Element Types
Beams in a Plane
- B21
-
2-node linear beam
- B21H(S)
-
2-node linear beam, hybrid formulation
- B22
-
3-node quadratic beam
- B22H(S)
-
3-node quadratic beam, hybrid formulation
- B23(S)
-
2-node cubic beam
- B23H(S)
-
2-node cubic beam, hybrid formulation
- PIPE21
-
2-node linear pipe
- PIPE21H(S)
-
2-node linear pipe, hybrid formulation
- PIPE22(S)
-
3-node quadratic pipe
- PIPE22H(S)
-
3-node quadratic pipe, hybrid formulation
Active Degrees of Freedom
1, 2, 6
Additional Solution Variables
All of the cubic beam elements have two additional variables relating to
axial strain.
The linear thin-walled pipe elements have one additional variable, and the
quadratic thin-walled pipe elements have two additional variables relating to
the hoop strain. The linear thick-walled pipe elements have two additional
variables, and the quadratic thick-walled pipe elements have four additional
variables relating to the hoop and radial strain components.
The hybrid beam and pipe elements have additional variables relating to the
axial force and transverse shear force. The linear elements have two, the
quadratic elements have four, and the cubic elements have three additional
variables.
Beams in Space
- B31
-
2-node linear beam
- B31H(S)
-
2-node linear beam, hybrid formulation
- B32
-
3-node quadratic beam
- B32H(S)
-
3-node quadratic beam, hybrid formulation
- B33(S)
-
2-node cubic beam
- B33H(S)
-
2-node cubic beam, hybrid formulation
- PIPE31
-
2-node linear pipe
- PIPE31H(S)
-
2-node linear pipe, hybrid formulation
- PIPE32(S)
-
3-node quadratic pipe
- PIPE32H(S)
-
3-node quadratic pipe, hybrid formulation
Active Degrees of Freedom
1, 2, 3, 4, 5, 6
Additional Solution Variables
All of the cubic beam elements have two additional variables relating to
axial strain.
The linear thin-walled pipe elements have one additional variable, and the
quadratic thin-walled pipe elements have two additional variables relating to
the hoop strain. The linear thick-walled pipe elements have two additional
variables, and the quadratic thick-walled pipe elements have four additional
variables relating to the hoop and radial strain components.
The hybrid beam and pipe elements have additional variables relating to the
axial force and transverse shear force in the linear and quadratic elements and
to the axial force only in the cubic elements. The linear and cubic elements
have three and the quadratic elements have six additional variables.
Open-Section Beams in Space
- B31OS(S)
-
2-node linear beam
- B31OSH(S)
-
2-node linear beam, hybrid formulation
- B32OS(S)
-
3-node quadratic beam
- B32OSH(S)
-
3-node quadratic beam, hybrid formulation
Active Degrees of Freedom
1, 2, 3, 4, 5, 6, 7
Additional Solution Variables
Element type B31OSH has three additional variables and element type B32OSH has six additional variables relating to the axial force and
transverse shear force.
Nodal Coordinates Required
Beams in a plane: X, Y, also
(optional) ,
,
the direction cosines of the normal. Beams in space:
X, Y, Z, also
(optional) ,
,
,
the direction cosines of the second local cross-section
axis.
Element Property Definition
For PIPE elements use the pipe section type to specify the thin-walled
pipe formulation or the thick pipe section type to specify the thick-walled
pipe formulation. No other section types can be used with PIPE elements. For open-section elements use only the arbitrary, channel, hat, I, L, and linear generalized
section types. Local
orientations defined as described in
Orientations
cannot be used with beam elements to define local material directions. The
orientation of the local beam section axes in space is discussed in
Beam Element Cross-Section Orientation.
Element-Based Loading
Distributed Loads
Distributed
loads are specified as described in
Distributed Loads. *dload
- Load ID (*DLOAD): CENT(S)
- FL−2
(ML−1T−2)
-
Centrifugal force (magnitude is input as ,
where m is the mass per unit length and
is the angular velocity).
- Load ID (*DLOAD): CENTRIF(S)
- T−2
-
Centrifugal load (magnitude is input as ,
where
is the angular velocity).
- Load ID (*DLOAD): CORIO(S)
- FL−2T
(ML−1T−1)
-
Coriolis force (magnitude is input as ,
where m is the mass per unit length and
is the angular velocity). The load stiffness due to Coriolis loading is not
accounted for in direct steady-state dynamics analysis.
- Load ID (*DLOAD): GRAV
- LT−2
-
Gravity loading in a specified direction (magnitude is input as
acceleration).
