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I model a simply supported reinforced beam, using nonlinearbeamcolumn, fiber section, concrete02,steel02, 3 nodes named 1,3,5. applying vertical concentrating force to node 3.
I want it to be displacement control. But after many times of testing, the result is always null. Please help me with my analysis part~~
Is there any fatal wrong in the analysis part?

#-gravity load-------------------------------------------------------------------------------------------------------------------
set p1 -2.6e3;
pattern Plain 101 Linear {
eleLoad -ele 11 12 -type -beamUniform $p1;
}

#pattern Plain 1 Linear {
# load 1 0.0 -4160 2220
# load 5 0.0 -4160 2220
#}

puts "ok4"
set Tol 1.0e-6;
constraints Transformation;
numberer RCM;
system BandGeneral ;
test NormDispIncr $Tol 6 ;
algorithm Newton;
set NstepGravity 10;
set DGravity [expr 1./$NstepGravity];
integrator LoadControl $DGravity;
analysis Static;
analyze $NstepGravity;
loadConst -time 0.0
puts "Model Built"

#-------------------------------------------------------------------------------------------------------------------------------
#---pushover analysis part--------------------------------------------------------------------------------------------------
set P2 -400e3;
set IDctrlNode 3;
set IDctrlDOF 2;
set Dmax [expr 0.2];
set Dincr [expr 0.0001];
#

# create load pattern for lateral pushover load
pattern Plain 102 Linear {
load 3 0.0 $P2 0.0;
}

integrator DisplacementControl $IDctrlNode $IDctrlDOF $Dincr;
set Nsteps [expr int($Dmax/$Dincr)];
analysis Static;
analyze $Nsteps;
puts "Pushover complete";
#----------------------------------------------------------------------------------------------------------------------

Really need your help~~Thank you so much~~

1,You mean a model with fiber section is not suitable with hysteretic material?
2,Then If I want to simulate the pinching effect with hyseretic material, what section should be used instead of fiber section?

Now I want to simulate a simply supported beam with reversed load. I have uesd steel02 and concrete02, but the result don't have pinching effect as the experiment. So I want to use the hysteretic material instead of steel02, do you think it makes sense?

If yes, the problem is that I cannot find how to define the parameters in the hyseretic material. Are they defined by experiment? Is there any references for me to read? Thank you.

##----uniaxialMaterial Hysteretic $matTag $s1p $e1p $s2p $e2p <$s3p $e3p> $s1n $e1n $s2n $e2n <$s3n $e3n> $pinchX $pinchY $damage1 $damage2 <$beta>-----

I have built a simply supported beam under cyclic loads. I considered shear effect into the section. But the results were messy.
Is there anything wrong with my codes?

Here is the part of my codes:
#----------------------------------------------------------------------------------------------------------------------
section fiberSec 17 {
patch quadr $IDconcCoreC70 10 1 -0.085 0.02 -0.085 -0.02 0.085 -0.02 0.085 0.02;
patch quadr $IDconcCoverC70 1 10 -0.125 0.05 -0.085 0.02 0.085 0.02 0.125 0.05;#左侧那块
patch quadr $IDconcCoverC70 1 10 -0.085 -0.02 -0.125 -0.05 0.125 -0.05 0.085 -0.02;#右侧那块
patch quadr $IDconcCoverC70 1 2 -0.125 0.05 -0.125 -0.05 -0.085 -0.02 -0.085 0.02;#下侧那块
patch quadr $IDconcCoverC70 1 2 0.085 0.02 0.085 -0.02 0.125 -0.05 0.125 0.05;#上侧那块
layer straight $IDSteelHRB400 2 $barArea12 0.085 0.02 0.085 -0.02;
layer straight $IDSteelHRB400 2 $barArea12 -0.085 0.02 -0.085 -0.02;
};

set IDBeamTransf 1; # all beams
geomTransf Linear $IDBeamTransf

set A [expr $HBeam*$BBeam]
set G3 [expr 1.48e4*$MP];
set GA [expr $A*$G3]
uniaxialMaterial Elastic 28 $GA

section Aggregator 27 28 Vy -section 17

set np 5;
element nonlinearBeamColumn 11 1 3 5 27 $IDBeamTransf;
element nonlinearBeamColumn 12 3 5 5 27 $IDBeamTransf;
#--------------------------------------------------------------------------------------------------------------------------

vesna wrote:
> In general your model is good and the response you are getting makes sense. The only
> thing I would not agree with is that the shear stiffness is EI. It is rather proportional
> to AG.
>
> For your definition of moment-curvature and shear force-deformation relationships
> there will be two points of slope change: one that comes from moment-curvature relationship
> and another that comes from shear force-deformation relationship. If you push your
> column up to a larger displacement but for the smaller "b" you will also see another
> change of slope. Change b to 0.01 and increase number of steps of analysis to 2000
> and you will see two slopes as well.

----------------------
What do you mean by"The only thing I would not agree with is that the shear stiffness is EI. It is rather proportional to AG."? If not, how to define the Vy

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I have finished simulating one simply supported reinforced concrete beam with fiber section and forced-nonlinear beamcolumn element. And I found the result not very satisfying. I considered it to be the effect from the shearing crack.

Therefore, I want to simulate the RC beam with a plane stress element. I wonder, is it possible to realize it? I have read relevant materials but failed to find any example about this.

