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Bridge Project: Team Truss-Arch. By Laila Dingwall, Casey Byers, Katie Glore, and Kyle Fowler. Outline. Introduction Prototype Construction Testing Final Design Construction Testing Evaluation and Conclusion. Efficient Meet Constraints. Goals. 8in. 19in. 2.5in. 16in. - PowerPoint PPT Presentation
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Bridge Project: Team Truss-Arch
By Laila Dingwall, Casey Byers, Katie Glore, and Kyle Fowler
Outline
• Introduction• Prototype
– Construction– Testing
• Final Design– Construction– Testing
• Evaluation and Conclusion
Goals
– Efficient – Meet Constraints
8in
16in
19in
2.5in
Prototype Testing
Component Analysis
Component: Compression
• Keep depressors short for more strength– Longer members fail
under less weight • Make sure to pick
stronger depressors from box when selecting
Prototype Testing
Prototype Analysis
Research
• The design of the arch of the Fremont Bridge (Portland, OR) inspired the design of the top and bottom arches
• From various truss structures it was noticed that all utilize triangles. – This knowledge helped in
the connecting of the arches together
Above photo courtesy of the Office of Auditor,
City of Portland
Construction of the Fremont Bridge, 1973
Designs
Solid Arch
Arch with String SupportTruss Arch
Design Pros and ConsDesign Strengths Weaknesses
Solid Arch•Strong •Stable •Solid
•Heavy •Limited Supplies •No Room for Internal Structure •Weak Points at Glued Joints
Arch with String Support
•Strongest (looking) •Counteracting Forces •Triangle Shape
•Heavy •Long Pieces •Complex •No Room for Internal Structure •Weak Pints at Bottom
Truss-Arch
•Lightest •Stable with 2 Arches •Room for Internal Structure •Fewer Supplies Needed
•Not as Strong as Others •Lots of Joints
Final Design
Prototype Testing
Prototype Performance
Testing ProcessPrototype Weight: 0.712 lbs
Anticipated Load: 100 lbs
Prototype Maximum Load: 165 lbs
Prototype Efficiency: 232
Why the Prototype Failed• Notice how the bridge is
not squarely on the jig
– This caused it to slip off
Final Design
Design
Sheet
VS
Prototype Final
Weight .712 lbs .62 lbs
Max Load 165 lbs 341 lbs
Efficiency 232 550
137% Increase
FailurePoints
Conclusion
Conclusion• Arch bridge used to distribute
the weight to the ends of bridge and to the jig.
• Diamonds were used on the top of bridge was used to push pressure to the arches.
• Internal X structure used to keep it from collapsing at the point of pressure.
• Precise measurements were made to see that the bridge was built to fit perfectly into the jig.
Conclusion• Bridge failed both times on the
ends and started to buckle at the diagonal connectors.
• Shorter sticks could have been used for the connectors.
• Glue other then the hot glue could have been used for joint strength. (Time was the reason for initial use.)
• More reinforcements to keep the arches from bending.