《梁桥外文翻译》word版.docx

附录英文翻译:BEAM BRIDGEIn designing a bridge, preference is often given to beam structure, unless it has a very long span. Simple in structure, convenient to fabricate and erect, easy to maintain, and with less construction time and low cost, beam structure has found wide application in bridgework. In 1937, over the Qiantang River, in the city of Hangzhou, was erected a railway-highway bi-purpose bridge, with a total length of 1453m, the longest span being 67m. When completed, it was a remarkable milestone of the beam bridges designed and built by Chinese engineers themselves before liberation. Since 1949, this kind of bridge has made giant strides. Reinforced concrete beam structure is the most commonly used for short- and medium-span bridges. A representative masterpiece is the Rong Jiang Bridge completed in 1964 in the city of Nanning, the provincial capital of Guangxi Zhuangzu Autonomous Region. The bridge, with a main span of 55m and its cross section of a thin-walled box with continuous cells, was designed in accordance with closed thin-walled member theory, the first of its kind in China.Pre-stressed concrete girder bridges cover a wide range of spans and types. In the short span range, pre-cast AASHTO beams with a composite cast-in-place non pre-stressed concrete slab are frequently used for simple spans. A similar form of construction is used for partially continuous spans using I-girders and box girder in the medium span range .In the medium to long span range, continuous pre-cast segmental box girders are common, while the longest spans are generally cast-in-place segmental box girders.For cost-in-place construction, the girders and slab are generally formed together and both cast before formwork and supports are removed. This construction is fully composite for dead load and live load. The usual cross sections are T-beams and box girders. Spans are usually continuous, and transverse post-tensioning of the slab is frequently prescribed to allow the use of thinner slabs or a reduced number of longitudinal girders at a larger spacing. Since longitudinal post-tensioning is required on site, transverse post-tensioning is usually economical and normally used.The design and analysis items given for reinforced concrete girder bridges also apply to pre-stressed girder bridges. For the box girder section, a detailed transverse live load analysis of the section should be carried out. Temperature effects are important for box girder, due to the possibility of large differential temperatures between the top and bottom slabs.For cast-in-place segmental construction built by the balanced cantilever method, a knowledge of the exact construction loads is necessary, in order to calculate stresses and deformations at each stage. A knowledge of the creep characteristics of the concrete is essential for calculating deformations after the addition of each segment, and also to calculate the redistribution of moments after completion and final stressing.Standard pre-cast, pre-stressed beams cover spans up to the 140ft (43m) range. After the beams are erected, forms for the slabs are placed between the beams and a reinforced concrete slab cast in place. The slab and beams act compositely for superimposed dead load and live load. Intermediate diaphragms are not normally used , and the design and analysis items given for reinforced concrete girder bridges, also apply to pre-stressed multi-beam type bridges. Pre-cast pre-stressed beams can be made partially continuous for multi-span bridges. This system is not only structurally efficient, but has the advantage of reducing the number of deck joints. Support moments are developed due to superimposed dead load, live load, differential temperature, shrinkage and creep. Continuity for superimposed dead load and for live load can be achieved by casting diaphragms at the time the deck concrete is placed. Reinforced steel placed longitudinally in the deck slab across the intermediate pier will resist the tension from negative moment at the supports. At the diaphragms, the bottom flanges of adjacent