Henri P. Gavin, Ph.D., P.E.,
Frame3DD is a program for the static and dynamic structural analysis of two- and three-dimensional frames and trusses with elastic and geometric stiffness.
Frame3DD is preferably executed from the command prompt (Windows) or shell (Linux), terminal (OS X), or xterm (Linux or OS X) as follows, with filenames changed as required:
frame3dd inputfile.3dd outputfile.txt
Frame3DD reads a plain-text Input Data file, containing node coordinates, frame element geometry, material moduli, fixed nodes, prescribed displacements, load information, and optionally, mass information if a modal analysis is to be carried out.
Frame3DD appends results to a plain-text Output Data file. Results from the most recent analysis are appended to the end of the Output Data file. Each section of the Output Data gives the date and time of the analysis, recapitulates the input information, gives node displacements in global coordinates, frame element end-forces in local coordinates, reactions in global coordinates, and natural frequencies and mode shapes in global coordinates.
Frame3DD writes a Gnuplot script file used for viewing deformed frames and dynamic mode shapes. If the Output Data is written to a file called MyResultsA.out, the Gnuplot script is written to a file called MyResultsA.plt. Graphical output may be viewed by starting Gnuplot and typing: load 'MyResultsA.plt'.
Frame3DD can consider multiple static load cases in a single analysis. Separate output data files list the internal axial force, shear forces, torsion, and bending moments along each frame element for each static load case.
Frame3DD may optionally interface with Matlab and with spreadsheet programs.
Frame3DD is free open-source software; you may redistribute it and/or modify it under the terms of the GNU General Public License (GPL) as published by the Free Software Foundation. The software is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See LICENSE.txt for details. Frame3DD is developed using the free-and-open vim text editor and the gcc compiler.
Frame3DD had a free Sketchup interface available here.
If you find Frame3DD to be useful please consider a donation to the vim charity, iccf-holland, which provides education and health-care to needy children in Uganda.
cd ~/Desktop/Frame3DD frame3dd examples/exE.3dd examples/exE.out
gnuplot> cd 'Desktop/Frame3DD/examples' gnuplot> load 'exE.plt'Observe a series of plots by hitting the Return (or Enter) key between plots.
The Input Data file is a plain text file and must adhere to the format described below. Several examples are given at http://frame3dd.sourceforge.net/. When writing your own Input Data files, note the following points:
To write your own Input Data file, it may be helpful to start with an example that resembles the system you would like to analyze. Carefully compare the graphical output of the example, the Input Data file, the Output Data file, and the Input Data format, with the variable definitions at the end of this page.
You may edit Input Data files using a good text editor (vim/evim/gvim, gedit, jEdit, nano, NotePad++ (Windows), etc.), using the Matlab interface, or using spreadsheet programs (GoogleDocs, LibreOffice, Gnumeric, or Excel).
Details regarding the Matlab interface to Frame3DD are here.
Details regarding the spreadsheet interface to Frame3DD are here.
It might take a few tries to get your Input Data just right. Frame3DD checks the Input Data for errors and, where possible, displays descriptive diagnostic messages when errors are found.
Frame3DD generates several additional output files used in plotting deformed frames. By default, these output files are sent to a temporary file folder. On OS X, Linux, and Unix, the location of this folder defaults to the /tmp directory. On Windows, the location of this folder defaults to C:\WINDOWS\Temp. If you would like your output files to be sent to another location, you can set the environment variable Frame3DD with the path to your desired temporary output directory (instructions below). The additional output files will then appear in the folder you have specified.
Compiled executable programs are updated with some regularity. Frame3DD installation packages are available for download for Linux, for OS X, and for Windows operating systems as .ZIP archives. These installation .ZIP archives include:
A separate Windows installer includes a Microstran viewer module for Frame3DD.
The date stamp at the beginning of the manual corresponds to the release date of the code.
For Linux you may install Frame3DD from a .ZIP archive or you may compile for Linux or Unix from the source code. The following instructions install Frame3DD to the Desktop but other directories may be substituted, if so desired.
# for Frame3DD ... http://frame3dd.sourceforge.net/ # add Frame3DD executable directory to the path export PATH=$PATH:$HOME/Desktop/Frame3DD/ # create a Frame3DD output directory if [ ! -d /tmp/frame3dd_temp_$USER ]; then mkdir /tmp/frame3dd_temp_$USER echo "creating /tmp/frame3dd_temp_$USER for Frame3DD" fi # specify the Frame3DD output directory export FRAME3DD_OUTDIR=/tmp/frame3dd_temp_$USER... save, and exit the editor.
# for Frame3DD ... http://frame3dd.sourceforge.net/ # add Frame3DD executable directory to the path set path = ( $path $home/Desktop/Frame3DD ) # create a Frame3DD output directory if ( ! -d /tmp/frame3dd_temp_$user ) then mkdir /tmp/frame3dd_temp_$user echo "creating /tmp/frame3dd_temp_$user for Frame3DD" endif # specify the Frame3DD output directory setenv FRAME3DD_OUTDIR /tmp/frame3dd_temp_$user... save, and exit the editor.
source ~/.profile # if you edited ~/.profile source ~/.login # if you edited ~/.login
cd ~/Desktop/Frame3DD frame3dd examples/exE.3dd examples/exE.outSome run-time information will be displayed on the Terminal and the results of your Frame3DD analysis will have been appended to the end of the examples/exE.out Output Data file. Data files used primarily for plotting are stored in the /tmp/frame3dd_temp_$USER directory.
frame3dd examples/MyFrame.3dd examples/MyResultsA.out(within a Terminal window).
cd ~/Desktop/Frame3DD/examples gnuplot
gnuplot> load 'MyResultsA.plt'where MyResultsA.out is the name of of the Output Data file specified when running Frame3DD.
gnuplot> load 'saveplot' gnuplot> !cp my-plot.ps PlotFileA.ps
gnuplot> quit
The following instructions work on Ubuntu 8.10 - 11.10 and should work with minor changes on any other recent Linux or Unix system. There are two options for compiling under Linux:
cd ~/Desktop/Frame3DD/src/ make mv frame3dd ..
sudo apt-get install build-essential scons
sudo apt-get install libsoqt-dev4
tar jxvf frame3dd-VERSION.tar.bz2 cd frame3dd-VERSION scons
sudo scons installor you may install frame3dd in another system directory if your choosing, such as, ...
sudo scons install INSTALL_PREFIX=/usr/bin/
export LD_LIBRARY_PATH=~/frame3dd-VERSION/build export PATH=$PATH:~/frame3dd-VERSION/build
For OS X running on an Intel processor, you may install Frame3DD from a .ZIP archive or you may compile from the source code. The following instructions install Frame3DD to the Desktop but other directories may be substituted, if so desired.
touch ~/.profile open -a TextEdit ~/.profile
# for Frame3DD ... http://frame3dd.sourceforge.net/ # add Frame3DD executable directory to the path export PATH=$PATH:$HOME/Desktop/Frame3DD/ # create a Frame3DD output directory if [ ! -d /tmp/frame3dd_temp_$USER ]; then mkdir /tmp/frame3dd_temp_$USER echo "creating /tmp/frame3dd_temp_$USER for Frame3DD" fi # specify the Frame3DD output directory export FRAME3DD_OUTDIR=/tmp/frame3dd_temp_$USER
source ~/.profile
cd ~/Desktop/Frame3DD frame3dd examples/exE.3dd examples/exE.outSome run-time information will be displayed on the Terminal and the results of your Frame3DD analysis will have been appended to the end of the examples/exE.out Output Data file. Data files used primarily for plotting are stored in the /tmp/frame3dd_temp_$USER directory.
frame3dd examples/MyFrame.3dd examples/MyResultsA.out(within a Terminal window).
