[雙語(yǔ)翻譯]--橋梁工程外文翻譯--自錨式懸索橋（原文）

1、JOURNAL OF BRIDGE ENGINEERING / AUGUST 1999 / 151SELF-ANCHORED SUSPENSION BRIDGESBy John A. Ochsendorf,1 Student Member, ASCE, and David P. Billington,2 Fellow, ASCEABSTRACT: This paper, summarizing the beginnings, analy

2、sis, and future of self-anchored suspension bridges, examines the development of this unique bridge form, its uses over the past century, and its advantages and disadvantages. The Konohana Bridge in Osaka, Japan, illustr

3、ates this type and provides a case study to compare conventional suspension bridge theory with the results of a finite-element model. The final portion of the paper evaluates the potential for self-anchored suspension br

4、idge design, and provides recommendations for design engineers. The goal here is to describe the structural behavior of self-anchored bridges in general, and of the Konohana Bridge in particular.FIG. 2. 1928 Seventh Stre

5、et Bridge in PittsburghFIG. 1. Original 1915 Cologne-Deutz Bridge in Germany (Prade 1990)INTRODUCTIONSelf-anchored suspension bridges differ from conventional suspension bridges because they do not require massive end an

6、chorages. Instead, the main cables are secured to each end of the bridge deck, or stiffening girder, which carries the hor- izontal component of cable tension. Therefore, the end sup- ports resist only the vertical compo

7、nent of tension, an advan- tage where the site cannot easily accommodate external anchorages. Because the stiffening girder supports the cable tension, the girder must be placed before the main cable can be erected. This

8、 construction sequence, the opposite of that of a conven- tional suspension bridge, limits the self-anchored form to mod- erate spans. Also unlike the conventional suspension form, the self-anchored bridge analysis must

9、include the influence of the large axial force in the deck. With these issues in mind, this paper will discuss the historical development, structural anal- ysis, and potential applications of this bridge form, and will c

10、onclude with some reflections on recent self-anchored sus- pension bridges.HISTORICAL DEVELOPMENTIn the second half of the 19th century, Austrian engineer Josef Langer and American engineer Charles Bender indepen- dently

11、 conceived of the self-anchored suspension bridge (Mul- lins 1936a). Langer first wrote of his idea in 1859, and Bender staked his claim with a patent issued in 1867 (‘‘Patent’’ 1867). Neither designer used continuous ca

12、bles; instead, they an- chored the main cables to the girder at the midspan as well as at each end of the bridge. In 1870 Langer built a small self- anchored bridge, in Poland, which carried train traffic, while Bender a

13、pparently never constructed a self-anchored bridge. Although these engineers did not directly influence future de- signs, the self-anchored suspension bridge form became com- mon in Germany in the beginning of the 20th c

14、entury. German engineers built the first large-scale, self-anchored suspension bridge over the Rhine River at Cologne, Germany, in 1915 (Mullins 1936b) (Fig. 1). This Cologne-Deutz Bridge had a main span of 185 m and uti

15、lized temporary wooden scaffolding to support the steel girders until the suspension cables were in place (‘‘Le Nouveau’’ 1920). An art commis- sion selected the suspension form for aesthetic reasons, and engineers opted

16、 to self-anchor the suspension cables for fear1Grad. Student, Dept. of Civ. Engrg. and Operations Res., Princeton Univ., Princeton, NJ 08544. 2Gordon Y. S. Wu Professor, Dept. of Civ. Engrg. and Operations Res., Princeto

17、n Univ., Princeton, NJ. Note. Discussion open until January 1, 2000. To extend the closing date one month, a written request must be filed with the ASCE Manager of Journals. The manuscript for this paper was submitted fo

18、r review and possible publication on March 23, 1998. This paper is part of the Journal of Bridge Engineering, Vol. 4, No. 3, August, 1999. ?ASCE, ISSN 1084-0702/99/0003-0151–0156/$8.00 ? $.50 per page. Paper No. 17921.th

19、at the soil conditions would not be adequate for external anchorages (Leonhardt 1984a). Chains composed of eyebars provided for ease of anchoring to the stiffening girder. Engi- neers around the world recognized the Colo

20、gne-Deutz Bridge as an innovative form, and for 15 years after its completion it influenced the design of other bridges. Specifically, the three Allegheny River crossings in Pittsburgh, Pennsylvania, and the smaller Kiyo

