How is seismic site response analysis performed?

Site response analysis determines ground motion amplification through soil column. Methods: (1) Equivalent linear - iterative adjustment of shear modulus and damping based on effective strain (SHAKE software), (2) Nonlinear time-domain - direct integration with hysteretic soil models (DEEPSOIL), more accurate for strong shaking, (3) 2D/3D FE for irregular topography or basin effects. Input: bedrock motion (outcrop or within), soil profile with dynamic properties (Vs, G/Gmax and damping curves). Output: surface motion, response spectra, and strain profiles. Used for site-specific design spectra.