Ramberg-Osgood steel model - stl_ro

This is the Ramberg-Osgood stress-strain model [Ramberg and Osgood, 1943], as described in the work of Kaldjian [1967] and Otani [1981].

Users have to assign the mean value of steel strength and the mean value minus the standard deviation or the characteristic value in order to describe the mechanical characteristics of the existing or the new material respectively.