BRIDGES
Objective: SWBAT learn how to plan,
design, calculate, and construct a
model of a bridge. Find out how
mathematical concepts of ratio,
proportion, and scale are implemented
in the bridge building process.
Warm Up Assignment:
1. What is a bridge?
2. There are seven types of bridges.
List all seven.
3. What is compression?
4. What is tension?
5. What is the difference between
compression and tension?
Warm up Activity
• Gather 9 popsicle sticks and a sheet of
plain paper;
• Make sure your table has white glue and
wood glue;
• Wait for further instructions;
Strength Test
• Glue three popsicle sticks together using
the same glue;
• Repeat this process for all three types of
glue (wood, white, and glue gun)
• Sit your sticks aside and wait for them to
dry.
Student Activity
• Gather your glued set of popsicle
sticks from last class period.
• Sit at your desk and prepare to break
your popsicle sticks.
Glue type
Strength Test
Wood Glue
Where did your sticks come apart?
How easy/hard was it to break?
White Glue
Where did your sticks come apart?
How easy/hard was it to break?
Glue Gun
Where did your sticks come apart?
How easy/hard was it to break?
Conclusion
What did you learn about all three glue
types?
Time To Break Them!
• Grab your popsicle sticks at each end.
• Bend them until they break!
• Notice how easy or hard it is to separate
your sticks!!!!
Let’s start building
1. Gather 20 popsicle sticks, a ruler, and a
cutter.
2. Cut one rounded end and then measure
four inches. Then cut at that point.
3. All your sticks must be the same length.
4. Use sandpaper to file your ends smooth.
Combine three sticks to make a
long one.
1. Glue three sticks together using wood glue.
2. Then, glue another three sticks together using
white glue.
3. Finally, glue three sticks together using the glue
gun.
Introduction to Bridges
• Bridges are essential to our everyday life
and possibly some of the oldest examples
of engineering available.
• As early as 2000 years ago, the Romans
built stone bridges to allow travel over
bodies of water. Today, there are millions
of bridges around the world that use
different designs
Bridge: Definition
• A bridge is a platform that spans over
obstacles, valleys, canyons, and water.
• A bridge extends a roadway across
gullies, streams, rivers, and bays.
Types of bridges
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Beam Bridge
Arch Bridge
Cable-Stayed Bridge
Truss Bridge
Movable Bridge (or a Draw Bridge)
Suspension Bridge
Cantilever Bridge
Types of Bridges
Types of Bridges
Types of Bridges
Loads on Bridges
Types of Loads on Bridges
• Static (Dead)
• Dynamic (Live)
Definitions (Copy)
• Dynamic or Live Load – Weight that
moves or changes; A variable weight on a
structure, such as moving traffic on a
bridge.
• Static or Dead Load – Weight that does
not move; The invariable weight of a
structure, such as a bridge. It may also
include any permanent loads attached to
the structure.
Static Loads
Dynamic Loads
Forces on Bridges
Types of Forces on Bridges
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Tension
Compression
Torsion
Shear
Forces
Tension vs. Compression
Trusses
• Trusses are triangulated frameworks used
as spanning or bracing elements in
buildings, bridges, transmission towers,
and other structures. What distinguishes
the truss from other structural forms is
precisely its triangulation
Truss Types
Multiple Kingpost (MKP)
The kingpost that forms the basis for this truss is found in
the center two panels. The multiple form is the simplest and
by far, the most common type in Ohio
Queenpost (Q)
A three panel truss used for short spans, the queenpost
was devised as an extension of the basic kingpost by
placing a horizontal member in the center panel.
Burr Arch (B)
Patented in 1804 by Theodore Burr of New York, this
design combined a large arch with a multiple kingpost
truss. The addition of an arch was a traditional way of
strengthening an existing truss. Many of Ohio’s bridges
were stiffened in this way.
Pratt (PR)
Long (L)
In 1830 Col. Stephen H. Long of the U.S. Topographical
Engineers became the first American to use mathematical
calculations to develop a truss. It became known as an "X"
truss.
Town (T)
Connecticut architect Thiele -Town received a patent for a
truss of crisscrossed diagonals, or lattice, in 1820.
Howe (H)
In 1840 Massachusetts builder William Howe introduced
iron into wooden truss design by substituting adjustable
iron rods for the vertical members of Long’s truss.
