*BEAM GENERAL SECTION

Products Abaqus/Standard Abaqus/Explicit Abaqus/CAE

Type Model data

LevelPartPart instance

Abaqus/CAE General beam sections with linear response are supported in the Property module.

Required parameters

ELSET: Set this parameter equal to the name of the element set for which the section is defined.

Required parameter in Abaqus/Explicit, optional parameter in Abaqus/Standard

DENSITY

Set this parameter equal to the mass density (mass per unit volume) of the beam material. In an Abaqus/Standard analysis this parameter is needed only when the mass of the elements is required, such as in dynamic analysis or gravity loading. This parameter cannot be used when SECTION=MESHED.

If the MATERIAL parameter is omitted, this density accounts for the mass of the beam because no material definition is provided.

If the MATERIAL parameter is included, the mass density from the material definition is ignored.

If the DENSITY parameter is omitted, the mass density from the material definition is used.

Optional parameters

DEPENDENCIES

This parameter cannot be used when SECTION=NONLINEAR GENERAL, when SECTION=MESHED, or when the MATERIAL parameter is included.

Set this parameter equal to the number of field variable dependencies included in the definition of material moduli, in addition to temperature. If this parameter is omitted, it is assumed that the moduli are constant or depend only on temperature.

LUMPED

This parameter is relevant only for linear Timoshenko beam elements in Abaqus/Standard.

Set LUMPED=YES (default) to use a lumped mass matrix in frequency extraction and modal analysis procedures.

Set LUMPED=NO to use a mass matrix based on a cubic interpolation of deflection and quadratic interpolation of the rotation fields in frequency extraction and modal analysis procedures.

MATERIAL

This parameter cannot be used when SECTION=NONLINEAR GENERAL or SECTION=MESHED. It also cannot be used when the DEPENDENCIES or ZERO parameters are included.

Set this parameter equal to the name of the material to be used with this beam section definition.

POISSON

Set this parameter equal to the effective Poisson's ratio for the section to provide uniform strain in the section due to strain of the beam axis (so that the cross-sectional area changes when the beam is stretched). The value of the effective Poisson's ratio must be between −1.0 and 0.5. The default is POISSON=0. A value of 0.5 enforces incompressible behavior of the element.

For PIPE elements with SECTION=PIPE, this parameter is also used along with the Young's modulus given on the third data line to compute the axial strain due to hoop strain.

This parameter is used only in large-displacement analysis. It is not used with element types B23, B33, or the equivalent “hybrid” elements (which are available only in Abaqus/Standard).

ROTARY INERTIA

This parameter is relevant only for three-dimensional Timoshenko beam elements.

Set ROTARY INERTIA=EXACT (default) to use the exact rotary inertia corresponding to the beam cross-section geometry in dynamic and eigenfrequency extraction procedures.

Set ROTARY INERTIA=ISOTROPIC to use an approximate rotary inertia for the cross-section. In Abaqus/Standard the rotary inertia associated with the torsional mode of deformation is used for all rotational degrees of freedom. In Abaqus/Explicit the rotary inertia for all rotational degrees of freedom is equal to a scaled flexural inertia with a scaling factor chosen to maximize the stable time increment. ROTARY INERTIA=ISOTROPIC is not relevant and cannot be used when SECTION=MESHED; the default value of EXACT always applies for meshed sections.

SECTION

Set SECTION=GENERAL (default) to define a general beam section with linear response.

Set SECTION=NONLINEAR GENERAL to define general nonlinear behavior of the cross-section.

Set SECTION=MESHED to define an arbitrarily shaped solid cross-section meshed with warping elements.

Set this parameter equal to the name of a library section to choose a standard library section (see Beam Cross-Section Library). The following cross-sections are available:

ARBITRARY, for an arbitrary section.
BOX, for a rectangular, hollow box section.
CHANNEL, for a channel section.
CIRC, for a solid circular section.
HAT, for a hat section.
HEX, for a hollow hexagonal section.
I, for an I-beam section.
L, for an L-beam section.
PIPE, for a hollow, circular section.
RECT, for a solid, rectangular section.
TRAPEZOID, for a trapezoidal section.

TAPER

This parameter is relevant only for Abaqus/Standard analyses.

It cannot be used when SECTION=MESHED.

Include this parameter to define a general beam section with a tapered cross-section.

ZERO

This parameter cannot be used when SECTION=MESHED or when the MATERIAL parameter is included.

