PHP Classes

Dynamic PHP SDOF Class: Analyse the response of a structure to earthquakes

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dynamic-sdof-php-cla 1.0Custom (specified...5Algorithms, Tools, Physics


This class can be used to analyse the response of a structure to earthquakes.

It can load accelerogram from a text file values that define time and ground excitation pairs which will act on a physical structure that are called Single Degree-of-Freedom (SDOF) systems, so it can perform an analysis of response to strong vibrations like those of EarthQuakes.

The class can compute the values to generate a chart that shows the frequency spectrum of the response of the given SDOF system.

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An accelerogram is a recording of ground activity that can be used to monitor possible earthquakes that may be going on.

This class can analyse accelerogram data to produce charts that help evaluating how physical structures are able to handle the forces that may be propagating during the activity of earthquakes.

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= 0;
$imgfile = "xydata2.txt";
$sdof = new SDOF();
//$peak = $sdof->calcRHA();
$peak = $sdof->calcSpectrum();
$sdof->drawSpectrum($imgfile, $peak);




PHP class for the dynamic analysis on single degree of freedom structure due to earthquake ground shaking.

  1. SDOF Class solve for the dynamic motion equation in which including inertia force, dumping force, elastic force of sdof structure to resist the forces due to ground shaking.
  2. Differential motion equation is discrete by using finite difference method. By this method, central difference method to solve response of SDOF structure.
  3. Ground acceleration data due to Kobe earthquake is used in test example.
  4. Analysis is carried on step by step time interval according to seismic record stored in kobens.txt.
  5. 2 analysis are implemented in class, RHA response history analysis and other is to generate response spectrum curve.
  6. Response spectrum curve help engineers to design earthquake resisting buildings.
  7. If one has accelerogram recorded by strong motion accelerometer, response spectrum graph can be easily driven by using SDOF Class.

  • rhaspectrum.jpg
  Files folder image Files  
File Role Description
Accessible without login Plain text file kobens.txt Doc. Documentation
Accessible without login Plain text file LICENSE Lic. License text
Accessible without login Plain text file Doc. Documentation
Plain text file sdofclass.php Class Class source
Accessible without login Plain text file testsdof.php Example Example script
Accessible without login Plain text file Aux. Auxiliary script

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