Frame element library

This section provides a reference to the frame elements available in Abaqus/Standard.

Related Topics
Frame elements
In Other Guides
*FRAME SECTION

ProductsAbaqus/Standard

Element types

Frame in a plane

FRAME2D

2-node straight frame element

Active degrees of freedom

1, 2, 6

Additional solution variables

Two additional variables relating to the axial and lateral displacements.

Frame in space

FRAME3D

2-node straight frame element

Active degrees of freedom

1, 2, 3, 4, 5, 6

Additional solution variables

Three additional variables relating to the axial and lateral displacements.

Nodal coordinates required

Frame in a plane: X, Y (Direction cosines of the normal are not used; any values given are ignored.)

Frame in space: X, Y, Z (Direction cosines of the normal are not used; any values given are ignored.)

Element property definition

Local orientations defined as described in Orientations cannot be used with frame elements to define local material directions. The orientation of the local section axes in space is discussed in Frame elements.

Input File Usage

FRAME SECTION

Element-based loading

Distributed loads

Distributed loads are specified as described in Distributed loads.

*dload
  1. Load ID (*DLOAD): GRAV
  2. LT−2

  3. Gravity loading in a specified direction (magnitude is input as acceleration).

  1. Load ID (*DLOAD): PX
  2. FL−1

  3. Force per unit length in global X-direction.

  1. Load ID (*DLOAD): PY
  2. FL−1

  3. Force per unit length in global Y-direction.

  1. Load ID (*DLOAD): PZ
  2. FL−1

  3. Force per unit length in global Z-direction (only for frames in space).

  1. Load ID (*DLOAD): P1
  2. FL−1

  3. Force per unit length in frame local 1-direction (only for frames in space).

  1. Load ID (*DLOAD): P2
  2. FL−1

  3. Force per unit length in frame local 2-direction.

Abaqus/Aqua loads

Abaqus/Aqua loads are specified as described in Abaqus/Aqua analysis.

*cload/ *dload
  1. Load ID (*CLOAD/ *DLOAD): FDD
  2. FL−1

  3. Transverse fluid drag load.

  1. Load ID (*CLOAD/ *DLOAD): FD1
  2. F

  3. Fluid drag force on the first end of the frame (node 1).

  1. Load ID (*CLOAD/ *DLOAD): FD2
  2. F

  3. Fluid drag force on the second end of the frame (node 2).

  1. Load ID (*CLOAD/ *DLOAD): FDT
  2. FL−1

  3. Tangential fluid drag load.

  1. Load ID (*CLOAD/ *DLOAD): FI
  2. FL−1

  3. Transverse fluid inertia load.

  1. Load ID (*CLOAD/ *DLOAD): FI1
  2. F

  3. Fluid inertia force on the first end of the frame (node 1).

  1. Load ID (*CLOAD/ *DLOAD): FI2
  2. F

  3. Fluid inertia force on the second end of the frame (node 2).

  1. Load ID (*CLOAD/ *DLOAD): PB
  2. FL−1

  3. Buoyancy load (closed-end condition).

  1. Load ID (*CLOAD/ *DLOAD): WDD
  2. FL−1

  3. Transverse wind drag load.

  1. Load ID (*CLOAD/ *DLOAD): WD1
  2. F

  3. Wind drag force on the first end of the frame (node 1).

  1. Load ID (*CLOAD/ *DLOAD): WD2
  2. F

  3. Wind drag force on the second end of the frame (node 2).

Foundations

Foundations are specified as described in Element foundations.

*foundation
  1. Load ID (*FOUNDATION): FX
  2. FL−2

  3. Stiffness per unit length in global X-direction.

  1. Load ID (*FOUNDATION): FY
  2. FL−2

  3. Stiffness per unit length in global Y-direction.

  1. Load ID (*FOUNDATION): FZ
  2. FL−2

  3. Stiffness per unit length in global Z-direction (only for frames in space).

  1. Load ID (*FOUNDATION): F1
  2. FL−2

  3. Stiffness per unit length in frame local 1-direction (only for frames in space).

  1. Load ID (*FOUNDATION): F2
  2. FL−2

  3. Stiffness per unit length in frame local 2-direction.

Element output

All element output variables are given at the element ends (nodes 1 and 2) and midpoint (node 3).

Section forces and moments

SF1

Axial force.

SF2

Transverse shear force in the local 2-direction.

SF3

Transverse shear force in the local 1-direction (only available for frames in space).

SM1

Bending moment about the local 1-axis.

SM2

Bending moment about the local 2-axis (only available for frames in space).

SM3

Twisting moment about the frame axis (only available for frames in space).

See Frame elements with lumped plasticity for a discussion of the section forces and moments.

Section elastic strains and curvatures

SEE1

Elastic axial strain.

SKE1

Elastic curvature change about the local 1-axis.

SKE2

Elastic curvature change about the local 2-axis (only available for frames in space).

SKE3

Elastic twist of the beam (only available for frames in space).

Plastic displacements and rotations in the element coordinate system

SEP1

Plastic axial displacement.

SKP1

Plastic rotation about the local 1-axis.

SKP2

Plastic rotation about the local 2-axis (only available for frames in space).

SKP3

Plastic rotation about the beam axis (only available for frames in space).

Section force and moment backstresses

SALPHA1

Axial force backstress.

SALPHA2

Bending moment backstress about the local 1-axis.

SALPHA3

Bending moment backstress about the local 2-axis (only available for frames in space).

SALPHA4

Twisting moment backstress about the beam axis (only available for frames in space).

Node ordering on elements



For frames in space an additional node may be given after a frame element's connectivity (in the element definition—see Element definition) to define the approximate direction of the first cross-section axis, n1. See Frame elements for details.