Construction+Features+of+Bridges

Construction and Features of Bridges  Bridges provide easy ways of getting over obstacles. There are three main types of bridges, each with different construction features. Trusses, columns, laminations, and corrugations each provide support for bridges even though they all have different design features.

= =  Truss
 * A truss is a strengthened or reinforced beam.
 * In a truss bridge the trusses are usually constructed in a series of smaller triangular parts.
 * Engineers use these triangular shapes help provide better support for holding up a bridge. Trusses can be made out of wood, but nowadays they are made of metal.
 * Trusses are stressed from tension and compression.
 * The trusses can also be on the top as well as the bottom of a bridge.
 * When the truss construction is on the bottom of the road bed it is classified as a deck truss.
 * Trusses below and on top of the road is called a through truss.
 * When the trusses extend about the road bed but are not connected it is called a pony truss.
 * Some well known truss designs include the Eiffel tower and the Bolman truss Bridge.







**Column **

A column transmits, through compression (weight of the structure above to other structural elements below). Engineers make some columns designed to resist lateral forces such as wind or earthquakes.Columns support the weight of the bridge from underneath so that it doesn't tip or crumble.For longer bridges they construct columns under the middle spans. They act as upward forces (reaction forces) to support a load.

**Corrugation ** The term corrugation refers to a series of parallel ridges and furrows. Corrugation is also used in manufacturing cardboard. If you slice open cardboard on the inside there will be a zig zag design between the actual papers (shown below). The same situation applies to bridges! Corrugated bridges help support the weight of the bridge and the objects on it. The difference is that one is used to store packing peanuts and the other is used to provide passage over an obstacle!



Do you see the similarities? **Girder **
 * A girder is a large iron or steel beam or compound structures used for building bridges and are sometimes used for the structure for large buildings.
 * Normally, girders are placed on the bridge abutments and foundation piers
 * Bridges with girders in them are most commonly found on the highway.
 * <span style="color: #2ac63c; font-family: 'Comic Sans MS',cursive;">Girders usually have an “I” shape to them but they can also have a “Z” or box shape.

<span style="color: #ff0020; font-family: 'Comic Sans MS',cursive; font-size: 160%;">Lamination

Some bridges in the highway system that have timber decks as the supporting members have not been designed to support a concrete deck. The type most commonly found are laminated timber decks where the lumber is placed transversely and on edge. Each piece of plywood is placed differently for an equal amount of support and so it will be sturdier.



Abutments An abutment is the point where two structures meet, located at the ends of bridges. They’re designed to support the load on the bridges. They have reaction forces acting upward to strengthen the bridge and keep it from collapsing. Bridges have balanced forces so that they are equal to the force acting upwards on the bridge, (columns, abutments, etc.) to the force acting down on the bridge (the load).



[]

** Work Cited ** []