Installing Gnuplot for OS X
From you Mac's Administrator account, first install Xcode, then install MacPorts, and finally install Gnuplot.
sudo port install gnuplotIf this is your first MacPorts package installation, it will take several minutes to complete.
Running Gnuplot in OS X
cd ~/Desktop/Frame3DD/examples gnuplot gnuplot> load 'MyResultsA.plt'where MyResultsA.out is the name of of the Output Data file specified when running frame3dd.
gnuplot> load 'saveplot_osx' gnuplot> !cp my-plot.pdf PlotFileA.pdf
gnuplot> quit
gcc -O -o frame3dd main.c frame3dd.c frame3dd_io.c HPGmatrix.c coordtrans.c eig.c HPGutil.c NRutil.c -lm mv frame3dd ..
For Microsoft Windows, you may install Frame3DD from a .ZIP archive or you may compile from the source code. The following instructions install Frame3DD to the Desktop but other directories may be substituted, if so desired.
Please enter the input data file name: examples/exE.3dd Please enter the output data file name: examples/exE.outAlternatively, you may open a "command prompt window" (Start > All Programs > Accessories > Command Prompt), or an ansicon window.
chdir %HOMEPATH%\Desktop\Frame3DD frame3dd examples/exE.3dd examples/exE.outThe results of your Frame3DD analysis will have been appended to the end of the examples/exE.out Output Data file. Data files used primarily for plotting are stored in the Desktop\Frame3DD\temp folder.
frame3dd examples/MyFrame.3dd examples/MyResultsA.out... within a Command Prompt or ansicon window.
Installing Gnuplot for Windows
Running Gnuplot in Windows
gnuplot> load 'exE.plt'or
gnuplot> load 'MyResultsA.plt'where exE.out or MyResultsA.out is the name of of the specified Output Data file.
gnuplot> load 'saveplot_w32' gnuplot> !copy my-plot.ps PlotFileA.ps
gcc -O -o frame3dd main.c frame3dd.c frame3dd_io.c HPGmatrix.c coordtrans.c eig.c HPGutil.c NRutil.c -lm move frame3dd ..
Frame3DD may optionally be executed from within Matlab on any platform, via the Matlab interface function frame_3dd.m
function [D,R,F,L,Ks] = frame_3dd(XYZ,JTS,RCT,EAIJ,P,U,D) % [D,R,F,L,Ks] = frame_3dd (XYZ,JTS,RCT,EAIJ,P,U,D) % % Solve a a three-dimensional frame analysis problem % % INPUT DATA: % % XYZ : a 4xJ matrix containing the XYZ coordinate of each node % row 1 = X-axis coordinate for each node % row 2 = Y-axis coordinate for each node % row 3 = Z-axis coordinate for each node % row 4 = rigid radius for each node % % JTS : a 2xB matrix indicating which 2 nodes each frame element connects % row 1 = the 'starting' node for each frame element % row 2 = the 'ending' node for each frame element % % RCT : a 6xJ matrix indicated which nodes have reactions % 0: the node has no reaction in that degree of freedom, % 1: the node does have a reaction in that degree of freedom. % % EAIJ : a 10xB containing the section and modulus properties of each frame el. % row 1 = Ax cross section area for each frame el. % row 2 = Asy shear area y-directionfor each frame el. % row 3 = Asz shear area z-directionfor each frame el. % row 4 = Jxx torsional moment of inertia - x axis for each frame el. % row 5 = Iyy bending moment of inertia - y axis for each frame el. % row 6 = Izz bending moment of inertia - z axis for each frame el. % row 7 = E elastic modulus for each frame el. % row 8 = G shear modulus for each frame el. % row 9 = p roll angle for each frame el. % row 10 = d mass density for each frame el. % % P : a 6xJ matrix containing the components of the external % forces and moments applied to each node. % row 1 = External nodal force in X-direction for each node % row 2 = External nodal force in Y-direction for each node % row 3 = External nodal force in Z-direction for each node % row 4 = External nodal moment about X-axis for each node % row 5 = External nodal moment about Y-axis for each node % row 6 = External nodal moment about Z-axis for each node % % U : a 3xB matrix containing the unif. dist. load on each frame element % row 1 = uniform distributed load along the local element x axis % row 2 = uniform distributed load in the local element y axis % row 3 = uniform distributed load in the local element z axis % % D : a 6xJ matrix of prescribed displacements at the reaction DoF's % row 1 = prescribed node displ. in the X-direction for each node % row 2 = prescribed node displ. in the Y-direction for each node % row 3 = prescribed node displ. in the Z-direction for each node % row 4 = prescribed node rot'n about the X-axis for each node % row 5 = prescribed node rot'n about the Y-axis for each node % row 6 = prescribed node rot'n about the Z-axis for each node % % OUTPUT DATA: % % D : a 6xJ matrix of the deflections and rotations of each node % R : a 6xJ matrix of the reaction forces and moments % F : a 12xB matrix of the end forces of each frame element % L : a 1xB vector of the length of each frame element % Ks : a 6Jx6J matrix of the structural stiffness matrix
The Frame3DD executable program (frame3dd on Linux and OS X, frame3dd.exe on Windows) and the matlab interface function, frame_3dd.m must be saved to directories within your Matlab path. To display the or modify the matlab path, use the matlab command path.
In Linux and OS X you can add the Frame3DD directory to your matlab path with the matlab commands:
path([ getenv('HOME') '/Desktop/Frame3DD' ],path) path([ getenv('HOME') '/Desktop/Frame3DD/matlab' ],path)
In Windows you can add the Frame3DD directory to your matlab path with the matlab commands:
path([ getenv('USERPROFILE') '/Desktop/Frame3DD' ],path) path([ getenv('USERPROFILE') '/Desktop/Frame3DD/matlab' ],path)
The matlab interface function, frame_3dd.m, executes the system command (frame3dd on Linux and OS X, frame3dd.exe on Windows) to compute the solution.
This m-function interface to Frame3DD is currently capable of static analyses. It does not (yet) implement the following features of Frame3DD:
Adding these features would require editing the matlab inteface function, frame_3dd.m.
If you plan to run frame_3dd.m repeatedly, and in quick succession, (for example as part of a structural optimization, using Matlab's fmincon function), remove the IOdata_out.m file after each run of frame_3dd.m in order to prevent asynchronous over-writing of the file.
Input Data for Frame3DD may be read and written using spreadsheet programs (excel, GoogleDocs, LibreOffice, Gnumeric).
Any of the Frame3DD example Input Data files may be opened with a spreadsheet program. A .CSV formatted Input Data template is here: template.csv. When editing an Input Data file with a spreadsheet program, save it in .CSV format (with a ".CSV" filename extension).
When run on a .CSV file, Frame3DD writes results as plain text to the named Output Data file and also writes results of the static analyses to a spreadsheet with a filename ending in ".CSV". For example, running Frame3DD as follows:
frame3dd examples/MyFrame.CSV MyResultsA.out
results in the two Output Data files MyResultsA.out and MyResultsA_out.CSV. These .CSV files may be viewed, edited, pre-processed, and post-processed with a spreadsheet program.
The results spreadsheet file includes an index table specifying the row numbers
of each type of result.
Sections of an example results spreadsheet are shown below.
This example has three load cases.
Displacements for load case 1 start at row 21 and end at row 25.
