Strata — The Complete Guide: Free Seismic Site Response Analysis
Strata is open-source software (GPL-3.0) by Albert Kottke for one-dimensional seismic site response analysis. You define a soil profile — layers, shear-wave velocity and modulus-reduction and damping curves — and a bedrock motion, and the program computes the motion at the ground surface. It has a graphical interface and runs on Windows, macOS and Linux.
Strata
Albert Kottke
One-dimensional seismic site response analysis: how soil layers amplify ground motion, by the equivalent-linear method with randomised soil properties.
Get it from the vendorWhat you get
- Equivalent-linear method — iterative adjustment of stiffness and damping to the strain level.
- Two input types — acceleration time series, or a spectral description via random vibration theory.
- Randomisation — varying velocities, layer thicknesses and dynamic properties to assess uncertainty.
- Results — response spectra, amplification functions and strain and stress profiles with depth.
- Batch runs — several motions and profiles in one analysis.
Who it suits
Geotechnical and earthquake engineers who need a site-specific spectrum, for example for soft soil or deep deposits that the code covers only approximately. The method suits moderate strain levels; for very large strains or pore-pressure build-up, a nonlinear analysis in dedicated software is the better choice.
Related tools
For the same kind of analysis as a Python library — pyStrata. For regional seismic hazard — OpenQuake Engine. For nonlinear soil-structure analysis — OpenSees.
pyStrata
Albert Kottke
One-dimensional seismic site response of a soil column — equivalent-linear, time series and RVT, in Python.
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OpenQuake Engine
GEM Foundation
Seismic hazard and risk calculations — PSHA, earthquake scenarios and damage and loss estimates, from the GEM Foundation.
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OpenSees
Pacific Earthquake Engineering Research Center, UC Berkeley
Nonlinear and dynamic structural analysis driven by scripts, from the earthquake engineering world.
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quoFEM
NHERI SimCenter
Uncertainty quantification around finite element models — sensitivity, Monte Carlo, Bayesian calibration and surrogates.
Get it from the vendorThe bottom line
Strata is a long-standing, well-known tool for site response, with a friendly interface and built-in handling of uncertainty. It is completely free, including for commercial use.