This page contains frequently asked questions related to links.
On this page:General FAQ
Does changing the length of the link element have impact on the results?
Changing the length of a link element has no effect on the stiffness values, since they are based on the total force or moment. The only effect is the generation of a moment due shear acting over the length. Likewise, changing the length location of the shear deformation (defined by specifying a distance from J end) may change the response as this parameter has impact on the internal link deformations. Please note that the link deformations occur at a single location specified by "Shear Distance from End J" on the link definition form. Please refer to the CSI Analysis Reference Manual, Chapter The Link/Support Element, Section Internal Deformations for the equations used to calculate link deformations.
Which link property is the most suitable to model shear behavior of reinforced concrete?
Multi-linear plastic link property with pivot hysteresis type would be most suited to model the shear behavior of reinforced concrete members.
Should I use hinge or link?
See "Comparison of hinges and links" page.
Link Directional Properties
There are the following three main options when you define link directional properties:
- You leave the Direction unchecked (as is the case for U1 in the screenshot below) - then the link will not contribute any stiffness for the given direction.
- You check the Direction and Fixed (as is the case for U2 in the screenshot below) - in this case, the link will not experience any deformation in the given direction. In other words, it will behave as being infinitely stiff for the given direction.
- You check Direction and NonLinear (as shown for U3 in the screenshot below) - then the link will contribute stiffness specified when you click the "Modify/Show ..." button below the Properties heading.
How should I calculate the link stiffness values?
There are various types of links available in the program and you can define their force deformation relationship (for axial, major and minor shear, torsion, major and minor pure bending DOFs) to represent the behavior of the structural component (such as bearing, isolator, soil spring, etc.) that is being modeled by the link.
Please review CSI Analysis Reference Manual, chapter "The Link/Support Element - Basic", sections "Internal Deformations" and "Link/Support Properties" for additional details on link internal deformations, force-deformation relationship and link internal forces.
You may also find it useful to review the Derivation of link equations page.
How can I plot force-displacement hysteresis curve for isolator?
Extended Question: How do I get output force-displacement hysteresis curve for isolator? I was trying to see under Display/Show plot function but I couldn’t figure it out force vs. displacement only I found time vs. displacement.
Answer: See plotting link hysteresis curve page.
What are the units for link effective damping?
For all link properties, the damping input is the actual damping in units of Force-Sec/Length (i.e. Force/Velocity).
