bridges unit test

8/7/2019 Bridges UNIT TEST

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GIRDER BRIDGES

Oldest and most common bridge type known. (Fallen logs were

used)

In modern girder bridges, steel I-beams are used, but theyare subject to twisting and are not good for bridges with

any curve to them.

Box beams are stronger and used for curving or longer bridges.


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Second oldest bridge type.

Unlike girders, can be built from stone.

Because no center pier is required, can be used to cross

valleys and rivers without interfering with river traffic.

Considered the most beautiful of bridge types.

Many ancient arches are still standing today!

ARCH BRIDGES


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CABLE-STAYED BRIDGES

Really just a continuous girder bridge with towers above

piers

The cables are flexible and affected by the wind.

Longer spans require very complex computations and

analysis.


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SUSPENSION BRIDGES

Of all the types of bridges used today, the suspension allows for the

longest spans.

Similar to a cable-stayed bridge except there is one main cable that

runs between the towers with hanger cables below it.

The girder and roadbed are not resting on the piers as with otherbridge types, but is hanging from the hanger cables!

Vulnerable to wind


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TRUSS BRIDGES

Because of the use of the triangular shape, trusses only

sustain compression and tension forces and not bending!

Can be built in small sections so are ideal in areas

where large machinery wouldnt have access.

The most common type is the Warren TrussFor longer spans and for a stronger Warren Truss,

vertical members are added. Notice that the roadbed can

be above or below the truss.


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Tacoma Narrows Bridge

o

o Suspension Bridge thatconnects Tacoma andSeattle, Washington.

o On the morning of

November 7, 1940, theTacoma NarrowsBridge twisted violentlyin 42-mile-per-hourwinds and collapsedinto the cold waters ofthe Puget Sound.

o Caused by self-excitedvibrations; the bridgetook over the wind anddestroyed itself.


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TERMS OF BRIDGE CONSTRUCTION

o TORSION- THIS IS A TWISTINGFORCE

o

SPAN- A DISTANCE UNSUPPORTEDBETWEEN 2 POINTS

o LOAD-THE WEIGHT SUPPORTED BYTHE BRIDGE

o TENSION- STRETCHING ASTRUTURAL MEMBER


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o DECK-THE ROAD BED OF A BRIDGESYSTEM

o

SUSPENSION- A BRIDGE SYSTEMTHAT USES CABLES TO SUPPORTTHE DECK

o COMPRESSION-DOWNWARD

PRESSURE ON A STRUCTURE

o


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o GIRDER- A SUPPORT BEAM OF ABRIDGE

o

BEAM- A BRIGE TYPE THAT USES ASOLID GIRDER AS A DECK

o TRUSS- A STURCTURAL SYSTEMTHAT USES TRIANGLES TO

EQUALIZE COMPRESSION ANDTENDSION


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o WHICH COLOR REPRESENTSCOMPRESSION AND TENSION?


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Need to know

o All 5 types of bridges (identify andsketch)

o All 10 terms (define; match; explain)

o Compare and contrast 2 types ofbridges with AT LEAST 3 differentUNIQUE qualities!!! (you choose

the 2 types)o Questions- T/F, M/C, fill in the blank,

short essay, Venn diagram

bridges unit test

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