Arch Bridges

There are different views on the origin of arches. Some believe the first arch was a natural formation over the caverns, others claim that it was brought into being by the piling of the collapsed stones, and still others hold that it was evolved from the "false arch" which was formed by the openings in the walls. However, a study of the tombs and the extant old arches in China indicates that the joint of the beam and sides evolved gradually into isometric trilateral, pentalateral and septilateral arches and finally into semicircular arch. The span, too, was gradually elongated, from 2m or 3m up to 37.02m (clear span). And it has kept the world record for more than a thousand years.

The oldest arch bridge in China, which is still surviving and well-preserved, is the Anji Bridge, also known as the Zhaozhou Bridge, at Zhouxian, Hebei Province, built in the Sui Dynasty . It is a single segmental stone arch, composed of 28 individual arches bonded transversely, 37.02m in span and rising 7.23m above the chord line. Narrower in the upper part and wider in the lower, the bridge averages 9m in width. The main arch ring is 1.03m thick with protective arch stones on it. Each of its spandrels is perforated by two small arches, 3.8m and 2.85m respectively in clear span, so that flood water can be drained and the bridge weight is lightened as well. The Anji Bridge has a segmental deck and the parapets are engraved with dragons and other animals. Its construction started in the 15th year of the reign of Kaihuang (A.D. 595) and was completed in the 1st year of Daye's reign (A.D. 605) of the Sui Dynasty. Up to now it has survived for 1387 years. The bridge, exquisite in workmanship, unique in structure, well-proportioned and graceful in shape, and meticulous yet lively in engraving, has been regarded as one of the greatest achievements in China. Great attention and protection have been given to it through successive dynasties. In 1991, the Anji Bridge was named among the world cultural relics.

Stone arches in China vary in structure in accordance with different land transport as well as different natures between the north and south waterways. In the north, what prevails is the flat-deck bridge with solid spandrels, thick piers and arch rings, whereas in the south crisscrossed with rivers, the hump-shaped bridge with thin piers and shell arches prevails.

The Lugou Bridge across the Youngding River is located at Wanping County, 30 li away from Guanganmen, Beijing. The project began in the 28th year of the reign of Dading (A.D. 1188)and was completed in the 3rd year of the reign of Mingchang (A. D. 1192) of the Jin Dynasty. 212.2m long, 9.3m wide, it has 11 semicircular arches, ranging from 11.4m to 13.45 m in span. The piers are from 6.5m to 7.9m wide; their pointed cutwaters upstream are inlaid with triangular iron bars, while the downstream sides are square in shape butwithout two angles. The parapets are divided into 269 sections with columns in-between, each column crowned with a carved lion. When the bridge was first erected in the Jin Dynasty, all the lions were alike and very simple, but through the ages they were replaced each time by better ones, more delicately carved and different in style. Now, each lion has its individual posture. And more fascinating are the lion cubs. They are playing around their parents, clinging to the breast, squatting on the shoulder, nestling at the feet, or licking the face. These exquisite sculptures on the bridge and on the ornamental columns, which show the practical application of the aesthetic principle of unity and variation, have become a scene of attraction. The bridge has long since been included in the historical relics under state protection.

In the southern part of China, say, Jiangsu and Zhejiang Provinces, networked with navigable rivers, boats were the main means of transportation. As bridges were to be built over tidal waters and their foundations laid in soft soil, even the stone arch bridge had to be built with thin piers and shell arches in order that its weight could be lessened as much as possible. The spans ranged in number from one to as many as 85. For example, the Chuihong Bridge in Wujiang, Jiangsu Province. But the bridge has collapsed and now only 8 ruined spans remain.

The thinnest arch ring is merely 1/66.7th the span, whereas for an average arch the ring is 1/20th the span. The extant Feng Bridge (the Maple Bridge) (built in the Qing Dynasty), mentioned in the well-known poem "A Night Mooring Near the Maple Bridge" by Zhang Ji of the Tang Dynasty, is characterized by its shell arch.

The thin pier is so thin that the arch stones of the neighboring arch rings meet on it. A special reference should be made here to the thin-pier bridge with 3 joint spans, a large middle span and two small side ones. There are steps on both approaches for pedestrians to ascend the bridge. It is hump-shaped and looks graceful. The Gongchen Bridge in Hangzhou, Zhejiang Province is a typical example. The bridge was built in the 4th year of Chongzhen's reign (A.D. 1631) of the Ming Dynasty and reconstructed in the 11th year of the reign of Guangxu (A.D. 1885) of the Qing Dynasty. The middle arch is 15.8m long in clear span, while the two side ones, 11.9m each. The arch ring stone is 30cm thick, 1/52.7 and 1/39.7 of the corresponding span. The middle pier is around 1m thick, 1/15.8 of the middle span. The longest surviving joint multi-span bridge with shell arches and thin piers is the Baodai Bridge in Suzhou, Jiangsu Province. Built in the Tang Dynasty and having undergone a series of renovations in successive dynasties, the bridge is now 316.8m long, 4.1m wide and has 53 spans in all, the three central arches higher than the rest for boats to pass through. Both ends of the bridge are ornamented with lions, or pavilions and towers, all of stone.

The bridge in classical Chinese gardens not only serves as a passage, but is an integral part of the garden scenery, either as a highlight or a setoff. One masterpiece of this kind is the Wuting (Five Pavilions) Bridge, also known as the Lianhua (Lotus Flower) Bridge in the Shouxi Lake in Yangzhou,Jiangsu Province.

The timber arch bridge in China dates back to the Song Dynasty. In the panorama "Riverside Scene on Qingming Festival" by Zhang Zheduan of the Song Dynasty, there is portrayed a timber arch bridge, known as the Hong Bridge (the Rainbow Bridge) spanning the Bian River in Bianjing, capital of the Song Dynasty (now Kaifeng, Henan Province). It was built following the pattern of guanmu (the interlocking of logs), put forward by a prison guard during the reign of Mingdao (A.D. 1032- 1033) of the Song Dynasty. Planks were interdigitated to form a kind of arch, thus obviating the necessity for piers which would usually get in the way of navigation. The span of this bridge was around 18.5m in length, 4.2m in height above the chord line, and the deck averaged 9.6m in width. See for its structural pattern. The Hong Bridge fell into ruin between the Jin and Yuan Dynasties. For hundreds of years it had been considered to be peerless. However, investigations during the recent decades have shown that in the mountain areas of Zhejiang and Fujian Provinces, there were found dozens of ancient timber arch bridges, similar to the Hong Bridge in structure, but with some improvements, their spans as long as 35m or so. illustrates the structural perspective and construction pattern of the Meichong Bridge in Yunhe, Zhejiang Province, which was built in the 7th year of Jiaqing's reign (A.D.1802) of the Qing Dynasty. Another example is the Xidong Bridge spanning the Sixi Stream at Taishun County, Zhejiang Province. The bridge is 41.7m long, 4.86m wide, with a 25.7m span rising 5.85m above the chord line. On the deck there is an exquisite gallery, both sides of which are panelled with overlapping boards for protection. It was constructed in the 4th year of the reign of Longqing (A.D. 1570) of the Ming Dynasty. Amazingly enough, the Yeshuyang Bridge, another of this kind in the same county, has survived for 511 years.

The timber arch of such bridges as the Hong Bridge is a unique achievement of ancient China. Besides, there are still other kinds of peculiar structures, like bamboo arch bridges, which are also unparalleled in the world.