TIS - Track Interaction Springs are complex spring elements where the constitutive relation of the shear terms is variable and bi-linear. It depends on the limit force F that separates the unloaded from the loaded case. Then spring contacts for the shear and rotations will be assumed, until the force limit, if delimited.

   

TIS, RIS, or Rail Interaction Springs are very useful in the Rolling Stock Analysis for HSR. It's a very complex dynamic interaction within loading and structure, velocities and accelerations, where the passenger comfort inside the RS could be a matter of analysis.

Modeling information can be found at the links below:

communities.bentley.com/.../rsi-wizard

communities.bentley.com/.../rsi-verification-uic-code-track-bridge-interaction