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In his name is the judge
Hi

I think the best way to assign the nonlinear effect of steel components like beams that to model it with a plastic hinge.
So To build a nonlinear model of a one-story steel structure I use the Modified Ibarra – Krawinkler model to model my beam. In fact, I model a beam with two hing (zero length element) at the start and end and one elastic beam in the middle.

I used material developed by Lignos and Krawinkler named uniaxial material Bilin and here is more information about this material

https://opensees.berkeley.edu/wiki/inde ... n_Material

After all, when I extract the output belonging to the stress-strain of this material under seismic loading like Kobe I get something like this diagram. (kobe0.5g) based on

"Ibarra L.F., and Krawinkler, H. (2005). “Global collapse of frame structures under seismic excitations”, Rep. No. TB 152, The John A. Blume Earthquake Engineering Center, Stanford University, Stanford, CA."
named article and this diagram (ref1) the stress-strain shows the right modeling and performance. consider that my record is near fault and the diagram of reference also belongs to near-fault loading.

If I use the 1g scale for the Kobe record I get this diagram (kobe1g) and here is the diagram of the 2g scale for the Kobe record (kobe2g) So my best shot is this when the record multiply and the ground accel become higher the material reaches the capacity of its deterioration very more quickly(In fact after a short time the strain of material switch between 1e10 an-1e10 and strain is between about -2 and 2) but it's a little non-sens for me in the other hand there is one benchmark( in the reference is named it before this benchmark is for standard loading) diagram for this material stress-strain (logos) and my diagram is different with it.

In the end here are the 1M$ questions

1- why when I give more scale to record the diagram become like that?
2- and why my diagram is different from the benchmark stress-stress of material?
3- hinge shows nonlinear behavior when the center of mass of the plane gives about 1.5m displacements, is this ok?
Any help is greatly appreciated.
Take refuge in the right.

here are the links to the photos

https://drive.google.com/file/d/1Z4uGTZ ... share_link
https://drive.google.com/file/d/1T_5BAS ... share_link
https://drive.google.com/file/d/1hKCdX1 ... share_link
https://drive.google.com/file/d/10kdfRH ... share_link
https://drive.google.com/file/d/14fWXkr ... share_link

thanks fmk and prof scott

i Awared that we can only use two modes parameters for Rayleigh Damping because of it's coding on opensees and also because of it's definition.

wish you best.

deer prof scott i did that in my code but when i ran the model i face this error

"
ArpackSolver::Error with _saupd info = -9999
Could not build an Arnoldi factorization.IPARAM(5) the size of the current Arnoldi factorization: is 3factorization. The user is advised to check thatenough workspace and array storage has been allocated.
WARNING StaticAnalysis::eigen() - EigenSOE failed in solve()
missing function argument at _@_
in expression "pow(_@_,0.5)"
(parsing expression "pow(,0.5)")
invoked from within
"expr pow($lambdaI,0.5)"
invoked from within
"set omegaI [expr pow($lambdaI,0.5)]"
(file "analysis.tcl" line 14)
invoked from within
"source analysis.tcl "
(file "D:\desktop n\01.Master\uni Ms\governingequationone\coding\one story assymetry structure\0.5 s period\model 0.5-0.5-0.1\own model\main.tcl" line

"
thank you truly for heloing me.

thank you so much i found a code for rayleigh damping in tcl editor,

"
set xDamp 0.02; # damping ratio
set MpropSwitch 1.0;
set KcurrSwitch 0.0;
set KcommSwitch 1.0;
set KinitSwitch 0.0;
set nEigenI 1; # mode 1
set nEigenJ 1; # mode 3
set lambdaN [eigen [expr $nEigenJ]]; # eigenvalue analysis for nEigenJ modes
set lambdaI [lindex $lambdaN [expr $nEigenI-1]]; # eigenvalue mode i
set lambdaJ [lindex $lambdaN [expr $nEigenJ-1]]; # eigenvalue mode j
set omegaI [expr pow($lambdaI,0.5)];
set omegaJ [expr pow($lambdaJ,0.5)];
set alphaM [expr $MpropSwitch*$xDamp*(2*$omegaI*$omegaJ)/($omegaI+$omegaJ)]; # M-prop. damping; D = alphaM*M
set betaKcurr [expr $KcurrSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # current-K; +beatKcurr*KCurrent
set betaKcomm [expr $KcommSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # last-committed K; +betaKcomm*KlastCommitt
set betaKinit [expr $KinitSwitch*2.*$xDamp/($omegaI+$omegaJ)]; # initial-K; +beatKinit*Kini

"
is this right?
if yes, why cant i set I & J based on number of modes i want to consider them for damping?

