1、中文 4735 字 毕业设计 外文翻译 题 目 跨 越 世 纪 之 桥 专 业 土木工程（桥梁） 2011 年 6 月 A Bridge For All Centuries An extremely long-and record setting-main span was designed for the second bridge to across the Panama Canal in order to meet the owners requirement that no piers be placed in the water.Because no disruption of ca
2、nal traffic was permitted at any time,the cable-stayed bridge of cast-in-place cancrete was carefully constructed using the balanced-cantilever method. In 1962 ,the Bridge of Americas(Puente de las America) opened to traffic,serving as the only fixed link across the Panama Canal .The bridge was desi
3、gned to carry 60,000 vehicles per day on four lanes, but it has beenoperating above its capacity for many years.Toalleviate bottlenecks on the route that the bridge carries over the canal-the Pan-American Highway(Inter-American Highway)-and promotegrowth on the western side of Panama,the countrys Mi
4、nistry of Public Works(Ministerio de Obras Publicas,or MOP )decided to build a new highway systerm linking the northern part of Panama City,on the eastern side of the canal, to the town of Arraijan,located on the western side of the canal.The Centennial Bridge named to commemorate 100 years of Panam
5、anian independence-has noe been constructed and, when opend, will carry six lanes of traffic. This cable-stayed bridge of cast-in-place cancrete features a main span of 420m,the longest such span for this type of bridge in the Western Hemisphere. In 200 the MOP invited international bridge design fi
6、rms to compete for the design of the crossing, requesting a two-package proposal:one techinical, the other financial. A total of eight proposals were received by December 2000 from established bridge design firms all over the world. After short-listing three firms on the basis of the technical merit
7、s of their proposals, the MOP selected T.Y.Lin International, of San Francisco, to prepare the bridge design and provide field construction support based on the firms financial package. The Centennial Bridge desige process was unique and aggressive,incorporating concepts from the traditional design/
8、build/bid method, the design/build method , and the sa-called fast-track design process.To complete the construction on time-that is ,within just 27 months-the design of the bridge was carried out to a level of 30 percent before construction bidding began, in December 2001.The selected contractor-th
9、e Wiesbaden,Germany,office of Bilfinger Berger,AG-was brought on board immediately after being selected by the MOP ,just as would be the case in a fast-track approach. The desige of the bridge was then completed in conjunction with construction , a process that id similan to desige/build. The design
10、 selected by the client features two single-mast towers,each supporting two sets of stay cables that align in one vertical plane.Concrete was used to construct both the towers and the box girder deck,as well as the approach structures. The MOP , in conjunction with the Panama Canal Authority,establi
11、shed the following requirements for the bridge design : A 420m,the minimum length for the main span to accommodate the recently widened Gaillard Cut,a narrow portion of the canal crossing the Continental Divide that was straightened and widened to 275m in 2002； A navigational envelope consisting of
12、80m of vertical clearance and 70m of horizontal clearance to accommodate the safe passage of a crane of World War 11 vintage-a gift from the U.S.government that is used by the Panama Canal Authority to maintain the canal gates and facilities； A roadway wide enough to carry six lanes of traffic, thre
13、e in each direction； A deck able to accommodate a 1.5m wide pedestrian walkway； A design that would adhere to the American Association of State Highway and Transportation Official standard for a 100-year service life and offer HS-25 truck loading； A structure that could carry two 0.6m dianeter water
14、 lines； A construction method that would not cross the canal at any time or interrupt canal operationa in any way. Because of the bridges long main span and the potential for strong seismic activity in the area,no single building code covered all aspects of the project.Therefore the team from T.Y. L
15、in International determinded which portions of several standard bridge specifications were applicable and which were not.The following design codes were used in developing the design criteria for the bridge， it is standard specifications for highway bridge ,16th ed,1996 It was paramount that the tow
16、ers of the cable-stayed structucture be erected on land to avoid potential ship collision and the need to construct expensive deep foundation in water. However, geological maps and boring logs produced during the preliminary design phrase revealed that the east and west banks of the canal, where the
17、 towers were to be located, featured vastly different geologicaland soil conditions. On the east side of the canal, beneath shallow layers of overburden that rangs in consistency from soft to hard, lies a block of basalt ranging from medium hard to hard with very closely spaced joint.The engineers d
18、etermined that the basalt would provide a competent platform for the construction of shallow foundation for tower, piers, and approach structures on this side of bridge.The west side, however,featured the infamous Cucaracha Formation, which is a heterogeneous conglomerate of clay shale with inclusions of sandstone, basalt,and ash that is prone to landslide. As a sudsurface
