CBEAM

Bulk Data Entry Defines a beam element (BEAM) of the structural model.

Attention: Valid for Implicit and Explicit Analysis

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CBEAM EID PID GA GB X1/G0 X2 X3 OFFT
PA PB W1A W2A W3A W1B W2B W3B

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CBEAM 2 39 7 3 13
513 3.0

Definitions

Field Contents SI Unit Example
EID Unique element identification number.

No default (Integer > 0)
PID PBEAM or PBEAML property entry identification number.
Integer
Specifies an identification number for this property.
<String>
Specifies a user-defined string label for this property. 8

Default = EID (Integer > 0 or <String>)
GA,GB Grid point identification numbers of connection points.

No default (Integer > 0; GA ≠ GB)
X1,X2,X3 Components of vector v, at end A, measured at the offset point for end A, parallel to the components of the displacement coordinate system for GA, or the basic coordinate system, to determine (with the vector from offset end A to offset end B) the orientation of the element coordinate system for the beam element. 5

No default (Real) 3
G0 Grid point identification number to optionally supply X1, X2, X3. Direction of orientation vector is GA to G0.

No default (Integer > 0) 3
OFFT Character string specifying the interpretation of the offset vector specification. 5

Default = GGG (Character or blank)
PA, PB Pin flags for beam ends A and B, respectively. Used to remove connections between the grid point and selected degrees-of-freedom of the beam. The degrees-of-freedom are defined in the element's coordinate system and the pin flags are applied at the offset ends of the beam. The beam must have stiffness associated with the PA and PB degrees-of-freedom to be released by the pin flags. For example, if PA=4, the PBEAM entry must have a non-zero value for J, the torsion stiffness. 4

No default (Integer > 0; up to 5 of the unique digits 1-6 with no embedded blanks)
W1A,W2A,W3A, W1B,W2B,W3B Components of offset vectors, measured in the displacement coordinate systems at grid points A and B or in the element coordinate system, from the grid points to the end points of the axis of shear center. 5

Default = blank (Real or blank)
Figure 1. Beam Element Coordinate System


Figure 2. Direction of Internal Forces and Moments (for CBEAM entry). For OPTI format output in .force and H3D format output with ELFORCE(DIRECT)


Comments

  1. Element identification numbers must be unique with respect to all other element identification numbers.
  2. If X1/G0 is a positive integer and X2 and X3 are blank, then G0 is used to orient the element, otherwise X1, X2, X3 is used.
  3. G0 ≠ GA or GB.
  4. If there are no pin flags or offsets the continuation may be omitted.
  5. The OFFT character string specifies how the offset and orientation vector components are computed. By default, the offset vectors are specified in the global (local displacement) coordinate system of both grid A and B, and the orientation vector is specified in the global coordinate system of grid A. With the codes below, the offset vector can be specified in the offset coordinate system and the orientation vector can be specified in the basic coordinate system. The valid character strings and their meanings are listed below.
    OFFT Orientation Vector End A Offset End B Offset
    GGG Global Global Global
    BGG Basic Global Global
    GGO Global Global Offset
    BGO Basic Global Offset
    GOG Global Offset Global
    BOG Basic Offset Global
    GOO Global Offset Offset
    BOO Basic Offset Offset
    The offset system x-axis is defined from GA to GB. The orientation vector and the offset system x-axis are then used to define the z and y axes of the offset system. A vector is formed from the cross product of a vector going from grid A to grid B and the orientation vector to create the offset coordinate z-direction.
  6. Offset vectors are treated like rigid elements. The length of the offset vectors is not affected by thermal loads.
  7. Torsional stiffness due to warping of the cross-section is not considered.
  8. String based labels allow for easier visual identification of properties, when being referenced by the elements cards. For more details, refer to String Label Based Input File in the Bulk Data Input File.
  9. In the ASCII .force file (see example below), the SHEAR-1, SHEAR-2 values are associated with Plane-1 and Plane-2 Shear Center respectively, while BENDING-1 and BENDING-2 values are associated with Plane-1 and Plane-2 Neutral Axis respectively in Figure 1. 
    ITER     0     1
        1        1 LOAD:      2 (LOAD) Transverse_Load
   BAR #-END  AXIAL     SHEAR-1     SHEAR-2     TORQUE    BENDING-1   BENDING-2
       1-A  0.000E+00  0.000E+00  -2.5000E+02  0.000E+00  0.000E+00  -2.5000E+04
       1-B  0.000E+00  0.000E+00  -2.5000E+02  0.000E+00  0.000E+00   1.4552E-11
  10. This card is represented as a bar2 element in HyperMesh.