英语翻译A bridge is a structure providing passage over an obstac

英语翻译
A bridge is a structure providing passage over an obstacle without closing the way beneath.The required passage may be for a road,a railway,pedestrians,a canal or a pipeline.The obstacle to be crossed may be a river,a road,railway or a valley.
Components of a bridge
The main parts of a bridge structure are as below:
Decking,consisting of a slab,girders,trusses,etc.;
Bearings for the decking;
Abutments and piers;
Foundations for the abutments and piers,such as concrete spread footing and groups of bearing piles;
River training works,like revetment for slopes at abutments,aprons at bed level,etc.;
Approaches to the bridge to connect the bridge proper to the roads on either side;
Handrails,guard stones,etc.
Classification
Bridges may be classified in many ways,as below:
According to the material of construction of superstructure bridge is divided into timber,masonry,steel,reinforced concrete,prestressed concrete or composite bridge;
According to function of bridge,it is divided into viaduct,aqueduct,pedestrian,high-way,railway,road-cum-rail bridge.
According to the structure system of bridge,it is divided into rigid frame,arch,cable-stayed or suspension bridge.
According to the interspan relations of bridge,it is divided into simple,continuous or cantilever bridge.
According to span length of bridge,it is divided into culvert ( less than 8 m) ,minor bridge ( between 8 m and 30 m ),medium span bridge (above 30 m ),long span bridge (above 120 m ).
According to the anticipated type of service and duration of use,it is divided into permanent,temporary,military bridge.
Historical development
The history of development of bridge construction is closely linked with the history of human civilization.Form the view point of structural system,bridge structures can be classified into four basic types:beam bridges,arch bridges,rigid frames and suspension bridges.Nature fashioned the first bridges.The tree fallen accidentally across a stream was the earliest example pf a beam type bridge.Similarly,the natural rock arch formed by erosion of the loose soil below and the creepers hanging from tree allowing monkeys to cross from one bank to the other were the earliest fore-bears of the arch and suspension bridges,respectively.
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一座桥是一个结构提供通道穿越障碍没有关闭的情形.所需的通道可能的公路,铁路,行人、运河或管道.要跨越的障碍可能是一条河,一条道路、铁路或一个山谷.
组件的一座桥主要部分的一个桥梁结构如下:装饰,由一个板、梁、桁架等;轴承的装饰;造成桥墩基础,如混凝土扩展底座和组轴承桩;
河培训工作,比如护岸边坡为基,在床上,围裙等;水平接近大桥连接桥的道路两边;扶手,后卫石头等等.
分类
桥梁可以用多种方法分类,如下:
根据建筑材料的上层建筑桥分为木材、砌筑、钢铁、钢筋混凝土,预应力混凝土或复合桥;
根据函数的桥,它分为高架桥、渡槽、行人、高速公路、铁路、公路和铁路桥梁.
根据结构系统的桥,它分为刚性构架,拱,斜拉桥或吊桥.
根据interspan关系的桥梁,它分为简单、连续或悬臂桥.
根据跨度桥,它分为涵(少于8 m),小桥(介于和),中等跨度桥(超过30米),大跨度桥梁(超过120美元).
根据预期的类型的服务和持续时间的使用,它分为永久性的,暂时的,军事桥.
历史发展
历史发展的桥梁施工是紧密地连接在人类文明的历史.形式角度对结构体系、桥梁结构可以分为四个基本类型:梁桥梁、拱桥、严格的框架和悬架桥梁.自然成形的第一个桥梁.这棵树倒下的意外,跨过一条小河是最早的例子一个梁式桥pf.同样,天然岩石拱由侵蚀的土壤疏松低于和爬行动物挂着树允许猴子交叉从一个银行的其他是最早的前熊的拱门和分别吊桥.