bridge building intro

8/10/2019 Bridge Building Intro

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BRIDGE BUILDING


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Bridge Facts!

Can you name the longest bridge in the world?

The Akashi-Kaikyo Bridge


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Bridge Facts!

Comparing the various bridges..


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Bridge Facts (cont.)

! Can you name the longest bridge in America?

The Lake Pontchartrain Causeway Bridge (23.9 miles)

(Louisiana)


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!

What is the oldest standing stone bridge in the world?

The Zhaozhou Bridge( China)


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!

What is the highest suspension bridge in the world?

The Royal Gorge Bridge above the Arkansas River

Click here to cross the bridge!


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!

New York City Bridges!!

Famous Bridges of New York!!


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!

Different types of Bridges!!

Tower Bridge -

London!!

Cable and Wooden

Planck Bridge

New Zealand!!

Tsurimi Tsubasa Bridge- Japan!!


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Definition

! What is a bridge?

"A structure built in order to allow people or vehicles tocross a river or a valley etc. Bridges are structures which

carry people and vehicles across natural or man-made

obstacles.

! When was the first bridge built?

"Prehistoric time


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Materials Used

! What materials are used in bridge construction?

"Stone"Wood

"

Grass

"Steel"Concrete


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Types of Bridges

"Do you know any type of bridges??

"Where did you see it??

"What engineering aspects did you notice??


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Types of Bridges

" Beam

"Truss

" Arch

" Suspension

"Modern Suspension

"Cable-Stayed


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Beam Bridge

! Beam bridgesare the simplest and least expensive type of bridges

to build!!

!

A horizontal beam supported at its ends comprises the structure of a

beam bridge (span a distance of approximately 200 feet).! Highway overpasses, flyovers or walkways


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Beam Bridge - (Truss Bridge)

! A truss bridge is built by connecting straight elements with the

help of pin joints (span a distance of approximately 1200 feet)

!

Deck truss railroad bridge that extends over the Erie Canal is

one of the many famous truss bridges.


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Suspension Bridge

Modern Suspension Bridges

! Modern Suspension bridgeshave an M-Shaped pattern and

are the most impressive type of bridge with their long main

span and beauty!!

! A bridge falling under this category is suspended from cables.

The suspension cables are anchored at each end of the bridge(span a distance of approximately 2000 to 7000 feet).


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! Cable-Stayed Bridges have an A-shaped pattern and use less

cable and are the BRIDGES OF CHOICE!!

! The forces Compressive and Tensile are same for both

suspension bridges (span a distance of approximately 500 to

3000 feet).

Suspension Bridge

Cable-Stayed Bridges


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The Tower Bridge in London is

three types of bridges in one.

The shore-to-tower spansare suspension bridges

The pedestrian walkwaysare truss (beam) bridges

The center span is movableto allow tall ships to pass.

Guess the types of bridges

embedded in this one bridge!!!


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Forces acting on

Beam Bridges and Truss BridgesTwo important forces dealt by all bridges:

Compression is a force that acts to compress or shorten

the thing it is acting on.

Tension is a force that acts to expand or lengthen the

thing it is acting on.When something pushes down on the beam, the beam bends. Its top edge

is pushed together, and its bottom edge is pulled apart.


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Forces acting on

Arch Bridges

The arch is squeezed together, and this squeezing force is carried

outward along the curve to the supports at each end. The supports,

called abutments, push back on the arch and prevent the ends of the arch

from spreading apart.


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Forces acting on Suspension Bridges

Modern Suspension BridgesIn all suspension bridges, the roadway hangs from massive steel cables,

which are draped over two towers and secured into solid concrete blocks,

called anchorages, on both ends of the bridge. The cars push down on the

roadway, but because the roadway is suspended, the cables transfer the

load into compression in the two towers. The two towers support most ofthe bridge's weight.


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Forces acting on Suspension Bridges

Cable- Stayed Bridges

Cables are anchored directly to the towers and eliminate the

need for an anchorage system. The same tensile and

compressive forces are seen in a cable-stayed bridge as they

are in a modern suspension bridge.


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#Designing the various load combinations and determining the

required size of the bridge.

#Creating models of beam, arch and suspension bridges and

apply forces to understand how they disperse the loads.

#Building a model Truss Bridge using straws and popsicle

sticks.

#Exploring the Bridge building software and designing new

bridges.#Bridge Building Competition.

Exploring Activities


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Bridge Challenge #1

A growing community needs a bridge, to connect the city and a major

highway crossing a river. They're very picky about what they want! Help

them by testing your engineering skills and match the right bridge to the

location shown in the figure below!!

Multi-lane bridge for commuters and tourists

Special Notes:"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

Span: 2,000 feet

Crossing: River

Connects: City and major

highway

Source: http://www.pbs.org/wgbh/buildingbig/bridge/challenge/


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Bridge Challenge #1

# Beam Bridge

#

Suspension Bridge

# Arch Bridge

# Draw Bridge


Span: 2,000 feet

Crossing: River

Connects: City and majorhighway



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Bridge Challenge #1

# Draw Bridge


Span: 2,000 feet

Crossing: River


highway

But, there is a problem - the residents of Craggy Rock spoke out

against the new drawbridge. "It's ugly," one angry resident said,

"and there's always traffic on the bridge. They open it for boats, but

what about us? We have to get to work, too!"



