2. Operands#
2.1. Operand MAILLAGE#
/◊ MAILLAGE
Name of the 2D mesh of the beam section whose characteristics will be calculated. If the name of the mesh is not given, you must enter the following keywords for the macro command to read by the LIRE_MAILLAGE command.
Note:
When the section is made up of thin elements (tubes, reconstituted sections,…) , it is necessary to have several meshes in this thickness to correctly calculate the characteristics associated with twisting.
/♦ UNITE
Logical unit number for reading the 2D mesh of the beam section whose characteristics will be calculated.
♦ FORMAT
Mesh file format
Note:
If you need to make several calls to MACR_CARA_POUTRE in the same command file on the same mesh or different meshes you must then change UNITE .
2.2. Operand TABLE_CARA#
◊ TABLE_CARA = “OUI”
When this option is present, the table produced contains only the parameters that are useful for AFFE_CARA_ELEM.
2.3. Operand NOM#
♦ NOM = name
Operand NOMdoit be given (unless TABLE_CARA =” OUI “and GROUP_MA filled in, as it is useless in this case).
This value is found in column LIEU of the table. This allows the user to give a name to their section, which they can use in affe_cara_elem.
Note: If group_ma is specified (and TABLE_CARA =” OUI “), the names of the mesh groups can be used directly in affe_cara_elem.
2.4. Operands SYME_Y/SYME_Z#
◊ | syme_y
Specify that the mesh provided by the user corresponds to a half mesh. The calculation of the characteristics of the straight section takes into account symmetry with respect to \(Y\mathrm{=}0\).
Specify that the mesh provided by the user corresponds to a half mesh. The calculation of the characteristics of the straight section takes into account symmetry with respect to \(Z\mathrm{=}0\).
Using both options simultaneously makes it possible to provide only a quarter of the mesh.
Symmetry properties are used to speed up the calculation of geometric characteristics.
Note:
The keywords SYME_Y and SYME_Z are only used for calculating geometric characteristics. The mechanical characteristics (torsional constant, warping constant, shear coefficients) do not take this into account. To calculate them, you must therefore mesh the entire section.*. That’s why* SYME_Y and SYME_Z cannot be filled in when GROUP_MA_BORD is used.
2.5. Calculation of mechanical characteristics#
◊ GROUP_MA_BORD = LGB
gb refers to one (or more) group of elements (SEG2 or SEG3) describing the (closed) outline of the mesh section. It is the presence of this keyword that leads to the calculation of the mechanical characteristics of the section (cf. [U4.42.01] AFFE_CARA_ELEM, keyword POUTRE).
◊ GROUP_MA_INTE = lgi
lgi designates one or more groups of cells describing the contours of possible holes. This data is used to calculate the torsional constant.
◊ GROUP_MA = lgm
lgm corresponds to a list of groups of cells for which the calculation of the characteristics must be carried out independently. In particular, this feature makes it possible to search for the characteristics of beams equivalent to several disjoint sections. If you want to calculate the mechanical characteristics for each group of cells, you must then give a group of edge elements per section (using the keyword GROUP_MA_BORD). The LGB and lgm lists must then match.
◊ ORIG_INER = (yp, zp)
This keyword defines the point where the inertial characteristics of the section are calculated. The values of the moments of inertia are then supplied at this point and at the center of gravity of the section (for the entire mesh or for each group of cells if GROUP_MA is specified).
◊ GROUP_NO = lgn
To calculate shear coefficients (if the keyword GROUP_MA_BORD is present), we have to solve a thermal problem on the section (or each group in the lgm list), with the only boundary condition being a source term. This can produce alarm messages due to the presence of zero pivots, without affecting the quality of the result. To avoid these alarm messages, it is possible to give a group of nodes or a list of groups of nodes (the same cardinal as lgm) for which the temperature is imposed. Each GROUP_NO should only contain one node.
◊ name= name
When name is entered and table_cara=”yes” the name of the section is entered in column LIEU of the table. This allows the user to directly use the table in affe_cara_elem to assign mechanical quantities to various line elements.
2.6. Beam network case#
♦ LONGUEUR = h,
♦ material = subdue,
♦ link = [“ROTULE”, “ENCASTREMENT”],
These three keywords allow the calculation of shear coefficients equivalent to a set of parallel beams (columns) located between two floors, separated by the length h. The sections of these beams are defined by the GROUP_MA keyword.
They are all composed of the same linear elastic material (keyword MATERIAU). The connection with the lower floor is of the « embedded » type. The one with the top floor is designated by the keyword LIAISON.
