Conflicting Constraints

There are various rules that must be followed when specifying constraints. Failure to abide by these rules results in constraints that are in conflict. Such conflicts are reported by the pre-analysis data checking.

The rules are as follows:

• a constrained degree of freedom may be constrained to only one primary node.
• a degree of freedom may not be constrained by more than one rigid constraint, link element, joint or constraint equation.
• a restraint applied at a constrained node may not conflict with the restraint conditions at its primary.
• in a linear analysis a primary degree of freedom may not be a constrained degree of freedom to another constraint. (Does not apply to nonlinear analysis.)

In addition:

• the constrained nodes of Joints can be the primary nodes of Links and Rigid Constraints
• the constrained nodes of Links can be the primary nodes of Rigid Constraints

Other arrangements of constrained and primary nodes can cause unbalanced nodal forces as well as total loads and reactions.