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Bridge Challenge #1Multi-lane bridge for commuters and tourists

Span: 2,000 feetCrossing: River


highway

The mayor is begging you to build a new bridge. The local steelworkers

are on strike, so she advises you to build a bridge with as little steel as

possible.# Cable-stayed Bridge

# Cantilever Bridge

# Combination Arch

& Beam Bridge



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Bridge Challenge #1Multi-lane bridge for commuters and tourists

Span: 2,000 feet

Crossing: River


highway

# Cable-stayed Bridge

These have become one of the most popular bridge types in recent years.The roadway hangs from cables like a suspension bridge, forming a

unique "A" shape. The mayor is happy because the bridge is made

mostly of concrete, a relatively cheap material. The residents are thrilled

because ships can pass beneath the bridge without causing traffic jams!



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Bridge Challenge #2

A growing community needs a bridge, to connect the bike paths in East and

West Craggy Rock. They're very picky about what they want! Help them by

testing your engineering skills and match the right bridge to the location

shown in the figure below!!

A bridge for rollerbladers and bikers

Special Notes:"We're tired of getting bumped off the road by

angry drivers! We want a simple bridge -- one

that will connect the bike paths in East and

West Craggy Rock over the city stream. We

don't have much money, so we're not asking for

much. We just want to get to work every daywithout risking our lives!"

-- Craggy Rock Bike-n-Blade CoalitionSpan: 100 feet

Crossing: Stream

Connects: Two bike paths



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# Beam Bridge

#

Suspension Bridge

# Arch Bridge

# Draw Bridge

Span: 100 feet

Crossing: Stream


Bridge Challenge #2A bridge for rollerbladers and bikers



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# Beam Bridge

This is an excellent spot for a beam bridge!! Beam bridges typicallyspan 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!


Span: 100 feet

Crossing: Stream




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When it rains, the city stream rises. A really strong storm could causeflash floods, turning the stream into a raging river. Piles of rocks and

a wall of gooey mud could push on the piers of the concrete beam

bridge and cause it to topple. Luckily, you can fix it before that

happens!


Span: 100 feet

Crossing: Stream


# Beam BridgeHowever, there isa problem.



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How will you build a new, flood-proof bridge?

# Build deeper piers

# Build higher deck

# Use stronger

material


Span: 100 feet

Crossing: Stream




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# Deeper piers

Great Idea!!

One of the best ways to strengthen a bridge in a flood zone is to

set the piers deeper into the ground. The deeper the piers are

lodged into the ground, the harder it is to knock them over. The

next time floodwaters pound on the piers of your new bridge, it

probably won't budge!


Span: 100 feet

Crossing: Stream




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Bridge Challenge #3

A growing community needs a bridge, to connect the two halves of the city

across the harbor entrance. They're very picky about what they want! Help

them by testing your engineering skills and match the right bridge to the

location shown in the figure below!!

A highway bridge across a busy shipping port

Special Notes:"Our records indicate that more than 500 ships

pass through Craggy Rock Harbor each day.

Please build a bridge that does not block the

flow of water traffic. We do not want angry

sailors or congestion of any kind in our harbor.

Thank you."

-- The United States Coast GuardSpan: 5000feet

Crossing: Ocean bay

Connects: Island and mainland



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# Beam Bridge

#

Suspension Bridge

# Arch Bridge

# Draw Bridge

Bridge Challenge #3

Span: 5000feet

Crossing: Ocean bay





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# Suspension Bridge

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!

Bridge Challenge #3

Span: 5000feet

Crossing: Ocean bay





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Your new bridge is moving up and down a lot in the wind! This isn't abig problem under normal conditions, but what if a hurricane were to

blow through town? It could cause the bridge to move too much, or

even twist so violently that it would snap in half!

However, there is a problem.# Suspension Bridge

Bridge Challenge #3

Span: 5000feet

Crossing: Ocean bay




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How can you strengthen the bridge to resist strong winds?

# Stiffen the deck

with an open

TRUSS?

# Stiffen the deck

with a solid steel

GIRDER?

# Make the bridge

NARROWER?

Bridge Challenge #3

Span: 5000feet

Crossing: Ocean bay





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# Open Truss

Great Idea!!

This is a great solution! By adding an open truss beneath the deck of

the bridge, you've designed a structure that is less likely to move up

and down a lot on a gusty day, because the wind will blow right

through it! Since the Tacoma Narrows Bridge disaster in 1940, many

major suspension bridges have been built with a stiffening truss.


Bridge Challenge #3

Span: 5000feet

Crossing: Ocean bay




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Conclusion

! Based on the above activities different types of bridges can be

built.

!

Different types of structures and materials can be experimentedwith in order to increase the strength of the bridge.

! Efficiency of the bridge can also be calculated.

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