Creaking and swaying, blowing and vibrating, scary and threatening to throw down. But nevertheless, unusually romantic suspension bridges! They were built in past centuries and are almost always located in beautiful and secluded places. They make appointments and make movies. You can also sit there with your legs dangling and wait for the sunset.

Although the term "suspension bridge" is incorrect - "suspension" is used in architecture and construction, I will call them in the usual way.

Few of the capital's residents happened to walk on a real suspension bridge. Krymsky does not count - he is too monumental. My only time was Disneyland Paris. And this despite the fact that only in the Moscow region there are more than fifty of them! You just need to open Wikimapia, select the category "suspension/suspension bridge" and drive 30-50 kilometers to the region. Which I did on Saturday, ranking ten random hanging bridges.

1. Suspension bridge across the Moscow River in Tuchkovo

It connects the Tuchkovskiy Motor Transport College (TATK) and the village of Ignatievo.

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Coordinates: 55°37"11"N 36°29"21"E

2. Bridge near the village of Karinskoye

On the Internet, it is known as the longest pedestrian suspension bridge in the Moscow region.

It looks no longer than the others seen that day. In Wikipedia, as evidence, a link is given to ... the site Afisha.ru, which only confirmed my doubts.

This is how legends are born - first someone writes their assumption, it is taken apart on sites, which the media, based on numerous references on the Internet, writes about as obvious. In the final - a Wikipedia article with a link to a reliable source - the official media.

This bridge is a favorite place for filmmakers. The "Suicides", "Children of Monday", "Petersburg Secrets" and other films were filmed here.

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Entrance - cars, directly to the bridge
Coordinates: 55°42"20"N 36°41"19"E

3. Suspension bridge near Ivanovsky

Crooked, lopsided and scary, but so wonderful!

Ducks swim, fish splash around - no one around.

To get to the place, you will have to drive on asphalt, slabs, a dirt road and a field. But it's worth it. The main thing - do not scratch your hands on the blossoming wires of old cables.

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Entrance - SUV, almost to the bridge
Coordinates: 55°47"34"N 37°6"26"E

4. Suspension bridge across the Moscow River in the village of Vasilyevskoye.

Despite the fact that the bridge is "inter-district" - it connects the Odintsovo and Ruza districts, for a long time it was in disrepair. It turned out that he was not on anyone's balance sheet. No transport goes to Vasilyskoye, there is no post office and a pharmacy, the whole civilization is on the other side of the bridge. Hundreds of people walk on it every day, but there is no owner.

The locals will tell you the story of how, returning from the cemetery (and where else, these are horror stories), eight people fell into the river with their children. Everyone survived, in that year she became very shallow. After that, the bridge was repaired on its own.

In 2002, several scenes for the film Saboteur were filmed here, and in the early seventies, during the filming of the film "Squadron of Flying Hussars", the church was damaged.

In the middle of the river near the bridge there are two small islands with an interesting story. In 1825, 30 barges with marble limestone were prepared at the Polushkinsky quarries. The cargo was intended for the construction of the Church of the Savior on Sparrow Hills. According to the first project, it was supposed to be located there. Barely starting off, two barges sank. Legend says that they were deliberately drilled. The ships rotted, the stones were covered with sand and silt, and over time they turned into islands, which you can see from this very interesting suspension bridge.

Fact: Domestic dogs are afraid to walk on suspension bridges. They have to be picked up. But local dogs roam absolutely calmly.

Riding a suspension bridge on a bicycle or motorcycle is considered a special chic. I even came across a list of bridges on a biker forum.

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Entrance - crossover, directly to the bridge
Coordinates: 55°36"33"N 36°35"19"E

5. Suspension bridge to Mars!

Designed and built in the late 60s by a simple Soviet peasant Yuri Sokolov from the neighboring village of Markovo.

At the beginning of the 2000s, the bridge was slightly updated and repaired. Connects the villages of Mars and Markovo.

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Entrance - cars, directly to the bridge
Coordinates: 55°36"30"N 36°25"35"E

6. Bridge in Timoshkino.

Pictured in the center. Unfortunately destroyed. It is impossible to approach it along the left bank of the Istra - solid cottages and fences. On the right, you can go down, passing through the field and the hole in the fence.

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Entrance - only on foot
Coordinates: 55°46"21"N 37°7"16"E

7. Suspension bridge over Ruza

It is located in a very beautiful place in the sanatorium "Dorokhovo".

Few people know that there are two bridges on its territory.

One - in the photographs, the other - through the ravine connecting buildings 1-4, with the 5th and 6th

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Entrance - crossover, almost to the bridge
Coordinates: 55°38"29"N 36°18"16"E

8. Suspension bridge in Ozhigovo.

Nothing particularly remarkable

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Entrance - cars, directly to the bridge
Coordinates: 55°37"13"N 36°22"7"E

9. Bridge in Kozhino

If you're lucky, you can hear the church bells ringing nearby.

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Entrance - cars directly to the bridge
Coordinates: 55°37"10"N 36°14"52"E

10. Bridge of the project "House 2"

Night, fog, retired participants of the TV project in the beams of searchlights go across the bridge into the unknown ...
The cable bridge over the ravine is located in a very protected area. Photograph failed.
Coordinates: 55°49"16"N 37°6"20"E

During the day I crossed eight suspension bridges. Why not a record for the Guinness book?

NedoSMI, together with the site

The bridge is one of the most ancient inventions of mankind. Bridges have become a kind of symbol of human self-affirmation and overcoming the forces of nature. Thanks to them, the time spent on the road is reduced, and the commercial and strategic importance becomes simply colossal.

According to their capacity, bridges are divided into railway, pedestrian, automobile and combined. According to the static scheme, bridges can be beam, pontoon, spacer or truss. TravelAsk presents the 10 longest suspension bridges in the spanning category. The main distinguishing feature of such bridges is their supporting structure, which is made of flexible braces. Thanks to her, the roadway can be in the so-called suspended state.

Mackinac Bridge (or "Big Mac")

The bridge is located in America and runs over the Strait of Mackinac, which unites Lakes Huron and Michigan. The length of its main span is 1158 meters.

Høgakustenbron Bridge

Swiss bridge crossing the river Ongermanelven. The length of the main span is 1210 meters.

Golden Gate Bridge

The Golden Gate Bridge was built in. It connects San Francisco in the north of the peninsula with southern Marin County. Its main span is 1280 meters long.

Verrazano Bridge

Another American bridge. Connects the New York City boroughs of Brooklyn and Staten Island. The length of the main span is 1298 meters.

Tsingma Bridge

The Tsingma Bridge is located in Hong Kong and serves as a link between Tsing Yi Island in the east and Ma Wan Island in the west. It has a main span of 1377 meters.

Humber Bridge

This single-span suspension bridge is located in the UK. It connects East Yorkshire and North Lincolnshire. The length of the main span is 1410 meters.

junyang bridge

The main span of this Chinese bridge is 1490 meters. It connects two ancient cities - Yangzhou and Zhenjiang.

