| Name | dvars JSON |
| Version |
0.1.6
JSON |
| download |
| home_page | None |
| Summary | Response spectra calculations for earthquake engineering |
| upload_time | 2025-07-24 11:23:57 |
| maintainer | None |
| docs_url | None |
| author | None |
| requires_python | >=3.4 |
| license | None |
| keywords |
response spectra
earthquake engineering
|
| VCS |
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No requirements were recorded.
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# DVARS - Elastic Displacement, Velocity and Acceleration Response Spectra
## Overview
In earthquake engineering response spectrum is used to analyze the dynamic reponse of structures to seismic events.
The response spectrum shows the maximum values of displacement, velocity and/or acceleration
as a function of frequency or period.
The calculation is based on the assumption that the structure behaves as a simple harmonic oscillator,
damped by default to only 5% and its natural frequency is tuned to the tested frequency.
The response spectrum can be determined by applying the same earthquake to a series
of simple oscillators with different natural frequencies and a uniform damping of 5%.
In the analog implementation of this test, the earthquake acts on a series of oscillators in parallel,
while computer simulation is usually arranged serially - by repeatedly processing
the time record of the earthquake on a sequentially retuned harmonic oscillator model.
For each excitation of the recorded acceleration waveform, the maximum observed response
in terms of relative displacement or absolute acceleration is recorded.
This repository provides a Python interface to a C implementation of response spectrum computation,
which is based on the widely used fortran code ``rdcalcdp``
[EXSIM12 repository](https://github.com/GFZ-Centre-for-Early-Warning/exsim),
[EXSIM12](https://www.seismotoolbox.ca/EXSIM12/EXSIM12.for),
published by David M. Boore in 2008 as part of the TSPP package.
This is a modified version of the algorithm ``Quake.For``, originally written by J.M. Roesset in 1971.
The formulation is from Nigam and Jennings (BSSA, v. 59, 909-922, 1969).
## Installation prerequisites
- Python 3.x
- Dependencies: ctypes, numpy, matplotlib
For building the C extension:
- C compiler (e.g., GCC)
- Cross-compilation tools Mingw64 if building for MS Windows
- Python build tools: `setuptools`, `wheel`, `build`
## Installation
The DVARS package is available on PyPI and can be installed using pip:
```bash
pip install dvars --upgrade
```
or you can install it directly from the wheel:
```bash
pip install dvars-0.1.2-cp311-cp311-linux_x86_64.whl --upgrade
```
## Building the wheel package
Download the git repository
```bash
git clone https://github.com/ipemu/dvars.git
```
or download the source package from the releases page and unzip.
To build the package and the C extension, you can use the provided Makefile
from the root directory of the package:
Native build (was tested on Linux only).
```bash
# linux native build
# creates both source and wheel distributions
make build
```
Linux cross-compilation creates a wheel distribution for Windows.
```bash
# buildw32 is for 32-bit Windows builds
make buildw32
# buildw64 is for 64-bit Windows builds
make buildw64
```
The resulting wheel files will be located in the ``dist`` directory.
## Usage
```python
# Import the dars function from the dvars module
from dvars import dars
# Use help for listing arguments
help(dars)
```
The ``dars`` function provides a calculation of the response spectrum.
The input is a time history of ground motion (accelerogram)
and the output is a tuple containing:
- A numpy array of frequencies (in Hz)
- A numpy array of relative displacements
- A numpy array of absolute accelerations
Simply as the output of the dars function we get DSR - Displacement Response Spectra.
Other modifications used in practice are:
- PSA (PARS) - Pseudo Acceleration Response Spectra,
- PSV (PVRS) - Pseudo Velocity Response Spectra,
which can be derived from DSR according to the following relationships:
- pseudo-velocity response spectrum PSV(f) = (2 pi f) DRS(f)
- pseudo-acceleration response spectrum PSA(f) = (2 pi f) PSV(f)
The series of absolute accelerations AA is given for completeness.
