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Code_Aster, Salome-Meca course materialGNU FDL licence (http://www.gnu.org/copyleft/fdl.html)
Modeling of steel elements in civil engineering structures
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Outline
Modeling of pre-tensioning
Modeling of reinforcing steel
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Modeling of pre-tensioning : principles
Cable = bar elements embedded in a 3D or DKT mesh Mesh of bars independent of the concrete mesh
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Modeling of pre-tensioning : principles
The DEFI_CABLE_BPcommand creates loads corresponding to : The link (assumed perfect) between the cable and concrete : automatic definition of Lagrange multipliersThe calculation of tension in the cables as recommended by BPEL (ETCC implementation in progress).
CAB1 = DEFI_CABLE_BP (...)
CMCABbi=AFFE_CHAR_MECA(
MODELE=MO,
RELA_CINE_BP=_F(CABLE_BP=CAB_BPi,
SIGM_BPEL=OUI' or 'NON',RELA_CINE='OUI' or 'NON'))
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Modeling of pre-tensioning : DEFI_CABLE_BPcommandcabl_pr = DEFI_CABLE_BP (
MODELE = modele,
CHAM_MATER = chmat,
CARA_ELEM = caelem,
GROUP_MA_BETON = grmabe,
DEFI_CABLE = _F (
GROUP_MA = grmaca,
GROUP_NO_ANCRAGE = l_gnoa,)
TYPE_ANCRAGE = (ACTIF, PASSIF),
TENSION_INIT = f0,
RECUL_ANCRAGE = delta,
RELAXATION = _F ( R_J = rj, )
CONE = _F ( RAYON = rayon,
LONGUEUR = long,
PRESENT = ('OUI','NON'))
TITRE = l_titr, [l_tx]
Required for calculating the tension
Required for kinematic links
Defining acable
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Modeling of pre-tensioning : DEFI_CABLE_BPcommandcabl_pr = DEFI_CABLE_BP ( MODELE = modele,
CHAM_MATER = chmat,
CARA_ELEM = caelem,
GROUP_MA_BETON = grmabe,
DEFI_CABLE = _F (
GROUP_MA =' cable1 ',
GROUP_NO_ANCRAGE = (' GRI',' GRF' ,)
TYPE_ANCRAGE = ( ACTIF , PASSIF ),
TENSION_INIT = f0,
RECUL_ANCRAGE = delta,
RELAXATION = _F ( R_J = rj, )
CONE = _F ( RAYON = rayon,
LONGUEUR = long,
PRESENT = ('OUI','NON'))
TITRE = l_titr, [l_tx]
GRI GRFN1 N6N5N4N3N2
cable1
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Modeling of pre-tensioning : potential difficulties[U4.42.04]
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Modeling of pre-tensioning : diffusion cone
Possibility of introducing a diffusion cone
Real situation Without modelling the shaft With modeling of the effect of shaft vanishing
mesh size required
management of redundant boundary conditions
[U4.42.04]
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Modeling of pre-tensioning : DEFI_CABLE_BPcommandcabl_pr = DEFI_CABLE_BP ( MODELE = modele,
CHAM_MATER = chmat,
CARA_ELEM = caelem,
GROUP_MA_BETON = grmabe,
DEFI_CABLE = _F (
GROUP_MA = 'cable1',
GROUP_NO_ANCRAGE = ('GRI','GRF',)
TYPE_ANCRAGE = (ACTIF, PASSIF),
TENSION_INIT = f0,
RECUL_ANCRAGE = delta,
RELAXATION = _F ( R_J = rj, )
CONE = _F ( RAYON = rayon,
LONGUEUR = long,
PRESENT = ('OUI','NON'))
TITRE = l_titr, [l_tx]
Calculation of the tension
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Modeling of pre-tensioning : calculating thetension in the cables
Calculating the tension at any point of the cable as recommendedby BPEL91
F (s)= F (s){x fluF 0+x retF 0+r ( j)5100
1000[ F (s)S a f prg 0]F (s)}
F c (s)=F 0 exp ( f s )
F c (s) F (s)=[F c(d )]2
Taking into account the instant losses by friction and anchor recoil
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Modeling of pre-tensioning : calculating thetension in the cables
Calculating the tension at any point of the cable as recommendedby BPEL91
F (s)= F (s){x fluF 0+x retF 0+r ( j)5100
1000[ F (s)S a y 0] F (s)}
Taking account of losses depending on time
Creep ofconcrete
Relaxation of steelShrinkage of concrete
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Modeling of pre-tensioning : calculating thetension in the cables
Data settingMBETON=DEFI_MATERIAU(ELAS=_F(E= 30.E9,...),
BPEL_BETON= _F( PERT_FLUA = 0,
PERT_RETR= 0),);
MCABLE=DEFI_MATERIAU( ELAS=_F(E=200.E9 ),
BPEL_ACIER=_F( FROT_COURB =3.0E-3,
FROT_LINE =1.5E-3,
F_PRG =1.94E11,
RELAX_1000 = 0,
MU0_RELAX = 0),)
in DEFI_CABLE_BP
in AFFE_CARA_ELEM
F 0, , r ( j )
S a
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Modeling of pre-tensioning : two strategies
Solving with STAT_NON_LINE, instant tensioning
Loss of tension due to the instant deformation of the concreteNo possible phasing
Tensions le long du cble
0,E+00
1,E+06
2,E+06
3,E+06
4,E+06
5,E+06
6,E+06
1 11 21 31 41 51 61 71 81 91 101 111 121 131
Elment
Tensio
n (
N)
BPEL DCBP sans correction DCBP aprs correction
Command CALC_PRECONTFinal tension in the cables = BPELAllows successive tensioning in cables
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Modeling of pre-tensioning : two strategies
Strategy #1
chcab =AFFE_CHAR_MECA(...
