Knowledge and legends about bridges

The bridge is an overhead man-made passage. It consists of an upper structure and a lower structure. The superstructure includes bridge body and bridge deck; The substructure includes pier, abutment and foundation. They hang high and lie flat, with diverse shapes, and some are simple and elegant; Some cross the rocks and streams, adding color to the mountains and rivers; Some are located in the main roads in the city center, with clever shapes; Some bridges are versatile and ingenious. No matter the wind and rain, no matter the heat and winter, they always cross the river to Tianjin in obscurity for the vast number of pedestrians, horses and chariots. The main purpose of building a bridge is to solve the traffic across water or valley, so that vehicles or pedestrians can walk on the bridge unimpeded. Judging from its earliest or most important function, a bridge should refer to a road across the water. Therefore, Duan Yucai's explanation of "Wen Jie Zi" is: "The word' Liang Zi' uses wood to cross the water, and today it is also a bridge." It shows that the original meaning of bridge refers to the passage with trees on the water, and later it is extended to the form of "plank road" on the cliff and "climbing over the wall" between pavilions and pavilions. Modern bridges also play an important role in urban traffic. Building a bridge (overpass) on the flat ground to connect the east, west, north and south will not only help alleviate traffic congestion, but also become a beautiful scenery in modern cities. China is the hometown of bridges, and it has been known as "the country of bridges" since ancient times, which was developed in the Sui Dynasty.

trait

China is a bridge country with many mountains and rivers. In ancient times, both the bridge-building technology and the number of bridges were in the leading position in the world. For thousands of years, bridges have long been an indispensable part of people's social life. However, due to the vast territory of China, there are great differences in geography, climate, cultural customs and the development level of social productive forces from south to north and from east to west. Therefore, based on their own actual conditions and needs, after a long period of development, they created a variety of bridge forms and gradually formed their own characteristics. Specifically, they have the following characteristics: (1) regional. China, a vast country, is a bridge connecting the North and the South and the East and the West. Influenced by its natural geography and humanistic society, it has formed its own relatively independent style and characteristics according to local conditions. For example, the Central Plains and the Yellow River Basin in the north have relatively flat terrain and few rivers and waters, so people rely on mules, horses and carts to transport materials. Therefore, most of the bridges here are Guan Dan's majestic stone arch bridge and Liang Shi bridge, so that ships can pass under the bridge; In the northwest and southwest regions, it is difficult to build piers because of the high mountains and steep valleys. Therefore, rattan, bamboo cable, logs and other mountain materials are often used to build rope suspension bridges or outrigger wooden beam bridges. The coastal areas of Lingnan, Fujian and Guangdong are rich in hard granite, so stone bridges abound. In Yunnan minority areas, unique bamboo bridges can be seen everywhere because of the abundance of bamboo. Judging from the style of the bridge, the bridge in the north is as rough and simple as the northerners; Bridges in the south are as smart and light as southerners. Of course, this is also closely related to physical geography. For example, the rivers in the north have changed greatly due to the bullying of water flow and the impact of mountain torrents and ice, so the bridge must be thick and stable; However, the South River is gentle and easy to navigate, so