Due to the small value of the standard oscillator damping (5 %), the values
of absolute acceleration AA and pseudo-acceleration response spectrum PSA are practically the same.
$$AA(f) \sim \mathsf{PSA}(f) = (2 \pi f)^2 \mathsf{DRS}(f)$$
The absolute acceleration and pseudo-acceleration values start to differ significantly in situations such as long periods and/or greater than standard damping.
For study purposes, the function ``osc_aa`` can be used,
which calculates the response of an oscillator tuned to a given frequency and damping
to the ground acceleration at the input.
## Example
Examples are not included in the distribution package,
but you can find them in the repository https://github.com/ipemu/dvars in the `examples` directory.
The notebook ``example_dars_esmdb.ipynb`` compares the response spectrum calculated by the `dvars.dars` function
with the data stored in the [ESM-DB](https://esm-db.eu), the Engineering Strong-Motion Database.
```bash
jupyter notebook examples/example_dvars.ipynb
```
## Limitations
- The algorithm is designed for linear oscillators and may not be suitable for non-linear systems.
- If non-standard damping is required, then the assumptions for calculating pseudo-acceleration
from the relative displacement series are not met and the results may not be accurate.
Use the absolute acceleration series instead.
## Contributing
Contributions are welcome! If you find any issues or have suggestions for improvements,
please open an issue or submit a pull request.
## License
This project is licensed under the MIT License.
## Literature
- Nigam, N.C., and Jennings, P.C. (1969). "Calculation of Response Spectra from Strong-motion Earthquake Records." Bulletin of the Seismological Society of America, Vol. 59, No.2, pp. 909-922. April, 1969
- David M. Boore (2008) TSPP - A Collection of FORTRAN Programs for Processing and Manipulating Time Series. U.S. Geological Survey Open-File Report 2008-1111. Version 1.2, March 2008. https://pubs.usgs.gov/of/2008/1111/of2008-1111_v1.2.pdf
Raw data
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"description": "\n# DVARS - Elastic Displacement, Velocity and Acceleration Response Spectra\n\n\n## Overview\nIn earthquake engineering response spectrum is used to analyze the dynamic reponse of structures to seismic events.\nThe response spectrum shows the maximum values of displacement, velocity and/or acceleration\nas a function of frequency or period.\n\nThe calculation is based on the assumption that the structure behaves as a simple harmonic oscillator,\ndamped by default to only 5% and its natural frequency is tuned to the tested frequency.\nThe response spectrum can be determined by applying the same earthquake to a series\nof simple oscillators with different natural frequencies and a uniform damping of 5%.\nIn the analog implementation of this test, the earthquake acts on a series of oscillators in parallel, \nwhile computer simulation is usually arranged serially - by repeatedly processing\nthe time record of the earthquake on a sequentially retuned harmonic oscillator model.\nFor each excitation of the recorded acceleration waveform, the maximum observed response\nin terms of relative displacement or absolute acceleration is recorded.\n\nThis repository provides a Python interface to a C implementation of response spectrum computation,\nwhich is based on the widely used fortran code ``rdcalcdp``\n[EXSIM12 repository](https://github.com/GFZ-Centre-for-Early-Warning/exsim),\n[EXSIM12](https://www.seismotoolbox.ca/EXSIM12/EXSIM12.for),\npublished by David M. Boore in 2008 as part of the TSPP package.\nThis is a modified version of the algorithm ``Quake.For``, originally written by J.M. Roesset in 1971.\nThe formulation is from Nigam and Jennings (BSSA, v. 59, 909-922, 1969).