beams should be connected to resist the tensile stress due to positive moments generated by differential temperature, shrinkage and creep. Continuous spans , beyond the range of the type pre-cast girder, temporarily supported on bends, with joints near points of minimum moment, are post-tensioned for continuity after placement of the deck slab. The maximum lengths of segments are usually determined by shipping length and weight restriction.Pre-cast segmental construction employs single or multiple cell boxes with transverse segments post-tensioned together longitudinally. For medium sans, the segments may be erected for the full span on falsework before post-tensioning. Longer spans are usually erected by the balanced cantilever method, where each segment is successively stressed after erection. The design and analysis considerations given for cast-in-place segmental construction also apply to pre-cast segmental construction. The deformation of the structure during cantilever erection is dependent upon the time difference between segment pre-casting and erection. The design calculations may need to be repeated if the construction schedule differ from that assumed at the design stages. Pre-stressed concrete beam bridge is a new type of structure. China began to make researches and develop its construction in the fifties. In early 1956, a simply-supported prestressed concrete beam bridge with a main span of 23.9m -a railway bridge -was erected over the Xinyi River along the Longhai Railway line. Completed at the same time, the first P.C. highway bridge was the Jingzhou Highway Bridge. The longest simply-supported P.C. beam which reaches 62m belongs to the Feiyun River Bridge in Ruanan, Zhejiang Province, built in 1988. Another example is the 4475.09m Yellow River Bridge, built in the city of Kaifeng, Henan Province in 1989. 77 of its spans are 50m simply-supported P.C. beams and its continuous deck extends to 450m. It is also noticeable that the bridge is designed on the basis of partially prestressed concrete theory.Elastic analysis and beam theory are usually used in the design of segmental box girder structures. For box girders of unusual proportion, other methods of analysis which consider shear lag should be used to determine the portion of the cross section effective in resisting longitudinal bending. Possible reserve shearing stress in the shear keys should be investigated, particularly in segments near a pier. At time of erection, the shear stress carried by the key should not exceed . The prestressed concrete rigid T-frame bridge was primarily developed and built in China in the sixties. This kind of structure is most suitable to be erected by balanced cantilever construction process, either by cantilever segmental concreting with suspended formwork, or by cantilever erection with segments of precast concrete. The first example of cantilever erection is the Wei River Bridge (completed in 1964) in Wuling, Henan Province, while the Liujiang Bridge (completed in 1967) in Liuzhou in Guangxi Zhuangzu Autonomous Region is the first by cantilever casting. Nevertheless, the Yangtze River Bridge at Chongqing (completed in 1980), having a main span of 174m, is regarded as the largest of this kind at present. On the basis of the design and construction of P.C. rigid T-frame bridges, was developed multi P.C. continuous beam and continuous rigid frame bridges, which can have longer spans and offer better traffic conditions. Among the others, the Luoxi Bridge in Guangzhou, Guangdong Province (completed in 1988) features a 180m main span. And the Huangshi Bridge crossing the Yangtze River in Hubei Province, which is still under construction, has a span of 245 meters. The representive of P.C. continuous girder railway bridge, the second bridge over the Qiantang River (finished in 1991), boasts its large span and its great length, its main span being 80m long and continuity over 18 spans. Its erection is an arduous task as the structure was subjected to a wave height of 1.96m and a tidal pressure of 32kPa when under construction. The extensive construction