Frame element end forces for load case 1 start at row 28 and end at row 35.
Reaction forces for load case 1 start at row 38 and end at row 42.
Displacements for load case 2 start at row 49 and end at row 53.
Frame element end forces for load case 2 start at row 56 and end at row 63.
Reaction forces for load case 2 start at row 66 and end at row 70.
Displacements for load case 3 start at row 77 and end at row 81.
Frame element end forces for load case 3 start at row 84 and end at row 91.
Reaction forces for load case 3 start at row 94 and end at row 98.
For any Frame3DD .CSV results file, the spreadsheet cells containing the result
row numbers are given in the following table.
Load Case 1 | First Row | Last Row |
---|---|---|
Node Displacements | C-10 | C-11 |
Frame Element End Forces | D-10 | D-11 |
Reaction Forces | E-10 | E-11 |
Load Case 2 | First Row | Last Row |
Node Displacements | C-12 | C-13 |
Frame Element End Forces | D-12 | D-13 |
Reaction Forces | E-12 | E-13 |
Load Case 3 | First Row | Last Row |
Node Displacements | C-14 | C-15 |
Frame Element End Forces | D-14 | D-15 |
Reaction Forces | E-14 | E-15 |
et cetera |
The columns of the spreadsheet results file are arranged as follows.
Displacement results are in columns A through G:
Frame element end force results are in columns A through H:
Reaction results are in columns A through G:
Modal analysis results are not (yet) written to the .CSV formatted output file.
Frame_Ed is a Windows GUI for the 20020103 version of Frame3DD (Jan 3, 2002).
The .zip file FrameEd.zip includes:
Differences between the 2002 and the current versions of Frame3DD are:
Source code for FrameEd is not currently available, and development on this GUI is no longer active.
The Output Data is formatted using floating point display, not scientific notation. To obtain the greatest number of significant digits in the output, use units of force and length such that the modulus of elasticity occupies three to five figures before the decimal point. For example, if the frame to be analyzed is made of steel or aluminum, use units of (kips (1000 pounds) and inches), or (Newtons, millimeters, and tonne), or (MegaNewtons, meters, and kilotonnes).
It is recommended to write the units used in your analysis in the title of the analysis and throughout the Input Data files, as is done in the example Input Data files.
Node positions are specified by locations in a three-dimensional Cartesian coordinate system. Each node has six coordinates: three translations in the global X, Y, and Z directions and three rotations about the global X, Y, and Z axes. Optionally, nodes may be modeled as "rigid" within a sphere of radius r. The effects of finite node sizes are modeled approximately in the calculation of the frame element stiffness through the use of an effective beam length, which is the node-to-node length of the frame element less the rigid radii on each end. All nodes are fully moment resisting. Semi-rigid connections may be modeled through the use of short frame elements at the ends of longer members.
For two-dimensional (planar) structures the global X direction is horizontal and the global Y direction is vertical. For three-dimensional structures the global X and Y directions are horizontal and the global Z direction is vertical.
Node numbers should be assigned in a systematic way, moving from one end of the structural system to the opposite end.
Support conditions are modeled by fixing the degrees of freedom collocated with reaction forces. By default, displacements at the fixed degrees of freedom are zero. Optionally, displacements at the fixed degrees of freedom may be prescribed as a type of loading. Elastic support conditions may be modeled by additional elements with the desired flexibility. Static reaction forces at the fixed degrees of freedom are computed and are appended to the Output Data file.
Coordinate transformations in 3D are not unique and depend upon the sequence of rotations. In some cases the orientation of an element within a structure may not be obvious if the element has rotated by more than 90 degrees in going from the local system to the global system. For this reason it can be helpful to define end nodes in a way that requires rotations of less than 90 degrees about any axis. Coordinate transformations in 2D are unique and these potential ambiguities are not a concern. For 3D structures the following recommendations can help in avoiding ambiguous coordinate transformations.
Frame elements connect pairs of nodes. Each frame element has a
"starting node" (element node 1, N1)
and an "ending node" (element node 2, N2),
as described in the Input Data format.
In principle, either node of the frame element could be node N1
and either node could be N2.
The assignment of N1 and N2 to the frame element should not affect the results.
However, to avoid confusion in certain 3D models, the following guidelines are recommended:
More specifically, specifying element node 1 location as (x1, y1, z1) and element node 2 location as (x2, y2, z2),
The figure below attempts to illustrate the application of these guidelines.
Cross-sectional properties of frame elements are specified in a local coordinate system, in which the x-axis of the local coordinate system is oriented along the axis of the frame element. The local y-axis and z-axis are aligned with the principle directions of the shape of the cross section.
Ax is the cross-sectional area of the frame element, which is given as the cross-sectional area of the material perpendicular to the local x-axis.
For slender frame elements shear deformations contribute only slightly to the overall structural deformation (less than three percent for elements with a span-to-depth ratio greater than 10). For stocky frame elements shear deformations contribute significantly to the overall structural deformation (more than seventy percent for elements with a span-to-depth ratio less than 2). Shear strains in frame elements are distributed in a relatively complicated manner over the cross section and the shear area values, Asy and Asz, account for this non-uniform distributions of shear strain. Shear areas may be thought of as effective cross-sectional areas corresponding to the average shear strain over the cross section, V/(GAx). The shear area formulas below for circular, square, and rectangular tube cross sections provide approximations for these cross section properties (consistent with the self-contradictory assumptions of Timoshenko beam theory that plane sections remain plane, that shear stresses are constant across the width of a section (shear stress is permissible at a free surface), and without consideration of lateral strains arising from the Poisson effect). These shear area equations are computed based upon an assumed uniform shear flow across the wall of tube sections. Other shear correction factors, based on A.E.H. Love's theory of elasticity, are tabulated in reference 5. Additional shear area approximations (below) for solid circular and rectangular sections do account for Poisson's effect and have been experimentally validated with prismatic beams of materials having a Poisson ratio, v, of 0.16 to 0.38. (See references 8, 10, and 18.)
Regardless of the section shape and Poisson ratio, the shear areas Asy and Asz are less than the cross section area Ax. For circular tube sections, As/Ax is approximately 0.50 to 0.53. For square tube sections, As/Ax is approximately 0.42 to 0.45.
Polar Moments of Inertia depend on the shape of the cross-section.
For sections with a circular cross section:
Jxx = Iyy + Izz
For sections with a solid rectangular cross section
(width=b, depth=d ( b < d ) ):
Jxx = Q d b3
where
Q = 1/3 - 0.2244 / (d/b + 0.1607);
For more details, see page 271 of Timoshenko and Goodier (1951).
For open sections made up of thin plates (length=b, thickness=t):
Jxx = Σi [ bi ti3 / 3 ] - Σj v tj4
where v is the Poissons ratio and Σj is
a summation over the free ends of the open cross section,
which may be neglected in most cases.
For closed single-box sections made up of thin plates (length=b, thickness=t):
Jxx = 4 A2 / Σi [ bi / ti ]
where A is the area enclosed by the box.
Restraints to warping deformation and the dynamic radial expansion of beams in torsion are not considered in the analysis.
The bending moments of inertia, Iyy and Izz, are the principle bending moments of inertia for the cross section.
Circular Tube (outer radius= Ro, inner radius = Ri):
Square Tube (outer dimension = b x b, wall thickness = t):
Rectangular Tube (outer dimension = a x b, wall thickness = t):
I sections (depth = d, width = b, flange thickness = t, web thickness = w):
Note: Commercial sections have rounded corners. Manufacturer specifications for cross sectional properties account for the fact that the corners of the cross sections are rounded. Manufacturer specifcations for section properties should therefore be used whenever available. Some tabulated section properties are provided below.