Hi,

I want to simulate simply supported beam applying static reversed cycle analysis.
Then the codes are as follows:


#--the model---------------------------------------------------------------------------
set L [expr 0.74*$m]; # beam length
set X1 0.;
set X3 [expr $X1 + $L];
set X5 [expr $X3 + $L];
set Y1 0.;

node 1 $X1 $Y1 # level 0
node 3 $X3 $Y1 # level 0
node 5 $X5 $Y1 # level 0

fix 1 1 1 0
fix 5 0 1 0

#--------------------------------------------------------------------
#---the cycle analysis-----------------------------------------------------------------
set IDctrlNode 3;
set IDctrlDOF 2;
# characteristics of cyclic analysis
set iDmax "0.00381 0.00762 0.01143 ";
set Dincr [expr 0.001];
set Fact [expr 2*$L]; # scale drift ratio by storey height for displacement cycles I donot know how to define Fact in beam
set CycleType Full;
set Ncycles 3;


set iPushNode "3 ";
pattern Plain 200 Linear {;
foreach PushNode $iPushNode {
load $PushNode 0.0 $P1 0.0 0.0 0.0 0.0
}
}
#----------------------------------------------------------------

I have tried the elastic element, which worked well. However, when it comes to nonlinear beamcolumn element, it doesnot work and the result is null.

Any advices? Thank you.

Thank you for your previous answers. And now I have new problems.
I used the ConcreteZ01 and SteelZ01 which are written by UT, and the results turn out to be satisfying.
But there still two problems confused with me.

1, after running the programs, part of it shows as follows, I never run into this, what may the reason be?
#-------------------------------------------------------------------------------------
approachFiveToComStrain = 0
reloadPath = 1
zeta = 1
reverseFromOneStrain = -0.000266248
reverseFromOneStress = 0
fiveToOneStrain = -1.#IND
ConcreteZ01::getApproachFiveToComStrain -- No intersection of reloading path wi
h descending branch!
ConcreteZ01::getApproachFiveToComStrain -- overflow the iteration limit!
ConcreteZ01::getApproachFiveToComStrain -- can not get approachFiveToComStrain!

approachFiveToComStrain = 0
reloadPath = 1
zeta = 1
reverseFromOneStrain = -0.000372723
reverseFromOneStress = 0
fiveToOneStrain = -1.#IND
#--------------------------------------------------------------------------------------

2, In case a node named node A already has vertical displacement,then I want to run displacement control and the control node is node A.
Is it workable?

ok, I have sent my codes as a email to you. Thank you for checking up for me.

I am very confused with my code. I have examined my model like node, section, element, load, all those seem ok, What could the reason be?
I have read the code in the example.chm about the canti2d column. I thought since it is suiItable for canti column,in theory, it must be ok with simply supported beam. However, my model didn't work out properly.
I have seen a few example about the cantilever beam and simply supported beam in your website, unfornately which are not suitable for reinforced concrete material.
I really don't know how to solve this...Please help me!
Waiting online about 11 o'clock...

===================
Thank you very much for coming back...
In my opinion, Since the middle node did not break the bar into two parts, Since the gravity I applied is distributed, then the deformation should be a curve not a "V", isn't it?

I have had the line you referred...It didnot help.

There are still two problems:
one is the shape after gravity is "V",
one is the result after the concentrated force is as follows, which means analyze failed.

#------------------------------------------------------------------------------------------------
WARNING - ForceBeamColumn2d::update - failed to get compatible element forces &
deformations for element: 11(dW: << 27.5952)
WARNING - ForceBeamColumn2d::update - failed to get compatible element forces &
deformations for element: 12(dW: << 0.000499223)
Domain::update - domain failed in update
DisplacementControl::update - model failed to update for new dU
WARNING NewtonRaphson::solveCurrentStep() -the Integrator failed in update()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at
load factor 5.91644e+014
OpenSees > analyze failed, returned: -3 error flag
Pushover complete
#--------------------------------------------------------------------------------------------------

You must go to lunch...ok, I will go back to my sleep ...

Yes ,It has display command and by which ,I know it is V shape after applied gravity. _________________ It means the element does not move at all !

==========================================================================================

OK, if the bar is not broken by node, what other may the reason be for the large deformation ?
I do think the result makes no sense. the gravity I applied is distributed along the whole beam element, but the deformation after it is shape of "V". And what's more then, the deformation remain precisely same when applying the concentrated force.

Maybe the process of applying loads have problem? I will be waiting on line at 11 (your time) .
Here is the codes of applying loads:

#--------------------------gravity load-------------------
set P1 -300e3;
set p1 -2.6e3;

pattern Plain 101 Linear {
eleLoad -ele 11 12 -type -beamUniform $p1;
}
set Tol 1.0e-8;
variable constraintsTypeGravity Plain;
if { [info exists RigidDiaphragm] == 1} {
if {$RigidDiaphragm=="ON"} {
variable constraintsTypeGravity Lagrange;
}; };
constraints $constraintsTypeGravity ;
numberer RCM;
system BandGeneral ;
test NormDispIncr $Tol 6 ;
algorithm Newton;
set NstepGravity 10;
set DGravity [expr 1./$NstepGravity];
integrator LoadControl $DGravity;

analysis Static;
analyze $NstepGravity;

#------------------------the concentrated force--------------

set Dmax [expr 0.3*$m ];
set Dincr [expr 0.001*$m ];
set IDctrlNode 3;
set IDctrlDOF 1;

pattern Plain 102 Linear {
load 3 0.0 $P1 0.0;

}

constraints Plain;
numberer RCM;
system BandGeneral;
test NormUnbalance 1.0e-6 400;
algorithm Newton;
integrator DisplacementControl $IDctrlNode $IDctrlDOF $Dincr;
analysis Static;
set Nsteps [expr int($Dmax/$Dincr)];
set ok [analyze $Nsteps];
puts "Pushover complete";
#---------------------------------------------------------------------------