3. Operands#

The classical post-processing of a seismic analysis in transient dynamics consists in carrying out the following calculations:

  • The floor spectrum obtained from the absolute accelerations, for each direction \(\text{X},\text{Y},\text{Z}\), calculated at a specified node of the mesh (for example in the case of a « skewer » model);

  • The envelope of the floor spectrum, calculated in a few nodes of the same floor, for each direction \(\text{X}\), \(\text{Y}\), \(\text{Z}\) and \(\text{H}\) (maximum between \(\text{X}\) and \(\text{Y}\)), (for example in the case of a 3D building structure), (for example in the case of a 3D building structure);

  • The surrounding movements of the structure in relation to ground movements.

Three*Code_Aster operators can produce result concepts corresponding to transient dynamic calculations:

  • DYNA_TRAN_MODAL [U4.53.21] produces a resu_gene concept, including acceleration and relative displacement fields. In this case, ground accelerations must be added to obtain the absolute accelerations, necessary for calculating the floor spectrum.

  • CALC_MISS [U7.03.12] produces a tran_gene or harm_gene concept, including the fields of acceleration and absolute displacements. In this case, the accelerations are directly used to calculate the floor spectrum; conversely, the deduction of ground displacements is mandatory (to be read with the command LIRE_FONCTION [U4.32.02] from a specific file given by its logical unit) to obtain the relative displacements.

  • DYNA_NON_LINE [U4.53.01]. The treatment is then the same as for the previous point.

Here is a basic diagram of the algorithm for calculating this macro command:

Loop #1**on the floors

Loop #2 on the floor knots

Loop #3 on all 3 directions \(>\)

Loop #4 on the results

• Retrieving acceleration functions relating to nodes: * RECU_FONCTION

• If acceleration calculation:

° Combination or not with the ground acceleration function: * CALC_FONCTION/COMB

° Calculation of the response spectrum, with specified values of frequencies and damping with CALC_FONCTION/SPEC_OSCI

• If calculation of trips (absolute movements) :

° Ground movements are deducted to obtain relative movements: * CALC_FONCTION/COMB * .

End of loop #4

• In the case of calculating accelerations:

° calculation of the average value for a given node and direction: * CALC_FONCTION/COMB

• In the case of calculating trips:

° recovery of maxima

End of loop #3

• Printing the acceleration spectrum for each node and each direction \(>\) : IMPR_FONCTION

End of loop #2

• Acceleration spectrum envelopes for a given floor, or maximum displacements CALC_FONCTION/ENVELOPPE

• Acceleration spectrum envelopes for each floor, for each direction \(>\) IMPR_FONCTION

End of loop #1

The table produced by the macro command contains 3 types of entries:

  • the calculated spectra:

    • in the case of displacement calculation: the envelope spectra on each floor;

    • in the case of acceleration calculation: the spectra envelope by floor and by specified damping values.

  • the correspondence between the depreciation indices and the values of these depreciations;

  • information (name, building, details) on the floors.

3.1. Keyword MAILLAGE#

This keyword corresponds to the mesh read by the operator LIRE_MAILLAGE [U4.21.01].

This keyword is optional. Knowledge of the mesh is necessary only in the case where the user uses the simple keyword GROUP_NO of the factor keyword PLANCHER. In fact, as described in the previous algorithm, the processing is carried out on the nodes and if the user directly gives the name of the nodes present in the table, the mesh is not necessary.

3.2. Keyword PLANCHER#

This keyword is mandatory to define the names of the floors, where the spectra will be calculated. These names will be used to select or filter display parameters in the table structure produced by the table_sdaster macro command.

3.2.1. Operand NOM#

This mandatory operand allows you to name the floor in question.

3.2.2. Operand BATIMENT#

This optional operand allows you to enter the name of the building to which the floor belongs. This information will then appear in the output table.

3.2.3. Operand COMMENTAIRE#

This optional operand allows you to give a comment. This information will then appear in the output table. It should not exceed 24 characters.

3.2.4. Operand GROUP_NO#

This operand makes it possible to define the nodes making up the floor where the spectra will be calculated. It is available only if the mesh has been filled in.

3.3. Keyword CALCUL#

This mandatory keyword allows you to define the nature of the dynamic transient calculation used for post-processing: in the absolute coordinate system (“ABSOLU”) or the relative coordinate system (“RELATIF”).

3.4. Keyword ENVELOPPE#

This mandatory keyword defines whether the output spectra should be edited with or without (respectively ENEVELOPPE = 'OUI' or ENEVELOPPE = 'NON') the envelope of the two horizontal directions. The two horizontal directions are commonly noted X and Y and their envelope is noted H.

3.5. Keyword NOM_CHAM#

This mandatory keyword allows you to define the nature of the field used: accelerations (“ACCE”) or movements (“DEPL”).

3.6. Case NOM_CHAM =” ACCE “#

In this case, the user must provide the following data required for calculating the acceleration response spectrum: in the 3 directions \(\text{X}\), \(\text{Y}\), \(\text{Z}\) (vertical) and \(\text{H}\) (maximum horizontal value between values according to \(\text{X}\) and \(\text{Y}\)).

3.6.1. Operand AMOR_SPEC#

This mandatory operand makes it possible to define the values of the reduced damping coefficient used in calculating the spectral response. See also CALC_FONCTION [U4.32.04], keyword SPEC_OSCI.

3.6.2. Operand LIST_INST#

This optional operand allows you to specify the list, produced by DEFI_LIST_REEL [U4.34.01], defining all the time steps for calculating transient dynamics.

3.6.3. Operand FREQ/LIST_FREQ#

/◊ FREQ = L_FR

L_FR = (f1, f2, f3,…) fi. frequencies.

