Lead Rubber Bearing > Stiffness Parameters
Lead Rubber Bearing (LRB) isolator is used for dynamic time history analysis when Non-linear dampers option is selected under Recalc pad. Damper has linear stiffness in static calculation and dynamic properties for time history calculation. LRB element is active for all translations degrees of freedom. Element does not consider any p-delta effects occurring due to axial load and translation of bearing.
| Setting | Description |
|---|---|
| From/To/Step | Element series, for which the section properties are input/modified. |
| Element type | Lead Rubber Bearing (LRB): Type name of the isolator. |
| Aero class / EccType | Irrelevant in this context |
| Lin-Kx, Lin-Ky, Lin-Kz | Linear stiffness in local x, y & z direction of the isolator element. This stiffness is only used in linear and Eigen analysis. The local x direction is always considered perpendicular to the plane of the isolator. |
| Dyn-Kx, Dyn -Ky, Dyn -Kz | Nonlinear dynamic stiffness is defined in local x, y & z direction of the isolator element and is working only in nonlinear time history calculation. The local x direction is always considered perpendicular to the plane of the isolator. The stiffness in the x direction is compression only stiffness. |
| Radius_y, Radius_z | Radii of the friction pendulum isolator in the local y and z directions respectively. Use of higher number or zero makes the isolator flat in respective direction. |
| Fy_y, Fy_z | These are the yield forces of the isolator in the local y and z directions respectively. |
| FAlpha_y, FAlpha_z | These are the ratios of post-yield stiffness to nonlinear dynamic stiffness in local y and z directions respectively. |
| A, Gamma & Beta | These are dimensionless evolutionary equation parameters which control the shape of the hysteresis loop. The following constant values are recommended for these variables: |