Great Belt Bridge

The Great Belt Bridge in Denmark is really big - its main span is 1624 meters long. It crosses the strait of the same name and connects the islands of Funen and Zealand.

Xihoumen Bridge

The Chinese tried hard and built the second longest bridge in the world, the main span of which is 1650 meters. The bridge connects Jintang Island and the Zezi Islands.

Akashi Kaikyo Bridge

Only the Japanese surpassed China. Their Akashi-Kaikyo bridge, which crosses the Akashi Strait, is considered the longest in the world, because its main span reaches 1991 meters.

Suspension bridge - a bridge in which the main supporting structure is made of flexible elements (cables, ropes, chains, etc.) working in tension, and the roadway is suspended. The operation of suspended structures in tension allows full use of the mechanical properties of high-strength materials (steel wire, nylon threads, etc.), and their low weight makes it possible to block structures with the largest spans. Hanging structures are relatively easy to install, reliable in operation, and are distinguished by architectural expressiveness.

Suspension bridges find the most successful application in the case of a large bridge length, the impossibility or danger of installing intermediate supports (for example, in navigable places). Bridges of this type look very harmonious, one of the most famous and beautiful examples is the Golden Gate Bridge, located at the entrance to San Francisco Bay.

The main load-bearing cables (or chains) are suspended between pylons installed along the banks. Vertical cables or beams are attached to these cables, on which the roadbed of the main span of the bridge is suspended. The main cables continue behind the pylons and are anchored at ground level. Cable extensions can be used to support two additional spans.

Under the action of a concentrated load, the supporting structure can change its shape, which reduces the rigidity of the bridge. To avoid deflections, in modern suspension bridges, the roadway is reinforced with longitudinal beams or trusses that distribute the load.

Constructions are also used in which the roadway is supported by a system of straight ropes fixed directly on the pylons. Such bridges are called cable-stayed.

Construction structure

The main stresses in a suspension bridge are tensile stresses in the main cables and compressive stresses in the supports, the stresses in the span itself are small. Almost all the forces in the supports are directed vertically downwards and stabilized by cables, so the supports can be very thin. The relatively simple distribution of loads over different structural elements simplifies the design of suspension bridges. Under the influence of their own weight and the weight of the bridge span, the cables sag and form an arc. An unloaded cable suspended between two supports takes the form of a so-called. "chain line". If the weight of the cables can be neglected, and the weight of the span is evenly distributed along the length of the bridge, the cables take the form of a parabola. If the weight of the cable is comparable to the weight of the roadway, then its shape will be intermediate between a catenary and a parabola.

Advantages of suspension bridges

• The main span can be made very long with a minimum amount of material. Therefore, the use of such a design is very effective in the construction of bridges across wide gorges and water barriers. In modern suspension bridges, wire cables and ropes made of high-strength steel with a tensile strength of 2–2.5 GN/m² are widely used, which significantly reduces the dead weight of the bridge.
• Suspension bridges can be built high above the water, allowing even tall ships to pass under them.
• There is no need to install intermediate supports, which gives great advantages, for example, in the case of mountain faults or rivers with strong currents.
• Being relatively malleable, suspension bridges can bend under strong winds or seismic loads without compromising structural integrity, while more rigid bridges need to be built stronger and heavier.

Drawbacks of suspension bridges

• Due to the insufficient rigidity of the bridge, it may be necessary to block traffic during stormy weather conditions.
• Bridge deflections in response to a concentrated load make suspension bridges inapplicable for railways, since in this case the locomotive will play the role of a concentrated load.
• In strong winds, the poles are subjected to a large torque, so they require a good foundation, especially in soft soils.

Now we know for sure what a suspension bridge is, what are its advantages and disadvantages, what is its design structure and its schemes, and much more. However, before people could not answer many questions, bridges were not so well studied, so destruction occurred. Such a bitter experience led people to study in detail the properties of hanging structures. To know how this happened, it is necessary to turn to the history of the development and use of suspension bridges.

1. Historical overview of the use of suspension bridges.

Suspension bridges are prominent in the history of bridge building. They appeared at the dawn of the development of human society and in the early period had very primitive constructive forms. Through a gorge, a mountain stream or a ravine, two or more thick ropes were thrown, sometimes just lianas (Basic load-bearing elements); the space between them was covered or laid with boards, and the bridge was ready. Sometimes another free rope was extended to serve as a handrail. Bridges of this type were found in South America, Japan, Tibet, the Caucasus and other places. They were very imperfect, had a low carrying capacity, poorly resisted wind loads and swayed strongly even from the weight of one person. The suspension bridge shown in Fig. 1 (above) had a span of 40 m, a width of 2.5 m and was fixed on trees standing on the banks. On the ropes of the bridge, made of agave, a light bamboo flooring was laid.

In China, about 3000 years ago, they began to build suspension bridges, the flooring on which was laid directly on tightly stretched chains or ropes, fixed in the rocks on the banks.

The first suspension bridge described in the literature, the design of which is close to modern suspension bridges, was built in 1741 in England across the River Tiss. A characteristic feature of this bridge was the presence of an independent roadway connected to the chain by suspension brackets. This bridge had a span of 21 m and served for the passage of miners.

Over the past 266 years since the opening of the above bridge, a large number of suspension bridges have been built in all countries of the world, the design of which has been constantly improved, and the spans have increased. Already at the beginning of the 19th century, their economic advantages over stone ones were revealed. By the end of the 19th century, the bridges already had significant spans. The span structures began to be based not on chain, but on cable hangers made of high-strength materials.

The transition from primitive structures of suspension bridges to modern systems dates back to the 17th-18th centuries. and is associated with the names of the Spaniard Verrantius (in his essay he gave a description of suspension bridges on iron chains, which indicated the design with the separation of the bridge deck from the supporting chains. The canvas was attached to chains on suspensions), the Frenchman Poyet (proposed a system in which the bridge deck was supported by guys, coming from two high masts) and the Englishman James Finlay. The latter received a patent for his hanging system in 1808, in which the chain was made of forged links connected to each other along the length of the bridge by short connecting links at the suspension points located at equal distances from each other. The chains on the banks rested on stone pillars and were passed into the anchor abutments, where they were fixed in them with their ends. The carriageway of the bridge, consisting of transverse beams and flooring, was suspended from the suspensions.

The first suspension bridges that proved to be able to meet modern requirements were built in North America at the end of the 18th century (more than 50 bridges). The first suspension bridge was built by James Finlay in Pennsylvania in 1796. At the beginning of the 19th century, quite a few such bridges already existed in this state. The largest of them was a 91.8 m bridge over the Skukl River.(Schuylkill) near Philadelphia.

It is characteristic that none of the suspension bridges of the early period of construction had any wind connections, since it was believed that the chain had a natural equilibrium shape and would return to it, regardless of the magnitude and direction of deflections.

So, in the first period, which lasted until about 1810, as a rule, chain bridges of small spans were built. They had a significant dead weight and a relatively small carrying capacity. The main load-bearing element of such bridges was a chain made up of rings or separate rigid elements interconnected by bolts (hinges).

