Designs and types of bridges

Bridges - an essential attribute of almost every river, they help to overcome obstacles, thanks to them, distances become smaller, and to get from point "A" to point "B" is more comfortable and faster. With the advent of new materials and technologies complex design of the river crossings become a reality.

What is a bridge

Bridges – the continuation of the road through the obstacle. Most often, they are routed through a water barrier, but also can connect the edge of the ravine, or channel. In connection with the development of transport infrastructure in Metropolitan areas bridges are built for movement over roads, forming a large roundabout. The main components of the construction are the spans and the supports.

Classification of structures bridges

Types of bridges can be classified according to several criteria:

• On the main purpose of the use;
• Constructive solution;
• Construction materials;
• Depending on length.
• On the term of service;
• Depending on the operation.

Ever Since man threw the tree from one Bank of the river to get to another, it took a lot of time and a lot of effort in the construction of engineering structures. The result was a different types of bridge designs. Take a closer look.

Beam

The Materials used for their construction are steel, its alloys, reinforced concrete, and the first material was a tree. The main elements of load-bearing structures of this type are beams, trusses that transfer loads to the supports of the base of the bridge.

Beams and girders are part of separate structures called "flying". The stairs are split, cantilever, and continuous, depending on the schema of connection with the supports. The first of these have two bearings at each end, a beam can have a larger number of supports, depending on need, and the cantilever bridge spans beyond the reference points which are connected with the subsequent spans.

The Arch

They are used with steel, cast iron, concrete casting or blocks. The first materials for the construction of this type of bridges were rocks, boulders or composed of these solid blocks.

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The basic structure is the arch (vault). The combination of several arches road or railway track is an arched bridge. The roadway may have two locations: over design or under it.

One of the varieties is hybrid, arch-cantilever bridge, where two semi arch-connect into the top and resemble the letter “T”. Arch construction may consist of one span, and then the main burden falls on the extreme support. If the bridge consists of multiple connected structures, then the load is distributed to all intermediate and extreme support.

Suspension bridges

The Main materials for construction in this case – steel, reinforced concrete. Structures erected in places where it is impossible to install intermediate supports. The carrier element are pylons connected by ropes. To keep the bridge in a stable condition, the pylons are mounted on the opposite sides, between them stretch a cable connection to the earth, where it is securely attached. Stretched out horizontal to the vertical cables are fixed, also adding chains that will support the fabric of the bridge. The stiffness of the canvas attach to beams and girders.

Suspension bridges

Building materials – steel, reinforced concrete. Like hanging analogs, their design involves the pylons and cables. The difference is that cable is the only connection that links the design of the entire bridge, i.e. the cables are not attached to the horizontally stretched media, and directly to end supports, making the structure becomes more rigid.

Pontoon

“Floating” the crossing does not have a rigid frame and communication with the shore. Their design is assembled from separate sections with a movable connection. A variation of this type of bridges are floating terminal. Most often they are temporary structures which were used prior to the establishment of ice on the water obstacles. They're dangerous in a period of strong excitement on the water, impeded navigation, and the movement on them has limitations for multi-ton trucks.

Metal bridges

Most modern bridges involves the use of metal in load-bearing parts of structures. Quite a long time, the metal bridge was considered the most durable form of construction. To date, this material is important, but not the only component of bridge connections.

Types of metal bridges:

• Arched structure.
• Viaducts with spans.
• A Suspension, cable-stayed.
• Trestle with pillars of reinforced concrete where the spans are assembled of metal compounds.

Designs of metal have the advantage of simplicity of collection, so almost all types of railway bridges built of this material. Metal parts are manufactured industrially in the factory, the size can be adjusted. Depending on capacity mechanisms, which will be the installation, form the factory template of the future of the whole compound.

Boil a design of the parts directly at the place of final installation. And if you had to connect the many parts of a single span, now crane 3600 t, it can move and hoist to support the metal stairs.

The Advantages of steel structures

As a material for bridge construction is rarely used iron because of its poor corrosion resistance. Relevant material was high-strength steel and its compounds. Her wonderful performance can be evaluated on projects such as cable-stayed bridge with a huge span. An example is the Moscow bridge across the Dnieper river in Kiev or Obukhovsky bridge in St. Petersburg.