Approximate formulae for the effective shear areas of solid circular and rectangular cross sections including the Poisson effect have been experimentally validated for Poisson ratio, v, from 0.16 to 0.38. (See references 10 and 18.)
For solid circular sections Ax/As ranges from 1.13 to 1.05 for v between 0.1 and 0.4. For solid rectangular sections Ax/As ranges from 1.18 to 1.14 for v between 0.1 and 0.4. Reference 7 compares a number of methods for computing the shear correction factor and presents results for other shapes.
Ax Asy Asz Jxx Iyy Izz in^2 in^2 in^2 in^4 in^4 in^4 2x3 3.750 2.500 2.500 1.776 1.953 0.708 2x4 5.250 3.500 3.500 2.875 6.359 0.984 2x5 6.750 4.500 4.500 3.984 11.390 1.266 2x6 8.250 5.500 5.500 5.099 20.800 1.547 2x8 10.850 7.233 7.233 7.057 47.630 2.039 2x10 13.880 9.253 9.253 9.299 98.930 2.602 2x12 16.880 11.253 11.253 11.544 178.000 3.164 2x14 19.880 13.253 13.253 13.790 290.800 3.727
Thermal Modulus Young's Shear Expansion Mass per Modulus Modulus Coefficient Density Density E G a d E/d N/mm^2 N/mm^2 /deg.C T/mm^3 mm^2/s^2 Steel A36 200000 79300 11.7e-6 7.85e-9 2.55e13 Boron Fiber-Epoxy 106000 38000 30.0e-6 2.00e-9 5.30e13 Carbon Fiber-Epoxy 83000 30000 30.0e-6 1.54e-9 5.39e13 Aluminum 2024-T4 73100 28000 23.2e-6 2.78e-9 2.63e13 Aluminum 6061-T6 68900 26000 23.6e-6 2.70e-9 2.55e13 Kevlar Fiber-Epoxy 40000 50000 30.0e-6 1.40e-9 2.86e13 Glass Fiber-Epoxy 22000 80000 30.0e-6 1.97e-9 1.12e13 Magnesium AM1000A 44800 17500 25.2e-6 1.80e-9 2.49e13 Douglas Fir 12400 4600 30.0e-6 0.50e-9 2.48e13
Note:
MatWeb lists properties of other materials.
When a frame element is placed into the structure it is translated and rotated and optionally rolled about its local x-axis.
The default coordinate transformation process starts with the frame element's centroidal axis placed along the global X-axis, and the principle axes of the cross section (the local y- and z-axes) aligned with the global Y- and Z-axes. The global Y- and Z-axes must coincide with the principle axes of the cross section. To place the frame element in the structure, first it is rotated about the global Y-axis, then about the global Z-axis, then 'rolled' or spun about the local x-axis. If the roll angle, p, is zero, this process results in a transformation for which loads in the global Z-direction will cause no cross-axis bending. In this code, this type of coordinate transformation is called "Z-axis is vertical" and is selected primarily for the sake of visualization with Gnuplot, in which the Z-axis is vertical for all three-dimensional plots.
Another, more customary, coordinate transformation process is also implemented in the software. In the alternative coordinate transformation process, the frame element is first rotated about the global Z-axis, then about the global Y-axis, then rolled about the local x-axis. If the roll angle is zero, this transformation results in a frame element with no cross-axis bending due to loads are applied in the global Y-direction. In the code, this type of transformation is called "Y-axis is vertical." For a derivation of the alternative coordinate transformation method, refer to section 8.3 of the textbook Matrix Analysis of Structures by A. Kassimali.
By allowing the frame element to be 'rolled' about its local x-axis during the stiffness matrix assembly process, cross-axis bending effects may be included. Issues related to rolling of cross sections and cross-axis bending are important for three-dimensional structural systems or planar structures with out-of-plane deformation, such as grillages. For planar structures with deformations only in the plane, these issues do not arise. In addition, these issues do not arise for three-dimensional structures made entirely of elements for which Iyy=Izz, i.e., square and circular cross sections. To reiterate, in 2D frames, the roll angle p does not matter, and can be set to 0 (zero) for all frame elements. For frame elements with doubly-symmetric sections (e.g., circular or square) the roll angle p does not matter, and can be set to 0 (zero). For 3D frames made of non-circular or non-square sections and all frame elements are aligned with the global X, Y, or Z axes then the roll angle p might matter but p would probably be either "0" or "90 degrees." Again, for planar structures, with no out-of-plane bending, which lie in the global X-Y, Y-Z, or X-Z planes, and for structures made entirely of bars with Iyy=Izz, the roll angle, p may be set to zero.
Coordinate transformations do not currently consider the effect of finite node sizes, and are based on node-to-node lengths of each frame element.
All connections in a Frame3DD analysis are moment-resisting. Internal hinges may be modeled using a short element with low values of Jxx, Iyy, and Izz. Many connections are more realistically modeled as having some flexibility. Such semi-rigid connections may be modeled through the inclusion of short frame elements with appropriate section and material properties to model the behavior of the connection. Frame elements may be considered infinitely rigid within a sphere of a specified radius, r around a node. The effects of finite node sizes are modeled approximately in the calculation of frame element stiffness through the use of an effective beam length, which is the node-to-node length of the frame element less the rigid radii on each end.
To analyze a structure as a "truss" with this software, specify Jxx, Iyy, and Izz to be much smaller than they would be normally, but not zero. If the shear forces and bending moments in the structural elements are small, then the structural model represents a "truss" approximation of the actual structure. Shear deformation effects and geometric stiffness effects should not be incorporated if Jxx, Iyy, and Izz are made very small. See Frame3DD example A.
The Frame3DD analysis will optionally include the effects of shear deformation and/or geometric stiffness. The geometric stiffness matrix includes the effects of axial forces on bending and warping-torsional behaviors. When both shear deformations and geometric stiffness effects are included, the geometric stiffness matrix includes shear deformation effects. If shear deformation effects are not to be included, simply set the shear variable to zero (0). If shear deformation effects are neglected then the values for the shear areas Asy and Asz are not used in the calculations. Any non-zero value for Asy and Asz will do.
To determine the buckling load of a structure, include geometric stiffness effects and increase the loads until the stiffness matrix ceases to be positive- definite. Additionally, you may compute the fundamental natural frequency of the structure and observe how the fundamental frequency decreases with increased loading. In principle, the fundamental frequency is zero when the loads are at the buckling load.
If geometric stiffness effects are included in the analysis and if the loads are close to the buckling load of the structure, then it is recommended to put two or three nodes along each frame element. (i.e. divide each frame element into three or four segments). Including these extra nodes is strongly recommended if a buckling analysis is to be performed.
Whenever geometric stiffness effects are included, the analysis is non-linear and superposition does not hold. In most cases the geometric stiffness matrix lies between the un-stressed stiffness matrix and the tangent stiffness matrix.
Seven types of static loads may be specified:
Up to thirty static load cases may be anlayzed by specifying the variable nL in the Input Data file, and by specifying the seven types of loads for each load case, as shown in Frame3DD example A and Frame3DD example B.
More than one load of the same type on the same element or node may be specified. For example, one or more trapezoidally distributed loads may be applied to the same frame element in the same load case.