At the beginning of XIX century, the economic advantages of suspension bridges have already been revealed in comparison with stone bridges, which were widespread at that time. So, for example, a suspension bridge across the Tweed River built in 1820 in England with a span of 110 m cost about 4 times cheaper than a stone bridge of the same length.

British engineers followed the example of the Americans, resulting in the construction of many chain bridges in England during the first quarter of the 19th century. The largest of these, the Meney Bridge, which connects the coast of Wales with the island of Anglesey, was designed and built by Thomas Telford. Construction was carried out from 1822 to 1826. In 1826, the opening of the Meneian chain bridge took place in England, which served for about a hundred years, had a span of 177 m with an arrow-to-span ratio of 1/12.

During the same period, a number of bridges were built in France, the USA and other countries, spans of which did not exceed 150 m.

The construction practice of suspension bridges was ahead of their theoretical development, since the suspension bridges under construction, which consisted of a chain to which the roadway was suspended, were a flexible variable system, which led to oscillations and large deflections of such primitive suspension bridges, to breakdown of connections, accidents and disasters. .

However, despite the adverse effects of the gap between the practice of building suspension bridges and the state of the theoretical development of this issue, suspension bridges were indispensable systems for large spans (their use was caused by the poor state of technology in the construction of bridge piers), and collapsed bridges were again and again restored and strengthened.

According to incomplete statistics, of suspension bridges of large spans from 60 m and above, built from 1741 to 1885, 82 bridges lasted from 50 to 120 years, 30 bridges - from 20 to 50 years and 6 bridges - less than 10 years .

Despite the negative qualities of the simplest suspension bridge form, these bridges have proved to be no less durable than other bridge systems, due to the ease of reinforcement and reconstruction that suspension bridges are characterized by.

For small loads that existed at that time, the flexibility of the bridge system did not raise any doubts about the strength of the bridge and did not impede the movement of “light loads” on it, as a result of which the engineers of that time were mistaken, considering the return of flexible suspension bridges as an advantage and natural natural qualities of flexible suspension bridges. the chain or rope of the bridge to its original form, after the passage of the load, i.e., they sought to build the theory of suspension bridges on the use of the simplest form of natural equilibrium of a rope thrown from coast to coast.

Flexible bridges of the simplest type were most developed after 1822, when a cable was invented from wire with high allowable voltages and with this cable being spun in place from individual wires or strands when building suspension bridges.

Second quarter of XIX century was markedwidespread use of cable suspension bridges, in which the main load-bearing element (chain) was replaced by a cable (wire cable). This led to significant progress, as the cable had a higher strength compared to the chain. The invention of steel wire ropes made it possible to build a canopy bridge without scaffolding and to expand the construction of suspension bridges to very large spans.

During this period, a number of cable bridges were built in France, England, America and other countries.

The suspension bridge opened in 1834 in Switzerland near Freiburg turned out to be unique at that time. It had a span of 265 m, a cable switch of 1/14 span, a carriageway width of 6.5 m and blocked the river valley at a height of 51 m above water level. The bridge is suspended on 4 cables, 135 mm in diameter, each cable consisting of 1056 wires 3.8 mm thick with a tensile strength of 82 kg/mm2.

Increased temporary loads, improper termination of ropes, etc. chains in the abutments, as well as the action of the wind, which led to large oscillations of the entire system (based on the primitive use of the natural form of rope balance) in the horizontal and vertical planes, led to severe catastrophes and accidents in a number of bridges. Disasters will be discussed in detail in the section "Disasters when using suspension bridges of the simplest form"

The subsequent period of about a hundred years is characterized by the mass construction of suspension bridges in many countries of the world. Suspension bridge designs improved rapidly. High-strength materials began to be used, and the spans of bridges were constantly increasing and by the beginning XX centuries approached 500 m. So, for example, in 1883 the famous Brooklyn Bridge was built in New York with a grandiose span for that time - 486 m.

In the 20th century, a large number of suspension bridges were built, the main achievements in the technology of their construction are as follows:

- In 1929, the Ambassador Bridge was built across the Detroit River, which came out on top among all bridge systems in terms of span, surpassing the Quebec Bridge with a span of 548 m. The bridge connected two neighboring countries - Canada and the USA. Construction lasted two years. The average span of the bridge is 563 m. The height of the steel lattice stiffening beam is 6.7 m. The ratio of the height of the stiffening beam to the span is 1: 84. The width of the carriageway is 14.1 m, the sidewalks are 2.4 m. The bridge is supported by two cables, consisting of parallel wires. The diameter of each cable is 48.9 cm.

- In 1931, a bridge was built across the Hudson (Fig. 1.2) with a length of 1067 m - the first bridge to exceed a kilometer span, finally consolidating the superiority of hanging systems. The bridge has steel lattice pylons 181 m high. Its span is 1067 m. The cross section of the bridge is shown in fig. 1.3. The distance between the two stiffening beams is 32.29 m. The roadway is supported by four cables with a diameter of 91.4 cm. The cables of this bridge consist of 61 strands. Each strand is made of 434 wires with a diameter of 4.9 mm. The tensile strength of the wire is 155 kN / cm2, and the conditional yield strength is -105 kN / cm2. Hangers between which sidewalks are located have a diameter of 78 mm. Each cross beam is suspended by four hangers. In total, one cable contains 26474 parallel wires. The total length of the wires in the cable is 171,000 km. The bridge was designed with two levels. In 1929, only the upper tier for eight traffic lanes was built. In the middle there is a 12.2 m wide passage designed for trucks, and on the sides there are lanes for cars.

Between 1959 and 1962 the lower tier was added, which made it possible to cope with the increased traffic flow. As a result of the extension, a stiffening truss 9.14 m high was formed.

- In 1937, the Golden Gate Bridge was built in San Francisco, 1280 m long, an object of national pride for Americans (150,000 people gathered at the celebration of the 50th anniversary of the bridge in 1987), received many prizes for beauty, a special effect from the orange cable on blue ocean background. In 1953, after the Tacoma Valley Suspension Bridge disaster (1940), the Golden Gate Bridge was reinforced with horizontal retaining cables.

- In 1940, the three-span Tacoma Bridge was built across the Puget Sound, which, after only four months, collapsed from vibrations caused by the action of the wind.

In October 1950, the new Tacoma Bridge was opened to traffic, built on the same site using the old pier foundations. The length of the main span is 853 m. The new bridge differs from the old one by a stiffening beam made in the form of a steel lattice truss with a height of 10 m. The stiffening beam is supported by two 50.8 diameter cables see each.

- In 1965, the Verrazano-Narrows Bridge was built in New York, 1298 m long, the last American world record, which is still the American record.

- In 1997, in Japan, between the islands of Shikoku and Honshu, the Akashi-Kaikyo Bridge was built, which entered the Guinness Book of Records twice: as the longest suspension bridge - the length of one span is 1991 m - and as the highest bridge, since its pylons rise to 297 m, which is higher than a ninety-story building. The total length of this unique three-span structure is 3911 m. Despite the huge size of the bridge, its construction is strong enough to withstand wind gusts up to 80 m per second and earthquakes up to 8 points on the Richter scale, which are not uncommon in the Far East.