RELA_CINE_BP=_F(
CABLE_BP=cable,
SIGM_BPEL=OUI',
RELA_CINE='OUI') )
RES1 = STAT_NON_LINE(...
EXCIT=(_F(CHARGE = CLIM,),
_F(CHARGE = chcab )),
...,)
Strategy #2
chcab =AFFE_CHAR_MECA(...RELA_CINE_BP=_F(
CABLE_BP=cable,SIGM_BPEL=NON' ,RELA_CINE='OUI' ,) ,);
RES1 = CALC_PRECONT(...EXCIT=(_F(CHARGE =CLIM,),
_F( CHARGE = chcab )),CABLE_BP=cable ,
...,)
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Modeling of pre-tensioning : two strategies
STAT_NON_LINEInstant tensioningLoss of tension due to the instant deformation of the concreteNo possible phasing
Easier implementation
Tensions le long du cble
0,E+00
1,E+06
2,E+06
3,E+06
4,E+06
5,E+06
6,E+06
1 11 21 31 41 51 61 71 81 91 101 111 121 131
Elment
Tensio
n (
N)
BPEL DCBP sans correction DCBP aprs correction
CALC_PRECONTProgressive tensioningFinal tension in cables = BPEL
Allows successive tensioning in cables
A little more complex
Strategy #2 : CALC_PRECONT
Strategy #1 : STAT_NON_LINE
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Modeling of pre-tensioning : tips for strategy #1
Combine a maximum cables in DEFI_CABLE_BPOption CONE: Pay attention to redundant connections (not factorable matrix) + size of elementsIf TYPE_ANCRAGE = ('PASSIF', 'PASSIF') , there is no tension in the cable !In case of a continuation calculation (POURSUITE), define a new load without tension, otherwise the two tensions will be added
chcab2=AFFE_CHAR_MECA(MODELE=MO,
RELA_CINE_BP=_F(CABLE_BP=CAB_BPi,
SIGM_BPEL=NON' ,
RELA_CINE='OUI' ,),);
RES1 = STAT_NON_LINE(reuse =RES1,
ETAT_INIT=_F(EVOL_NOLI=RES1,
EXCIT =(_F(CHARGE = CLIM,),
_F(CHARGE = Chcab2 ),
),)
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Modeling of pre-tensioning : DEFI_CABLE_BPcommand
statnl [evol_noli] = CALC_PRECONT( reuse = statnl, ETAT_INIT = _F()
MODELE = mo ,
CHAM_MATER = chmat ,
CARA_ELEM = carac ,
COMP_INCR = _F()
INCREMENT =_F( LIST_INST = litps ,
INST_FIN = instfin,),
EXCIT =(_F( CHARGE = chi ), ),
CABLE_BP = cabl_pr ,
CABLE_BP_INACTIF = cabl_pr ,
+ mot-cl facteur STAT_NON_LINE )
The cables that will be strained between instini and instfin
Inactive cables (no stiffness)
Boundary conditions, instant loads, kinematic links related to cables
already strained
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Modeling of pre-tensioning : DEFI_CABLE_BPcommand, example
CAB_BP=DEFI_CABLE_BP(...)