\n\n## Installation prerequisites\n- Python 3.x\n- Dependencies: ctypes, numpy, matplotlib\n\nFor building the C extension:\n- C compiler (e.g., GCC)\n- Cross-compilation tools Mingw64 if building for MS Windows\n- Python build tools: `setuptools`, `wheel`, `build`\n\n## Installation\n\nThe DVARS package is available on PyPI and can be installed using pip:\n```bash\npip install dvars --upgrade\n```\n\nor you can install it directly from the wheel:\n```bash\npip install dvars-0.1.2-cp311-cp311-linux_x86_64.whl --upgrade\n```\n\n## Building the wheel package\n\nDownload the git repository\n```bash\ngit clone https://github.com/ipemu/dvars.git\n```\nor download the source package from the releases page and unzip.\n\nTo build the package and the C extension, you can use the provided Makefile\nfrom the root directory of the package:\n\nNative build (was tested on Linux only).\n```bash\n# linux native build\n# creates both source and wheel distributions\nmake build\n```\nLinux cross-compilation creates a wheel distribution for Windows.\n```bash\n# buildw32 is for 32-bit Windows builds\nmake buildw32\n# buildw64 is for 64-bit Windows builds\nmake buildw64\n```\nThe resulting wheel files will be located in the ``dist`` directory.\n\n## Usage\n```python\n# Import the dars function from the dvars module\nfrom dvars import dars\n# Use help for listing arguments\nhelp(dars)\n```\nThe ``dars`` function provides a calculation of the response spectrum.\nThe input is a time history of ground motion (accelerogram)\nand the output is a tuple containing:\n- A numpy array of frequencies (in Hz)\n- A numpy array of relative displacements\n- A numpy array of absolute accelerations\n\nSimply as the output of the dars function we get DSR - Displacement Response Spectra.\nOther modifications used in practice are:\n- PSA (PARS) - Pseudo Acceleration Response Spectra,\n- PSV (PVRS) - Pseudo Velocity Response Spectra,\n\nwhich can be derived from DSR according to the following relationships:\n- pseudo-velocity response spectrum PSV(f) = (2 pi f) DRS(f)\n- pseudo-acceleration response spectrum PSA(f) = (2 pi f) PSV(f)\n\nThe series of absolute accelerations AA is given for completeness.\nDue to the small value of the standard oscillator damping (5 %), the values\nof absolute acceleration AA and pseudo-acceleration response spectrum PSA are practically the same.\n\n$$AA(f) \\sim \\mathsf{PSA}(f) = (2 \\pi f)^2 \\mathsf{DRS}(f)$$\n\nThe absolute acceleration and pseudo-acceleration values start to differ significantly in situations such as long periods and/or greater than standard damping.\n\nFor study purposes, the function ``osc_aa`` can be used,\nwhich calculates the response of an oscillator tuned to a given frequency and damping\nto the ground acceleration at the input.\n\n## Example\nExamples are not included in the distribution package,\nbut you can find them in the repository https://github.com/ipemu/dvars in the `examples` directory.\n\nThe notebook ``example_dars_esmdb.ipynb`` compares the response spectrum calculated by the `dvars.dars` function\nwith the data stored in the [ESM-DB](https://esm-db.eu), the Engineering Strong-Motion Database. \n```bash\njupyter notebook examples/example_dvars.ipynb\n```\n\n## Limitations\n- The algorithm is designed for linear oscillators and may not be suitable for non-linear systems.\n- If non-standard damping is required, then the assumptions for calculating pseudo-acceleration\n from the relative displacement series are not met and the results may not be accurate.\n Use the absolute acceleration series instead.\n\n## Contributing\nContributions are welcome! If you find any issues or have suggestions for improvements,\nplease open an issue or submit a pull request.\n\n## License\nThis project is licensed under the MIT License. \n\n## Literature\n- Nigam, N.C., and Jennings, P.C. (1969). \"Calculation of Response Spectra from Strong-motion Earthquake Records.\" Bulletin of the Seismological Society of America, Vol. 59, No.2, pp. 909-922. April, 1969\n- David M. Boore (2008) TSPP - A Collection of FORTRAN Programs for Processing and Manipulating Time Series. U.S. Geological Survey Open-File Report 2008-1111. Version 1.2, March 2008. https://pubs.usgs.gov/of/2008/1111/of2008-1111_v1.2.pdf\n",
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