In our country, suspension bridges have not received such great development as in the USA, England, France, Japan and other countries. First, they appeared with us much later. G.P. Perederiy believes that the first suspension bridge in Russia was built in 1823 in St. Petersburg in the Ekateringof park and had a span of 15.2 m. The lag in this area is due to many reasons, one of which is the absence of relatively large water barriers that would require the construction of such large spans.

The first suspension bridges in Russia were built in St. Petersburg in the 1820s-1830s:

1823 ., footbridge in Yekateringofsky park with a span of 15.2 m;

1824 ., Panteleimonovsky bridge across the river. Fontanka near the Summer Garden, L = 40 m (dismantled in 1905 after the destruction of the neighboring Egyptian bridge during the passage of a cavalry detachment).

Some pedestrian hanging bridges of that period have survived to this day: Pochtamtsky (across the Moika), Bankovsky and Lviny (across the Griboyedov Canal).

1836 ., Brest-Litovsk, Russia's first suspension bridge on wire ropes, L = 89 m.

1847 ., Kyiv, r. Dnieper, four-span bridge, L = 134 m, destroyed by the White Poles in 1920

In the XX century. on the territory of the USSR, a number of suspension bridges of very large spans were built for pipelines (the Amu Darya River, L = 660 m; the Dnieper River, L = 720 m) and a temporary bridge with a span of 874 m across the Volga under the conveyor line during the construction of a hydroelectric power station.

The most famous Russian suspension bridge is the Krymsky Bridge across the Moskva River. The bridge inherited its name from the Crimean ford that once existed on the site of the bridge, through which the Tatars crossed during raids on Moscow. Built in 1938, with a total length of 688 m, at that time it entered the top six bridges in Europe along the length of the river span - 168 m. The type of construction used by engineer B. P. Konstantinov and architect A. V. Vlasov when designing Crimean bridge, is very rare in world practice. Its pylons stand alone and are not connected at the top. Despite the fact that the weight of the metal structures of the Crimean bridge reaches 10,000 tons, the bridge seems very light and delicate. And although the Crimean Bridge has already become one of Moscow's calling cards, it occupies a more than modest place in the world ranking table. (More about the Crimean bridge in the section "Examples of suspension bridges").

2. Catastrophes when using suspension bridges of the simplest pho r we.

The initial period of construction of suspension bridges of the simplest type and their distribution are associated with a large number of accidents andcatastrophes of these bridges.

The technique of bridge building does not know more accidents than was the case with the use of suspension bridges.

From the moment when suspension bridges began to be built, both in our country and abroad, the issues of vibrations of suspension bridges, from which the destruction of bridges occurred, did not receive the necessary analysis.

The primitiveness of the simplest suspension bridge system and the geometric variability of the system did not bother bridge builders. However, during the operation of such bridges, they swayed from vertical and wind loads, which led to damage to the bridges, their catastrophes, or, at best, caused noticeable operational inconvenience.

One of the first suspension bridges across the river. A tweed in Scotland, with a span of 78 m, was destroyed by winds of 5 - 6 points a few months after construction.

Soon a bridge was built across the river. Tweed in Berwick (England), with a span of 40 m, which was destroyed by wind 6 months after construction was completed.

Brighton Bridge, built in 1823, was destroyed by a storm in 1833 and then destroyed again after repairs - in 1836.

According to the sketches of an eyewitness at the time of the disaster, it can be seen that the disaster occurred from the suspension bridge characteristic of the simplest form. S -shaped vibrations accompanied by twisting of the carriageway.

The Montrose Bridge in Scotland, built in 1829, collapsed in 1829 from overload, with many casualties.

After repairs, it was again destroyed by the wind in 1838. Witnesses saw how the bridge oscillated in two half-waves, which caused it to collapse.

The bridge across the Menay Strait in Wales, built in 1826, with a span of 177 m, was subject to menacing vibrations. The span fluctuated in waves, in waves 4.8 m long. A month later, the bridge was damaged and then damaged in 1836 and 1839.

Bridge over the river Lahn near Nassau (Germany), built in 1830, was badly damaged by the wind in 1833, when the chain was broken and the stiffening beam was broken.

The Roche-Bernard Bridge in France, built in 1840, with wire cables with a span of 194 m, was destroyed by wind in 1852. The Wheeling Bridge over the river. Ohio (USA) overflight in 308 m, built in 1848-1849, destroyed in 1854

Eyewitnesses said that ordinary S -shaped vibrations suddenly turned into strong torsional vibrations, "the bridge dived like a ship in a storm", and each vibration gave a new, stronger push, until the entire span collapsed from a break in the cables in the cable.

Lewiston-Quixton Bridge across the river. Niagara with a span of 306 m, built in 1851, almost collapsed during a storm in 1855,

In order to reduce threatening the safety of the bridge, S-shaped its oscillations (in two half-waves) near the pylons, inclined guys were added to support the roadway. After the inclined shrouds were disconnected in 1864 for the duration of repairs, the bridge swayed from the wind and collapsed.

The bridge over Niagara Falls, built in 1868, with a span of 372 m, was destroyed after being repaired in 1888. A doctor passing over the bridge at night described its movement as the rocking of a boat on the waves. In the morning, no traces of the bridge were left, but it was soon restored "so that tourists would not notice its disappearance."

A number of bridges collapsed from the passage of the crowd, such as: Broughton Bridge in Lancashire, built in 1831, a bridge in Angers (France) with a span of 100 m (collapsed in 1850), a bridge inOstrava (Czech Republic), built in 1891 (collapsed in 1896), etc. A number of bridges in America collapsed from the passage of livestock.

The Philadelphia Bridge, built in 1809, collapsed in 1811 after less than two years; bridge in Yorkshire in 1830, railway. Bridge in Durkhel across the river. The yew, the Kentucky bridge, etc. These lessons of disaster were essentially forgotten until the collapse of the Tacoma Suspension Bridge in the United States on November 7, 1940, with an average span of 855 m.

From the action of a relatively weak wind, its horizontal fluctuations turned into ever-increasing in time S -shaped (in two half-waves) oscillations, accompanied by twisting of the carriageway. The magnitude of the vertical amplitudes of the roadway reached 8 m, and the roadway twisted by 45 - 50 ° (Fig. 2.1)

As experience gained in the construction of suspension bridges of the simplest form in order to increase rigidity - reduce vibrations, suspension bridges began to be strengthened. Strengthening consisted in the device of wind connections, the device of rigid beams located along the bridge in the plane of the cables, called stiffening beams, the device of inclined cables supporting the roadway near the pylons.

All these measures, however, are insufficient, since the Tacoma Bridge, built in 1936, had both stiffening beams and wind ties. The essence of the issue lies in the very system of the main trusses of the suspension bridge, since it was based on the simplest form of suspension trusses, in connection with which these bridges retained their inherent shortcomings.