- Load ID (*DLOAD): PX
- FL−1
-
Force per unit length in global X-direction.
- Load ID (*DLOAD): PY
- FL−1
-
Force per unit length in global Y-direction.
- Load ID (*DLOAD): PZ
- FL−1
-
Force per unit length in global Z-direction (only for
beams in space).
- Load ID (*DLOAD): PXNU
- FL−1
-
Nonuniform force per unit length in global X-direction
with magnitude supplied via user subroutine
DLOAD in
Abaqus/Standard
and
VDLOAD in
Abaqus/Explicit.
- Load ID (*DLOAD): PYNU
- FL−1
-
Nonuniform force per unit length in global Y-direction
with magnitude supplied via user subroutine
DLOAD in
Abaqus/Standard
and
VDLOAD in
Abaqus/Explicit.
- Load ID (*DLOAD): PZNU
- FL−1
-
Nonuniform force per unit length in global Z-direction
with magnitude supplied via user subroutine
DLOAD in
Abaqus/Standard
and
VDLOAD in
Abaqus/Explicit.
(Only for beams in space.)
- Load ID (*DLOAD): P1
- FL−1
-
Force per unit length in beam local 1-direction (only for beams in space).
- Load ID (*DLOAD): P2
- FL−1
-
Force per unit length in beam local 2-direction.
- Load ID (*DLOAD): P1NU
- FL−1
-
Nonuniform force per unit length in beam local 1-direction with magnitude
supplied via user subroutine
DLOAD in
Abaqus/Standard
and
VDLOAD in
Abaqus/Explicit.
(Only for beams in space.)
- Load ID (*DLOAD): P2NU
- FL−1
-
Nonuniform force per unit length in beam local 2-direction with magnitude
supplied via user subroutine
DLOAD in
Abaqus/Standard
and
VDLOAD in
Abaqus/Explicit.
- Load ID (*DLOAD): ROTA(S)
- T−2
-
Rotary acceleration load (magnitude is input as ,
where
is the rotary acceleration).
- Load ID (*DLOAD): ROTDYNF(S)
- T−1
-
Rotordynamic load (magnitude is input as ,
where
is the angular velocity).
*dload
The following load types are available only for PIPE elements: - Load ID (*DLOAD): HPI
- FL−2
-
Hydrostatic internal pressure (closed-end condition), varying linearly with
the global Z-coordinate.
- Load ID (*DLOAD): HPE
- FL−2
-
Hydrostatic external pressure (closed-end condition), varying linearly with
the global Z-coordinate.
- Load ID (*DLOAD): PI
- FL−2
-
Uniform internal pressure (closed-end condition).
- Load ID (*DLOAD): PE
- FL−2
-
Uniform external pressure (closed-end condition).
- Load ID (*DLOAD): PENU
- FL−2
-
Nonuniform external pressure (closed-end condition) with magnitude supplied
via user subroutine
DLOAD.
- Load ID (*DLOAD): PINU
- FL−2
-
Nonuniform internal pressure (closed-end condition) with magnitude supplied
via user subroutine
DLOAD.
Abaqus/Aqua Loads
Abaqus/Aqua
loads are specified as described in
Abaqus/Aqua Analysis.
They are not available for open-section beams and do not apply to beams that
are defined to have additional inertia due to immersion in fluid (see
Additional Inertia due to Immersion in Fluid).
In
Abaqus/Explicit,
Aqua loads can be applied only on linear beam and pipe
elements. *cload/
*dload- Load ID (*CLOAD/
*DLOAD): FDD
- FL−1
-
Transverse fluid drag load.
- Load ID (*CLOAD/
*DLOAD): FD1
- F
-
Fluid drag force on the first end of the beam (node 1).
- Load ID (*CLOAD/
*DLOAD): FD2
- F
-
Fluid drag force on the second end of the beam (node 2 or node 3).
- Load ID (*CLOAD/
*DLOAD): FDT
- FL−1
-
Tangential fluid drag load.
- Load ID (*CLOAD/
*DLOAD): FI
- FL−1
-
Transverse fluid inertia load.
- Load ID (*CLOAD/
*DLOAD): FI1
- F
-
Fluid inertia force on the first end of the beam (node 1).
- Load ID (*CLOAD/
*DLOAD): FI2
- F
-
Fluid inertia force on the second end of the beam (node 2 or node 3).
- Load ID (*CLOAD/
*DLOAD): PB
- FL−1
-
Buoyancy load (closed-end condition).
- Load ID (*CLOAD/
*DLOAD): WDD
- FL−1
-
Transverse wind drag load.
