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This page is devoted to frequently asked questions (FAQ) related to constraints. |
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What is the difference between a line constraint and an edge constraint?
This is the same type of constraint. The edge constraint terminology is used in SAP2000, while the line constraint terminology is used in ETABS.
ConstraintAnswer: Line and edge constraint both refer to the same modeling feature except that line constraint is terminology specific to ETABS, while edge constraint is used in SAP2000.
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Review to check if this Q/A be removed. It is possible that edge constraint is now used in ETABS as well as SAP2000. |
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.
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Related Incidents:
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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.
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Question 1: When would a body constraint be applied with only some DOF constrained? Answer 1: OPEN QUESTION Question 2: What behaviors occur when only some DOF are constrained? Answer 2: OPEN QUESTION Question 3: Is there an example of how constraint coupling may cause numerical instability? Answer 3: OPEN QUESTION |