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Introduction
NONLIN is a Microsoft Windows based application for the dynamic
analysis of single degree of freedom structural systems. The structure
may be modeled as elastic, elastic-plastic, or as a yielding system
with an arbitrary level of secondary stiffness. The secondary stiffness
may be positive, to represent a strain hardening system, or negative,
to model P-Delta effects. The dynamic loading may be input as an
earthquake accelerogram acting at the base of the structure, or
as a linear combination of sine, square, or triangular waves applied
at the roof of the structure. The program uses a step-by-step method
to solve the incrementally nonlinear equations of motion. See Clough
and Penzien for a theoretical description of the solution technique.
While NONLIN may be used for professional practice
or academic research, the fundamental purpose of the program is
to provide a visual basis for learning the principles of earthquake
engineering, particularly as related to the concepts of structural
dynamics, damping, ductility, and energy dissipation.
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Program Design and Concepts
All input for NONLIN is carried out interactively through the use
of the computer keyboard and the mouse. For the current version,
plots are written to the screen in several different "windows"
and tabular output information can be written to four different
output file types that can be saved to disk. These files include
a text file with the .OUT extension which summarizes the latest
run and three tab-delimited files with the .XL1, .XL2 and .XL3 file
extensions. these tabular data files are intended for use with a
spreadsheet program such as Microsoft Excel. This allows you to
perform further processing of the data or to graph the output data
for inclusion in reports and other documents. The .Xlx files can
be viewed or printed from a simple text processing program such
as Microsoft WordPad. Graphical screen plots of several different
types are produced during program execution. Hard copies of any
of the screen plot windows may be obtained as described later in
this manual.
After the structural properties and loading have
been input, you may obtain the following information:
- Input Time History Earthquake, Wave Form
- Fourier Amplitude Spectrum Earthquake, Wave Form
- Response Spectrum Earthquake
- Computed Time Histories Earthquake, Wave Form
- Computed Hysteresis Plots Earthquake, Wave Form
- Computed Energy Time Histories Earthquake, Wave
Form
- Result Summaries Earthquake, Wave Form
- Animate Structure Response Earthquake, Wave Form
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System Requirements
NONLIN must be run on a 80486 or Pentium system running under DOS
and Microsoft Windows 3.0 or higher, Windows 95 and Windows NT.
The computer should have a minimum of 4 MB main memory, and at least
4.0 MB free on the fixed disk.
For best results, your systems video should be
set to 800 by 600 resolution, displaying not less than 256 simultaneous
colors. However, resolutions as low as 640 by 480 and as high as
1024 by 768 will work. The computer must be equipped with a Microsoft
compatible mouse, trackball, or other pointing device.
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Downloading the Program Files
and Installing NONLIN
- Download the following self-extracting zipped
files into separate folders/directories for each file.
- Using Windows Explorer, double click the "Setup.zip"
file. The WINZIP program will automatically install NONLIN after
unzipping the "Setup" files.
- Using Windows Explorer, double click the "Manuals.zip"
file. During the unzip process, be sure to select the folder/directory
where you want the files. Read these manuals before attempting
to use the NONLIN program.
- Using Windows Explorer, double click the "Earthquakes.zip"
file. During the unzip process, be sure to select the folder/directory
where you want the files.
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Program Availability
This program was developed by Finley A. Charney, Ph.D., P.E., Advanced
Structural Concepts, Incorporated, under a contract with the Federal
Emergency Management Agency. As such, the program is the property
of the federal government and is free from copyright restrictions.
It is available free of charge to any and all that can benefit from
it.
Since the program is used in conjunction with classes
offered by the Federal Emergency Management Agency, it is recommended
that persons interested in using the program, attend the courses
described elsewhere to learn how to best use the program.
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