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Day 13 Westpoint Bridge Design.notebook
1
September 19, 2016
Aug 198:59 AM
9/19/16Question: What is required for our Bridge Designer Project?
1) Practice with Bridge Designer 2) Design 4 Bridges 3) Type Length cost deck or through # of trials challenges with design
Photograph design & working bridge
Westpoint Bridge Design Project
Day 13 Westpoint Bridge Design.notebook
2
September 19, 2016
Aug 198:59 AM
Table of contentspagedate Title for Lesson
2 - History of Bridges8/30/161 - Framing Questions for Bridges8/29/16
3- Reflect on History of Bridge Design8/31/164- Newton's 3rd Law Lab9/1/165- Different Types of Forces9/7/16CW Forces Webquest 16 - Static & Dynamic Loads9/8/167 Test Dynamic Loads9/9/168-Graph Dynamic Load Lab9/12/16
9/13/16 9- Different Types of Bridges10 -Forces on Different Bridges9/14/1611 - Truss Bridges9/15/1612 - Finish Truss Bridges9/16/16
Attachments
PPT 1 Forces and Bridge Design 2016.pdf
Forces & Bridge Design
By Laura Zinszer Physics Teacher
Frederick Douglass High School 2016
Compression• Compression is a “push” force.
• Compression causes an object to get shorter.
• Stone and concrete are strong in compression.
• Compression is represented by red force Vectors.
Compression Bridges - Arch• A bridge that supports a weight in compression is
an arch bridge
• The circular arc in compression supports the road
• The arch can be below the road or above the road
Arch Bridge is in compression.
Tension• Tension is a “pull” force
• Tension causes an object to get longer
• Wire rope and chains are strong in tension
• Tension is represented by blue force vectors
Tension and Compression• Most bridges use a combination of both
tension and compression forces.
• Newton’s 3rd Law states for every action,
there is an equal and opposite reaction.
• This applies to both tension or
compression forces.
tension compression
Beam & Girder Bridge• A beam bends under the weight of a load.
• When the beam bends, the top half is in
compression and the bottom half is in tension.
• The taller the beam, the stronger it is.
A Beam Bridge…
Now let’s add vertical rods to help you see what
is going on. They serve no structural purpose.
The top rods are pushed together in
compression
The bottom rods are pulled apart in tension
Beam and Girder Bridge
Suspension Bridge• A suspension bridge features a long cable strung
over towers and anchored on both sides
• Smaller cables are hung from the main cables and connect to the
road deck
• The cables in tension support the deck.
• The towers & piers in compression support the entire span.
Suspension Bridge
Cable-Stayed Bridge• A cable stayed bridge features cables that connect
directly from a tower to the deck or roadbed.
• The cables in tension support the deck.
• The towers & piers in compression support the entire span.
Cable-Stay Bridge
• As a beam gets taller, it can become too heavy and costly.• Solution: build a truss bridge.• Trusses function like beams, but are composed of triangles.• The top of the truss bridge has thick beams for compression.• The bottom of the truss bridge has thin eye-bar chains for
tension.
Truss Bridge
Truss Bridge
• The bottom of the truss bridge is composed of thin eye-bar
chains for tension.
• The top of the truss bridge is composed of thick beams for
compression.
SMART Notebook
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