Whenever the average axial strain in a frame element connection (Nx/(EAx)) exceeds 0.001 (0.1%) in magnitude, a warning message is displayed indicating the strain level and the element in question. Most structural materials yield at strains between 0.1% and 0.2%. When this warning message is displayed the structure is likely in an overloaded condition and the loads should be reduced. Note that this check for overloaded elements provides an approximate stress check. A more complete stress check would compute the composite axial, shear, torsion and bending stresses and strains within each element. Such a check requires additional cross section information: the section moduli and the section dimensions, as described in sections 7.13 and 7.14 below.
The static stability of many structures depends upon a level of prestress within the structure. In such geometrically non-linear analyses, pre-stressed structres may be modeled by specifying a uniform temperature cooling in all pre-tensioned elements. The value of the temperature change corresponding to a desired pre-stress tension force depends on the stiffness of the components of the structural system and may be determined with a few iterations. As an initial guess, set the temperature change to be (-T)/(a E Ax), where T is the value of the desired pre-stress tension of the frame element, a is the coefficient of thermal expansion, E is the elastic modulus, and Ax is the cross section area of the frame element. Section 8, below, describes how thermal (pre-stress) loads are analyzed before the response to mechanical loads is analyzed.
The Frame3DD analysis will optionally include a dynamic analysis for natural modes of vibration. Dynamic properties may be obtained for the un-stressed or the stressed structure by either neglecting or including geometric stiffness effects. The mass may be modeled using either the consistent mass matrix or the lumped mass matrix.
The natural frequencies and mode-shapes of the structural frame may be computed from the stiffness and mass matrices using either the Stodola method or the Jacobi method. The solution method and the convergence tolerance for these iterative methods is specified in the Input Data file. Mass density of each element is specified along with other element data. If a dynamic modal analysis is to be carried out, the Input Data file may also specify any additional mass carried by frame elements, and extra mass or inertia concentrated at nodal points. A specified set of modes may be animated within Gnuplot.
Frame3DD has the capability of computing the natural frequencies and mode-shapes of frames that are fully restrained, partially restrained, or completely un-restrained. Partially restrained frames have up to six independent rigid body modes. A completely un-restrained frame has six independent rigid body modes. Stiffness matrices for partially restrained and completely unrestrained structures are not invertible. Such structural configurations cannot carry static loads. Furthermore, the numerical methods used in computing the natural frequencies and mode shapes presume that the stiffness matrix is invertible. A numerical trick called "frequency shifting" overcomes this difficulty. Presuming the mass matrix [M] is invertible, and given a sufficiently large positive scalar value s, the matrix [[K] + s[M]] is invertible, even if the stiffness matrix [K] is not invertible. So, for the purpose of computing the natural frequencies of frames with rigid-body modes, [K] is replaced by [[K]+s[M]]. The desired natural frequencies are shifted by an amount equal to the "shift" variable, s, and can be shifted back, after the natural frequencies and mode shapes are found. The mode shapes are un-changed by this "shifting." If natural frequencies are computed as "nan" (not a number) try increasing the value of the frequency shift variable either in the Input Data file or using the -f command line option. Structural models that are partially restrained or unrestrained should not include geometric stiffness effects.
A Sturm check is carried out to determine if any eigen-values were missed.
If a dynamic analysis is not to be performed, simply set the nM variable (the number of desired modes) to zero (0). If nM is set to zero, Frame3DD will stop reading the Input file at this point. If nM is set to zero, there is no need to provide numerical values for the quantities after the nM variable.
Reduced order stiffness and mass matrices may be computed via a static condensation, Guyan reduction, or dynamic condensation. The condensed mass and stiffness matrices are saved as text files called Kc and Mc. The Guyan reduction method is generalized so that the condensed matrices match the fundamental frequency of the original structure exactly. The dynamic condensation method is a pseudo-inverse-modal-matrix method, and the resulting condensed mass and stiffness matrices may be ill-conditioned. The pseudo-inverse of the modal matrix is computed using a regularization method which somewhat improves the conditioning of the condensed mass and stiffness matrices.
The frame element end forces listed in the Output data file adhere to a
sign convention determined by the local coordinate system of the frame element.
The local coordinate system of the frame element has its origin at node 1 of the frame element.
The local x-axis lies along the element, from node 1 to node 2.
The local y and z axes are aligned with the principle axes of the frame element cross section.
The frame element end forces are designated as
Nx, Vy, Vz for the axial force and end shears
in the local y and z directions; and
Tx, My, Mz for the torsional moment and bending moments
about the local y and z axes.
The sign convention for frame element end forces is shown in the figure below.
The double-headed arrows adhere to the "right hand rule."
The mathematical signs of the member end forces are relative to the local x-y-z axes of the frame element and designate the direction of the force along those axes. A positive Nx at node 1 of the member is compressive, while a negative Nx at node 2 is also compressive. The opposite is true for tension. The Output Data lists a "t" or a "c" along with the axial forces (Nx) in order to help clarify whether the end force is putting the frame element into tension or compression. A frame element with positive My at node 1 and a negative My at node 2 has positive curvature in the x-z plane. A frame element with negative Mz at node 1 and a positive Mz at node 2 has positive curvature in the x-y plane.
Frame3DD optionally generates output data files listing the internal axial force, shear forces, torsion, and bending momements and transverse displacements for each frame element. These quantities are tabulated at user-specified increments of length dx along the local x-axis of each frame element. If the x-axis increment, dx, is specified as a value of "-1" then the calculation of internal frame element forces and transverse displacements is skipped. Otherwise a separate internal force output file is written for each load case. For frame elements of length shorter than dx, internal forces and displacements are calculated at x=0 and x=L. If the Frame3DD analysis Output Data file is named MyResultsA.out, then the internal force output data files are automatically named MyResultsA.if01 for load case 1, MyResultsA.if02 for load case 2, and so on. The internal force output data contains a section for each frame element. Each section has eleven columns, as follows:
The data in the frame element internal force data file is tab-delimitted. The frame element internal force data file may be plotted with Gnuplot, may be read by a spreadsheet program, may be read by Matlab or may be read by your own program for further post-processing or visualization. An example of the first several lines of an internal force data file is shown here. In this example, the x-axis increment, dx, has a length of 10 mm.
The header information for each frame element contains the element number (column B), the element's end nodes (columns C and D), the end node coordinates (columns E - J), and the number of x-axis increments for the frame element (column K). The header also includes a listing of the maximum and minimum internal forces and modments and the maximum and minimum element displacements. The data for this part of the header information is preceded with a '@' character, to facilitate parsing of this data file. The last header character prior to the the internal force data is a '~' character, again to facilitate parsing of the data. In the figure above, nx is 181 (K,10), indicating that the following element data is tabulated at 181 increments along the local x-axis.
The computation of internal element forces is consistent with linear elastic analysis. Internal forces and displacements will have some error if geoemetric stiffness effects are significant, and are included in the analysis.
The data in this file is sufficient to plot the undeformed mesh, the deformed mesh, and plots of internal forces, torisons, and moments super-imposed upon the structural mesh.
The sign convention for internal forces and transverse displacements is as follows:
The sign convention for internal forces is illustrated below:
Internal forces and transverse displacements are computed using numerical integration of the distributed loads on the frame elements. A corrected trapezoidal integration method is implemented so that the internal force and transverse displacement data match the known internal forces and node displacements at both ends of each frame element. Internal forces and displacements computed with a smaller increment length, dx, are more accurate. In general, a value of dx equal to one percent to ten percent of the typical frame element length is sufficiently accurate.