the bridge is slender and beautiful. (2) Diversity. China is an ancient civilization, with vast territory and abundant resources, beautiful mountains and rivers, and great differences in geology and geomorphology between the north and the south, so the technical requirements for bridge construction are also very high. Around the Han Dynasty, four basic types of bridges: beam bridge, pontoon bridge, cable bridge and arch bridge, all came into being. According to the different building materials and structural forms, these four kinds of bridges have evolved into: wooden bridge, stone bridge, brick bridge, bamboo bridge, salt bridge, ice bridge, rattan bridge, iron bridge, reed bridge, stone pillar bridge, stone pier bridge, flood bridge, cantilever bridge, covered bridge, wind and rain bridge, bamboo bridge, stone bridge, telescopic bridge, cable-stayed bridge and third bridge. (3) Multifunctional. Ancient craftsmen in China paid great attention to the maximization of bridge benefits when building bridges. They should not only consider adjusting measures to local conditions, but also consider making the bridge play a multi-functional role as much as possible. For example, most arch bridges in the south of the Yangtze River are flat at both ends and high in the middle, which not only produces the beauty of arc in modeling, but also facilitates sailing. Covered bridges can be seen everywhere in the south of China, which fully embodies the multi-purpose characteristics of one bridge. There is a lot of rain and strong sunshine in the south, so the bridge builders built a gallery on the bridge, which not only provided a place for passers-by to avoid the wind and rain, but also increased the self-weight of the bridge, prevented the bridge from being washed away by the flood, and protected the wooden beams and iron cables from being corroded by the wind and rain. In particular, many of these covered bridges are also used for markets, accommodation and business activities, because people are used to being in a hurry. For example, Xiangzi Bridge in Chaoan County, Guangdong Province, with a total length of more than 500 meters, is known as "a long bridge in one mile and a city in one mile", and there is an openable pontoon bridge in the bridge to facilitate navigation; Build a gallery house on the bridge and make a market behind it. During this period, shops are lined up, from morning till night, bustling and lively, so that you can't smell the roaring tide and the wide river. Therefore, there is a joke among the people that "ask Xiangqiao when you arrive at Xiangqiao". (4) public welfare. Since the bridge came into being, it has emerged as a kind of sociality belonging to the people. Traditional buildings in China are generally private, and only bridges (except those in private gardens) are owned by the society, whether government-owned or private. Therefore, for thousands of years, loving bridges and protecting roads has become a good fashion, while "repairing bridges and paving roads" is a charitable act that benefits the public and is highly respected by the public. Therefore, repairing or building a bridge has a broad mass character. According to historical records, there are probably four ways to build bridges in China: one is civil construction, that is, the bridge is built independently by one family and one surname; The second is to raise funds and report them to the government for support and joint construction. This is the most common, such as the famous Zhao Zhouqiao and Quanzhou Luoyang Bridge, which were all built in this way. Third, the official presided over the people's repair, which was pledged by local officials and gentry, and appointed officials or businessmen to preside over it. This is mostly a bridge; Fourth, it is all funded by the government. So there are ancient bridges all over China, and even more bridges are built in the hinterland. Its quantity and wide distribution rank first in the world.

