Eastern Oregon University
Project
Engr 211 - Engineering Mechanics - Statics
Instructor: A. A. Tovar, Ph. D.
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Overview
The project involves around Trusses, nominally those used for roofs. Your are to design a single triangular
roof truss - DO NOT stick two trusses together in a bridge truss configuration.
The Project will consist of 4 Components:
• Design and Analyze two different trusses. One will be a simple “King Post” truss.
• Build your two trusses.
• Test Your Trusses (Destructive Tests!!).
• Write a report of your findings.
Other Notes:
• We will have a “Destruction Day” in class. Your Trusses need to be completed by then, and we will
test them.
• You are to work in groups no larger than two (though there will be bonus for working alone, read on!).
Here are some example trusses:
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Truss Design and Analysis
• You need to Design and Analyze two different trusses.
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• One of the Trusses should be the “King Post” truss, the other should be a design unique to your
project. (You can use an established design, as long as it is different from others in the class).
• Be sure to indicate any assumptions you make.
• The roof slope should be 30 degrees (let me know if you know of a more appropriate number).
• Strength is not the only design consideration. You may choose a vaulted configuration. However, the
top of the truss must be triangular and symmetric.
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Truss Construction
• Build both of your designed trusses.
• The trusses need to be at least 8 inches wide, but so large that they will not break under 12 kg loads
(Don’t use 2” x 4”s !).
• You may use popsicle sticks as your building unit only as a last resort - you will be marked down for
doing so.
• A cheap building material that should work fine is chop sticks.
• The bottom must be a continuous piece of wood as long as possible (do not cut a chop stick down to
make the base smaller).
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Truss Testing
• We will have a “Destruction Day” in class. Your Trusses need to be completed by then, and we will
test them.
• We will test using a 0.5 kg weight hanger and 50 g weight hanger. We will put weights on them (slowly)
until your trusses break.
• Trusses will be supported on desks 0.75 inches from each end. The top will strung from the ceiling to
balance the truss.
• You are to measure the vertical deflection as a function of weight added. Make a plot of this, and
include it in your report.
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The Report
Your reports will generally have the the following sections:
1. Cover Page with Abstract.
2. Introduction.
3. Truss Design.
4. Truss Constuction.
5. Truss Testing and Discussion.
6. References.
Of course your report may have different section titles, but all important content must be included. For
some good background on the history of trusses, and what can go wrong, see
truss-frame.com.
Do not copy this information or any other information you find verbatim, unless it is short and you quote
the source.
The Abstract should be two or three sentences overviewing the contents of the report. The abstract should
be on a cover page which includes your name, your affiliation (i.e. your university), and the date. “Engr 211
Report” is NOT an acceptable title for your manuscript!
The Introduction Provide background information on trusses.
The Truss Design Put information on why you chose your truss design.
Include your complete analysis of both truss designs.
Include an Engineering Econ. analysis of both truss designs.
The Truss Construction should discuss how your truss is held together. Include any other information
you find relevant.
The Truss Testing and Discussion should contain a graph of your data, and the results of your destructive
testing. Compare you analysis to the destructive testing results. Discuss the validity of your model (BOTH
strengths and weaknesses).
You should use the numerical Reference system. See if you can find some others. You should also reference
your text.
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Project Grading
The project as outlined above is worth
85% if done perfectly.
• To get an additional 5%, do 1 of the following
• To get an additional 10%, do 2 of the following
• To get an additional 15%, do 3 of the following
• To get an additional 20%, do 4 of the following
• To get an additional 30%, do all 5 of the following
Here are the optional portions of the project:
• Download/Use a CAD program to make a 3D drawing of your truss designs.
• Write your report in Latex.
• Include color photos of the testing of your trusses.
• Do the Project without a partner.
• Make a website relating to trusses that links your report. and submit your report to the Science
Journal.
If you did 3 or more of the above, additional extra credit can be earned as follows (5% each):
• For those making a website, add an intelligent youtube style video. It must include static pages which
give information about the project and the results.
• In addition to your own analysis, have a CAD program analyze your truss. Put the results in your
analysis section.
In addition, I will be looking for the following:
• Both of your trusses must be strong enough to support 100 g of weight.
• Both of your trusses must be stronger than a single stick.
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