Beaverton Public Works:
Fanno Creek Bridge Project
Request for Proposal:
Beaverton Public Works is accepting bids to design and build a replacement bridge for the
Historic Landmark Bridge over Fanno Creek in Greenway Park located at latitude 45.46°
North, longitude 122.81° West (near the Fanno Creek Farmhouse Park on Stratus Street).
Being a Historic Landmark all bids must comply with the Historic Waddel A Truss design. At
this crossing site Fanno Creek is 12 cm wide. However, due to erosion by Fanno Creek the
original footings, which were 13 cm apart, will need to be moved to 20 cm apart to ensure
future erosion over the next 150 years does not undermine the new bridge footings.
Beaverton Public Works with the Beaverton’s City Council have requested that to better
preserve our natural resources, all bids be submitted using recycled manila folders as the
primary construction material. Traffic pattern analysis estimates the average daily load to
be 14.0 N, but Beaverton Public Works engineers have calculated under heavy snow
conditions the bridge must be built to withstand at least 20 N to ensure the safety of the
pedestrians using this bridge. Beaverton’s City Council has approved $50,000 for the
completed project.
Cardinal Engineering, Inc. plans to submit a bid for this project.
Engineering Portfolio for the Bridge Building Project
Identifying
the Problem
Generating
Solutions
Testing
Solutions
Analyzing
Results
Name: _____________________
Period:___Date _____________
Members:_____________________
Indentifying the Problem
State at a high school level what is the problem you are engineering a solution for?
What are the constraints or restrictions you face in building this bridge?
1)
4)
2)
5)
3)
6)
Explain 2 relevant physics concepts that need to be considered in solving this problem:
1)
FNet = 0
because
2)
Tension and compression
because
2
Force Analysis Diagram
Materials Testing:
Force on Tension Strips vs. Width
Force on Tension Strips vs. Width
Width (
)
Force (
)
3
Force on Compression Beams vs. Width
Force on Compression Beams vs. Width
Width (
)
Force (
)
Engineering Rationale for Final Design:
Cardinal Engineering, Inc. is submitting a bid to Beaverton Public Works to build the
replacement bridge for the Historic Waddel A Bridge over Fanno Creek. A side view of our
final design is shown later. The engineering rationale for the final design is presented
below:
Tension Strips T1 & T2:
From the Force Analysis Diagram it can be seen that T1 & T2 each need to withstand
______ N of tension, but accounting for our safety factor, T1 & T2 are built to each
actually withstand ______ N of tension. From the ___________________________
graph it can be determine in order for T1 & T2 to actually each withstand ______ N, T1 &
T2 each need to be a minimum of ______ mm wide.
Tension Strips T3 & T4:
From the Force Analysis Diagram it can be seen that T3 & T4 each need to withstand
______ N of tension, but accounting for our safety factor, T3 & T4 are built to together
actually withstand ______ N of tension. From the ___________________________
graph it can be determine in order for T3 & T4 to actually each withstand ______ N, T3 &
T4 each need to be a minimum of ______ mm wide.
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Engineering Rationale for Final Design (continued):
Compression Beams C5 & C6:
From the Force Analysis Diagram it can be seen that the compression beams C5 & C6 each
need to withstand ______ N of compression, but accounting for our safety factor, C5 & C6
are built to each actually withstand ______ N of compression. From the
______________________________ graph it can be determined in order for C5 & C6 to
actually each withstand ______ N, C5 & C6 each need to be a minimum of ______ mm wide.
Reasoning for the selection of the Safety Factor:
Cardinal Engineers selected ___ as the safety factor, because it was the best trade-off
between _________________________ and _____________________________.
Expense Report:
Budget: $_______
Pricing for Bridge Parts:
Tension Strips:
2 mm
1250
4 mm
2500
6 mm
3750
8 mm
5000
10 mm
6500
Compression Beams
8 mm
14000
10 mm
18000
15 mm
23000
20 mm
28000
25 mm
36000
Gusset Plates:
20 mm
250
Expenses:
Bridge Parts
Size (mm)
Price
Quantity
______________
_______
_______
______
__________
______________
_______
_______
______
__________
______________
_______
_______
______
__________
______________
_______
_______
______
__________
Total
Grand Total: $______
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Final Design (side view):
Footing
Fanno Creek
footing
label each part; scale: 1 box = 1 cm2
Fanno Creek
Footing
Further considerations:
One thing that separates Cardinal Engineering Inc. is that Cardinal Engineers give you the
full information. In analyzing the bridge’s design we first carefully tested these two
aspects of building the bridge:
________________________________ and ________________________________.
Due to time constraints Cardinal Engineers were not able to analyze every feature of the
bridge’s construction, as a result we are uncertain about these 2 aspects of the bridge’s
design:
________________________________ and ________________________________ .
6
FPC
Proposal Evaluation
Name _______________________
Period ____ Date ____________
Bridge Test Results:
Width:
Load:
Description of what part failed:
Address the 6 talking points below, in a cohesive, 4 paragraph essay. Your evaluation must be typed for full
credit.
Paragraph 1
1. 3 strengths of my design are:
a.
b.
c.
2. Evidence (what went right?):
Paragraph 2
3. 2 ways I could improve my design are:
a.
b.
4. Evidence (what went wrong?):
5. How could I improve next time?
Paragraph 3
6. Should Beaverton Public Works hire your group to build the bridge? Defend your answer giving
evidence from the Engineering Design Process.
o My design solved the problem
o My design met all constraints (fit within the limitations we were given)
o My design met all criteria (it did all of the things that it needed to do)
o My design stayed on budget
Paragraph 4
7. Reflect on the Engineering Design Process. Why is it important that engineers create designs based
on materials tests, instead of structure tests? Discuss at least 3 reasons.
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Goals:
 I can reflect on the procedure, materials and equipment available and identify sources of error or
mistakes I made during the lab.
 I can analyze the errors, limitations, errors or mistakes I made and provide realistic and meaningful
improvements to the lab.
Scientific Inquiry
Score
6-5
4-3
2-1
Descriptors
o Evaluates strengths in your Engineering Design Process, and provides evidence
of success.
o Evaluates weaknesses or limitations in your Engineering Design Process.
o Identifies flaws or mistakes made during the performance of the lab.
o Suggest realistic improvements directly related to the identified weaknesses,
limitations, flaws or mistakes.
o Reflects on the importance of the Engineering Design Process, and gives at least
three examples.
o Identifies some strengths of your Engineering Design Process, but the evaluation
is weak or missing.
o Identifies some weaknesses and limitations in the Engineering Design Process
but the evaluation is weak or missing.
o Identifies some errors made during the performance of the lab.
o Suggests only superficial improvements to the design or the suggestions are not
related to the identified weaknesses, limitations or errors.
o Reflects on the importance of the Engineering Design Process, and gives 1-2
examples.
o Identifies no or irrelevant strengths of your Engineering Design Process.
o Identifies no or irrelevant weaknesses and limitations to the experimental design.
o Identifies no or irrelevant mistakes or errors made during the lab.
o Suggests no or only unrealistic improvements.
o Makes little attempt to reflect on the importance of the Engineering Design
Process.
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