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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?
Answer: 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 |