# The Beam Bridge

Updated on September 10, 2009

## Beam Bridge - a simple sketch

A Beam Bridge is the simplest design for crossing a distance.

It consists of a horizontal beam supported at each end by piers. The weight of the beam pushes straight down on the piers. The farther apart its piers, the weaker the beam becomes. This is why beam bridges rarely span more than 250 feet.

## Modern Beam Bridges

Load is a consequence of gravity and always acts vertically.

The ground exerts an equal and opposite force upwards on the weight. This force is called thrust.

When a weight is placed on a beam it exerts a load. However, the weight is not directly in contact with the ground.

Hence the load reaches the ground by passing along the beam and the down the piers as shown in the diagram opposite.

1. easy to construct
2. relatively cheap

1. cannot span great distances

If the deck is supported by a number of beams instead of just one then it would be easier to erect and easier to fix.

As a bridge is loaded, the beam bends in a downward direction - sag. When the beam bends, new forces are imposed along the length of the beam:

The top of the beam is compressed (shortened)

The bottom of the beam is tensioned (pulled apart).

As you can see from the diagram, the lines mark equal distance on the beam and the angle of these lines converge at a point above the beam.

## Testing to destruction

General rule: material breaks far more readily when it is under tension the when it is compressed.

Elastic Substances: materials that deform under a load and then returns to its original shape when the load is removed. Steel is slightly elastic

1. when exposed to a massive load they will deform before collapsing entirely
2. they give warning (visual inspections can determine if buckling has occurred)

## The Bridge Challenge

view quiz statistics

## Popular

28

1

• ### Agritecture, or vertical farming: a history and present-day applications

2

0 of 8192 characters used

• abdu m 3 years ago

it is so short

• jenny 3 years ago

sup dawg

• Bob 4 years ago

:P

• the dons 5 years ago

me and my primary friend commented on this along time ago, he moved somewhere else :D

Irfaan

• Jess 5 years ago

Amazing ! Helped SOOOO much with my work!

• megs xx 5 years ago

THIS REALY HELPED ME

• Kylee 5 years ago

I was killed last night and now i am coming to haunt who ever commented on this. Did you know it takes approximentally 24 minutes for blood to dry? Well, just as i had to find this out, so you all will too!

• TY :3 5 years ago

THANK U IT REALLY HELPED WITH MY PROJECT

• yoyoyoyoy 5 years ago

we in the hood tonight we be getting candy all ova my bod

• someone 5 years ago

hi hi hi hi

• gtg 5 years ago

nnnnnnnnanananannn

• GERSATA 5 years ago

STUPS

• Ouuo 5 years ago

So much spam here... Thanks tho!

• fighter 5 years ago

i also want a fight

• weggy woggy weg weg 5 years ago

i want a fight

• BOB 5 years ago

who wants to fight???

• BOB 5 years ago

who wants to fight???

• the dons 5 years ago

really people? you dont have a life

• me 5 years ago

llllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll

• higilmk; 5 years ago

idgi

• mrproffeserdude 5 years ago

nice piece, might i say, and you kids are soo annoying get a life for crying out loud.

• big daddt 5 years ago

wow you kids on here are kinda sad...

• SuperCrackbaby 6 years ago

For SPARTA

• nabaa 6 years ago

nabaa rocks

• none 6 years ago

you stink

• faridz 6 years ago

• spem34 6 years ago

im board

• yfxcy 6 years ago

tuirfdc

• Tegan Swope 6 years ago

I am in a club called 'Bridges'at school.

• I11 6 years ago

ok. akward

• spem34 6 years ago

I still like her ian

• Ian Graffunder 6 years ago

YES!!!!!!!!!!!!!!!

• spem34 6 years ago

REALLY!!!!!!!!!!!!!!!!!!!!

• Ian Graffunder 6 years ago

Why? U just hit her with a rubber band!

• Spem34 6 years ago

i wanna be friends with klyee

• spem34 6 years ago

who are u?

• yourmom 6 years ago

im a monkey

• olololol 6 years ago

cooooooooooooool

• jas55 6 years ago

stupid

• jas55 6 years ago

yoyoyoyoyoyoyoyo

• Ian Graffunder 6 years ago

How is Kylee going to get killed? And why?

• spem34 6 years ago

klyee is going to get killed to night

• spem34 6 years ago

yeah ian

• Ian Graffunder 6 years ago

OOOO Spem34. :)

• spem34 6 years ago

I sort of like u

• texas freak 6 years ago

who?

• Spem34 6 years ago

I like Some one in this room

• sant 6 years ago

Hi peoples

• Spem34 6 years ago

never mind they didn't

• Spem43 6 years ago

Bradon and Kylee kissed on the lips

• Texas 6 years ago

klyees awsome

• Lukas 6 years ago

^^

• Ian Graffunder 6 years ago

Spencer. Email me. MY email adress is iangraffunder@gmail.com

• texas freak 6 years ago

heyyy honey

kylee awsome

• jack 6 years ago

hi jackson

• spencer 6 years ago

hey yall

hi people i dont now

• oroog 6 years ago

hjhdg

• jaskson seyfarth 6 years ago

dfhdufgydkgydruigydrk

• lol 7 years ago

this really helped!

• Die all 7 years ago

Hi all Beam Bridge

• hi 7 years ago

hi hi hi hi hi hi

• hannna montana 7 years ago

oh my cosh wt kind of things that we can tell something else hahahahahahahahaha.

• destiny 7 years ago

you are a bitch

• Author

lydia_rae 8 years ago

no I haven't I have no idea how to get it but I deffinately need to start. thnx for the comments :)

• Waren E 8 years ago from HAS LEFT THE BUILDING............

Hi nice hub on architecture ,have you started using CAD programs yet? If so which one ,"auto cad" perhaps!

working