Bridges

Bridges are known to be structures created to allow people and vehicles to cross an obstacle. There are tree main types of bridges (beam bridge, arch bridge and suspension bridge). In order to decide which type of bridge will be the better solution to a determined problem we most look at the size of the obstacle. If we want to understand this better we must study the tree types of bridges.


 * First the Beam Bridge: This of bridge is a rigid horizontal structure supported by two piers located one in each end of the bridge. A beam bridge works using the force of compression and tension. The force of compression is located on the upper side of the bridge. As a result tension appears on the lower portion of the deck making the beam lenghen. The common material used to build this bridge are concrete or steel. The size of the bridge can span depending on the size of the beam but it has a limit because a larger bridge requires more material to dissipate the tension and at some point the bridge's own weight is too large for the truss to support.
 * Secong the Arch Bridge: This is a semicircular structure with abutments on each end. This structures are the ones receiving the weight of the bridge (the compression force), tension is negligible in this structure. The limits of the size are determines by the abutments, once again at some point the structure will be to big for them to support.
 * Third the Suspension Bridge: This bridge has cables strung across the obstacle and the deck is suspended from these cables. They have two towers in wich the cables are strung, these structures are the ones supporting the roadway's weight and they also have a suporting truss system. The cables transfer the compression to the towers and they transfer it to the ground and the tension is received by the supporting cables. Some examples of bridges are: The Sunshine Skyway Bridge located in Tampa Bay, The Akashi-Kaikyo Bridge located in Japan, The Alamillo Bridge in Valencia and Gateshead Millenium Bridge.

Technology is always having new discoveries specially in the design and that's why now there are certain rules ingeniers most follow in order to create better and saver bridges. These constructions have many benefits: connecting people, making easier and faster to travel, it is also an economic solution, they also allow importation and exportation of food and some other articles between states. On the other hand they required a lot of money to be construct and maintein, if one of these aspects fails then the bridge won`t be save for people to use. That's why it's not only important to have the right amount of money to develop the structure but also to have the resources for it to be maintein later (with the years the bridge will probably need to be check to verify it's still working propertly).

Bridges have a huge influence in people's lifes. They connect people from different countries and states, therefore they are responsable for some of the cultural and social mixing in the world and also facilitate and helping the economy world

. Alamillo Bridge

Sunshine Bridge



Gateshead Millenium Bridge
__References.__ - [|http://www.makingthemodernworld.org.uk] - [|http://www.jb-honshi.]