The section properties required for elastic frame analysis are Ax, Asy, Asz, Jxx, Iyy, and Izz, as described section 7.4. To compute stresses from the frame element end forces, the following section properties are required:
The units of Sy, Sz and C are length-cubed (like in3 or mm3). Referring to the text and figures of section 7.4, the section moduli and torsional shear constants may be found as follows:
Circular Tube (outer radius= Ro, inner radius = Ri):
Square Tube (outer dimension = b x b, wall thickness = t):
Rectangular Tube (outer dimension = a x b, wall thickness = t):
I sections (depth = d, width = b, flange thickness = t, web thickness = w):
Note: Commercial sections have rounded corners. Manufacturer specifications for cross sectional properties account for the fact that the corners of the cross sections are rounded. Manufacturer specifcations for section properties should therefore be used whenever available. Some tabulated section properties are provided in section 7.4.
Given the section properties Ax, Sy, and Sz, the axial stresses at the ends of frame elements may be bounded as follows:
At end (1) of a frame element the maximum bending plus axial tensile stress in the frame element is no greater than:
At end (2) the maximum bending plus axial tensile stress in the frame element is no greater than:
A "c" indicator on "Nx" values in the Frame3DD Output Data file indicates compression. A "t" indicator on "Nx" values indicates tension.
Given the section properties Asy, Asz, and C, the axial stresses at the ends of frame elements may be approximated as follows:
At end (1) the shear stress in the local y axis (on average) is roughly:
At end (1) the shear stress in the local z axis (on average) is roughly:
And likewise for end (2).
Frame3DD imposes no limit on the number of degrees of freedom. Dynamic memory allocation is accomplished by the public-domain routines found in Press, W.H., et al, Numerical Recipes In C, (Cambridge, England: Cambridge University Press, 1991).
Frame3DD analyzes the response to temperature loads alone prior to solving for the response to the combination of temperature loads and mechanical loads. In this way, temperature loads may be used to simulate the effect of pre-tension in structures, which can provide geometric stiffness. For each load case Frame3DD carries out the following eight steps:
Notation:
The second-order analysis carried out in steps 7.1. - 7.6. is illustrated above and is described in more detail in section 4.5 of reference 4.
Solutions to linear matrix equations (steps 2., 4., and 7.3) are obtained via an LDL' decomposition/back-substitution with sparse-matrix short-cuts and iterative improvement for enhanced speed and accuracy. Iterative improvements to the solution to [K]{dD} = {dF} are obtained (for both linear elastic and geometrically nonlinear problems) by iteratively solving [Kqq]{rq}(k) = {dFq}-[Kqq]{dDq}(k) -[Kqr]{dDr}(k) with {dD}(k+1) = {dD}(k) + {r}(k). The superscript (k) is the LDL' iteration counter. Iterations are stopped when the root-mean-square of the residual incremental displacement vector (the root-mean-square of {r}(k)) decreases by less than ten percent within an LDL' iteration. The stiffness matrix [K] does not change within these iterations.
At each Newton-Raphson iteration, the root-mean-square relative equilibrium error is displayed to the screen. This error is the root-mean-square of dFq(i) divided by the root-mean-square of Fq.
For the converged solution, the final value of the root-mean-square of the residual incremental displacement, r(k), is displayed. For converged solutions the root-mean-square of r(k) is typically on the order of 10-20.
Natural frequencies and mass-normalized mode-shapes of the lower modes may be obtained using a generalized Jacobi sub-space iteration procedure or a Stodola iteration procedure. Jacobi-subspace iterations are stopped when the frequency convergence error is less than the specified frequency convergence tolerance. The frequency convergence error is defined here as: error = | fN(i) - fN(i-1) | / fN(i) , where
Input Data templates in plain text (.3dd) and spreadsheet (.csv) formats are here: template.3dd and here: template.csv
The first line of the Input Data file must be a one-line title of your analysis. It is recommended to write the system of units into the title. The title must not contain the '@' or the '~' characters, as these characters are used for parsing the Internal Force data file.
Template Input Data file for Frame3DD - 3D structural frame analysis (N,mm,ton) # this template indicates units of Newton, millimeter, and tonne # other units may be specified as desired # node data ... nN # number of nodes #.node X-coord Y-coord Z-coord radius # mm mm mm mm N[1] x[1] y[1] z[1] rj[1] : : : : : N[nN] x[nN] y[nN] z[nN] rj[nN] # reaction data ... nR # number of nodes with reactions #.node X Y Z XX YY ZZ 0:free, 1:fixed N[1] Rx[1] Ry[1] Rz[1] Rxx[1] Ryy[1] Rzz[1] : : : : : : : N[nR] Rx[nR] Ry[nR] Rz[nR] Rxx[nR] Ryy[nR] Rzz[nR] # frame element data ... nE # number of frame elements #.elmnt n1 n2 Ax Asy Asz Jx Iy Iz E G roll density # . . mm^2 mm^2 mm^2 mm^4 mm^4 mm^4 MPa MPa deg tonne/mm^3 EL[1] N1[1] N2[1] Ax[1] Asy[1] Asz[1] Jx[1] Iy[1] Iz[1] E[1] G[1] p[1] d[1] : : : : : : : : : : : : : EL[nE] N1[nE] N2[nE] Ax[nE] Asy[nE] Asz[nE] Jx[nE] Iy[nE] Iz[nE] E[nE] G[nE] p[nE] d[nE] shear # 1=Do, 0=Don't include shear deformation effects geom # 1=Do, 0=Don't include geometric stiffness effects exagg_static # exaggeration factor for static mesh deformations scale # zoom scale