug 24, 2020 2:13 pm Fy is the shear capacity and in a bilinear model that you use, it corresponds to the yield force.

A is shear area which is equal to 5/6 of the total area for rectangular sections and 9/10 of the total area for circular sections

Brilliant, for the shear area, I am trying to find some references where you can derive the shape factor for any shape, would you have any resources for it? Thanks.