Input Nodal Boundary Condition

Table tbNodalBoundaryCond

PURPOSE:

Define nodal contraints. A bridge model MUST be statically stable.

Parameters

tbNodalBoundaryCond

Field	Type	Units	Description
CogoPoint	text		Cogo Point Name
Fx	chr		[Y|N] Constrain node translation in X direction
Fy	chr		[Y|N] Constrain node translation in Y direction
Mz	chr		[Y|N] Constrain node in rotation axis
Stage	int		Stage that this condition becomes effective.
ReactionStage	int		Stage to apply reactions back into analysis.

• CogoPt

  Enter a name of a COGO point to be constrained. The same point can be listed multiple times. See the notes below on multiple point entry.

• Fx,Fy, and Mz

  Enter a “Y” in this field to constrain the point in that DOF.

• Stage

  Normally a constraint is active in every stage, but this field can be used to specify that a constraint only be active in a single stage. If this entry is used, also use the Reaction Stage entry or else the forces resisted by this constraint will be lost and not re-applied to the model. This might be what is intended but typically not if this feature is used to simulate form-work.

• Reaction Stage

  If the Stage feature is used (described above) then specify the stage that the constrained forces are to be re-applied to the model.

Duplicate Point Entry Note

If the same Cogo Point is listed multiple times for the same stage, then the resulting boundary condition is the “OR” of all fixity codes. For example, if point AA is listed once with a constraint in the Fx direction, and on another line is listed as having a constraint in the Fy direction, then point AA will be constrained in both the Fx and Fy directions. This makes entry more convenient when point constrains are listed by purpose, not by point number. For example listing all physical supports, then simplification constrains, then model stability constraints.

Example