/◊ LIST_FREQ = LFREQ

List of frequencies previously defined by a listr8 concept.

This optional operand allows you to define frequency values, see also CALC_FONCTION [U4.32.04], keyword SPEC_OSCI.

3.6.4. Operand NORME#

♦ NORME = r

The response spectrum will be normalized by the value \(\text{r}\) (pseudo-acceleration value). The calculations are made in most cases in International System Units (USI) and the acceleration histories are often given in units. Response spectra are generally given with.

Thus, this mandatory operand NORME can be used as a unit conversion factor between the calculated accelerations and the response spectrum, see also CALC_FONCTION [U4.32.04], keyword SPEC_OSCI.

3.6.5. Keyword RESU#

This mandatory keyword allows you to specify the names of the result concepts where nodal accelerations are considered.

Possible values are:

/”RESU_GENE” = TG [TRAN_GENE]

if the post-processing is carried out from a concept DYNA_TRAN_MODAL [U4.53.21] (transitory dynamics on a reduced modal basis). However, this result must be calculated in the relative coordinate system.

or:

/”RESULTAT” = RESU [DYNA_TRANS] [EVOL_NOLI]

if the post-treatment is carried out from a transient dynamic result (coming for example from CALC_MISS [U7.03.12], product concept: tran_gene or harm_gene, or from DYNA_NON_LINE, product concept: evol_noli).

or:

/”TABLE” = TAB [TABLE_SDASTER]

if the post-processing is carried out from a table containing the results to be read. Typically, an observation table deduced from a transient dynamics calculation.

3.6.6. Case CALCUL =” RELATIF “#

♦ ACCE_X =/AC_X [FONCTION]

♦ ACCE_Y =/AC_Y [FONCTION]

♦ ACCE_Z =/AC_Z [FONCTION]

In this case, the user must provide the ground acceleration functions, defined on the same list of times, in each direction of space, in order to combine them with the relative accelerations to calculate the absolute accelerations.

3.6.7. Case CALCUL =” ABSOLU “#

◊ MULT_APPUI = “OUI”

In this case, the user can specify whether it is a multi-support modeling. By default, this is a single-support model. Multi-support modeling is only feasible when the result concept is of the resu_gene type.

3.7. Keyword IMPRESSION#

This optional keyword allows you to specify the nature of the results to be printed (spectra, envelopes). The outputs will be in the directions” X “,” Y “,” Y “,” Y “,” H “and the damping values.

3.7.1. Operand TRI#

This optional keyword allows you to specify the nature of the curves to be printed sorted according to: the value of the damping coefficient (“AMOR_SPEC”) or the spatial direction (“DIRECTION”).

3.7.2. Operand FORMAT#

This optional keyword allows you to specify the format for printing the curves: by printing in table format (“TABLEAU”) or in a form readable by the Xmgrace software (“XMGRACE”). The x-axis scale (frequencies) is logarithmic.

3.7.3. Operand UNITE#

◊ UNITE = U

Logical unit of the file in which the results are written (integer between 10 and 90). The unit by default is 29. This unit number should be consistent with the statement made in the astk interface for the file in question.

3.7.4. Case FORMAT =” XMGRACE “#

For more details, see the documentation for command IMPR_FONCTION [U4.33.01].

3.7.5. Operand TOUT#

This optional operand TOUT =” OUI “can be used to print the entire spectrum (calculated) at the end of loop #4: the average values at each node, for all directions and all damping values.

3.8. Case NOM_CHAM =” DEPL “#

In this case, the user must provide the following data required to calculate the displacement envelope: in the 3 directions \(\text{X}\), \(\text{Y}\), \(\text{Z}\) (vertical) and \(\text{H}\) (maximum horizontal value according to \(\text{X}\) and \(\text{Y}\)).

3.8.1. Operand LIST_INST#

This operand allows you to specify the list, from DEFI_LIST_REEL [U4.34.01], defining all the dynamic transient time steps for calculating the envelope displacement.

3.8.2. Keyword RESU#

This mandatory keyword allows you to specify the names of the result concept from which the nodal accelerations are extracted. The associated operand can be:

/”RESU_GENE” = TG [TRAN_GENE]

if the post-processing is carried out from a concept DYNA_TRAN_MODAL [U4.53.21] (transitory dynamics on a reduced modal basis). However, this result must be calculated in the relative coordinate system.

or:

/”RESULTAT” = RESU [DYNA_TRANS] [EVOL_NOLI]

if the post-processing is carried out from a transitory dynamic result (coming for example from LIRE_MISS3D [U7.02.31], product concept: DYNA_TRANS or from DYNA_NON_LINE, product concept: evol_noli).

or:

/”TABLE” = TAB [TABLE_SDASTER]

if the post-processing is carried out from a table containing the results to be read. The table can be produced by:

  • a transitory dynamic calculation and come from an observation table. In this case the table column names are (“INST”, “NOEUD”, “”, “”, “NOM_CHAM”, “NOM_CMP”, “VALE”) with “NOM_CHAM” = “ACCE”.

  • any order that produces a table. In this case the names of the columns in the table must be (“INST”, “”, “NOEUD”, “”, “”, “NOM_CHAM”, “DZ”) with “NOM_CHAM” = “ACCE”).

3.8.3. Case CALCUL =” ABSOLU “#

♦ DEPL_X =/DE_X [FONCTION]

♦ DEPL_Y =/DE_Y [FONCTION]

♦ DEPL_Z =/DE_Z [FONCTION]

In this case, it is necessary to introduce the ground driving displacement functions, for each result concept, defined on the same list of moments, in each direction of space, which must be deduced from the absolute displacements in order to obtain the relative displacements.