This page is devoted to frequently asked questions (FAQ) related to constraints.
On this page:
What is the difference between a line constraint and an edge constraint?
What are the advantages and disadvantages between using rigid links and body constraints?
Extended Question: I am using the Bridge Modeler to model an offset rocker bearing. A combination of link objects seems to simulate the connection between girder and pier systems. Is there an explanation for the difference between links and body constraints?
Answer: Application of either rigid links or body constraints is suitable for modeling a rigid connection. A comparison of these modeling techniques is described as follows:
Advantages of using links:
- Links are clearly shown in the model, which may assist review.
- Internal forces are obtained for links, which is not the case for body constraints.
- Link stiffness may be modified, if necessary, to match that of the component being modeled. Joints constrained using body constraints are always fully fixed.
Advantages of using body constraints:
- Using body constraints reduces the number of degrees of freedom (DOF) in the model, which speeds numerical solution.
Why are numerical problems reported for diaphragm constraints?
Answer: Please see the Diaphragm constraint article for response.
Why do edge constraints have displacement discontinuity?
Answer: Please see the Line (edge) constraint article for response.