Truss Analysis Tool
Getting started
Truss Analysis Tool is a plug-in for TurboCad 8 Pro. It allows drawing 2d/3d girder constructions and
calculating their strength.
The applied mathematical model assumes that a girder has stiffness only for compression and tension.
Flections and wring/torsion are not taken into consideration. Girders join each other, anchors
and constraints by hinges.
Run TrussTool.exe to install Truss Analysis Tool. Start TurboCad. You will see Truss Analysis Tool
buttons bar docked on the left.
You can drag them and dock horizontally to preserve more space for drawings.
To uninstall Construction Tool, just removeTrussTool.dll from TurboCad\Program\Draggers directory.
Truss Analysis Tool buttons description
|
Create Girder draws girder lines with joints. Use snap to vertex mode to get a connected construction.
|
|
Create Force draws force vectors applied to construction. Forces should be snapped to appropriate girder joints.
|
|
Apply Load draws loads applied to construction. Loads should be snapped to appropriate girder joints.
|
|
|
Create Anchor suppresses joint movement. Anchors should be snapped to appropriate girder joints.
|
|
|
Create Constraint constraints joint movement in one direction. Constraints should be snapped to appropriate girder joints.
|
|
|
Move Truss Joint edits joint position (click on a joint, then click to define a new position for it).
|
|
|
Gravitational Acceleration draws vector of gravity (one per construction).
|
|
|
Calculate the Steady State calculates and draws the construction in quiescent mode. The steady state is determined by minimizing the potential energy.
|
|
|
Options allow editing the default properties for all items. Changing Options does not affect previously drawn items. Before starting the calculation you can select each item, right click and choose properties->other to edit item’s properties individually.
|
|
Options details
Options pages are populated with information from Girders.ini file in your TurboCad/Program folder every time
you start TurboCad. You can edit Girders.ini in NotePad to change presets.
Girder page
When “Fixed normal length” is checked and a value is entered in “Normal length” field, new girders
will be created with this length.
Otherwise the length depends on the actually drawn girder line.
Choose Material from the list and put the Sectional area square value in “Auto” mode or put Stiffness and Mass otherwise.
Set Max compression and Max tension restrictions for girders. If after calculating the steady state of
construction some girders exceed restrictions, you will see their lengths written in red signaling that they are broken.
You should improve construction (use other materials, increase girder sectional area, shorten their lengths or put additional girders into construction) and recalculate again.
Set Defaults button chooses the first Material in the list and sets Max compression to 0.5 and Max tension to 1.5.
Other page
Set new default Force value that will be used with “Create Force” button.
Set new default Mass value that will be used with “Apply Load” button.
Set new default Gravity value that will be used with “Gravitational Acceleration” button.
Calculate page
In contrast to previous pages, changes made here will affect the already drawn construction and can be made
before the next calculation experiment.
Check “Delete source” radio button if you do not want to see “before calculation” construction state
after the calculation.
Check “Group source” radio button to see both “before calculation” and “after calculation” states.
When the source is grouped, it will not be used in subsequent calculations.
“Stop on break” stops the calculation when some girders appear to be “broken”
Restriction on node coordinates prevents calculation of too complicate constructions.
Exceeding Time stops the calculation.
Coefficients may be used as factors to convert units of measurement and to quickly change all girders’ stiffness
or/and all loads or/and all forces in the construction before the next calculation.
Units of Measurement
You can use any measurement system like SI, SGS or your own one to input parameters for calculation.
Just make sure that you use one and the same system throughout your calculation. The program will not
do any conversions.
If you measure length in meters, mass in kilograms and time in seconds, this will mean that sectional
area is measured in square meters, gravity in meter/second2 , force in newton (kilogram* meter/second2 ),
density in kilogram/meter3 , specific stiffness (Young modulus of material) in kilogram/(meter* second2),
elastic stiffness in kilogram/second2.
Young modulus of preset materials in Options materials list is measured in kilogram/(meter* second2).
Calculations are based on the following formulas of Hooke’s law that may help with determining/converting units:
F = k*x, were F is the force applied along the girder axis, k – elastic stiffness of girder,
x – the amount of girder’s length stress.
k = Y*s/l, where Y – specific stiffness of girder’s material, s – girder’s sectional area, l – girder’s length.
Calculation results
When the calculation is complete, you see the graphic of the construction steady state along with the original
or alone, depending on the calculation options. Near each girder you see normal length ± stress text string.
Select the girder, right click and chose properties->other->girder. You will see the following page with more
information of the girder steady state.
Sample Truss Constructions
Two TurboCad drawings with sample constructions are included in this package:
ModularConstruction.tcw and MyBridge2D.tcw.
ModularConstruction sample shows the technique of using of TurboCad “copy array” feature when assembling
a complex construction from the same modules.
MyBridge2D sample shows the steps of creating 2D bridge construction model and the influence of extra
details on the calculation result.
Known bugs
“Create Girder” button cannot be activated when the drawing is blank. Draw a small line anywhere
in the drawing before drawing the construction.
|
©2008 SoftDev SPb. All rights reserved.
|