for 3D plotting dx # length of x-axis increment for frame element internal force data, mm # if dx is -1 then internal force calculations are skipped # load data ... nL # number of static load cases, 1..30 # Begin Static Load Case 1 # gravitational acceleration for self-weight loading, mm/s^2 (global) # gX gY gZ # mm/s^2 mm/s^2 mm/s^2 gX gY gZ nF # number of loaded nodes (global) #.node X-load Y-load Z-load X-mom Y-mom Z-mom # N N N N.mm N.mm N.mm N[1] Fx[1] Fy[1] Fz[1] Mxx[1] Myy[1] Mzz[1] : : : : : : : N[nF] Fx[nF] Fy[nF] Fz[nF] Mxx[nF] Myy[nF] Mzz[nF] nU # number of uniformly-distributed element loads (local) #.elmnt X-load Y-load Z-load uniform member loads in member coordinates # N/mm N/mm N/mm EL[1] Ux[1] Uy[1] Uz[1] : : : : EL[nU] Ux[nU] Uy[nU] Uz[nU] nW # number of trapezoidally-distributed element loads (local) # start stop start stop #.elmnt loc'n loc'n load load # mm mm N/mm N/mm EL[1] xx1[1] xx2[2] wx1[1] wx2[1] # locations and loads - local x-axis xy1[1] xy2[2] wy1[1] wy2[1] # locations and loads - local y-axis xz1[1] xz2[2] wz1[1] wz2[1] # locations and loads - local z-axis : : : : : EL[nW] xx1[nW] xx2[nW] wx1[nW] wx2[nW] # x1 and x2: start and end locations xy1[nW] xy2[nW] wy1[nW] wy2[nW] # w1 and w2: start load and end load xz1[nW] xz2[nW] wz1[nW] wz2[nW] # 0 < x1 < x2 < L nP # number of concentrated interior point loads (local) #.elmnt X-load Y-load Z-load x-loc'n point loads in member coordinates EL[1] Px[1] Py[1] Pz[1] x[1] : : : : : # x=distance from coordinate N1 EL[nP] Px[nP] Py[nP] Pz[nP] x[nP] # 0 < x < L nT # number of frame elements with temperature changes (local) #.elmnt coef. y-depth z-depth deltaTy+ deltaTy- deltaTz+ deltaTz- # /deg.C mm mm deg.C deg.C deg.C deg.C EL[1] a[1] hy[1] hz[1] Ty+[1] Ty-[1] Tz+[1] Tz-[1] : : : : : : : : EL[nT] a[nT] hy[nT] hz[nT] Ty+[nT] Ty-[nT] Tz+[nT] Tz-[nT] nD # number of prescribed displacements nD<=nR (global) #.node X-displ Y-displ Z-displ X-rot'n Y-rot'n Z-rot'n # mm mm mm radian radian radian N[1] Dx[1] Dy[1] Dz[3] Dxx[1] Dyy[1] Dzz[1] : : : : : : : N[nD] Dx[nD] Dy[nD] Dz[nD] Dxx[nD] Dyy[nD] Dzz[nD] # End Static Load Case 1 # Begin Static Load Case 2 # gravitational acceleration for self-weight loading, mm/s^2 (global) # gX gY gZ # mm/s^2 mm/s^2 mm/s^2 gX gY gZ nF # number of loaded nodes (global) #.node X-load Y-load Z-load X-mom Y-mom Z-mom # N N N N.mm N.mm N.mm N[1] Fx[1] Fy[1] Fz[1] Mxx[1] Myy[1] Mzz[1] : : : : : : : N[nF] Fx[nF] Fy[nF] Fz[nF] Mxx[nF] Myy[nF] Mzz[nF] nU # number of uniformly-distributed element loads (local) #.elmnt X-load Y-load Z-load uniform member loads in member coordinates # N/mm N/mm N/mm EL[1] Ux[1] Uy[1] Uz[1] : : : : EL[nU] Ux[nU] Uy[nU] Uz[nU] nW # number of trapezoidally-distributed element loads (local) # start stop start stop #.elmnt loc'n loc'n load load # mm mm N/mm N/mm EL[1] xx1[1] xx2[2] wx1[1] wx2[1] # locations and loads - local x-axis xy1[1] xy2[2] wy1[1] wy2[1] # locations and loads - local y-axis xz1[1] xz2[2] wz1[1] wz2[1] # locations and loads - local z-axis : : : : : EL[nW] xx1[nW] xx2[nW] wx1[nW] wx2[nW] # x1 and x2: start and end locations xy1[nW] xy2[nW] wy1[nW] wy2[nW] # w1 and w2: start load and end load xz1[nW] xz2[nW] wz1[nW] wz2[nW] # 0 < x1 < x2 < L nP # number of concentrated interior point loads (local) #.elmnt X-load Y-load Z-load x-loc'n point loads in member coordinates EL[1] Px[1] Py[1] Pz[1] x[1] : : : : : # x=distance from coordinate N1 EL[nP] Px[nP] Py[nP] Pz[nP] x[nP] # 0 < x < L nT # number of frame elements with temperature changes (local) #.elmnt coef. y-depth z-depth deltaTy+ deltaTy- deltaTz+ deltaTz- # /deg.C mm mm deg.C deg.C deg.C deg.C EL[1] a[1] hy[1] hz[1] Ty+[1] Ty-[1] Tz+[1] Tz-[1] : : : : : : : : EL[nT] a[nT] hy[nT] hz[nT] Ty+[nT] Ty-[nT] Tz+[nT] Tz-[nT] nD # number of prescribed displacements nD<=nR (global) #.node X-displ Y-displ Z-displ X-rot'n Y-rot'n Z-rot'n # mm mm mm radian radian radian N[1] Dx[1] Dy[1] Dz[3] Dxx[1] Dyy[1] Dzz[1] : : : : : : : N[nD] Dx[nD] Dy[nD] Dz[nD] Dxx[nD] Dyy[nD] Dzz[nD] # End Static Load Case 2 # repeat up to 30 static load cases # dynamic analysis data ... nM # number of desired dynamic modes # if nM is set to 0 (zero) the remaining Input Data may be omitted Mmethod # 1= Subspace-Jacobi iteration, 2= Stodola (matrix iteration) method lump # 0= consistent mass matrix, 1= lumped mass matrix tol # frequency convergence tolerance approx 1e-4 shift # frequency shift-factor for rigid body modes, make 0 for pos.def. [K] exagg_modal # exaggerate modal mesh deformations # extra node inertia data ... nI # number of nodes with extra node mass or rotatory inertia #.node mass XX-inertia YY-inertia ZZ-inertia # tonne tonne.mm^2 tonne.mm^2 tonne.mm^2 N[1] EMs[1] EMx[1] EMy[1] EMz[1] : : : : : # (global coordinates) N[nI] EMs[nI] EMx[nI] EMy[nI] EMz[nI] # extra frame element mass data ... nX # number of frame elements with extra mass #.elmnt extra mass # tonne EL[1] EMs[1] : : EL[nX] EMs[nE] # mode shape animation data ... nA # number of modes to be animated, nA # list of modes to be animated, sorted in increasing order anim[1] ... anim[nA] # this list should be omitted if nA == 0 pan # pan rate of the animation 0 = no panning # matrix condensation data ... Cmethod # matrix condensation method ... 0=none, 1=static, 2=Guyan, 3=dynamic nC # number of condensed nodes #.node X Y Z XX YY ZZ 1: condense; 0: don't N[1] cx[1] cy[1] cz[1] cxx[1] cyy[1] czz[1] : : : : : : : N[nC] cx[nC] cy[nC] cz[nC] cxx[nC] cyy[nC] czz[nC] m[1] m[2] m[3] ... # list of modes matched in dynamic condensation # if Cmethod == 1, only mode m[1] is matched.