Emergence and development

Before artificial bridges appeared, many natural bridge forms were formed in nature due to the influence of crustal movement or other natural phenomena. For example, Liang Shi Bridge in Tiantai Mountain, Zhejiang Province, a stone arch bridge (Xianren Bridge) in Guixi, Jiangxi Province, a "single-plank bridge" formed by natural fallen tree trunks along the river, or a natural "suspension bridge" formed by winding vines on both sides. Inspired by these natural bridges, human beings constantly imitate nature in the process of survival. At first, some wooden bridges were built on the river with a piece of wood, or on the ditches around clan settlements (the bridge was originally called "beam", probably because this beam passed by), or a stone pedal was set up in a narrow and shallow stream to slightly emerge from the water, forming a simple "jumping pier" Liang Shi bridge (the original bridge was often imitated in gardens and called "pavilion"). These "single-plank bridges" and "jumping pier bridges" are the most primitive bridges of human architecture. Later, with the development of social productive forces, it gradually evolved from low-level to high-level, and then gradually produced various bridges across the air. Bridges in China have gone through four stages of development. The first stage is mainly in the Western Zhou Dynasty and the Spring and Autumn Period, including the previous historical era, which is the founding period of the ancient bridge. At this time, in addition to the original wooden bridge and Tingbu bridge, there are mainly two forms of bridge: beam bridge and pontoon bridge. At that time, due to the backward level of productivity, most of them could only be built in areas with flat terrain, narrow rivers and gentle water flow, and bridges could only be wooden beams, so the technical problems were relatively easy to solve. On the other hand, pontoons are often used in rivers with wide water surface and fast flowing water. The second stage is dominated by Qin and Han dynasties, including the Warring States and the Three Kingdoms, which is the period of creation and development of ancient bridges. Qin and Han dynasties are a dazzling development stage in the history of Chinese architecture. At this time, not only the bricks of artificial building materials were invented, but also the arch coupon structure with the theme of masonry structure system was created, which created the prerequisite for the emergence of arch bridges later. The appearance of ironware in the Warring States period also promoted the multi-faceted utilization of stone materials in buildings, thus adding new components such as stone pillars, Liang Shi and stone bridge surfaces to the log beam bridge. Not only that, but also its great significance lies in the stone arch bridge came into being. The establishment of stone arch bridge has played an epoch-making role in the history of ancient bridge construction in China, which is not only practical, but also economical and beautiful. The great development of Liang Shi stone arch bridge not only reduces the maintenance cost and prolongs the service life of the bridge, but also improves the scientific level of structural theory and construction technology. Therefore, the use of building stone and the emergence of arch coupon technology in Qin and Han dynasties are actually a major revolution in the history of bridge construction. Therefore, according to some documents and archaeological data, about the Eastern Han Dynasty, four basic bridge types, namely, beam bridge, pontoon bridge, cable bridge and arch bridge, were formed. The third stage is dominated by the Tang and Song Dynasties, supplemented by the Jin, Southern and Northern Dynasties and the Sui, Tang and Five Dynasties, which is the heyday of the development of the ancient bridge. Compared with Qin and Han Dynasties, Sui and Tang Dynasties had stronger national strength, and Tang and Song Dynasties achieved long-term stability and unity. The level of industry and commerce, transportation and science and technology was very developed, and it was the most advanced country in the world at that time. After the Eastern Jin Dynasty, because a large number of Han nobles moved south, the economic center moved from the Yellow River basin to the Yangtze River basin, which made the economy of the southeast water network area develop greatly, and the development of economy and technology in turn stimulated the great development of the bridge. Therefore, many bridges that attracted worldwide attention came into being at this time, such as Zhao Zhouqiao, which is an open-shouldered stone arch bridge initiated by Li Chun, a stonemason in Sui Dynasty, Hongqiao, a stoplog wooden arch bridge invented by abandoned soldiers in Northern Song Dynasty, and Wan 'an Bridge in Quanzhou, which was founded by reciting, and Xiangzi Bridge in Chaozhou, Guangdong Province, which is a combination of Liang Shi Bridge and telescopic pontoon bridge in Southern Song Dynasty. These bridges are very famous in the history of bridges in the world, especially in Zhao Zhouqiao. Seven centuries later, similar bridges appeared in other countries in the world. Throughout the history of Chinese bridges, almost all major inventions and achievements, as well as bridges that can compete for the first place in the world, were produced at this time. The fourth stage is Yuan Dynasty, Ming Dynasty and Qing Dynasty, which is the saturation period of bridge development, and there are almost no major innovations and technological breakthroughs. At this time, the main achievement is to repair and transform some ancient bridges, leaving many construction documents for bridge construction, providing a lot of written materials for future generations. In addition, some arduous projects, such as Wannian Bridge in Cheng Nan, Jiangxi and Panjiang Bridge in Guizhou, were completed. At the same time, Sichuan, Yunnan and other places have built many cable bridges, and the construction technology of cable bridges has also improved. In the late Qing Dynasty, that is, 188 1 year, with the opening of the first railway in China, another technological revolution in the history of Chinese bridges was ushered in.

