KIKUCHI BEARINGS-BASE ISOLATION

[aflo]

hi,
I'm using the kikuchiBearing element to model the behaviour of elastomeric isolators. At the moment I'm trying to calibrate the behaviour of a single bearing using a simple model.

The aforesaid element (kikuchibearing element) works in a cyclic analysis as that proposed in your example (KikuchiBearing_Sample.tcl) while strange results come out performing a dynamic ground motion analysis.

Can you please check my SIMPLE model...

here is the code
model basic -ndm 3 -ndf 6

node 1 0.0 0.0 0.0
node 2 0.0 0.0 0.15


fix 1 1 1 1 1 1 1

mass 2 1 0 0 0 0 0

set D 0.3
set ar [expr 3.14*$D*$D/4]
set hr 0.052
set tg [expr $hr/40]

#coeff controllo G, csi, Q
set cg 1
set ch 1
set cu 1
set rs 1
set rf 1

set limDisp [expr $tg*0.25]
set lambda [expr $D/$tg*sqrt(3*0.683e6/584e6)]

# set MATERIALI

# $matTag $tp $ar $hr <-coGHU $cg $ch $cu> <-coMSS $rs $rf>
uniaxialMaterial KikuchiAikenHDR 10 X0.6 $ar $hr -coGHU $cg $ch $cu -coMSS $rs $rf
# $matTag $sce $fty $fcy <$bte $bty $bcy $fcr>
uniaxialMaterial AxialSp 20 1013e6 1e6 -100e6 1.00 0.01 0.50 0e6

# materiale molla per controllo spostamenti
# $matTag $E
uniaxialMaterial Elastic 99 1e12



# DEFINIZIONE ELEMENTI

#orient: local(x,y,z)=Global(Z,X,Y)

element KikuchiBearing 1 1 2 -shape round -size $D $hr -totalHeight 0.15 -nMSS 8 -matMSS 10 -nMNS 30 -matMNS 20 -lambda $lambda -orient 0 0 1 1 0 0 -limDisp $limDisp -noPDInput -noTilt ;




#---------------------------------------- recorder
recorder Element -file KikuchiBearing_output_deformation.txt -time -ele 1 basicDeformation
recorder Element -file KikuchiBearing_output_force.txt -time -ele 1 basicForce
recorder Node -file nodeDisp.txt -time -node 2 -dof 1 disp



# DISPLAY MODE

# display displacement shape of the column
recorder display "Displaced shape" 20 20 500 500 -wipe
prp 200. 100. 1;
vup 0 0 1;
vpn 0 1 0;
display 1 5 40


# vup 0 0 1
# vpn 1 0 0 ----> vista Y-Z

# vup 0 1 0
# vpn 0 0 1 ----> vista X-Y

# vup 0 0 1
# vpn 0 1 0 ----> vista X-Z



# DEFINIZIONE CARICHI

# define GRAVITY -------------------------------------------------------------
pattern Plain 1 Linear {
load 2 0 0 [expr $P*$ar] 0 0 0; #axial stress P [N/mq]
}
constraints Plain; # how it handles boundary conditions
numberer Plain; # renumber dof's to minimize band-width (optimization), if you want to
system BandGeneral; # how to store and solve the system of equations in the analysis
test NormDispIncr 1.0e-8 6 ; # determine if convergence has been achieved at the end of an iteration step
algorithm Newton; # use Newton's solution algorithm: updates tangent stiffness at every iteration
integrator LoadControl 0.1; # determine the next time step for an analysis, # apply gravity in 10 steps
analysis Static # define type of analysis static or transient
analyze 10; # perform gravity analysis
loadConst -time 0.0; # hold gravity constant and restart time

# DYNAMIC ground-motion analysis -------------------------------------------------------------
# create load pattern
set accelSeries "Series -dt 0.01 -filePath BM68elc.acc -factor 1"; # define acceleration vector from file (dt=0.01 is associated with the input file gm)
pattern UniformExcitation 2 1 -accel $accelSeries; # define where and how (pattern tag, dof) acceleration is applied
#rayleigh 0. 0. 0. [expr 2*0.02/pow([eigen 1],0.5)]; # set damping based on first eigen mode

# create the analysis
wipeAnalysis; # clear previously-define analysis parameters
constraints Plain; # how it handles boundary conditions
numberer Plain; # renumber dof's to minimize band-width (optimization), if you want to
system BandGeneral; # how to store and solve the system of equations in the analysis
test NormDispIncr 1.0e-8 10; # determine if convergence has been achieved at the end of an iteration step
algorithm Newton; # use Newton's solution algorithm: updates tangent stiffness at every iteration
integrator Newmark 0.5 0.25 ; # determine the next time step for an analysis
analysis Transient; # define type of analysis: time-dependent
analyze 1000 0.02; # apply 1000 0.02-sec time steps in analysis


puts "Done!"

[AryanRZRD]

Dear User
did you solve your problem ?
did element work properly in 3D Space ?
i worked with that element and it Diverged in most cases while the 2D link element with shear Properties of KIKUCHI MATERIAL worked properly and made sense !

[aflo]

Hi Aryan,

I worked a lot with this element (kikuchi bearing) and I found some problems... Actually I agree with you... the results obtained using the Kikuchi material are consistent while the results obtained using the Kichuki element are weird in particula for what concerns the axial behaviour...In my opinion this element is not well developed yet... For that reason I suggest you to use a simpler model...By the way, I'm actually using the MSS model coupled with a simple truss element in order to catch both the shear and the axial behaviour of the bearing (in 3d)...

[Jenniferun]

aflo wrote:
> Hi Aryan,
>
> I worked a lot with this element (kikuchi bearing) and I found some
> problems... Actually I agree with you... the results obtained using the
> Kikuchi material are consistent while the results obtained using the
> Kichuki element are weird in particula for what concerns the axial
> behaviour...In my opinion this element is not well developed yet... For
> that reason I suggest you to use a simpler model...By the way, I'm actually
> using the MSS model coupled with a simple truss element in order to catch
> both the shear and the axial behaviour of the bearing (in 3d)...

Hi
I am having the same problem. I think you are right that it's not well developed. What model do you suggest?

[aflo]

hi jennifer, I'm actually using the MSS+truss element

[AryanRZRD]

Dear Jenniferun and alfo
i suggest TwoNodeLink Element and assigning Kikuchi Material.
i works Correctly. "especially in 2D Space"

[aflo]

Hi Aryan,

I'm sure that it works (because the kikuchi material works very well) but how do you take into account the axial behaviour of the bearing

[AryanRZRD]

exactly !
there is problem here. you can utilize this interaction by self simulating based on limit state curves that are available in LRB factory catalog

[aflo]

I'm sorry but I didn't understand your reply,

could you explain yourself?

thanks