In recent years, after studying the accident of the Tacoma suspension bridge, it was found that the simplest suspension bridge system, which is based on the natural form of equilibrium of a suspended rope, is an aerodynamically unstable system, which explains the large number of suspension bridge accidents of this type.

Aerodynamically stable systems are cable-stayed systems and double-chain suspension bridges.

3. Transition to rational systems of suspension bridges.

Using examples of catastrophes associated with swinging and vibrations of suspension bridges, the necessity of introducing rigid beams into the structure of a suspension bridge was proved. Starting from the middle of the 19th century. in addition to the flexible chain, rigid wooden railings of the Gau truss type and inclined guys supporting the roadway near the pylons began to be used in bridges.

Against horizontal swings began to use diagonal ties under the roadway.

In the words of one of his contemporaries, "catastrophes drove suspension bridges out of Europe." Rather, it should be said that errors in theoretical ideas about the operation of suspension bridges excluded their use in Russia and Western Europe. An example of this was the suspension bridge built in 1850 under railway loads Bridge "Britain" (England), which was converted during the construction process to a beam, and the whole alteration was that the chains of the suspension bridge were thrown out and only rigid beams with a roadway were left, which indicates completely unjustified safety margins in the stiffening beam, able to perceive independently loads as a beam system.

This approach to the construction of suspension bridges in Europe continued even after the science of calculating building structures was created and when the calculation of a suspension bridge was only a particular problem of the general method.

At the end of the 19th century and the beginning of the 20th century. in the USA, the use and construction of suspension cable bridges continued (an example of which is the Brooklyn Bridge, with a span of 486 m with stone pylons, with a total height of up to 130 m together with supports), while in Europe they argued for a long time about the advantages and disadvantages of chain and cable bridges.

The exception at that time was France, where the cable-stayed systems of the Gisclair, Leinekugel-le Coq and others bridges were developed, and where the use of cable-stayed bridges was developed along with the construction of suspension bridges.

The builders of suspension bridges in Europe, starting from the end of the 19th century, took the path of increasing the rigidity of suspension bridges (the bridge in Bratislava has a rigidity of 1/1500 of the span), by refusing to use steel ropes.

The question of the use of suspension bridges in Europe was put on the plane of security from the possible consequences of incomplete theoretical knowledge. There is no trace left of the economy and simplicity of solutions.

It should be noted that for a long time there was a belief that a suspension bridge would be more rigid if small rope or chain sag was accepted, since suspension bridges without stiffening beams had smaller S -shaped deflections, when the carriageway is bent along two half-waves, with a decrease in the sag, and as a result, the first suspension bridges were built with a sag of 1/12 1/15 of the span. But what is valid for a flexible thread and economically advantageous for suspension bridges of the simplest type, in which massive stone pylons were used, is disadvantageous and impractical for suspension bridges at the present stage of their development.

Therefore, the arrows used in suspension bridges gradually, depending on the period of construction of the bridge, increased to 1/7 of the span. This increase or decrease in the advantageous amount of sag is dictated mainly by the economics of the use of pylons. In the last century, it was unprofitable and difficult to build stone pylons of great height (the stone pylons of the Brooklyn Bridge were built for more than 9 years, i.e. 70% of the total construction time of the bridge), as a result of which it was advantageous to reduce the chain boom, especially since this coincided with the requirements to suspension bridges of the simplest type on the reduction of the arrow of the outline of the chain, based on the reduction in the magnitude of the deflections.

Thus, the transition period from the simplest forms of suspension bridges to rational systems was characterized by the desire to improve the constructed bridges and, based on the experience of bridge construction, to apply the most rigid and economically viable suspension bridge systems and structures.

Basically, with the exception of the use of cable-stayed bridges in France, all the efforts of builders and scientists were reduced to improving the simplest single-circuit system of a suspension bridge by refining the calculation and applying various structural measures (introduction of inclined cables, etc.). However, these aspirations did not solve the issue and were half measures, since the ability of the simplest suspension bridge system to S -shaped bending of the stiffening beams was preserved in them.

An example of this is the failed Tacoma Suspension Bridge and many of the US suspension bridges built in the 1940s, which were subjected to threatening vibrations during their operation.

In particular, the Bronk-Whitestone Suspension Bridge was immediately strengthened after the collapse of the Tacoma Bridge, and monitoring and control of their oscillations were organized on the remaining US suspension bridges.

The conclusions that were obtained in the United States as a result of an analysis of the Tacoma Bridge disaster note that the main danger lies not in the fact that the width of suspension bridges of large spans is too small (the Tacoma Bridge had a width of 1/72 of the span, but in the fact that the rigidity is too low stiffening beams of a suspension bridge having a "ribbon-like structure").

AT Concluding their conclusions, American experts are forced to declare: “It is more expedient to scientifically eliminate the causes of instability and low rigidity of suspension bridges than to try to find any antidotes.”

4. Examples of modern suspension bridges.

4.1. Golden Gate Bridge.

Figure 4.1 Golden Gate Bridge.

The Golden Gate Bridge is a suspension bridge across the Golden Gate Strait. It connects the city of San Francisco in the north of the San Francisco Peninsula and the southern part of Marin County, near the suburb of Sausalito. The Golden Gate Bridge was the largest suspension bridge in the world from its construction in 1934 until 1964.

The bridge was designed by engineer Joseph Strauss and was consulted by architect Irving Morrow, who used Art Deco elements in the design. All mathematical calculations for the bridge were made by Charles Alton Ellis, who lived in New York City, but due to bad relations between him and Joseph Strauss, Ellis's name does not appear in the construction of the bridge and is not inscribed on the bridge builders' plaque on the south tower. It should be noted that all calculations were made using arithmometers and slide rules.

History reference.

The need to connect the shores of the Golden Gate Strait with a bridge structure became quite obvious as early as 1923, but its construction was only started after President Franklin Roosevelt proclaimed the so-called "New Deal" in order to revive the economy. In the period 1933 - 1937. two bridges were erected in San Francisco: one over the strait in the direction of the Oakland area and the other called the Golden Gate.

The construction of the bridge was a serious technical challenge due to the heavy loads on the structure, which was complicated by the nature of the local Pacific currents. The new structure had to withstand the flow of ocean waters flowing at speeds up to 185 km per hour, as well as gusts of wind causing vibrations up to 9 m. then the main span deviated by 8 m horizontally and 2 m vertically, which, however, did not cause serious damage. A difficult task was the construction of the base of the southern support at a depth of 30 m, where it was necessary to use a giant air caisson. Also, during the installation of the structure, a special safety net was stretched under the flooring, which saved the lives of 19 workers, but there were also those who died during construction. From the very beginning, the bridge was painted orange-red. Red and orange are the colors that are always used in the construction of steel structures, because these paints contain a lead component that protects the steel from rust. The color of the Golden Gate Bridge also has the advantage of being clearly visible in the fog that so often thickens over this area. But in foggy weather, the paint decomposes into elements that are harmful to the environment.