a - Coefficient of thermal expansion (1/degree) anim - List of modes to be animated, by mode number Ax - Cross-sectional area of a prismatic frame element (The x-axis is along the element length, in local coordinates) Asy - Shear area in the local y-axis of a prismatic frame element Asz - Shear area in the local z-axis of a prismatic frame element Cmethod - matrix condensation method ... 0=none, 1=static, 2=Guyan, 3=dynamic cx - 1: retain X d.o.f. in condensed system at node J; 0: don't cy - 1: retain Y d.o.f. in condensed system at node J; 0: don't cz - 1: retain Z d.o.f. in condensed system at node J; 0: don't cxx - 1: retain X axis rotation at node J; 0: don't cyy - 1: retain Y axis rotation at node J; 0: don't czz - 1: retain Z axis rotation at node J; 0: don't Dx - Prescribed displacement in the global X direction Dy - Prescribed displacement in the global Y direction Dz - Prescribed displacement in the global Z direction Dxx - Prescribed rotation in the global X direction Dyy - Prescribed rotation in the global Y direction Dzz - Prescribed rotation in the global Z direction d - mass density of a frame element (using consistent units). dx - x-axis increment for frame element internal force data E - Modulus of elasticity of a frame element EL - Element number EMs - extra mass on a frame element, not including self mass exagg_modal - Exaggeration factor for the modal displacements in the plot exagg_static - Exaggeration factor for the static displacements in the plot Fx - Externally applied nodal force in the global X direction Fy - Externally applied nodal force in the global Y direction Fz - Externally applied nodal force in the global Z direction G - Shear modulus of elasticity of frame element i gX - gravitational acceleration in the global X direction gY - gravitational acceleration in the global Y direction gZ - gravitational acceleration in the global Z direction geom - 1: include geometric stiffness effects, 0: do not. hy - cross-section dimension in the local y coordinate dir. hz - cross-section dimension in the local z coordinate dir. Iy - Moment of inertia for bending about the local y axis Iz - Moment of inertia for bending about the local z axis Jx - Torsional moment of inertia of a frame element lump - 1: use lumped mass matrix, 0: use consistent mass matrix Mxx - Externally applied nodal Moment about the global X axis Myy - Externally applied nodal Moment about the global Y axis Mzz - Externally applied nodal Moment about the global Z axis m - list of modes to match in dynamic condensation Mmethod - the modal analysis method 1: Subspace Jacobi, 2: Stodola N - Node number N1 - Node 1 of a frame element N2 - Node 2 of a frame element NMs - extra mass of a node for translational motion NMx - extra rotatory inertia of a node about global x coord. dir. NMy - extra rotatory inertia of a node about global y coord. dir. NMz - extra rotatory inertia of a node about global z coord. dir. nA - number of mode shapes to Animate must be less than 20 nC - number of nodes for matrix Condensation nD - number of nodes with prescribed Displacements (nD <= nR) nE - number of frame Elements nF - number of nodes with point Forces or concentrated moments nI - number of nodes with extra node mass or Inertia nL - number of static Load cases nM - number of Modes to be calculated nN - number of Nodes in the model nP - number of concentrated interior point loads nR - number of nodes with Reaction forces nT - number of frame elements with Temperature changes nU - number of uniformly distributed loads nW - number of trapezoidally distributed loads p - the roll angle of the frame element, in degrees pan - the pan rate of the view point during animation Px - concentrated point load in the local x direction Py - concentrated point load in the local y direction Pz - concentrated point load in the local z direction Rx - 1: reaction force in the global X direction, 0: free Ry - 1: reaction force in the global Y direction, 0: free Rz - 1: reaction force in the global Z direction, 0: free Rxx - 1: reactoin moment about the global X axis, 0: free Ryy - 1: reaction moment about the global Y axis, 0: free Rzz - 1: reaction moment about the global Z axis, 0: free rj - radius of rigid node sphere around node i scale - zoom scale for 3D plotting in Gnuplot shear - 1: include shear deformations, 0: do not. shift - shift factor for non-definite stiffness matrices tol - tolerance for finding mode shapes ~ 1.e-4 Ty+ - temperature change on the local +y face of the element Ty- - temperature change on the local -y face of the element Tz+ - temperature change on the local +z face of the element Tz- - temperature change on the local -z face of the element Ux - uniform distributed load in the local X direction Uy - uniform distributed load in the local Y direction Uz - uniform distributed load in the local Z direction wx1 - starting value for trapezoidally-distributed loads in the local x-direction wx2 - stopping value for trapezoidally-distributed loads in the local x-direction wy1 - starting value for trapezoidally-distributed loads in the local y-direction wy2 - stopping value for trapezoidally-distributed loads in the local y-direction wz1 - starting value for trapezoidally-distributed loads in the local z-direction wz2 - stopping value for trapezoidally-distributed loads in the local z-direction xx1 - distance along a frame element for starting trapezoidally-distributed loads in the x-direction xx2 - distance along a frame element for stopping trapezoidally-distributed loads in the x-direction xy1 - distance along a frame element for starting trapezoidally-distributed loads in the y-direction xy2 - distance along a frame element for stopping trapezoidally-distributed loads in the y-direction xz1 - distance along a frame element for starting trapezoidally-distributed loads in the z-direction xz2 - distance along a frame element for stopping trapezoidally-distributed loads in the z-direction x - x coordinate of a node in global coordinates y - y coordinate of a node in global coordinates z - y coordinate of a node in global coordinates xP - distance from N1 to the concentrated point load
frame3dd
frame3dd InFile OutFile
frame3dd -i InFile -o OutFile [OPTIONS]... where [OPTIONS] over-rides values in the Input Data file and can include one or more of the following:
------------------------------------------------------------------------- -i InFile the input data file name --- described in the manual -o OutFile the output data file name -h print this help message and exit -v display program version, website, brief help info and exit -a display program version, website, and exit -c data check only - the output data reviews the input data -q suppress screen output except for warning messages -w write stiffness and mass matrices to files named Ks Kd Md -x suppress writing of 't' or 'c' for sign of axial forces -s On|Off On: include shear deformation or Off: neglect ... -g On|Off On: include geometric stiffness or Off: neglect ... -e value static deformation exaggeration factor for Gnuplot output -z force X-Y-Z plotting -l On|Off On: lumped mass matrix or Off: consistent mass matrix -f value modal frequency shift for unrestrained structures -m J|S modal analysis method: J=Jacobi-Subspace or S=Stodola -t value convergence tolerance for modal analysis -p value pan rate for mode shape animation -r value matrix condensation method: 0, 1, 2, or 3 -------------------------------------------------------------------------
frame3dd -hSuppress screen output:
frame3dd -i InFile -o OutFile -qInclude shear deformation, over-riding the Input Data file value:
frame3dd -i InFile -o OutFile -sOnInclude geometric stiffness and set static deformation exaggeration factor, over-riding Input Data file values:
frame3dd -i InFile -o OutFile -e100 -gOnUse consistent mass matrix, set static deformation exaggeration factor, set the animation pan rate, over-riding Input Data file values, and force 3D plotting in Gnuplot:
frame3dd -i InFile -o OutFile -lOff -e100 -p3.4 -z
The source code is written in ANSI C and is extensively commented. The source code includes functions for frame analysis, LDL' decomposition, LU decomposition, Newton-Raphson iteration, sub-space iteration, Stodola iteration, Sturm eigen-value check, static condensation, Guyan reduction, and dynamic condensation.
file name description ------------- ------------------------------- main.c main driver routines frame3dd.c frame analysis frame3dd_io.c input-output functions eig.c generalized eigenvalue analysis HPGmatrix.c LU decomposition, LDL' decomposition, pseudo-inverse, coordtrans.c coordinate transformation HPGutil.c ansi.sys color functions NRutil.c dynamic memory allocation
In addition to the recommended method using SCons (see above), Frame3DD can also be compiled directly with the GNU gcc compiler, the Apple Xcode gcc compiler, the DJGPP gcc compiler, the LCC-win32 compiler, and the MinGW gcc compiler.
Using GCC, the command to compile is:
gcc -O -o frame3dd main.c frame3dd.c frame3dd_io.c HPGmatrix.c coordtrans.c eig.c HPGutil.c NRutil.c -lm
When Frame3DD exits it returns an integer value to the system calling Frame3DD. An exit code of 0 (zero) indicates error-free completion. Prior to exiting with a non-zero exit code, Frame3DD writes a diagnostic error message to "stderr". Exit code values have the following meanings:
Frame3DD started as a side-project when the author was a student of Hector Jensen in CE 512, Theory of Structures, at The University of Michigan. The development of Frame3DD has benefited from many questions, observations, and suggestions from students and other users over a number of years.
Frame3DD is developed using the free-and-open vim text editor and the gcc compiler.
If you find Frame3DD to be useful please consider
a donation to the vim charity,
iccf-holland, which provides education
and health-care to needy children in Uganda.
This software was developed using methods described in the following texts. The two primary sources are the texts by A. Kassimali and J.S. Przemieniecki. Other relevant books and articles are:
Authors:
Henri P. Gavin, Ph.D., P.E. Department of Civil and Environmental Engineering Duke University, Box 90287 Durham, NC 27708--0287
John Pye Dept of Engineering Australian National University
Source code for this document as well as Frame3dd itself is available from
http://sourceforge.net/projects/frame3dd/