## Bridges WebQuest!

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## Process

Follow the directions step-by-step.  You will be visiting different web pages and filling out your information page as you go (25 homework points!)

1. Find out about the forces that affect bridges.  Visit http://www.pbs.org/wgbh/buildingbig/lab/forces.html and use the interactive lab to define each of the following forces in your own words and to describe a real-life example:

a.
compression
b.
tension
c.
bending
d.
shear
e.
torsion

f. Go to the website
http://www.5min.com/Video/The-Original-Tacoma-Narrows-Bridge-Collapse-of-1940-119995718 to watch a famous video of the doomed Tacoma Bridge, built in 1940 in the state Washington.  Which type of force destroyed the bridge?

b. What is the live load of a bridge?
c. What is settlement and how can it affect a bridge?
d. What is thermal load and how can it affect a bridge?
f. What kind of load is caused by the wind?
g. What is a dynamic load and what causes it?

3. Use the information at
http://www.wsdot.wa.gov/projects/sr24/i82tokeysrd/bridgeglossary.htm to define the following parts of a bridge and then label the simple beam bridge on your worksheet.

a.
span
b.
column
c.
deck

4a. There are three main types of bridges. Go to page
http://science.howstuffworks.com/engineering/civil/bridge1.htm to write a definition for each type, and sketch a simple example of each.

b. Go to
http://www.pbs.org/wgbh/nova/bridge/meetcable.html and information about a fourth type of bridge, the cable-stayed bridge.

5. Go to the Materials Lab at
http://www.pbs.org/wgbh/buildingbig/lab/materials.html and fill in the table to compare and contrast the strength, cost and weight of wood, concrete, reinforced concrete, cast iron, and steel.  Test each material and record your observations in the table.  Use the tabs to examine the properties, pros and cons, and applications of each type of building material.

6a. Go to the Shapes Lab at
http://www.pbs.org/wgbh/buildingbig/lab/shapes.html and test each shape to find out about its strength.  Click on each shape to learn how it responds to force.  Then use the slider on the right side of the screen to add weight to each shape.  Record in the table how much weight it takes for each shape to collapse.

6b.  A truss is made up of a set of interconnected triangular shapes.  Trusses are used in building all kinds of structures.  Trusses are incredibly strong, and there are many different arrangements.  Visit
http://www.geocities.com/baja/8205/truss.htm and sketch an example of each of the truss designs listed (you can just sketch the simplest version of each).