Set this parameter equal to the reference temperature for thermal expansion ( $θ^{0}$ ), if required. The default is ZERO=0.

Data lines for SECTION=GENERAL

First line

Area, A.
Moment of inertia for bending about the 1-axis, $I_{11}$ .
Moment of inertia for cross bending, $I_{12}$ .
Moment of inertia for bending about the 2-axis, $I_{22}$ .
Torsional constant, J.
Sectorial moment, $Γ_{0}$ . (Only needed in Abaqus/Standard when the section is associated with open-section beam elements.)
Warping constant, $Γ_{W}$ . (Only needed in Abaqus/Standard when the section is associated with open-section beam elements.)

Second line (optional; enter a blank line if the default values are to be used)

First direction cosine of the first beam section axis.
Second direction cosine of the first beam section axis.
Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, $- 1$ ) for planar beams. The default for beams in space is (0, 0, $- 1$ ) if the first beam section axis is not defined by an additional node in the element's connectivity. See Beam Element Cross-Section Orientation for details.

Third line

Young's modulus, E.
Shear modulus, G.
Coefficient of thermal expansion.
Temperature.
First field variable.
Second field variable.
Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

Fifth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.

Data lines for SECTION=GENERAL if the TAPER parameter is included

First line (properties of the first beam node)

Area, A.
Moment of inertia for bending about the 1-axis, $I_{11}$ .
Moment of inertia for cross bending, $I_{12}$ .
Moment of inertia for bending about the 2-axis, $I_{22}$ .
Torsional constant, J.
Sectorial moment, $Γ_{0}$ . (Only needed in Abaqus/Standard when the section is associated with open-section beam elements.)
Warping constant, $Γ_{W}$ . (Only needed in Abaqus/Standard when the section is associated with open-section beam elements.)

Second line (properties of the second beam node)

Area, A.
Moment of inertia for bending about the 1-axis, $I_{11}$ .
Moment of inertia for cross bending, $I_{12}$ .
Moment of inertia for bending about the 2-axis, $I_{22}$ .
Torsional constant, J.
Sectorial moment, $Γ_{0}$ . (Only needed in Abaqus/Standard when the section is associated with open-section beam elements.)
Warping constant, $Γ_{W}$ . (Only needed in Abaqus/Standard when the section is associated with open-section beam elements.)

Third line (optional; enter a blank line if the default values are to be used)

First direction cosine of the first beam section axis.
Second direction cosine of the first beam section axis.
Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, $- 1$ ) for planar beams. The default for beams in space is (0, 0, $- 1$ ) if the first beam section axis is not defined by an additional node in the element's connectivity. See Beam Element Cross-Section Orientation for details.

Fourth line

Young's modulus, E.
Shear modulus, G.
Coefficient of thermal expansion.
Temperature.
First field variable.
Second field variable.
Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

Fifth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.

Data lines for SECTION=NONLINEAR GENERAL

First line

Area, A.
Moment of inertia for bending about the 1-axis, $I_{11}$ .
Moment of inertia for cross bending, $I_{12}$ .
Moment of inertia for bending about the 2-axis, $I_{22}$ .
Torsional constant, J.

The axial and bending behaviors of the section are defined by using the AXIAL, M1, M2, TORQUE, and THERMAL EXPANSION options.

Second line (optional)

First direction cosine of the first beam section axis.
Second direction cosine of the first beam section axis.
Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, $- 1$ ) for planar beams. The default for beams in space is (0, 0, $- 1$ ) if the first beam section axis is not defined by an additional node in the element's connectivity. See Beam Element Cross-Section Orientation for details.

Data lines for SECTION=MESHED

First line

First direction cosine of the first beam section axis.
Second direction cosine of the first beam section axis.
Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, −1) for planar beams. The default for beams in space is (0, 0, −1) if the first beam section axis is not defined by an additional node in the element's connectivity. See Beam Element Cross-Section Orientation for details. The elastic behavior and the mass and inertia properties are defined using the SECTION STIFFNESS, SECTION INERTIA, TRANSVERSE SHEAR STIFFNESS, CENTROID, and SHEAR CENTER options. The entries on the data lines for these options result from the two-dimensional meshed cross-section generation procedure. The options are written to the jobname.bsp file during the cross-section generation and are typically read into a subsequent beam analysis using the INCLUDE option. See Meshed Beam Cross-Sections for details.