This became clear much later, and harmless compounds are being developed now. While nothing came of the experiments, some sections of the bridge were painted with gray paint. But this departure from tradition did not find support.

Bridge settings.

The length of the bridge is 1970 meters, the length of the main span is 1280 meters, the height of the supports is 230 meters above the water. From the roadway to the surface of the water - 67 meters. A 7.6 m high steel lattice truss is supported by two 92.7 cm diameter parallel wire cables (the cable consists of 61 strands, each strand consists of 450 wires.

Bridge today.

The Golden Gate Bridge is the only route north from San Francisco. Vehicle traffic on the bridge is carried out on six lanes. On average, one hundred thousand cars a day pass over the bridge. The speed limit on the bridge is 45 mph (~72 km/h).

In the southern end of the bridge and in its central part, there are two sound signals for escorting ships in the fog. These horns are used for five hours a day during the foggiest period of the year from July to October. And on the tops of the bridge supports are signal lights designed for aircraft.

The Golden Gate Bridge is a unique architectural structure that can be called one of the new wonders of the world.

4.2. Brooklyn Bridge.

Brooklyn Bridge (English) Brooklyn Bridge ) - one of the oldest suspension bridges in the United States, it crosses the East River and connects the Brooklyn and Manhattan areas in New York City. At the time of completion, it was the largest suspension bridge in the world and the first bridge to use steel bars in its construction. Original name: New York and Brooklyn Bridge New York and Brooklyn Bridge).

History reference.

The idea of ​​how to connect the separate cities of Manhattan and Brooklyn (now representing areas of New York) has been discussed in society since 1806. Studies have been carried out to evaluate this project; the question of building a tunnel was considered, which was then considered less difficult than ground work. For more than 60 years, debates were going on (sometimes acquiring a caustic character), until, finally, the matter got off the ground. In 1869, John Augustus Roebling presented his project to the New York Bridge Company, which approved it on September 1 of that year. Construction of the bridge began on January 3, 1870.

John Augustus Roebling (1806-1869) received a good theoretical education at the Faculty of Civil Engineering of the Royal Polytechnic Institute in Berlin. In the United States, where he emigrated in 1831, he gained extensive professional experience building such significant structures as the Allegheny Aqueduct on the Uplegany River, the Monongahila River Bridge at Pittsburgh, the Delaware Aqueduct Bridge (still in operation), and the Suspension bridge on the Ohio River (120 m long) in Cincinnati. At the end of the 60s. 19th century New York City experienced rapid growth: in the previous decade, its population increased from 266 to 396 thousand people, which was a record figure compared to any other city in the country. At the same time, Brooklyn was actively developing, and the construction of the bridge became an urgent need.

In developing his idea, Roebling included the use of steel (a material rarely used at that time) because of its double strength compared to the usual cast iron. Even the construction equipment seemed completely new: for the first time, when excavating a pound directly under water, pneumatic caissons were used to install supports. Unfortunately, the construction process was accompanied by unpleasant episodes. At first, there was an accident with Roebling himself: before starting work, while on the ferry while inspecting the place for future supports, he broke his leg. This was followed a few days later, on July 20, 1869, by the death of the designer himself from tetanus. Responsibility for project management passed to his son Washington, who gained the necessary experience working alongside his father on the construction of a suspension bridge on the Ohio River in Cincinnati. Personally controlling the excavation of land under water, Washington Roebling in 1872 himself descended into a caisson with compressed air and received decompression syndrome (caisson disease). Now he was forced to manage all the work only from the window of his own home.

The construction of the bridge took 13 years, during which time there were many other fatal accidents. The bridge cost $15.1 million. Finally, on May 23, 1883, the Brooklyn Bridge was put into operation.

On the same day, about 1,800 vehicles and about 150,300 people used it to cross to the other side. However, a week later, there was a rumor among the people about the possibility of a sudden collapse of the bridge, which caused a stampede and the death of 12 people. To assure the people of the strength of the bridge, the authorities led 21 elephants from a circus touring nearby.

Bridge settings.

The length of the main span is 486.3 m, the length of the side spans is 287 m, the total length of the bridge is 1825 m, the height of the bridge is 42 m, the height of the supports is 84 m. The carriageway is supported by four cables with a diameter of 39.4 cm each. The cable consists of 5282 parallel wires with a diameter of 3 mm. In the plane of each cable, 40 inclined guys are placed on both sides of the pylons. The main beam consists of 6 longitudinal lattice trusses connected by transverse beams. The trusses have a height of 5.2 m. The ratio of the height of the stiffening beam to the span is 1:94.

Bridge today.

The appearance of the Brooklyn Bridge is known all over the world: the flooring of its cobweb-like metal structure is suspended from four cables fixed at the edges, supported by two neo-Gothic granite towers.

The bridge is used for both vehicular and pedestrian traffic - along it is divided into three parts. The side lanes are used by cars, and the middle one, at a considerable height, by a pedestrian

us and cyclists.

4.3. Qing Ma Bridge.

Qing Ma (Tsing Ma, 青馬大橋) is a suspension bridge in Hong Kong, the fifth longest in the world. It connects Qing Yi Island in the east and Mawan Island in the west, is part of the Lantau Highway, which, with three other bridges, connects the New Territories, and Chek Lap Kok Island, where Hong Kong International Airport is located. The railway is part of the MTR subway system, the Tung Chung line and the international airport. The bridge, designed by Yee Associates, is the longest road and rail bridge in the world. (The bridge has no sidewalks. Parking is also prohibited on it). The creation of the bridge began in 1992 and ended in 1997. The Lantau highway opened on April 27, 1997. The bridge cost HK$7.2 billion to build. The opening ceremony was attended by former British Prime Minister Margaret Thatcher.

Bridge design features

Foundation and support structure.One pillar was built from the side of Qing Yi Island, and the other - 120 meters from the coast of the artificial island of Mawan. Each support rises 206 meters above sea level, and is dug into a relatively shallow depth. Supports consist of two "legs" connected to each other at some intervals.

Crossbars. The "legs" are made of high-strength concrete using the technology of continuous pouring of concrete using a mobile formwork.

Anchoring . The tension forces in the cables are balanced by large support structures located at both ends of the bridge. These are massive concrete structures buried deep into the ground on the coast of Qing Yi and Ma Wan Islands. The total weight of concrete used to create the two supporting structures is approximately 300,000 tons.

Main cables . The cables were made by the hanging method of fiber formation. This process involves pulling the wire, ensuring that the wire is fed with constant tension and drawn from one tower to the next, passing through a 500-ton cast-iron skid at the top of each bridge tower. 70,000 wires, each with a diameter of 5.38 mm, were combined into a main cable with a diameter of 1.1 meters.

Hanging canvas. The steel structure of the canvas was made in England and Japan. After delivery, it was processed and assembled in Dongguan, China into modules. A total of 96 modules were prepared, each 18 meters long and weighing 480 tons. The modules were delivered to the installation site by specially made barges and installed by two coastal cranes that could move along the main cable.

