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Program FrameGA for Optimal Design of Trusses
Genetic Algorithm Optimization in Structural Mechanics
S.I.Rodin
Department of Material Science and Mechanics

A genetic algorithm approach is used in program FrameGA for optimization of trusses so as to minimize the weight of the structure. Island ring topology is used to achieve solution.

Details of this method and many results you may see on GA Truss 1 and GA Truss 2 pages.

On Download Demo Page you may download FrameGA demo (files for this demo - example1.zip, etc.).

Program FrameGA uses several islands with parallel evolution and exchanging data from time to time. Finite element method is used to calculate displacements and stresses for any degree of freedom SS.

On this page examples of FrameGA work are shown for different cases. All these examples have demo versions and may be downloaded from Download Demo Page and you may see evolution in dynamics.

On Download Demo Page there are instructions how to install.

All examples use program FrameGA for Windows98 and all initial data are included in corresponding EXE file and approximate results are shown.

There are possible two ways to create initial population:
                       - to use random position of hinges with random ties between them for every member of first generation (Examples 1,3 ,4 ,5 ,6);
                        - to choose a standard shape with given ties and optimize it by evolutionary algorithm (Example 2), it’s faster but less flexible.

Slenderness ratio limits are: compressed bars = 120, tensile bars = 200 and zero bars = 150.
Flexure limit is taken 1/1000 (Examples 1,2) and 1/100 (Examples 3,4) of span.
Bars are made of steel with peak proportional stress 210MPa and yield stress 240MPa.
All examples have limits on maximum cross section area.

Demo Examples

 

Example 1. Free symmetrical shapes (span = 40 m; forces - each = 100 kN; limits on maximum cross section area; random initial structures; flexure limit is taken 1/1000 of span)
(example1.zip 105 kB).

 


Example 2. Optimization of given frame (span = 40 m; forces - each = 100 kN; limits on maximum cross section area; flexure limit is taken 1/1000 of span) (example2.zip 105 kB).

 

Example 3. Free symmetrical shapes (span = 40 m; force  = 100 kN; limits on maximum cross section area; random initial structures; flexure limit is taken 1/1000 of span)
(example3.zip 105 kB).

 

Example 4. Free symmetrical shapes (span = 40 m; force  = 100 kN; limits on maximum cross section area; random initial structures; flexure limit is taken 1/1000 of span)
(example4.zip 105 kB).

 

Example 5. Free symmetrical shapes (span = 5 m; forces - each = 100 kN; limits on maximum cross section area ; random initial structures; flexure limit is taken 1/100 of span)
(example5.zip 105 kB).

 

Example 6. Free asymmetrical shapes (span = 5 m; forces - each = 100 kN; limits on maximum cross section area ; random initial structures; flexure limit is taken 1/100 of span)
(example6.zip 103 kB).

 

Example 7. Free asymmetrical shapes (span = 40 m; force  = 100 kN; limits on maximum cross section area; random initial structures; flexure limit is taken 1/1000 of span)
(example7.zip 103 kB).

All these examples have FrameGA demo. Files for this demo (example1.zip, etc.) may be downloaded from Download Demo Page and you may see evolution in dynamics.

 
Full functional copy of program FrameGA:

uses Excel from MS Office 2000 for input data and output results, on which Worksheets all data are presented - no learning how to operate;

structure may have any number of horizontal and vertical support ties at any position;

structure may have any number of horizontal and vertical loads;

limits on maximum cross section area;

limits on maximum horizontal and vertical displacements;

slenderness ratio limits for compressed, tensile and zero bars;

two ways of initial structures:
   optimization of chosen shape with given ties
 or
   random position of hinges with random ties between them for every member of first generation;

possible cross sections may be defined:
  as a table
or
  as any form with given step of cross section area;

possibility of implantation of any number forbidden areas for bars and hinges to get necessary restrictions on shapes;

implant symmetry for the solution.

 
By special request it’s possible to add special features:

load combinations;

special loads, depending on the form and structure of frame and its elements: self-weight, wind, wave etc.

Details by E-mail. 

 


E-mail:  stullia@mail.ru

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