Bridges+notes

Bridges Notes:


 * Bridge is a conection between two places that have an obstacle therefor it cannot be reached be other medium.
 * Bridge is a tool that solve the problem of crossing and obstacle.
 * Some of the benefits of the bridges are that shorten the tranportation time from one place to another which facilitates trade and social cohesion between communities.
 * International trade and travel depend on shipping and air routes, but efficient distribution networks depend on bridges.
 * The type of bridges depend of the size of the obstacle.
 * A far deeper art than decoration is concerned with the original conception, with the details and overall balance of the design, with the need for economy in materials and construction, with utility to the users, and to longevity and economy of maintenance.
 *  Some bridges are corrosion resistant by galvanization. This is a method that consists on cover the iron or steel with aluminum or zinc and finally put it an electrical current.
 * Water produces stalactites when running down the bridges sides.
 * Some concrete beam bridges near the "Second Severn Crossing" have plastic coverings which give a very clean appearance. These are not merely cosmetic, there is room inside for inspectors and other workers to operate with some protection from traffic noise and weather.
 * All structures including bridges have weight, and all experience forces within themselves.
 * The scale is very important in terms of the quality of detail on the bridge
 * The human eye and brain seem to need some detail at certain scales in order to feel comfortable. Masonry provides this in the form of joints between blocks or bricks, and in the case of stonework, in the surface of the blocks, which may be flat or bulging, rough or smooth.
 * A bridge with long spans may be curved in plan, not only to provide for expansion, but to reduce the amplitude of oscillations.
 * The main types of bridges are arches, beam bridges, cable-stayed bridges, cantilever bridges and suspension bridges.



__Arche bridge __: <span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 160%; text-align: left;"> The essence of an arch is that ideally there should be no tendency for it to bend, except under live loads. It should be purely in compression, and for that reason it can be made of materials such as, masonry, cast iron and concrete, that perform poorly in tension.The ideal shape is called the funicular, the exact shape of which depends on the weight distribution, so the funicular is not necessarily a simple mathematical curve such as a circle or a parabola. An arche is curved because over it are acting two kinds of forces, those that pulling down such as the weight of the section and the load. And the other forces are those from the section on either side. A real arch has to have a flat deck that is propped above it or hung below it, to allow wheeled trafic. Arches have been made of stone, brick, cast iron, wrought iron, wood, steel and aluminium. The largest are in steel, while the smaller ones may be in concrete. The oldest arches were in masonry, brick or stone. Some of the advantadges of arches is that they work mostly with compression, this caracteristic makes them quite resilient.



Beam bridge



Cable- stayed bridge Cantilever bridge



Suspension bridge