uniaxialMaterial('RambergOsgoodSteel', matTag, fy, E0, a, n)
This command is used to construct a Ramberg-Osgood steel material object.
integer tag identifying material
initial elastic tangent
“yield offset” and the Commonly used value for a is 0.002
Parameters to control the transition from elastic to plastic branches. And controls the hardening of the material by increasing the “n” hardening ratio will be decreased. Commonly used values for n are ~5 or greater.