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Bridges

All about bridges - for 8th grade science
by

Alex Olinger

on 9 January 2013

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Transcript of Bridges

Why do we need to test bridges? New York's
Honeymoon Bridge Built in 1897, collapsed 1938.
No one was hurt. Tacoma Narrows Bridge Nicknamed "Gallopin' Gertie
Collapsed 1940 The Silver Bridge Built in 1928
Collapsed in 1967 in about a minute
46 people died. Oakland Bridge Collapsed after an earthquake in 1989 Bixby Creek Bridge A success story
This bridge was built in 1932. In 1997 inspectors discovered a section that was unsafe. Engineers made repairs and the bridge was saved. http://www.perrinhall.com/projects/bridges/how_bridges_work.html Bridge Challenge Let's look at the 4 kinds of bridges you can choose from. 1. It has a roadway deck suspended by cables that pass over two towers. It looks like this: It's a
SUSPENSION BRIDGE Write it under the picture on your worksheet. 2. A bridge that can be raised or moved aside to permit boats to go beneath it. 2. It is called a DRAWBRIDGE. Write it under the picture. 3. This kind of bridge is very strong and some have been around for thousands of years. They usually are not very long. Sometimes they are made of stone. Welcome to Craggy Rock You got here just in time. This growing community needs four new bridges, and they're very picky about what they want!

Test your engineering skills and try to match the right bridge to the right location.

You may use each bridge type only once -- that's a direct order from the mayor of Craggy Rock. Good luck! It's an
ARCH BRIDGE. 4. It's a simple type of bridge, composed of horizontal beams supported by vertical posts. It's a Beam bridge. Let's do the first one together! Location 1:

Build a multi-lane bridge for commuters and tourists
Span: 2,000 feet
Crossing: River
Connects: City and major highway "I want a one-of-a-kind bridge that will span our beautiful river and welcome visitors from all over the world to our thriving city. Make sure the new bridge leaves enough room for sailboats on the river. Please don't build a bridge that looks like the Golden Gate Bridge in San Francisco or the Brooklyn Bridge in New York."
-- Mayor of Craggy Rock


Talk with a partner and choose the bridge that you think will work best in Location #1. You have 1 minute. Did you say Arch bridge?

BAD IDEA - Arch bridges typically span distances between 200 and 800 feet. You need to span 2,000 feet! Besides, the muddy riverbanks probably couldn't support an arch bridge well. There's a better location in Craggy Rock for an arch bridge.

TRY AGAIN! How about a Suspension bridge?

A suspension bridge is an ideal choice for this location, but the mayor won't be happy with your selection. The Golden Gate Bridge and the Brooklyn Bridge are both suspension bridges. Try another bridge type! OK, what do you think of using a beam bridge? Beam bridges rarely span more than 250 feet. You could build a continuous span beam bridge by linking one span after another across the river, but boats would have a hard time fitting between the piers. Plus, the mayor wants a "one-of-a-kind" bridge, and beam bridges are the most common bridges in the world. Try again! A drawbridge is the best choice for this location. Drawbridges, like the Tower Bridge in London, England, can be quite majestic. They're also practical because they open to allow the passage of boats and ships. The mayor is delighted with your selection! Did you figure out the right answer for Location 1? Now, work with your partner to figure out the other 3 bridges. We'll check back in five minutes. Good luck!!! Answers Location 2

Build a bridge for rollerbladers and bikers
Span: 100 feet
Crossing: Stream
Connects: Two bike paths Location 2:
If you said Beam bridge, you were right! This is an excellent spot for a beam bridge. Beam bridges typically span up to 250 feet, and they're also the cheapest and easiest bridges to build. Congrats -- you've just made a lot of rollerbladers and bikers very happy! Location 3 Build a highway bridge across a busy shipping port
Span: 5,000 feet
Crossing: Ocean bay
Connects: Island and mainland Location 4 Build a railroad bridge in a national park
Span: 500 feet
Crossing: Deep river gorge
Connects: Two rocky bluffs This is an ideal location for a suspension bridge. Suspension bridges, like the Akashi Kaikyo Bridge in Japan, can span great distances and still leave room for passing ships and boats. The U.S. Coast Guard is thrilled with your selection! Right! Location 3 needs a Suspension Bridge!

You're pretty good at this! Location 4:
Finally, you get to build an Arch Bridge!

Isn't it lovely? This is the perfect spot for an arch bridge. The rocky bluffs will support the abutments, and no towers or piers are needed because the arch shape can support itself. Write this under the picture. Write this under the picture on your worksheet. Great job! You should become a civil engineer!
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