bridges

writing 1

They are primarily simple structures which are made of different materials and they are built for different purposes to. Their main function is to facilitate the movement of people or vehicles through different ground or natural or artificial obstacles.
 * What are bridges? **

**Arch bridge **
 * Different types of bridges: **

As the name implies, it uses the bow as the main element of construction, in order to prevent the double bridge. The compression force is always present, so the materials used to build this type of bridge should be especially strong to compression.



**Cable-Stayed Bridges **

Also related to the cantilever bridge they present cords along their structure together ultimately in the center, these ropes are found in tension while the cover is in compression.



**Suspension bridge **

This type of bridge has a cable that is intension,this type of bridge is cheaper than the arc bridge, but not recommended for vehicular traffic.



**Materials used ** These are some of the materials that available for bridge building: Wood, brick, stone, cast iron, wrought iron, mild steel, high-tensile steels, alloy steels, aluminum, steel-reinforced concrete, pre-stressed concrete, glass-reinforced plastic. Bending, compression, impact, oscillation, pressure, tension, torsion, vibration; contraction, corrosion, erosion, expansion, fatigue, friction, rain, river flow, sea-water, scouring, temperature changes, tidal flow, turbulence, waves, wind erosion, wind gusts, wind pressure. These are some of the stresses that bridge materials must withstand, in a variety of combinations.

**Advantages and disadvantages **

Some of the benefits that bridges have are: the movement of food supplies and goods through multiple obstacles and difficult terrain in a shorter time. This means that, in economic terms, the cost of travel and trade fell and the financial benefits of greater social cohesion and a greater distribution of resources. A disadvantage might be the improper construction or lack of maintenance of the bridge, which can in a disaster. Also, to select the wrong type of bridge can be a problem.

**Examples of bridges found in the world **

As an example we can see the Juscelino Kubitschek Bridge located in Basel (Brazil), on the river Paranoá, this bridge has 1200 meters long, 24 meters wide and 60 meters high. It is made of steel and concrete. The most striking element of this structure are the three asymmetrical steel arches that cross diagonally, that are responsible for maintaining the bridge firm, plus the help of four pillars which are located submerged in the river.

media type="file" key="puente.mp3"

<span style="color: #808080; font-family: 'Comic Sans MS',cursive; font-size: 140%;">References:

<span style="color: #808080; font-family: 'Comic Sans MS',cursive; font-size: 140%;">[]

<span style="color: #808080; font-family: 'Comic Sans MS',cursive; font-size: 140%;">[]

<span style="color: #808080; font-family: 'Comic Sans MS',cursive; font-size: 140%;">[]

<span style="color: #808080; font-family: 'Comic Sans MS',cursive; font-size: 140%;">[]