Tie

Multipoint Constraint Implemented As Element

• Number of Nodes: varies
• Number of DoFs: varies

Syntax

element Tie (1) (2) (3) [(4) (5) (6)...]
# (1) int, unique element tag
# (2) double, right hand side of the constraint equation, the constraint is homogeneous if this parameter is zero
# (3) double, penalty number, a relatively large number
# (4) int, node tag
# (5) int, dof tag
# (6) double, weight

Example

Each Tie element can have multiple DoFs included. For example, to define the following constraint,

$$5u_2+6v_4=9,$$

where $u_2$ and $v_4$ are horizontal displacement of node 2 and vertical displacement of node 4 in a 2D model, then

element Tie 1 9. 1E8 2 1 5. 4 2 6.

In the above command, a large number 1E8 is used as penalty.