Types and forms

According to the main materials, wood, stone, brick, bamboo, rattan, iron, salt, ice and paper bridges are the earliest bridge forms, and almost all bridges before Qin and Han Dynasties in China were wooden bridges. Such as the earliest wooden bridge and wooden column beam bridge. Boat bridges appeared around Shang and Zhou Dynasties, and row-column wooden beam bridges and outboard wooden beam bridges appeared around Warring States Period. However, due to the characteristics of wood itself, such as looseness, perishable, and dominated by the strength and length of materials, it is not only difficult to build bridges on rivers with wide rivers, but also difficult to build durable bridges. So in the Northern and Southern Dynasties, it was replaced by a bridge with mixed wood and stone. Stone and brick bridges. Generally speaking, the bridge deck structure is a bridge made of stone or brick. Bridges made of pure brick are rare, usually made of brick, wood or masonry, and stone bridges are more common. During the Spring and Autumn Period and the Warring States Period, a wooden bridge with stone piers appeared, and the Western Han Dynasty further developed into a Liang Shi bridge with stone pillars, and a single-span stone arch bridge appeared in the Eastern Han Dynasty. In the Sui Dynasty, the world's first single-hole arc stone arch bridge with shoulder was born, while in the Tang Dynasty, Li Zhaode created a porous Liang Shi bridge. The Song Dynasty witnessed the vigorous development of large stone bridges, creating Liang Shi Bridge which spans several miles at the intersection of rivers and seas, such as Luoyang Bridge and Ping 'an Bridge in Quanzhou, and large stone arch bridges, such as Lugou Bridge in Beijing and baodai bridge in Suzhou. Bamboo bridge and rattan bridge. Mainly distributed in the south, especially in the southwest. Generally, it is only used on rivers with narrow river surface, or as a temporary crossing. In the early days, it was mainly a cable bridge. In the Northern and Southern Dynasties, the bamboo cable-stayed bridge was called "Ruxiang Bridge". Later, bamboo cable bridge, bamboo pontoon bridge and bamboo slab bridge appeared. In ancient times, iron bridges included iron cable bridges and iron column bridges. The former belongs to the category of cable bridge, which is relatively common and appeared in the Tang Dynasty. The latter is a kind of beam bridge, which is actually a wood-iron mixed bridge, which is relatively rare. Jiangxi has seen an example. Salt bridge and ice bridge. Mainly exists in special natural environment. The former is mainly found in salt lake area of Qinghai, while the latter is mainly found in cold areas in the north. Paper bridges appear in some toys. According to the structure and appearance, there are four basic types: beam bridge, pontoon bridge, cable bridge and arch bridge. Beam bridge, also known as flat bridge and span bridge, is a bridge supported by piers at a horizontal distance, and then beams are erected to tile the deck. This is the most widely used bridge, which appeared earlier than other bridges in history. It takes the form of wood, stone or a mixture of wood and stone. In the pre-Qin period, all beam bridges used wooden columns as piers, but this kind of wooden column beam structure showed its weakness very early and could not adapt to the development of the situation. Therefore, it was replaced by the Shizhu wooden beam bridge, such as the multi-span long bridge built in Qin and Han Dynasties: Wei Qiao, Baqiao, etc. About the Han Dynasty, the pile foundation technology was invented, and stone piers appeared, which showed that bridges made of wood and stones could cross wider rivers and bear the impact of rough waves. However, because the wooden beam on the stone pier is not resistant to wind and rain erosion, a bridge house was built on the bridge to protect the bridge body. This type of bridge (covered bridge) is more common in the south, but it was first seen in the Yellow River basin. Small and medium-sized Liang Shi or stone slab bridge is the most popular bridge type for its convenient structure, durable materials and labor-saving maintenance. Especially after the Southern Song Dynasty, it was very popular in Quanzhou, Fujian, and many Liang Shi bridges were created. If there is no pier in the middle of a beam bridge, it is called a single-span beam bridge; If there are piers in the water, so that the bridge body forms two holes, it is called a double-span beam bridge; If there are more than two piers, it is called a multi-span beam bridge. The pontoon bridge is also called pontoon bridge, pontoon boat and pontoon truss. Because it is easy to erect, it is often used in military affairs, so it is also called "Zhanqiao"-a bridge where hundreds of wooden boats (including rafts or bamboo rafts on the water) are placed side by side on the water with chains, and the boats are paved with boards for people to pass. If the bridge in the strict sense is marked by crossing the air and having column piers, it is not a bridge in the full sense. The pontoon bridge is mainly built where the river is too wide, too deep or fluctuating, which is beyond the reach of ordinary wooden columns and bridges. Wooden stakes, iron oxen, iron mountains, Shi Zhuan and stone lions are set on both sides of the pontoon bridge, and ropes