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Nonlinear multi-axial constant ductility response spectra for horizontal, vertical and tilt motions

version (3.56 MB) by Dr. Erol Kalkan, P.E.
Robust function to generate multi-component constant-ductility nonlinear-inelastic response spectra.


Updated 16 May 2017

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Robust function to generate multi-component constant-ductility nonlinear-inelastic response spectra for multi-axial simultaneous excitation including horizontal, vertical and rotational motions (i.e. rotational acceleration and tilt).
It also computes components of seismic input energy imparted to the SDOF oscillator.
Its features are:
- Multi-axial excitation (simultaneous horizontal, vertical and rotational input ground motions)
- Material nonlinearity is presented by Ozdemir's rate-independent force-displacement model
- P-delta (at global level) is included
- Spectral analysis for constant yield displacement
- Input energy computations and output results for components of absolute and relative energy
zip file contains reference papers and example input ground motions from Pacoima Dam and output results.
Any questions, please contact me at

Comments and Ratings (3)

You are most welcome !!!


Thanks Dr. Erol Kalkan for sharing these valuable programs. These programs and their related research are at the leading edge of earthquake engineering. They could be used in lots of research fields including the analysis of three dimensional earthquake response.



Updated ReadME.txt file

updated description

Updated state-space formulation to include derivative of vertical acceleration in dy(5) as reminded by Wang Zhen.
Updated figures so they will be saved to a folder called "figs" in PNG format

updated notes

MATLAB Release Compatibility
Created with R2014a
Compatible with any release
Platform Compatibility
Windows macOS Linux

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