Smith (S)
Tipp City, Ohio, native Robert W. Smith received truss
patents in 1867 and 1869. Three different variations of his
basic design still exist in Ohio’s bridges.
Partridge (P)
Reuben L. Partridge of Marysville, Ohio, received a patent
for a design that was remarkably close to Smith’s truss. He
was especially active in Union County.
Childs (C)
Developed in 1846 by Horace Childs, the Childs truss was
used exclusively after 1883 by Ohio bridge builder Everett
Sherman. The truss simply added diagonal iron rods to a
multiple kingpost design.
Warren (W)
Patented in 1848 by two Englishmen, one of whom was
named James Warren, it utilizes isosceles triangles.
Warren + Arch (W + Arch)
Wernwag (WW)
King Post Truss
BRIDGE BUILDING
ASSIGNMENT
• In groups of two’s, log on to a computer
station;
• Go to the website on the worksheet:
http://www.pbs.org/wgbh/buildingbig/bridge/
challenge/index.html
Write two paragraphs about the bridge
challenge. Include how you completed the
locations with their bridges.
BRIDGE CONSTRUCTION
TIPS
POPSCICLE STICK TRUSS CONNECTIONS:
VERTICAL AND HORIZONTAL MEMBERS
POPSCICLE STICK TRUSS CONNECTIONS:
VERTICAL AND HORIZONTAL MEMBERS
POPSCICLE STICK TRUSS CONNECTIONS:
(ANGLED TRUSS CONNECTIONS)
POPSCICLE STICK TRUSS CONNECTIONS:
(ANGLED TRUSS CONNECTIONS)
Notable Bridge Disasters
• 2007: A truck packed with passengers and merchandise
overloads a bridge in the West Africa's Republic of
Guinea, causing it to collapse, killing 65 people.
2006: Bridge collapse in Quebec, Canada kills five.
2005: A flood washes away a rail bridge in India, killing
114.
2005: A highway bridge under construction in southern
Spain collapses, killing six.
2002: A barge hits a 500-foot section of a bridge
spanning the Arkansas River in Webbers Falls, causing
it to collapse, killing 14 people.
2001: A bridge collapses in Lisbon, Portugal, causing a
tour bus to plunge into a river, killing more than 50.
Notable Bridge Disasters
• 1994: The Seongsu Bridge collapses in Seoul, South
Korea, killing 32.
1987: A bridge on the New York State Thruway near
Amsterdam, New York, gives way, killing 10. Together
with the 1983 Mianus River bridge accident, it prompts
major efforts to reduce U.S. bridge failures.
1983: Rusty pins fail, causing 100 feet of I-95 to fall into
the Mianus River in Connecticut, killing 3.
1980: The Sunshine Skyway Bridge in Tampa Bay
collapses, killing 35 people. A ship hit the bridge during a
storm.
Notable Bridge Disasters
• 1967: The Silver Bridge over the Ohio River connecting
Point Pleasant, West Virginia, to Kanauga, Ohio,
collapsed December 15, 1967, during evening rush hour.
Forty-six people died. The accident prompted major
reforms in government efforts to inspect and maintain
bridges in the United States.
1876: A railroad bridge falls into the Ashtabula River in
Ohio, killing 92. The designers later commit suicide.
Assignments
• Bridge-Building Vocabulary
• Virtual Bridge-Building and Forces
Experiment
• Virtual Bridge-Building Research
Assessment
• Bridge-Building Comparison Assignment
• Truss Bridge Drafting Assignment
Two Minute Sales Pitch
Includes:
1. Your choice truss type
2. Why you choose that particular truss;
3. How you plan to support loads
(compression, tension, torsion and
shear) on your bridge;
4. Why your bridge should be selected as
dependable, safe, and strong.
Brief Constructed Response #1:
(Prompt)
• You are a hired Engineer designed to build
a truss bridge for the new town.
• Your employers are not convinced that
your bridge design would be successful.
• Write a BCR that explains how your truss
bridge will withstand the forces placed on
bridges: Compression, Tension, Shear,
and Torsion.
Brief Constructed Response #2:
(Prompt)
• You are a bridge inspector that has been
hired to inspect truss bridges.
• Write 4 to 6 sentences that explains how
“Live” and “Dead” loads would be handled
in your truss design.
• Use examples to illustrate how these loads
would be supported.
Homework Activity
Students must identify at least
three different truss bridges in
Connecticut and bring in a
picture of each type of truss
bridge.