4.13.5.4. BilinearOilDamper Material¶

uniaxialMaterial('BilinearOilDamper', matTag, K_el, Cd, Fr=1.0, p=1.0, LGap=0.0, NM=1, RelTol=1e-6, AbsTol=1e-10, MaxHalf=15)

This command is used to construct a BilinearOilDamper material, which simulates the hysteretic response of bilinear oil dampers with relief valve. Two adaptive iterative algorithms have been implemented and validated to solve numerically the constitutive equations within a bilinear oil damper with a high-precision accuracy.

`matTag` (int)	integer tag identifying material
`K_el` (float)	Elastic stiffness of linear spring to model the axial flexibility of a viscous damper (e.g. combined stiffness of the supporting brace and internal damper portion)
`Cd` (float)	Damping coefficient
`Fr` (float)	Damper relief load (default=1.0, Damper property)
`p` (float)	Post-relief viscous damping coefficient ratio (default=1.0, linear oil damper)
`LGap` (float)	Gap length to simulate the gap length due to the pin tolerance
`NM` (int)	Employed adaptive numerical algorithm (default value NM = 1; `1` = Dormand-Prince54, `2` = 6th order Adams-Bashforth-Moulton, `3` = modified Rosenbrock Triple)
`RelTol` (float)	Tolerance for absolute relative error control of the adaptive iterative algorithm (default value 10^-6)
`AbsTol` (float)	Tolerance for absolute error control of adaptive iterative algorithm (default value 10^-10)
`MaxHalf` (int)	Maximum number of sub-step iterations within an integration step (default value 15)