are used. Tianjin Bridge, built on the Luoshui River in the first year of the Sui Dynasty, was the first pontoon bridge to connect ships with chains. At present, pontoon bridges are still widely used in southern China, such as Jiangxi, Zhejiang and Guangxi. Advantages of the pontoon bridge: First, the construction is fast. In the second year of Xianfeng in the Qing Dynasty (AD 1852), the Taiping Army besieged Wuchang and built two pontoons across the Yangtze River overnight. Second, the cost is low. In the Ming Dynasty, Zou Shouyi made a comparison between the stone bridge and the pontoon bridge in Xiufenglin: "If you use the Liang Shi Bridge, it costs 1,000 yuan, and if you use the pontoon bridge, it costs 500 gold, depending on your needs." Third, it can be opened and closed at will, and it is very convenient to disassemble and assemble. Disadvantages are small deadweight, fluctuating with the waves, weak flood resistance, complicated management, frequent maintenance and replacement of ships, bridge decks and mooring cables, and high maintenance costs. Therefore, the ultimate destination of many pontoons is to develop into wooden bridges, Liang Shi bridges or stone arch bridges. Cable bridge is also called suspension bridge, cable bridge and suspension bridge. , is a bridge suspended with bamboo cables or rattan cables and iron cables as the backbone. Most of them are built on steep river banks and dangerous valleys, and the current is too fast to be used as docks, mainly in the southwest of China. Its practice is to build houses on both sides of the river, set up posts for tying ropes and rotating posts for twisting ropes respectively, then tie several thick ropes flat, and then put boards horizontally on the ropes, and some even add one or two ropes on both sides as handrails. It was first seen in Qin and Han Dynasties. For example, Qin built a bamboo cable bridge in the southwest of Yizhou (now Chengdu) in Sichuan, also called Yili Bridge. The existing famous ones are Luding Iron Cable Bridge and guanxian Bamboo Cable Bridge built in Ming and Qing Dynasties. Crossing the cable bridge feels very thrilling, just as the ancients described the cable bridge: "People are hanging in the air, and if they don't quit in an instant, they will fall into a bottomless valley." Monk Zhimeng in the Tang Dynasty said, "If you can't see the end, the shadows are fighting." In fact, it is still safe to really cross the past, just like Xu Xiake's Travels commented on the Panjiang Bridge in Guizhou: "Look at it and you will stop." Arch bridge appeared late in the history of Chinese bridges, but once the arch bridge structure was adopted, it developed rapidly and became the most vital bridge type in ancient bridges. Even today, it still has broad prospects for further development. Arch bridges are divided into stone arch bridges, brick arch bridges and wooden arch bridges, among which brick arch bridges are rare and only occasionally used in temples or gardens. Stone arch bridges are commonly used and can be divided into single arch, double arch and multi-arch. The number of arches depends on the width of the river. Generally, the arch in the middle is particularly high, and the arches on both sides are slightly smaller. According to the shape of the arch, there are pentagons, semicircles, pointed arches and flat arches. The bridge deck is generally paved with stone slabs, and the side of the bridge is paved with stone railings. The image of the arch bridge was first seen in the portrait bricks in the Eastern Han Dynasty. It was produced by the shape of the wooden and Liang Shi bridge with outriggers, and was influenced by the shape of the tomb arch and water pipes. Documentary records can be found in Zhu in the Southern and Northern Dynasties. The earliest existing physical object is the Zhao Zhouqiao designed and built by Li Chun in Sui Dynasty. After the Ming dynasty, especially in the Qing dynasty, stone arch bridges issued whole coupons, that is, "bucket coupons." Other shapes of cable-stayed steel cable-stayed bridge with cable-stayed concrete cable-stayed composite beams: flying pavilion plank road, canal bridge, optical fiber bridge, curved bridge, fish pond flying beam and geomantic bridge. "Feiting", also known as Pavilion Road and Courtyard Road, is the overpass. The crossing passage between ancient palaces and pavilions. "Three Auxiliary Huang Tu": "It is to build a flying pavilion and a chapter palace in the west of the palace (referring to Weiyang Palace in Han Dynasty), and to build roads up and down." During the Qin and Han dynasties, the main halls of the palace were connected by pavilions and roads. Because there was a way up and down, it was called the complex road. Qin Shihuang built a pavilion road from Epang Palace to Lishan, on the footbridge and under the vehicle bridge, which was the earliest overpass in China. "plank road", also known as stack pavilion, bridge pavilion and single-arm wooden beam bridge. A road paved with wooden frames in steep places in mountainous areas. "Canal Bridge" is not only a water diversion channel, but also a bridge for pedestrians. That is to build a canal on the bridge to divert water. For example, Huiyuan Bridge in Hongdong County, Shanxi Province was built in the Jin Dynasty. Therefore, there is still slang for "water bridge, there is water on the bridge" in