Linear Member Cutbacks

Structural Design User Guide

SDNF Export/Import : Technical Information : 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 for further information.

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 you want 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 example displays the interpretation of the SDNF record data for Linear Members and their cutbacks. The example 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

The data fields are interpreted.

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 )

The diagram displays each interpretation. Refer to Export for further information.

Export

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

Where the member is connected, for example, the Joistart and/or Joiend attributes are set, the start and/or end cutback value is set to 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 tends to be at the same position as the attached node.

Where the member is unconnected, for example, either the Joistart and/or Joiend attributes are unset, the start and/or end cutback value is set to zero.

When the Use Cutbacks check box is checked the start and end positions are the positions of the virtual nodes derived from the nodes to which the start/end is connected. The start and end cutbacks are set to 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 is the start and/or end position of the Justification Pline and the cutbacks is zero.

The example displays the relevant Export window with the Use Cutbacks option indicated.

Import

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

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

The example displays the relevant Import window with the Use Cutbacks option indicated.