Second line (optional)

You can define the elastic behavior on this line instead of using the SECTION STIFFNESS option, unless full coupling is defined.

Axial stiffness of the section, $(E A)$ .
Bending stiffness about the 1-axis of the section, ${(E I)}_{11}$ .
Stiffness for cross-bending, ${(E I)}_{12}$ .
Bending stiffness about the 2-axis of the section, ${(E I)}_{22}$ .
Torsional constant, $(G J)$ .

Third line (optional)

You can define the mass and inertia properties on this line instead of using the SECTION INERTIA option.

Total mass of the section per unit length, $(ρ A)$ .
Rotary inertia about the 1-axis of the section, ${(ρ I)}_{11}$ .
Rotary product of inertia, ${(ρ I)}_{12}$ .
Rotary inertia about the 2-axis of the section, ${(ρ I)}_{22}$ .
Local 1-coordinate of the center of mass, $x_{1 c m}$ .
Local 2-coordinate of the center of mass, $x_{2 c m}$ .

Data lines for BOX, CHANNEL, CIRC, HAT, HEX, I, L, PIPE, RECT, and TRAPEZOID sections

First line

Beam section geometric data. Values should be given as specified in Beam Cross-Section Library for the chosen section type.
Etc.

Second line (optional; enter a blank line if the default values are to be used)

First direction cosine of the first beam section axis.
Second direction cosine of the first beam section axis.
Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, $- 1$ ) for planar beams. The default for beams in space is (0, 0, $- 1$ ) if the first beam section axis is not defined by an additional node in the element's connectivity. For more information , see Beam Element Cross-Section Orientation.

Third line (only needed if the MATERIAL parameter is omitted)

Young's modulus, E.
Shear modulus, G.
Coefficient of thermal expansion.
Temperature.
First field variable.
Second field variable.
Etc., up to four field variables.

Subsequent lines (only needed if the MATERIAL parameter is omitted and the DEPENDENCIES parameter has a value greater than four)

Fifth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.

Data lines for BOX, CHANNEL, CIRC, HAT, HEX, I, L, PIPE, RECT, and TRAPEZOID sections if the TAPER parameter is included

First line (properties of the first beam node)

Beam section geometric data. Values should be given as specified in Beam Cross-Section Library for the chosen section type.
Etc.

Second line (properties of the second beam node)

Beam section geometric data. Values should be given as specified in Beam Cross-Section Library for the chosen section type.
Etc.

Third line (optional; enter a blank line if the default values are to be used)

First direction cosine of the first beam section axis.
Second direction cosine of the first beam section axis.
Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, $- 1$ ) for planar beams. The default for beams in space is (0, 0, $- 1$ ) if the first beam section axis is not defined by an additional node in the element's connectivity. See Beam Element Cross-Section Orientation for details.

Fourth line (only needed if the MATERIAL parameter is omitted)

Young's modulus, E.
Shear modulus, G.
Coefficient of thermal expansion.
Temperature.
First field variable.
Second field variable.
Etc., up to four field variables.

Subsequent lines (only needed if the MATERIAL parameter is omitted and the DEPENDENCIES parameter has a value greater than four)

Fifth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.

Data lines for SECTION=ARBITRARY

First line

Number of segments making up the section.
Local 1-coordinate of first point defining the section.
Local 2-coordinate of first point defining the section.
Local 1-coordinate of second point defining the section.
Local 2-coordinate of second point defining the section.
Thickness of first segment.

Second line

Local 1-coordinate of next section point.
Local 2-coordinate of next section point.
Thickness of segment ending at this point.

Repeat the second data line as often as necessary to define the ARBITRARY section.

Third line (optional; enter a blank line if the default values are to be used)

First direction cosine of the first beam section axis.
Second direction cosine of the first beam section axis.
Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, $- 1$ ) for planar beams. The default for beams in space is (0, 0, $- 1$ ) if the first beam section axis is not defined by an additional node in the element's connectivity. See Beam Element Cross-Section Orientation for details.

Fourth line (only needed if the MATERIAL parameter is omitted)

Young's modulus, E.
Shear modulus, G.
Coefficient of thermal expansion.
Temperature.
First field variable.
Second field variable.
Etc., up to four field variables.

Subsequent lines (only needed if the MATERIAL parameter is omitted and the DEPENDENCIES parameter has a value greater than four)

Fifth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.