Span closest to Qing Yi Islandsimilar in shape and cross-section to a suspended span, but resting on a foundation instead of being suspended by a cable. It was the first span to be assembled on land and installed by coastal cranes. Further constructions were made by attaching modules using lifting devices located at the level of the web. It was envisaged that expansion of the joints could occur with a permissible maximum movement of ± 850 mm, which should occur inside this span.

Bridge parameters.

Total length - 2.200 m., length of the main span - 1.377 m., height of supports - 206 m., di a meter of cables -1.1 m., bridge height - 62 m.

The bridge has two levels, on the upper level there are six with naya motorway and stral, three p o stripes in every direction. On the bottom, two e railway tracks and a spare two-lane a in the road for the next steel purposes and for movement during strong winds. The bridge has no trot a ditch.

Qing Ma has become a favorite scenic spot and famous landmark. For up-to-date information, you can visit the Lantau Tourist Center and Viewpoint, located in the northwest of Qing Yi Island.

4.4 Akashi-Kaikyo Bridge.

Akashi Kaikyo (Japanese 明石海峡大橋 Akashi Kaikyo: Ohashi) is a suspension bridge in Japan that crosses the Akashi Strait (Akashi Kaikyo:) and connects the cities of Kobe on the island of Honshu with the city of Awaji on the island of Awaji. (GIP Akashi-Kaike - Suritano Karina.) It is part of the Honshu-Shikoku highway. The central span of the bridge is the longest in the world and has a length of 1991 meters. This is one of the three bridges connecting the islands of Honshu and Shikoku.

History reference.

Before this bridge was built, there was a ferry across the Akashi Strait. This dangerous waterway was often subjected to severe storms. In 1955, two ferries sank during a storm, killing 168 children. The unrest of the inhabitants and general discontent forced the Japanese government to draw up plans for the construction of a suspension bridge. Initially, it was planned to build a railway-road bridge, but in April 1986, when the construction of the bridge began, it was decided to limit it to only 6 lanes of car traffic. In fact, the construction of the bridge began in 1988. The construction of the bridge began in March 1988 in the complicated conditions of the sea strait with a maximum depth along the bridge route of 110 m, a current speed of 4.5 m/s and a navigation intensity of 1400 ships/day, not counting the fishing fleet. (The Akashi Strait is an international waterway and must be at least 1,500 meters wide.)

During the construction of the Akashi-Kaikyo bridge in Japan, a strong earthquake occurred. The epicenter was located just 3.2 km from the center of the bridge. After the earthquake, the displacement of the foundations of the supports, caused by the movement of the earth's crust, was found to be up to 72 cm horizontally and 22 cm vertically. There was a need to redesign the stiffening beam. The erected structures were almost not damaged. Additional forces in the structural elements, which arose from a change in the configuration of the bridge, determined using spatial analysis, turned out to be insignificant. The opening of the bridge took place on April 5, 1998. The cost of building the bridge was 500 billion yen.

Bridge settings.

The bridge has three spans: a central span of 1991 meters and two sections of 960 meters each. The total length of the bridge is 3911 meters. The length of the main span was originally planned to be 1990 meters, but it increased by one meter after the Kobe earthquake on January 17, 1995. The bridge design has a system of double-hinged stiffening beams that can withstand wind speeds up to 80 meters per second, seismic activity up to 8.5 on the Richter scale and withstand sea currents. The pylons rise to a height of 297 m.

Cable parameters.

• The length of each main cable is 4,073 meters.
• Main cable diameter - 112 cm

Diameter of each wire - 5.23 mm (3/16 inch)

• Number of strands in each main cable - 290
• Number of wires in each strand - 127
• Total number of wires in each cable - 36,830

Weight of each main cable - 50,460 metric tons (~56,000 tons)

The bridge is designed for 6-lane high-speed traffic

The Akashi-Kaikyo Bridge has twice entered the Guinness Book of Records: as the longest suspension bridge, and as the highest bridge. And one more curious fact: if all the steel cables of the Akashi-Kaikyo bridge were stretched out in length, then they could encircle the Earth as many as seven times!

4.5. Ataturk bridge.

Ataturk bridge(Bosphorus bridge, tour. Boğaz Köprüsü, English. Bosphorus bridge or First Bosphorus Bridge ) - the first suspension bridge across the Bosphorus. It connects the European and Asian parts of Istanbul.

The length of the bridge is 1560 meters, the length of the main span is 1074 meters, the width of the bridge is 33 meters, the height of the supports is 165 meters above the water. From the roadway to the surface of the water - 64 meters.

The laying of the bridge, planned back in 1950, was carried out on February 20, 1970. The opening of the bridge took place on October 29, 1973, on the occasion of the 50th anniversary of the establishment of the Republic of Turkey. The bridge was built by the German firm Hotchtief and the British firm Zleveland Engineering, the construction of the bridge took 23 million US dollars.

Every day, more than 200,000 vehicles pass through the bridge, carrying about 600,000 passengers. According to its length, the bridge is considered the 13th bridge in the world. The passage on the bridge is paid, the passage on the bridge is closed to pedestrians (due to the fact that the bridge was regularly used to commit suicide).

4.6. Sultan Mehmed Fatih Bridge.

Sultan Mehmed Fatih BridgeFatih Sultan Mehmet Köprüsu, eng. Fatih Sultan Bridge or Second Bosphorus Bridge) is the second suspension bridge across the Bosphorus. It connects the European and Asian parts of Istanbul.

History reference.

Construction of the bridge began in 1985 and was completed in 1988. Its construction in 1988 also marked one of the memorable dates in the history of Turkey - the 535th anniversary of the conquest of Constantinople in 1453 by Sultan Mehmed Fatih, which is why the bridge got his name. It is also noteworthy that the bridge of Sultan Mehmed Fatih was built on the same place where the first pontoon bridge of King Darius was located almost 2500 years before. The opening of the bridge took place on May 29, 1988. The bridge was built by Japanese builders, the construction of the bridge took 130 million US dollars.

Bridge settings.

The length of the bridge is 1510 meters, the length of the main span is 1090 meters, the width of the bridge is 39 meters, the height of the supports is 165 meters above the water. The height of the bridge is 64 meters.

Sultan Mehmed Fatih Bridge today.

Every day, more than 150,000 vehicles pass through the bridge, carrying about 500,000 passengers. According to its length, the bridge is considered the 12th bridge in the world. The passage on the bridge is paid, the passage on the bridge is closed to pedestrians (due to the fact that the bridge was regularly used to commit suicide).

4.7. Crimean bridge.

The Krymsky Bridge is the only suspension bridge in Moscow, passes through the Moskva River, is located on the Garden Ring Road and connects Krymskaya Square with Krymsky Val Street.

The passages along the embankments pass under the bridge in the coastal spans between the pylons and anchor abutments at the ends of the chains. Approach ramps are built along reinforced concrete flyovers, the facade sides of which are covered with walls lined with granite. Garages are located under the overpasses. To descend from the sidewalks of the bridge, stairs are arranged along the walls of the approaches.