Shanxi today. "Fibre Channel Bridge" is a long ribbon bridge parallel to the river, which is built for the convenience of fiber drawing. More common in Zhejiang Canal area. Some are as long as one or two kilometers, or even five or six kilometers. For example, there is a "100-hole Guantang" optical fiber bridge in Ruanshe, Shaoxing, which was built during the Tongzhi period of the Qing Dynasty. The bridge is more than 380 meters long with a span of165,438+05. The bridge deck consists of three stones, with the bottom level with the water surface. "Curved bridge" is a unique bridge type in gardens, so it is also called garden bridge. Bridges, trails and corridors are all channels for tourists to enjoy the scenery in the garden. "The scenery is more beautiful than the curve", so the bridges in the garden are mostly made into corners, such as the zigzag bridge, forming a broken line that swings back and forth and looks around, so as to extend the landscape and expand the landscape picture. Curved bridges are generally composed of stone slabs and railings. Slates are slightly higher than the water surface, and railings are lower, which makes them seem inseparable from the water surface, and the space seems to be separated from each other, which is especially meaningful. (1) adopts the form of circular arch, which changes the tradition that most large stone bridges in China are semi-circular arches. The arches of ancient stone bridges in China are mostly semicircular, which are beautiful and complete, but they also have two defects: First, the traffic is inconvenient, and the semicircular arch is more suitable for small-span bridges, while the adoption of semicircular arch for long-span bridges will make the arch very high, resulting in steep bridges and inconvenient for pedestrians and cars to cross the bridge. Second, the construction is unfavorable, and the scaffolding used for semi-circular arch stone masonry will be very high, which will increase the construction risk. To this end, Li Chun and craftsmen creatively adopted the form of circular arch, which greatly reduced the height of stone arch. The net span of Zhao Zhouqiao's main span is 37. 02 meters, while the arch height is only 7.25 meters, and the arch height-span ratio is about 1:5. In this way, the dual purposes of low bridge deck and long span are realized, and the bridge deck transition is smooth, which is convenient for vehicles and pedestrians. It also has the advantages of saving materials and convenient construction. Of course, the thrust of the circular arches at both ends on the bridge foundation also increases accordingly, which puts forward higher requirements for the construction of the bridge foundation. (2) adopt our shoulders. This is a major improvement made by Li Chun on the arch shoulder. The solid shoulder arch used in bridge construction is changed into an open shoulder arch, that is, two small arches are set at both ends of the big arch, and the clear distance between the small arch near the foot of the big arch is 3.8 meters, and the clear distance between the other arch is 2.8 meters. This kind of open-shouldered arch with large arch and small arch has excellent technical performance. First of all, it can increase the flood discharge capacity and reduce the impact of flood on bridges caused by the increase of water volume in flood season. The flood potential of Gujiao River in flood season is great, which is a test for the flood discharge capacity of the bridge. Four small arches can share part of the flood. According to the calculation, four small arches can increase the water area by about 16%, greatly reduce the impact of flood on the bridge and improve the safety of the bridge. Secondly, compared with solid shoulder arch, open shoulder arch can save a lot of earthwork materials and reduce the dead weight of the bridge. According to the calculation, four small arches can save 26 cubic meters of stone and reduce the dead weight by 700 tons, thus reducing the vertical pressure and horizontal thrust of abutment and bridge foundation on the bridge body and increasing the stability of the bridge. Third, it adds a beautiful shape. The four small arches are balanced and symmetrical, and the large arch and the small arch form a complete picture, which is lighter and more beautiful, reflecting the complete unity of architecture and art. Fourthly, according to the theory of structural mechanics, the open-shouldered arch structure can make the bridge in a favorable state when bearing load, reduce the deformation of the main arch ring and improve the bearing capacity and stability of the bridge. (3) Single hole. In the traditional construction methods in ancient China, generally long bridges often take the form of multiple holes, so that each hole has a small span, a gentle slope and is easy to build. However, porous bridges also have disadvantages, such as many piers, which are not conducive to the navigation of ships and hinder flood discharge; The pier has been impacted and eroded by the current for a long time, and it is easy to collapse over time. Therefore, when designing this bridge, Li Chun adopted the form of single hole and large span, and no pier was erected in the middle of the river, which made the stone arch span as long as 37 meters. This is an unprecedented initiative in the history of Chinese bridges.

