02 Pre Tensioning

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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

  • 2 - Code_Aster and Salome-Meca course material GNU FDL Licence

    Outline

    Modeling of pre-tensioning

    Modeling of reinforcing steel

  • 3 - Code_Aster and Salome-Meca course material GNU FDL Licence

    Modeling of pre-tensioning : principles

    Cable = bar elements embedded in a 3D or DKT mesh Mesh of bars independent of the concrete mesh

  • 4 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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'))

  • 5 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 6 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 7 - Code_Aster and Salome-Meca course material GNU FDL Licence

    Modeling of pre-tensioning : potential difficulties[U4.42.04]

  • 8 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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]

  • 9 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 10 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 11 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 12 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 13 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 14 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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 ,

    ...,)

  • 15 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 16 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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 ),

    ),)

  • 17 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 18 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 19 - Code_Aster and Salome-Meca course material GNU FDL Licence

    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

  • 20 - Code_Aster and Salome-Meca course material GNU FDL Licence

    Mode