Bridges

 Types of bridge

  1. Beam Bridge
  2. Arch Bridge
  3. Truss Bridge
  4. Suspension Bridge
  5. Cable stayed bridge
  6. Cantilever Bridge

 

Building your own bridges from lolly sticks

Buy lolly sticks from Amazon: (£7.20 for 1000)

You do not have to use lolly sticks and glue.
Try art-straws, spaghetti or  match-sticks.
Instead of glue you could use modelling clay or Plasticine to hold he sticks together.
Use your imagination.

Download: West Point Bridge Designer 2016 (Windows)


Beam Bridge

  • The simplest of all bridges.
  • A plank across a stream is a beam bridge.
  • Advantages:  Simple and cheap
  • Disadvantages:  Cannot span wide areas.

 

A modern beam bridge is often made out of reinforced concrete

Swanport Bridge

 

A load on the bridge squashes the top of the of the bridge deck (compression and tries to stretch the lower part (tension)

The deck can be made lighter and stronger by changing the  shape of the beams.

The deck can be supported by piers to help it take more load but this is more expensive if the piers have to be long.

Task

Find out which shape of beam supports the most load
Make different shapes of beam from a piece of A4 paper and support the paper bridge on two piles of books.
Place coins (or anything else of similar size) on the paper bridge until the bridge collapses and record what load mad it collapse.

Keeping it a fair test

  1. Same size paper for each beam (eg half a sheet A4)
  2. Same size gap for each beam
  3. Same distribution on load

 


Arch Bridge

The deck will support larger loads if it is supported by an arch

Click here to build your own arch bridge from lolly sticks


Truss Bridge

The truss bridge uses a metal (or wood) framework (the ‘trusses) to help support the deck.

Truss Bridge

Warren Truss Bridge

West Point Bridge Designer is a program you can download and run on your computer. It lets you design and test a truss bridge.
Download: West Point Bridge Designer 2016 (Windows)

Note that the bridge will not be allowed unless all the Trusses form triangles.

Click here to build a Warren Truss bridge from lolly sticks

Click here to build a Howe Truss bridge from Lolly sticks


Suspension Bridge

The deck is supported by flexible cables

  • Advantages:
    Can span much larger distances.
    Looks attractive and elegant.
  • Disadvantages:  Costs more to build.

Suspension Bridge Golden Gate Bridge San Francisco

Clifton Suspension Bridge, Bristol, UK

Click here to build a suspension bridge from Lolly sticks