Materials and structures

The structure of a bridge, except the original single-plank bridge, Tingbu bridge and pontoon bridge, is generally composed of span-span parts and span-span supporting parts, namely pier and bridge body. (a) beam bridge, according to its material and structure, can be divided into wooden beam bridge and Liang Shi bridge. "Wooden beam bridge" includes wooden beam-column bridge, wooden beam-column bridge, wooden beam-column pier bridge and wooden support bridge, among which "wooden beam-column bridge" is developed from the original wooden bridge with wooden beams and columns. "Liang Shi Bridge" includes Shizhu Bridge in Liang Shi, Shidun Bridge in Liang Shi, Stone Cantilever Bridge (similar to wooden cantilever bridge), Trilateral Liang Shi Bridge, Shuiman Stone Bridge and Flat Bridge (more common in garden "curved bridge" and "fiber bridge"). Among them, "Liang Shi Shidun Bridge" is the most common. This kind of bridge goes further than using wooden beams with stone piers, and avoids the shortcomings that the wooden beam deck is easy to decay and often needs maintenance. There is also a combination of bridge and pontoon bridge, that is, "opening and closing bridge". The floating bridge in the middle can be opened and closed as required. Such as Xiangzi Bridge in Chaoan County. The east and west ends of the bridge are the Liang Shi Bridge, and the middle of the bridge is connected by 18 wooden boats, so as to facilitate the drainage of flood water and the use of "connecting with giant boats to row rafts". (2) Arch bridges can be divided into: steep arch bridge and flat arch bridge, pointed arch bridge and round arch bridge, multi-arch bridge and fixed-end arch bridge, single-hole arch bridge and multi-hole arch bridge, solid-bellied arch bridge and hollow arch bridge, and Hongqiao. The arcs of arched coupons are semicircle, horseshoe, full circle, pot bottom, egg circle, ellipse, parabola circle and hem, and the arrangement forms are parallel and cross-linking, among which cross-linking is the most widely used, and two kinds of cross-linked coupons with edges and frames are derived. (3) Cable bridges can be divided into bamboo cables, iron cables, rattan cables, cable-stayed bridges, urban defense suspension bridges, single cables, double cables, multi-cable bridges and parallel multi-cable bridges according to their different textures and structural forms.

