how simulate a real bahaviour in pushover analysys

laura83 · Post by **laura83** » Mon Oct 15, 2007 9:35 am

i create a model of a pier following line by line the example
Ex3.Canti2D.build.InelasticFiberSection
but i don't obtain the real behaviour , infact if i Impose 10 m as displacement the pire doesn't collapse.
why?
how must i do?

silvia · Post by **silvia** » Mon Oct 15, 2007 10:44 am

you can try using the hysteretic material.

laura83 · Post by **laura83** » Mon Oct 15, 2007 11:20 am

I try with hysteretic material

but the result is the same : the structure doesn't collapse.
Rbase never moves to zero.
Why?
I pray to you. help me!!!!!

set Fy [expr 450]; # STEEL yield stress
set Es [expr 206000*$MPa]; # modulus of steel
set epsY [expr $Fy/$Es];
set Fu [expr 494.5];
set epsU 1;
set pinchX 1;
set pinchY 1;
set damage1 0.0;
set damage2 0.0;
set beta 0.0;
uniaxialMaterial Concrete02 $IDconcCore $fc1C $eps1C $fc2C $eps2C $lambda $ftC $Ets; # build core concrete (confined)
uniaxialMaterial Concrete02 $IDconcCover $fc1U $eps1U $fc2U $eps2U $lambda $ftU $Ets; # build cover concrete (unconfined)
uniaxialMaterial Hysteretic $IDreinf $Fy $epsY $Fu $epsU -$Fy -$epsY -$Fu -$epsU $pinchX $pinchY $damage1 $damage2 $beta ; # hysteritic reinforcemnet model

laura83 · Post by **laura83** » Mon Oct 15, 2007 12:16 pm

why Rbase never moves to zero?

silvia · Post by **silvia** » Tue Oct 16, 2007 7:41 am

if you want collapse of some sort, Fu needs to be lower than Fy.

laura83 · Post by **laura83** » Tue Oct 16, 2007 1:57 pm

when the pier colapses opensees ends the analysys before of the imposed displacement, is it right?

silvia · Post by **silvia** » Tue Oct 16, 2007 2:15 pm

opensees keeps going until you tell it to stop.
please review your model in general and what you are trying to achieve.

laura83 · Post by **laura83** » Wed Oct 17, 2007 6:06 am

want to know when( in correspondence of what displacement) my pier reduces its strenght.
How can I do?

silvia · Post by **silvia** » Wed Oct 17, 2007 7:40 am

you do that in the post-processing.

laura83 · Post by **laura83** » Wed Oct 17, 2007 7:54 am

can you explain this?
if my curve (displacement,Rbase) during elastic phase grows, then decreases without arrives at zero and then grows still until the imposed displacement what means?

silvia · Post by **silvia** » Wed Oct 17, 2007 11:14 am

it means that you had some strange behavior in your model. unless it is bar-fracture of your rc section

laura83 · Post by **laura83** » Wed Oct 17, 2007 11:33 am

ok. but is it possible that a big number of bars create problem?

laura83 · Post by **laura83** » Wed Oct 17, 2007 11:49 am

there are material's parameter:

I don't understand the problem the unit are N/mm2
set IDconcCore 1; # material ID tag -- confined core concrete
set IDSteel 2; # material ID tag -- reinforcement
# nominal concrete compressive strength
set fc [expr -30]; # CONCRETE Compressive Strength, ksi (+Tension, -Compression)
set Ec [expr 31220]; # Concrete Elastic Modulus
puts "$Ec"
# CALCESTRUZZO CONFINATO
set fpc [expr $fc]; # CONFINED concrete (mander model), maximum stress
set epsc [expr -0.002]; # strain at maximum stress
set fpcu [expr 0.8*$fpc]; # ultimate stress
set epsU [expr -0.0035]; # strain at ultimate stress
# -----------

set fy [expr 430]; # STEEL yield stress
set fu [expr 494.5];
set Es [expr 206000]; # modulus of steel
set Esh [expr 8062.5];
set esh 0.002;
set eult 0.001;
uniaxialMaterial Concrete01 $IDconcCore $fpc $epsc $fpcu $epsU; # build core concrete (confined)
uniaxialMaterial ReinforcingSteel $IDSteel $fy $fu $Es $Esh $esh $eult -MPCurveParams 0.333 18 4;

silvia · Post by **silvia** » Wed Oct 17, 2007 11:57 am

i do not know enough about what your are doing.
you should talk to your advisor about this, please.