Hi
I had a questiones about the operation of the Riley damping command in Opensees.
First, how does the Rayleigh Damping Command affect the damping in any structural mode?
Second, can the Rayleigh Damping Command be set to affect only certain modes of the structure?
Any help is greatly appreciated
I wish you all the best

hi
my thesis is about new damper named tlcgd (tuned liquid column gass damper) wich has a special damping coefficint and stiffness coeeficinet in it's equation of motion. i tried to model damper with using viscouse damper material and two node link element. first i evalute damper coefficinet in damper equation of motion ( which i find in chuan fu thesis). first i evaluate damping coefficient and stiffness ratio, then i import these into viscous damper material which i evaluate from equation of motion. but i think something wrong because i could not verify my model with last works. i think my problem may cuses from three things. first in my resourse, forces in motion eqution is different from force i subject to my damper in opensees and i don't know how can i fix it. second, it's about boundry condition of dampers wich i am very skeptical about it. (i used two rigid link for link two node element with center of mass). third, maybe i choosed a uncorrect way to model my damper, i mean material and element.
i share my modeling in opensees and equation of damper motion and also the force and moment which damper release.
by difference in results, i mean different in damper dispalcement and also whole model dispalcement presence of dampers.
if you ever modeling damper like this in opensees or have any idea, i am very grateful for your help
wish you best.
https://drive.google.com/file/d/1lm_5pd ... sp=sharing
https://drive.google.com/file/d/1_K2Hfk ... sp=sharing

dear all
i think make a progress with this question. i used two change wich think make better result. first i used rigidLink beam between cm and each node insted od rigid diaphragm command. second i used Elastic TimoshenkoBeam insted of elastic element or other type of element and it also made me beetter result. but i steel have big problem in understanding rotational mass in opensees.
any help will so appreciated.

dear selimgunay
i used this command for my model but it didn't work.
also when i assign mass to center of mass, i get more far result.
wish you best

dear prof scott
thank you so much for offering that post i'm afraid it didn't helpful.
wish you best

hello everyone,

i'm trying to model a 3D one story buiding with mass IIrregularity, the model has 4 elastic columns and rigid diaphragm. the model has no beam, so i used rigid diaphragm to equal dof of top nodes of columns. i use a model from a reasercher's article, he note that the modal frequences of first three mode is 1.16 , 1.96 , 2.37 HZ respectively. i builded the model in etabs and can verify my model with 0.33% error, but i couldn't verify model in opensees. i trying almost everythings to verify it but Unfortunately all my work was unsuccsesfull. in my reaserch i found that mass moment of inertia is principle parameter in model with mass IIrregularity, so i try figure out how modal analysis run in etabs and opensees and what difference between them. i found that etabs centeralized all masses in center of mass and then make mass matrix with 3 parameters like that
[mass in x direction 0 0
0 mass in y direction 0
0 0 mass moment of inertia about hight axis ]
but i wondering opensees generate mass matix for each node(also we can use center of mass for assigne mass) and also mass matrix for 6 dof model with 3 limited dofs (dofs limited in z direction and rotation about x ,y axis) is 6*6, so i'm confused to understad how opensees derrive mass matix and calculate modal frequences. i try both assigning mass to nodes and center of mass. in first condition i assigned mass moment of inertia like that
mass n "mass in x direction" "mass in y direction" 0. 0. 0. "mass moment of inertia about height axis"
etabs calculate mass moment of inertia with multiple each mass of nodes by distance of node from center of mass then sum these valus and attain mass moment of inertia abuot height axis. also we can use another formula for it. i try all patterns i found but i can't verify my model because i can't understand how opensees run modal analysis and make eigen values. for best understanding i upload my model in opensees and etabs.
https://drive.google.com/file/d/1MEJ_zE ... sp=sharing
I'm so thankful if you can help me.
with best regard