During the construction of railway bridges widely used metal construction with lattice girders. The main advantage of these solutions is efficient in operation, speed of construction and dismantling of individual parts and a relatively low production cost, possibility of construction of designs in the shortest time available on the sites and in any geographical area.

Wooden bridges

The First bridge in the history of mankind were constructed from wood. Long these structures could not be used without proper repair, regular maintenance and replacement parts and fasteners. It was difficult of construction and the fragility of the material itself. Currently, there are following types of wooden bridges:

1. Depending on the system – braced, braced.
2. Depending on the design – a batch structure with spans, truss bridges.

The girder structure is most simple, and therefore quickly mounted structure. Support beams embedded in soil to a depth of 4 m. On the upper ends of the piles with steel pins fit the nozzle, all the piles are linked together, laying on top of the canvas for movement. During the construction of the wooden bridge it is important to create a strong pairing structure with an embankment of ground at both ends, this is done to ensure that the bridge was stable.

Now there is a tendency of revival of the construction of wooden bridges, that is associated with the advent of technology the manufacture of laminated veneer lumber is more resistant to aggressive environment, external forces of torsion and more durable in use, besides its length does not depend on natural growth.

Poetics and practice

In Saint-Petersburg is 93 waterway includes rivers, streams, channels and almost 100 ponds. Unimpeded communication between the Islands and parts of the city provide bridges, of which there are about 800, of which 218 are intended for pedestrians. From the beginning of construction of the city was laid tradition of building bridges, without which St. Petersburg is unthinkable. They form part of its architecture, history, traditions and culture.

Perhaps, in any city of Russia actively do not use adjustable links, as in St. Petersburg.

The Symbol of the Northern capital is considered to be one of the oldest bridges – the Palace. It was built by the engineer of Pshenichnogo AP and connects Admiralty island Arrow of Vasilevsky island. Modern mechanisms lift the 700-tonne construction of the Central passage for the passage of vessels.

The longest drawbridge in Saint-Petersburg is named after Alexander Nevsky. Its length 905,7 m, Central bascule span is made of metal, the time of breeding structure is only 2 minutes.

The Types of the bridges of St. Petersburg include the history of bridge building – from the wooden to the modern multi-lane cable-stayed structures. Big Obukhovsky bridge, for example, has a length of 2824 metres, and today it is one of the longest engineering structures in Russia. It is composed of two parallel parts in which organized four-lane one-way traffic.

St. Petersburg legends

In St. Petersburg in the abundance of different types of bridges, there are old, have become symbols of a bygone era, but their purpose has not changed, although overgrown Fleur stories and romance. So, Kissing the bridge across the Moyka river attracts tourists with its name, but it came from the name of the merchant Potselueva, whose drinking house “Kiss” was located near the ferry, and for romantic gestures, the name is irrelevant.

Interesting legends overgrown Foundry bridge, and the dramatic story emerged immediately after its Foundation. It is believed that one of the embedded stones of the pillars become sacrificial stone Atakan. Now he's depressing at passers-by and provoke suicide. To appease the bloody boulder, some citizens thrown off a bridge into the Neva coin and pour red wine. Also many argue that Foundry can meet the Ghost of Lenin.

Five of the longest bridges in Russia

Not Yet built a bridge across the Kerch Strait, five large links looks like this:

• Russian bridge in Vladivostok. The construction length is 3100m opening was held in 2012 for the First time, about the need for thought in 1939, but realized at the present stage.
• Bridge in Khabarovsk. Its length is 3891 m. It has two tiers. Lower railway traffic, and on the top - automobile. His image adorns five thousandth dollar bill.
• The bridge on the river Yuribey. It is located in the Arctic circle in Yamalo-Nenets Autonomous district. Length of the structure – 2893 m.
• Bridge over Amur Bay has a length of 5331 m. opened in 2012, It is an interesting lighting system, saving 50% of energy.
• The Presidential bridge over the Volga in Ulyanovsk. Length – 5825 m. the Construction lasted for 23 years.