Classification by function

Highway Bridges: For example, Fusi Railway Bridge (the world's first steel bridge) Railway Bridge: For example, Yuanjiang Bridge (the first cement road in China) Overpass: For example, Beijing Old Xizhimen Overpass is a highway-railway bridge: for example, Sanshu Songhua River Bridge in Harbin New District (the first highway-railway bridge in China).

Related arts and literature

Mountains and rivers are naturally beautiful, because China's writers and artists have a special liking. As Dong Qichang, a great artist in the Ming Dynasty, said, "Poetry is based on mountains and rivers, and mountains and rivers are also based on poetry." The bridge is a building built between mountains and rivers. It stands in nature for a long time and becomes a member of embellishing and beautifying nature. Where there are mountains and water, there will naturally be bridges. The bridge itself is also a combination of practicality and artistry. The straightness of the bridge, the volley of the cable bridge, the charm of the pontoon bridge and the shadow of the arch bridge are originally swaying artistic style. So Mr. Needham of Britain said, "There is no China Bridge that is not beautiful, and many of them are extraordinarily beautiful." The artistry of bridges in China is mainly manifested in two aspects, namely, modeling style and decoration technology. The modeling style is mainly reflected in the soft curve, harmonious rhythm and magnificent momentum. And some small beams and bridges in Jiangnan water town are poetic bridge decorations reminiscent of "small bridges with flowing water". Generally speaking, they are not very developed in China, mainly reflected in stone bridges, and their parts are generally in places where people can easily stop and watch. For example, there are dragons, phoenixes, lions, elephants and rhinoceroses, and there are patterns such as rabbits, monkeys, horses, dogs, clouds, lotus flowers and herbs. There are also a few embossed river statues, warrior statues and character story images. For example, the head of the river god embossed on the flower wall of Yongtongqiao Mountain in Zhao County, Hebei Province, the head of the dragon and lion on the sentry box in Zhao Zhouqiao, and the head of the lion on the sentry box in Lugouqiao, Beijing. These stone carvings are exquisitely made and are often closely related to folk customs, myths and legends. For example, dragons control water, rhinos divide water, and beasts subdue demons, thus forming a unique style of Chinese bridge art. In addition, many bridges in China often have many ancillary buildings built on the bridge or at the bridge head. The building built on the bridge played the role of anti-corrosion and foundation pressure of the wooden bridge, and later became a combination of bridge and building. Bridge-head building is the sign of bridge entrance and exit, which has the function of setting off, guarding and decorating the bridge.

Legends and stories of bridges

Qinqin Bridge-Hundreds of meters north of nanqiao town, there is a small stone bridge called Qinqin Bridge. According to legend, a long time ago, an official named Qian gave birth to three daughters. The youngest daughter played the piano very well. There is a young man nearby named Han Zhong, who is also a master of playing the piano. After a long time, the two fell in love, and Master Qian refused. The daughter had to persuade Han to go back to Beijing to practice the piano and win fame, and the father agreed to their marriage. Han left in tears. But money forced her daughter to marry a powerful man, and her daughter missed Han Zhong and died with a grudge. Soon after, Han Zhong came back and learned that his lover was dead, so he sat on a small stone bridge and played a sad song to show his memory. Play, throw yourself into the river. Mahjong Bridge-During the Daoguang period of Qing Dynasty, a bridge named Mahjong Bridge was built on Huajing River. There was no bridge here before, so it was inconvenient for pedestrians. There is an old man named Zhou who hates folk gambling very much. He gathered 10 people of insight, surrounded all casinos, arrested gamblers, confiscated financial bets and burned financial instruments. Confiscated gambling proceeds were used to build the bridge. It's ruined now.