hello everyone,

i'm trying to model a 3D one story buiding with mass IIrregularity, the model has 4 elastic columns and rigid diaphragm. the model has no beam, so i used rigid diaphragm to equal dof of top nodes of columns. i use a model from a reasercher's article, he note that the modal frequences of first three mode is 1.16 , 1.96 , 2.37 HZ respectively. i builded the model in etabs and can verify my model with 0.33% error, but i couldn't verify model in opensees. i trying almost everythings to verify it but Unfortunately all my work was unsuccsesfull. in my reaserch i found that mass moment of inertia is principle parameter in model with mass IIrregularity, so i try figure out how modal analysis run in etabs and opensees and what difference between them. i found that etabs centeralized all masses in center of mass and then make mass matrix with 3 parameters like that
[mass in x direction 0 0
0 mass in y direction 0
0 0 mass moment of inertia about hight axis ]
but i wondering opensees generate mass matix for each node(also we can use center of mass for assigne mass) and also mass matrix for 6 dof model with 3 limited dofs (dofs limited in z direction and rotation about x ,y axis) is 6*6, so i'm confused to understad how opensees derrive mass matix and calculate modal frequences. i try both assigning mass to nodes and center of mass. in first condition i assigned mass moment of inertia like that
mass n "mass in x direction" "mass in y direction" 0. 0. 0. "mass moment of inertia about height axis"
etabs calculate mass moment of inertia with multiple each mass of nodes by distance of node from center of mass then sum these valus and attain mass moment of inertia abuot height axis. also we can use another formula for it. i try all patterns i found but i can't verify my model because i can't understand how opensees run modal analysis and make eigen values. for best understanding i upload my model in opensees and etabs.
https://drive.google.com/file/d/1MEJ_zE ... sp=sharing
I'm so thankful if you can help me.
with best regard

hello everyone,

i'm trying to model a 3D one story buiding with mass IIrregularity, the model has 4 elastic columns and rigid diaphragm. the model has no beam, so i used rigid diaphragm to equal dof of top nodes of columns. i use a model from a reasercher's article, he note that the modal frequences of first three mode is 1.16 , 1.96 , 2.37 HZ respectively. i builded the model in etabs and can verify my model with 0.33% error, but i couldn't verify model in opensees. i trying almost everythings to verify it but Unfortunately all my work was unsuccsesfull. in my reaserch i found that mass moment of inertia is principle parameter in model with mass IIrregularity, so i try figure out how modal analysis run in etabs and opensees and what difference between them. i found that etabs centeralized all masses in center of mass and then make mass matrix with 3 parameters like that
[mass in x direction 0 0
0 mass in y direction 0
0 0 mass moment of inertia about hight axis ]
but i wondering opensees generate mass matix for each node(also we can use center of mass for assigne mass) and also mass matrix for 6 dof model with 3 limited dofs (dofs limited in z direction and rotation about x ,y axis) is 6*6, so i'm confused to understad how opensees derrive mass matix and calculate modal frequences. i try both assigning mass to nodes and center of mass. in first condition i assigned mass moment of inertia like that
mass n "mass in x direction" "mass in y direction" 0. 0. 0. "mass moment of inertia about height axis"
etabs calculate mass moment of inertia with multiple each mass of nodes by distance of node from center of mass then sum these valus and attain mass moment of inertia abuot height axis. also we can use another formula for it. i try all patterns i found but i can't verify my model because i can't understand how opensees run modal analysis and make eigen values. for best understanding i upload my model in opensees and etabs.
https://drive.google.com/file/d/1MEJ_zE ... sp=sharing
I'm so thankful if you can help me.
with best regard

hello
you can use "print A" command to get mass matrix and eigenvectors
https://opensees.berkeley.edu/wiki/index.php/PrintA