Bridges have been around for quite some time. For example, I've walked across one originally built by the Romans. This lab will explore building under certain restraints. Lets explore shall we?

Bridge Types

Beam

• simplest
• often built from concrete or steel
• steel built elsewhere and assembly on site
• often has short spans
• think a box

Arch

• stress spread out along two curved paths
• deck at or near top of arch
• deck above arch
• has larger spans than beam bridge

SUSPENSION

• towers support cables that hold deck
• large spans
• subject to wind loads
• tower to cable, to vertical suspenders, to deck

Cable-Stayed

• similar to suspension
• towers have cables to deck
• towers transfer load to ground
• The cables attach directly to deck and uses a beam approach
• More stable in wind then suspension

cantilever

• uses counterweighted cantilevers
• deck is the third component
• can have beam arch components
• or cable-stay elements

Bridge Parts

• Abutment - retaining wall supporting ends of bridge
• approach - part that carries load from land to bridge
• bearing - between beam and post or abutment
• expansion joint - to account for thermal loads
• deck - where you walk on the bridge

Loads

• dead - mass of bridge
• live - non-permenant load
• dynamic - moving load
• thermal - heat load
• wind - load due to wind

Collect

• Newspaper, tape,string
• Lego, knex
• Toothpicks, glue
• Etc

The Lab

• Span a distance of .25 metres
• Mass of the bridge below a kg
• Can hold 50 grams