Using Linear Member Cutbacks

Structural Design User Guide

SDNF Export/Import : Technical Information : Using Linear Member Cutbacks

The interface can handle cutbacks as entered in Record 5 of Packet 10 of the SDNF file Refer to Packet 10 - Linear Members.

The start and end 3D eccentricities are ignored as in previous releases.

The default setting is not to use cutbacks for compatibility with previous versions of SDNF. If the user wants to change the default setting, this is set in the sdnfUserData.pmlfnc file in the folder SDNF\dflts\user\SDNFPML\functions in the user data folder.

    -- Flag to handle a supplied trimmed model or one where cutbacks must be used

    -- |CP| = trimmed positions;

    -- |WP| = worked out positions

  !!SDNFModelType      = |CP|

The interpretation of the SDNF record data for Linear Members and their cutbacks is illustrated below. Here is an SDNF description of a Linear Member.

1 10 0 0 "ANG" "15322/826" 0

"L60x6" "Steel, carbon" 180.0000 0 0

-287.3480 0.0000 957.8260 138100.0000 166000.0000 … 106000.0000 140796.5000 166000.0000 106808.9530 10.0000 30.0000

0.0000 0.0000

0.0000 0.0000 20.0000 0.0000 10.0000 -50.0000

0 0 0 0 0 0 0 0 0 0 0 0

In the above data the fields are interpreted as shown:

Orientation vector = ( -287, 0, 958 )

Start position = ( 138100, 166000, 106000 )

End position = ( 140796, 166000, 106809 )

Start cutback = 10

End cutback = 30

Start eccentricity = ( 0, 0, 20 )

End eccentricity = ( 0, 10, -50 )

Diagram showing each interpretation. The text below describes this diagram in more detail.

Exporting

The use of the Use Cutbacks option will be the same for exporting an AVEVA E3D™ model in either SDNF format, i.e. v2.0 or v3.0.

When the Use Cutbacks check box is left unchecked the start and end positions will be the start and end positions of the Justification Pline of the member.

Where the member is connected, i.e. the Joistart and/or Joiend attributes are set, the start and/or end cutback value will be set to be the absolute length of the vector between the node position and the Justification Pline position as projected along the member's axis. In effect, this calculates a virtual node. For simple, orthogonal structures which have not been manipulated too much, this will tend to be at the same position as the attached node.

Where the member is unconnected, i.e. either the Joistart and/or Joiend attributes are unset, the start and/or end cutback value will be set to zero.

When the Use Cutbacks check box is checked the start and end positions will be the positions of the virtual nodes derived from the nodes to which the start/end is connected. The start and end cutbacks will be set to be the distance between the virtual node position and the Justification Pline position.

If either or both member ends are unconnected the start and/or end position will be start and/or end position of the Justification Pline and the cutbacks will be zero.

Below is the relevant Export dialog with the Use Cutbacks option indicated.

Importing

The use of the Use Cutbacks option will be the same for importing a model in either SDNF format, i.e. v2.0 or v3.0.

When the Use Cutbacks check box is left unchecked the start and end positions of the member will be set to the start and end positions. Any cutback values will be ignored.

When the Use Cutbacks check box is checked the Start and End positions of the member will be 'trimmed' in accordance with the start and end cutback values.

Below is the relevant Import dialog with the Use Cutbacks option indicated.