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中国是一个5000年文字记载历史的伟大国家。我国幅员辽阔，地形东南低而西北高，河道纵横交错，有著名的长江、黄河和珠江等流域，这里孕育了中华民族，创造了灿烂的华夏文化。在历史的长河中，中华民族建设了数以千万计的桥梁，成为华夏文化的重要组成部分。
中国古代桥梁的辉煌成就举世瞩目，曾在东西方桥梁发展史中，占有崇高的地位，为世人所公认。
中国古代桥梁不外梁、拱、索、浮等类型。
（一）梁桥
我过历史上最早记载的梁桥为钜桥，桥建于商代（公元前16~
前11世纪）。周武王伐纣，克商都朝歌（今河北省曲周县东北），发钜桥头积粟，以赈济贫民。自周代以迄秦汗，中国多造石柱、木梁桥。
宋代建造为数众多的石墩、石梁桥。200多年间，仅泉州一地，见于古籍的桥梁就有110座，其中名桥10座。如安平桥（图1），有362孔，桥长5里（2223m），故又名五里
桥（现桥长2100m），保持了700余年的桥长记录。桥始建于宋，绍兴八年（公元1138年），
图1.
成于绍兴二十一年（公元1151年），历时13年。又如泉州万安桥，俗称洛阳桥（图2），共有47孔，建于洛阳江入海口，桥总长约890m，桥宽3.7。桥始建于宋，皇佑五年（公元1053年），完成于宋，嘉裕四年（公元1059年）。两桥均为国家重点文物单位。
图2.
福建漳州江东桥的石梁最为巨大。该桥于宋·嘉熙元年（公元1237年）由木梁桥改为石梁桥，计有15孔，每孔三片石梁。石桥现存5孔，其中最大的石梁长23.7m，宽1.7m，高1.9m，重量达2000kN(200t)。这样巨大的石梁，在没有重型起重设备的古时，其采、运、安装等工作都是十分艰巨的。
不论木梁或石梁，为了加长桥跨，采用了多层并列梁，由下向上逐层外挑的方法，以支承中部的简支梁。在当时石梁称为叠涩；木梁称飞桥或称握桥，即为伸臂梁桥。木伸臂梁在公元4世纪时已有记载。石桥叠涩，出檐不远；木桥伸臂达到20m。现存清代重修的甘肃文县阴平桥为单孔木伸臂桥，桥跨达60余m，桥上建有桥屋。
图3.
木梁桥上一般建有桥屋或桥廊，侗族风雨桥就是一种桥屋。广西三江侗族自治县的程阳永济桥，是一座4孔5墩的木伸臂桥屋，全长644m，建于1916年，5座墩台上均有桥亭，用桥廊把桥亭相互贯通。桥亭起着重力平衡作用，把装饰与功能有机结合在一起（图3）。
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China is a great country with a written history of about 5000 years. She has a vast territory, topographically higher in the northwest and lower in the southeast. Networked with rivers, she has the best-known valleys of the Yangtze River, the Yellow River and the Pearl River, which are the cradle of the Chinese nation and her brilliant culture. Throughout history, the Chinese nation has erected thousands of bridges, which form an important part of her culture.
Ancient Chinese bridges are universally acknowledged and have enjoyed high prestige in the bridge history of both the East and the West.
Ancient Chinese bridges can be classified under four categories: the beam, arch, cable suspension and floating bridges.
I. Beam Bridges
The earliest reference to the beam bridge in Chinese history is the Ju Bridge dating from the Shang Dynasty (16th-11th century B.C.). King Wu of the Zhou Dynasty launched a campaign against King Zhou (Zhou Wang), and having captured Zhaoge -capital of the Shang Dynasty (now northeast to Quzhou County, Hebei Province), at the Ju Bridge, he ordered a hoard of millet distributed to the relief of the poor. From the Zhou Dynasty through to the Qin and Han Dynasties, bridges with timber beams and stone piers were predominant.
During the Song Dynasty, a large number of stone-pier and stone-beam bridges were constructed. In Quanzhou alone, as recorded in ancient books, 110 bridges were erected during the two centuries, including ten well-known ones. For example, the 362-span Anping Bridge (Fig. 1) was known for its length of 5 li (2223m), a national record for over 700 years, and so gained the other name Five Li Bridge. It is now 2100m long. Its construction lasted 16 years, from the 8th year (A.D. 1138) to the 21st year (A.D. 1151) of the reign of Shaoxing of the Song Dynasty. Another famous one is the 47-span Wan'an Bridge, situated at the outlet of the Luoyang River to the sea, better known as Luoyang Bridge (Fig.2). It is about 890m long and 3.7m wide. The construction began in the 5th year of the reign of Huangyou (A.D. 1053) and ended in the 4th year of the reign of Jiayu (A.D. 1059) of the Song Dynasty. Both bridges are included in the list of major cultural relics under state protection.
The Jiangdong Bridge in Zhangzhou, Fujian Province boasts the largest stone beams. In the first year of the reign of Jiaxi (A.D. 1237) of the Song Dynasty, the timber beams of this bridge were replaced by stone ones. The bridge had 15 spans, each consisting of 3 slices of stone beams. But today only 5 spans remain. The largest stone beam, 23.7m in length, 1.7m in width and 1.9m in height, weighs 2000 kN (200 tons). It seems incredible that such an arduous task could be performed then as there was no heavy-duty craning equipment to quarry the stone and to haul to the site and set in position such enormous stone beams.
To elongate the span, either the timber beams or the stone ones were placed horizontally on top of each other, the upper layer cantilevering over the lower one, thus supporting the simple beam in the middle. That kind of stone beam is called Diese (overlapping beam), which, however, could not extend long; while the timber cantilever beam, called "flying bridge" or "extended arm bridge", could reach as far as 20m. The earliest record of the timber cantilever beam dates as far back as the 4th century B.C. The extant single-span timber cantilever bridge, the Yinping Bridge at Wenxian, Gansu Province, which was rebuilt in the Qing Dynasty, has a span of more than 60m with covered housings on it.
It was common practice to build bridge housings or galleries on timber beam bridges, and a case in point is the fengyu bridge (all-weather bridge) built by the Dong people. Situated at Sanjiang Dong Autonomous County, Guangxi Zhuangzu Autonomous Region, the Chengyang Bridge across the Yongji River (Fig. 3), built in 1916, is a 644m 4-span timber cantilever covered bridge. Each of its 5 piers is crowned by a pavilion and the decks are roofed by a spacious gallery, which joins the pavilions. The pavilions not only perform the function of balance, but have added to the charm and elegance of the bridge as well.
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