- Load ID (*CLOAD/
*DLOAD): WD1
- F
-
Wind drag force on the first end of the beam (node 1).
- Load ID (*CLOAD/
*DLOAD): WD2
- F
-
Wind drag force on the second end of the beam (node 2 or node 3).
Foundations
Foundations are available only in
Abaqus/Standard
and are specified as described in
Element Foundations. *foundation
- Load ID (*FOUNDATION): FX(S)
- FL−2
-
Stiffness per unit length in global X-direction.
- Load ID (*FOUNDATION): FY(S)
- FL−2
-
Stiffness per unit length in global Y-direction.
- Load ID (*FOUNDATION): FZ(S)
- FL−2
-
Stiffness per unit length in global Z-direction (only
for beams in space).
- Load ID (*FOUNDATION): F1(S)
- FL−2
-
Stiffness per unit length in beam local 1-direction
(only for beams in space).
- Load ID (*FOUNDATION): F2(S)
- FL−2
-
Stiffness per unit length in beam local 2-direction.
Surface-Based Loading
Distributed Loads
Surface-based distributed loads are specified as described in
Distributed Loads. *dsload
- Load ID (*DSLOAD): P
- FL−1
-
Force per unit length in beam local 2-direction. The distributed surface
force is positive in the direction opposite to the surface normal.
- Load ID (*DSLOAD): PNU
- FL−1
-
Nonuniform force per unit length in beam local 2-direction with magnitude
supplied via user subroutine
DLOAD in
Abaqus/Standard
and
VDLOAD in
Abaqus/Explicit.
The distributed surface force is positive in the direction opposite to the
surface normal.
Incident Wave Loading
Element Output
Stress, Strain, and Other Tensor Components
Stress and other tensors (including strain tensors) are available for
elements with displacement degrees of freedom. All tensors, except for meshed
sections, have the same components. For example, the stress components are as
follows: - S11
-
Axial stress.
- S22
-
Hoop stress (available only for pipe elements).
- S33
-
Radial stress (available only for thick-walled pipe elements).
- S12
-
Shear stress caused by torsion (available only for beam-type elements in
space). This component is not available when thin-walled, open sections are
employed (I-section, L-section, and arbitrary open section).
Stress and strain
for section points for meshed sections
- S11
-
Axial stress.
- S12
-
Shear stress along the second cross-section axis caused by shear force and,
for beam elements in space, torsion.
- S13
-
Shear stress along the first cross-section axis caused by shear force and
torsion (available only for beams in space).
Section Forces, Moments, and Transverse Shear Forces
- SF1
-
Axial force.
- SF2
-
Transverse shear force in the local 2-direction (not available for B23, B23H, B33, B33H).
- SF3
-
Transverse shear force in the local 1-direction (available only for beams in
space, not available for B33, B33H).
- SM1
-
Bending moment about the local 1-axis.
- SM2
-
Bending moment about the local 2-axis (available only for beams in space).
- SM3
-
Twisting moment about the beam axis (available only for beams in space).
- BIMOM
-
Bimoment due to warping (available only for open-section beams in space).
- ESF1
-
Effective axial force for beams subjected to pressure loading (available for
all
Abaqus/Standard stress/displacement
analysis types except response spectrum and random response).
See
Beam element formulation
for the definitions of the section forces and moments.
The effective axial section force for beams subjected to pressure loading is
defined as
where
and
are the external and the internal pressures, respectively, and
and
are the external and the internal pipe areas as defined in the load definition.
The pressure loadings (with a closed-end condition) that are relevant to the
effective axial force are external/internal pressure (load types PE, PI, PENU, and PINU); external/internal hydrostatic pressure (load types HPE and HPI); and, in an
Abaqus/Aqua
environment, buoyancy pressure, PB, which includes dynamic pressure if waves are present.
For beams that are not subjected to pressure loading, the effective axial
force ESF1 is equal to the usual axial force SF1.
Section Strains, Curvatures, and Transverse Shear Strains
- SE1
-
Axial strain.
- SE2
-
Transverse shear strain in the local 2-direction (not available for B23, B23H, B33, and B33H).
- SE3
-
Transverse shear strain in the local 1-direction (available only for beams
in space, not available for B33 and B33H).
- SK1
-
Curvature change about the local 1-axis.
- SK2
-
Curvature change about the local 2-axis (available only for beams in space).
- SK3
-
Twist of the beam (available only for beams in space).
- BICURV
-
Bicurvature due to warping (available only for open-section beams in space).
Beam Radius
- BRADIUS
- Original beam radius for a
solid circular
beam.
Node Ordering on Elements
Numbering of Integration Points for Output
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