of continuous beam bridges has led to the application of incremental launching method especially to straight and plane curved bridges. Besides, large capacity (500t) floating crane installation and movable slip forms as well as span by span erection scheme have also attained remarkable advancement. In order to optimize the bridge configuration, to cut off the peak moment value at supports, and to diminish the constructional height, V-shaped or Y-shaped piers are developed for P.C. continuous beam, cantilever or rigid frame bridges. The prominent examples are the medium or the short Bridge (1981) in Taiwan Province and the Lijiang Bridge (1987) at Zhishan in the city of Guilin. Steel structure is employed primarily for railway-highway bi-purpose bridges. The longest steel highway bridge is the Beizhen Yellow River Bridge in Shandong Province (1972), its main span being 113m long. It has a rivet-connected continuous truss. The foundation is composed of f1.5m concrete boring piles, whose penetration depth into subsoil reaches 107m, the deepest pile ever drilled in our country. A new structure of field bolting welded box girder paved with orthotropic steel deck was first introduced in the North River Highway Bridge at Mafang, Guangdong Province, which was completed in 1980. In 1957, in the city of Wuhan, over the Yangtze River was erected a railway-highway bi-purpose superstructure, another milestone in Chinas bridge construction history. The bridge has a continuous steel truss with a 128m main span. The rivet-connected truss is made of No. 3 steel. A newly developed cylinder shaft of 1.55m In diameter was initially used in the deep foundation. (Later in 1962, f5.8m cylinder shaft foundation was laid in the Ganijang South Bridge in Nanchang, Jiangxi Province.) In 1968, another wonder over the Yangtze River -the Nanjing Yangtze River Bridge- came into being. The whole project, including its material, design and installation, was completed through the Chinese own efforts. It is a rivet-connected continuous truss with a 160m main span. The material used is high quality steel of 16 Mnq. In erection, deep water foundation was developed. Open caissons were submerged to a depth of 54.87m, and pretensioned concrete cylinder shafts 3.6m in diameter were laid, thus forming a new type of compound foundation. And subwater cleaning was performed in a depth of 65m. Another attractive and gigantic structure standing over the Yangtze River is the Jiujiang Bridge completed in 1992. Chinese-made 15 MnVNq steel was used and shop-welded steel plates 56mm thick were bolted on site. The main span reaches 216m. The continuous steel truss is enforced by flexible stiffening arch ribs. In laying the foundation, a double-walled sheet piling cofferdam was built, in which concrete bored pile cast-in-situ was set up. When erecting the steel beams, double suspended cable frame took the place of single one, which is another innovation.梁桥梁桥构造简单、施工方便、工期短、造价低、且维修容易，除特大跨度桥梁外，是设计中优先考虑的结构体系，应用甚广。1949年前由国人设计监造的梁桥，以总长1453m，最大跨度67m的杭州钱塘江公路铁路两用桥（1937年建成）为一里程碑，1949年后这种梁桥已有长足的发展。钢筋混凝土梁桥是一种常用的中小跨度桥梁，以广西壮族自治区的南宁邕江桥（1964年）为代表，主跨醉大55m，系中国最早按闭口薄壁构件设计的一座箱形悬臂梁桥。预应力混凝土梁桥在本世纪50年代中国即已开始研制，1956年初首先在陇海线新沂河铁路桥上建成了跨度23.9m的简支梁。跨度20m的京周公路桥也于同期建成。这种桥型的最大跨度为浙江省瑞安飞云江桥（跨度为62m，1988年）；1989年建成的开封黄河大桥总长4475.09m，其中有77孔50m简支梁采用连续长度达450m，并按部分预应力混凝土结构设计。预应力混凝土梁桥跨度范围广，形式多样。预制的AASHTO梁和组合的现浇非预应力混凝土板常用于小跨径的简支跨。上述结构性失业可用于使用了工字梁和箱形梁的中等跨径的部分连续梁。而连续的预制分段装配式箱梁则普遍地使用与中等跨径及大跨径的桥梁，而最长的跨一般采用分段现浇箱梁。现浇的施工方法一般是将梁和板组合在一起，并在移去模板和支承之前对其进行现浇。这种结构作为一个整体来承担静载和活载。一般来说梁的横截面一般呈T型和箱形。通常桥跨为连续跨。将板进行横向后张拉时，允许使用较薄的板或者减少纵梁数目来扩大空间。纵向后张拉要求在现场进行；而横向后张拉更经济，因而运用更广泛。对钢筋混凝土梁桥的设计和分析同样也适用于预应力桥梁。对于箱梁截面，其横向活载应进行详细分析。由于顶板和底板之间的温度可能存在较大的差异，所以温度效应对箱梁来说很重要。应用平衡悬臂梁施工法进行现浇分段施工时，为了计算各个阶段的应力和变形，有必要知道准确的施工荷载。混凝土的徐变特性不仅对每增加一段后得变形的计算很重要，而且对竣工和最后加压后弯矩重新分布的计算也很重要。标准的预制预应力梁最大跨径可达140ft(43)m。梁安装之后，板模就放置在梁和现浇的钢筋混凝土板之间以浇筑混凝土加劲板。板与梁共同承受叠加的静载和活载。一般不使用中横隔板，对钢筋混凝土梁桥的设计和分析同样适用于预应力多梁桥。预制的预应力梁可以做成部分连续形成多跨桥。这种体系不仅在结构上有效，而且可减少桥面结点数。由于叠加的静载和活载、温度差异，以及收缩和徐变作用，支承弯矩就产生了。浇筑桥面混凝土的同时浇筑横隔板就可得到连续的叠加静载和连续的叠加活载。在桥面板里纵向放置的、与中间桥墩垂直的加强钢筋承受支点处负弯矩产生的拉应力。横隔板处。相邻梁的底翼缘应连在一起抵制由于温差、收缩和徐变产生的正弯矩而形成的拉应