History reference.

Previously, on the site of the modern bridge was the Nikolsky wooden bridge, built in 1789 according to the project of A. Gerard. In the 1870s the dilapidated bridge was replaced by a metal one with two lattice beam spans (designed by V. K. Shpeyer); in 1936 the bridge was moved 50 m downstream of the Moskva River, and then dismantled.

The bridge got its name from the ancient Crimean ford, through which the Crimean Tatars crossed during raids on Moscow.

Design

The type of construction used by engineer B.P. Konstantinov and architect A.V. Vlasov when designing the Crimean bridge is original and rare in world practice: its pylons, each 28.7 meters high, stand separately and are not connected at the top. Chains pass through the top, fixed in abutments at the ends of the bridge. The total length of each chain is 297 m, the total weight of metal structures is about 10,000 tons.

Bridge settings.

The opening of the bridge took place on May 1, 1938. At that time, the Crimean bridge entered the top six bridges in Europe in terms of the length of the river span - 168 meters. The bridge has three spans (47.5 + 168 + 47.5 m), its total length is 688 m, width is 38.5 m. The height of the pylons is 28.7 m. . The chain of plates is connected on bolted hinges. Chain length - 297 m.u Continuous stiffening beam, U-shaped section with a solid wall. The pylons do not have a connecting crossbar on top.

Conclusion.

So, among other systems, suspension bridges occupy a special position, being highly industrial structures, which in their parts can be made of various materials. They are advantageous for use starting from spans of 60-80 meters and with spans of 120 m and above, they compete with most possible solutions on highways.

In addition, suspension bridges are one of the most beautiful and graceful bridges. However, history, using the example of disasters, has shown that beauty must be combined with reliability. It is necessary to take into account all the factors affecting the bridge, and after that choose the most rational option that meets all requirements, including aesthetic ones. Today, in the world practice, a large number of suspension bridges are being built, each of which will amaze people with its grandeur and beauty.

And in conclusion, I would like to note that in our country, sooner or later, they should start building suspension bridges, which will still break all records and become the real pride of Russia.

Appendix.

Table 1.1 - The largest suspension bridges in world practice.

The country	City (place)	Let	Span, m	Year of construction completion	Name of the bridge
Japan	about. Honshu - oh. Shikoku	strait	1991	1998	Akashi-Kaikyo (Akashi)
Denmark	Halskov-Sprogö	strait	1624	1997	Big Beldt
Hong Kong (Hong Kong)	about. Lantau	strait	1413	1997	Tsing Ma (Tsing Ma)
United Kingdom	Hull	bay of the humber	1410	1981	Humber (Humber)
USA	New York	R. Hudson	1298	1965	Verrazano-Narrows (Verrazano-Narrows)
USA	San Francisco	bay	1280	1937	Golden Gate (Golden Gate)
Sweden	Veda Hornyo	strait	1210	1997	Hoga Husten
USA	Michigan	Strait of Mackinac	1158	1957	big poppy
Japan	about. Honshu - oh. Shikoku	strait	1100	1988	1) Seto Ohashi (Seto Ohashi) 2) Minami Bisan Seto (Minami Bisan Seto)
Turkey	Istanbul	Bosphorus	1090	1988	Fatah Sultan Mehmet
Turkey	Istanbul	Bosphorus	1074	1973	Bosphorus
USA	New York	R. Hudson	1067	1931	J. Washington
Japan	about. Honshu - oh. Shikoku	strait	1030	1999	Kurushima-Z
Japan	about. Honshu - oh. Shikoku	strait	1020	1999	Kurushima-2
Portugal	Lisbon	R. Tacho	1013	1966
United Kingdom	Edinburgh	bay fort	1006	1964	Forth (Fort bridge)

Bibliography.

1. Smirnov V.A. Suspension bridges of large spans. - M .: Higher School, 1970. - 408s.: ill.

2. Tsaplin S.A. Hanging bridges. - M.: DORIZDAT, 1949 - 288s.: ill.

3 Perederiy G.P. Bridge course. - M.: GOSZHELDORIZDAT, 1933. - 489p.: ill.

4. Silnitsky Yu.M. Suspension bridges: textbook. Benefit. - Leningrad, 1969. - 86s.: ill.

5. Shchusev P.V. Bridges and their architecture. - M .: publishing house on construction and architecture, 1953. - 360s.: ill.

A suspension bridge is such a bridge, the main structure of the bearing type of which is made of flexible type elements. Such elements can be ropes, cables, all kinds of chains and other similar elements. These elements perform the so-called tensile work. And the part of the bridge, which is the carriageway, is accordingly suspended on these flexible elements.

The use of suspension bridges is often associated with the impossibility of installing the bridge on supporting pillars. This can be dangerous, for example, where there is frequent traffic of ships. Also, the popularity of suspension bridges is due to the fact that the part itself, which is a carriageway, can be made quite long.

The very appearance of suspension bridges is a rather stylish design that looks monumental and dignified. A striking example of a suspension bridge is the most beautiful and famous bridge in America, which bears the harmonious name "Golden Gate".

Construction and arrangement of a suspension bridge

Structurally, the suspension bridge looks like this. On special structures, or as they are called pylons, which are located along the banks, cables are suspended, which are the main elements for the structure.

Already to these load-bearing cables, beams are suspended, which have a vertical position. These parts of the bridge are intended for attaching the canvas to them, which becomes the carriageway of the bridge. The cables, which are the main ones, do not stop at the pylons, but continue all the way to the shore, where they are strengthened at ground level. As a rule, such a continuation of the length of the cables is due to additional fixation of the entire bridge structure, as well as one more span, which are located before the start of the pylons.

Under the influence of gravity, a suspension bridge can change its structural qualities, which is why at present such bridges have been strengthened by laying additional reinforcing elements along the roadway. This strengthening is carried out at the expense of longitudinally laid special beams and so-called trusses, which are designed to distribute the load on the bridge. Thus, the bridge structure remains stationary, which guarantees safety and its stability.

Characteristics and features of the construction of suspension bridges

The advantages of suspension bridges include minimizing material costs even with a very long span of the bridge. The construction of this type of bridges can produce high enough above the water surface, which allows ships to move freely. Also, the absence of support devices in the design of such a bridge can be attributed to the great advantages of this type of bridge over others.

And this, first of all, saves on material. And secondly, it allows you to avoid situations with the destruction of bridges during mountain breaks, or, let's say, with a strong river current. Since the design of this bridge has elastic properties, this makes it more pliable to such phenomena as strong gusts of wind or seismic loads, which in turn is a protective property, since the bridge on supports in this case would have to be significantly strengthened.

But this type of bridge has some disadvantages. So, for example, they include the fact that with strong gusts of wind, traffic on the bridge can be suspended, since the bridge can begin to sway strongly. Also, in strong winds, the bridge supports are most susceptible to torque, which in turn requires the installation of a particularly strong foundation, especially in places with unstable soil. Suspension bridges are rarely used as railway bridges, because for structural strength, the load distribution of this type of bridge must be uniform.