BRIDGESObjective: 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 GlueWhere did your sticks come apart?

How easy/hard was it to break?

White GlueWhere did your sticks come apart?

How easy/hard was it to break?

Glue GunWhere did your sticks come apart?

How easy/hard was it to break?

ConclusionWhat 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

• 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

• 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.