# Steel01 Material for Sensitivity

This command is used to construct a uniaxial bilinear steel material object with kinematic hardening and optional isotropic hardening described by a non-linear evolution equation (refer to http://peer.berkeley.edu).

```tcl uniaxialMaterial Steel01 $matTag $sigmaY $E $b <$a1 $a2 $a3 $a4> ```
matTag

unique material object integer tag

E

initial tangent stiffness

sigmaY

yield strength

b

strain-hardening ratio (ratio between post-yield tangent and initial elastic tangent stiffness)

a1 a2 a3 a4

isotropic hardening parameters: (optional, default: no isotropic hardening)

Note: For this material class, the sensitivity parameters can be: E, sigmaY, b, a1, a2, a3, a4