Inelastic Response Spectra for a Specified Ductility

This function can obtain inelastic spectra for a bilinear elastoplastic system according to a specified ductility (μ).

This function can obtain these following items for an input accelerogram according to a specified ductility (μ) by iteration:
1. Inelastic Displacement Spectrum (iSd-T),
2. Inelastic Velocity Spectrum (iSv-T),
3. Inelastic Acceleration Spectrum (iSa-T),
For this purpose, Newmark's method was employed and the Equation of Motions was solved, numerically. This function is completely compatible with the 4th edition of the book "Dynamics of Structures" by A. K. Chopra.