CH_L=AFFE_CHAR_MECA(MODELE=MO,RELA_CINE_BP=_F(CABLE_BP=CAB_BP,
SIGM_BPEL=NON', RELA_CINE='OUI' ,),);
EVOL = CALC_PRECONT(CABLE_BP = CAB_BP,
EXCIT = _F(CHARGE = CL),
INCREMENT =_F(LIST_INST=L,
INST_FIN = 1.,
)
EVOL = STAT_NON_LINE(reuse =EVOL,
ETAT_INIT =_F(EVOL_NOLI= EVOL)
EXCIT=(_F(CHARGE= CL),
F(CHARGE=CH_L),
1. definition of cables2. CH_Lcontains the
kinematic links
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Modeling of pre-tensioning : DEFI_CABLE_BPcommand, example
CAB_BP=DEFI_CABLE_BP(...)
CH_L=AFFE_CHAR_MECA(MODELE=MO, RELA_CINE_BP=_F(CABLE_BP=CAB_BPi,
SIGM_BPEL=NON', RELA_CINE='OUI' ,),);
EVOL = CALC_PRECONT(CABLE_BP = CAB_BP,
EXCIT = _F(CHARGE = CL),
INCREMENT =_F(LIST_INST=L,
INST_FIN = 1.,
)
EVOL = STAT_NON_LINE(reuse =EVOL,
ETAT_INIT =_F(EVOL_NOLI= EVOL)
EXCIT=(_F(CHARGE= CL),
F(CHARGE=CH_L),
.
Tensioning of cables defined in CAB_BP, from t= 0 to 1
Loads : only boundary conditions + instant loads
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Modeling of pre-tensioning : DEFI_CABLE_BPcommand, example
CAB_BP=DEFI_CABLE_BP(...)
CH_L=AFFE_CHAR_MECA(MODELE=MO, RELA_CINE_BP=_F(CABLE_BP=CAB_BPi,
SIGM_BPEL=NON', RELA_CINE='OUI' ,),);EVOL = CALC_PRECONT(CABLE_BP = CAB_BP,
EXCIT = _F(CHARGE = CL),
INCREMENT =_F(LIST_INST=L,
INST_FIN = 1.,
)
EVOL = STAT_NON_LINE(reuse =EVOL,
ETAT_INIT =_F(EVOL_NOLI= EVOL)
EXCIT=(_F(CHARGE= CL),
F(CHARGE=CH_L),
.Continuation of the calculationLoad : boundary conditions + kinematic links related to cables + other loads
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Modeling of pre-tensioning : staging
For staging, possibility of alternate or link STAT_NON_LINEand CALC_PRECONT
Pay attention to the loads to be taken into account !
See documentation U2.03.06 or practical sessions
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Modeling of staging
Simulation suggested : BARREelement + DEFI_CABLE_BP+ STAT_NON_LINEor CALC_PRECONT
But always possible to use temperature differentials, imposed deformation, ...
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Outline
Modeling of pre-tensioning
Modeling of reinforcing steel
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Modeling of reinforcing steel
In a 3D model Option #1 : use the BARREmodel (or if needed POUTRE)
Mesh steels with SEG2 elements
Steel and concrete nodes must be identical
Option #2 : use the GRILLE_MEMBRANEmodelSteel is meshed with 2D elements : QUAD4, TRIA3, QUAD8, TRIA6
Overlay meshes for different directions of reinforcement (CREA_MAILLAGE)
CREA_MAILLAGE( MODELE=MO,CREA_GROUP_MA=_F(NOM = 'barreH',
GROUP_MA = 'surf',PREF_MAILLE='h'))
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Modeling of reinforcing steel
With a shell model (DKT)Use GRILLE_EXCENTREE
The steel is meshed with linear 2D elements : QUAD4 or TRIA3
Overlay meshes for different directions of reinforcement (CREA_MAILLAGE)
For a 1D modelUse of multi-fiber beam POU_D_EM
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Modeling of reinforcing steel
Model GRILLE_MEMBRANEKinematics of the surface : no unknown for rotation
Membrane elements without torsional stiffness
Only one direction of reinforcementNo possibility of eccentricity
Model GRILLE_EXCENTREEDKT shell kinematics: unknown for rotation
Only one direction of reinforcement
Opportunity to offset the grid
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Modeling of reinforcing steel
Possibility to explicitly represent the steels :With 1D elements
With 2D elements, of membrane type (for isoparametric modeling) or DGT type (for plate modeling)
Possibility of using global modeling of reinforced concrete : DKTG elements and GLRC-DM or GLRC-DAMA constitutive laws
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End of presentation
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