21、su Bridge in Tokyo, Japan, closely replicated the appearance of the Cologne-Deutz Bridge (Tajima and Sugi- yama 1991). It was destroyed in 1945, and a steel box girder bridge exists today on the original abutments (Prade

22、 1990). The three nearly identical bridges constructed over the Al- legheny River in Pittsburgh from 1925 to 1928 represent the most important American application of the self-anchored form. In evaluating the proposed Si

23、xth, Seventh, and Ninth Street crossings, the city art commission of Pittsburgh re- quested a suspension form for aesthetic reasons. Inspired byJ. Bridge Eng. 1999.4:151-156.Downloaded from ascelibrary.org by Tongji Univ

24、ersity on 07/22/13. Copyright ASCE. For personal use only; all rights reserved.JOURNAL OF BRIDGE ENGINEERING / AUGUST 1999 / 153TABLE 1. Konohana Bridge DimensionsDimension (1) Value (2)Main span 300 m (984 ft)Total susp

25、ended span 540 m (1,771.2 ft)Sag: span 1:6Depth of girder 3.17 m (10.4 ft)Width of girder 26.5 m (86.9 ft)Girder depth: main span 1:95Self-weight 0.87 tons/m2 (170 psf)Traffic capacity 4 lanesFIG. 5. Elevation Diagram of

26、 Konohana BridgeTABLE 2. Major Self-Anchored Suspension BridgesName (Location) (1) Year (2)Main span (m) (3)Side spans (m) (4)Sag: Span (5)Cologne-Deutz (Germany) 1915 184.5 92.3 1:8.6Seventh Street (Pittsburgh) 1926 134

27、.8 67.5 1:8.1Kiyosu (Japan) 1928 91.5 45.8 1:7.1Cologne-Mu ¨lheim (Germany) 1929 315.0 91.0 1:9.1Konohana (Japan) 1990 300.0 120.0 1:6.0Yong Jong (Korea) 1999 300.0 125.0 1:5.0bridge a slender appearance. Table 1 su

28、mmarizes the general dimensions of the Konohana Bridge (Fig. 5 gives an elevation diagram). The success of the Konohana Bridge is due to three main aspects of its design: (1) the method of erection; (2) the use of inclin

29、ed hangers; and (3) the use of a steel box girder. First, an efficient erection scheme resulted from prefabricating the girder in five large sections, weighing as much as 2,700 tons each. Floating cranes lifted these sec

30、tions into place, and two temporary supports within the main span supported the girder sections during erection (Kamei et al. 1992). After construct- ing the two towers, the builders installed the main cable using prefab

31、ricated parallel wire strands, thus avoiding the time-con- suming process of cable spinning. The second successful design aspect were the inclined sus- penders, pretensioned to avoid slackening under any loading conditio

32、n. The pretensioning also jacked up the main girder to ensure accurate control during erection. Third, the inverted trapezoidal box girder, designed with sufficient moment ca- pacity to span 120 m between the temporary s

33、upports, made the erection scheme possible and minimized the necessary falsework. In addition, the closed box shape provides excellent aerodynamic performance and high torsional rigidity, critical requirements for a brid

34、ge supported by only one main cable. Like the landmark Cologne-Deutz Bridge of 1915, the Ko- nohana Bridge has influenced other bridge designs. Most no- tably, the Yong Jong Bridge, which will provide a critical link wit

35、h the new airport in Seoul, South Korea, when completed in 2,000, is very similar to the Konohana Bridge in its overall form and dimensions. Its 300-m main span and A-frame tow- ers are clearly derived from the Konohana

36、Bridge, but it has three significant differences. First, in order to decrease the ax- ial girder force due to self-anchoring, the main span cable sag is increased to 60 m, 20% greater than the Konohana Bridge. Second, th

37、e Yong Jong Bridge utilizes two main cables, which curve three-dimensionally from the top of each tower to the outside of the girder at midspan, and provide increased lateral stability (Kwon et al. 1995). Third, the stif

38、fening girder utilizes a 7-m deep truss, which carries rail traffic on the lower level, and eases construction by spanning long distances without the support of the main cable (Gil and Cho 1998). Table 2 presents a summa

39、ry of the development of self-anchored suspension bridges. Because the force in the stiff- ening girder is equal to the horizontal component of main ca- ble tension, recent designs have increased the sag of the main cabl

40、e in order to reduce the value of axial compression in the stiffening girder. In general, the sag:span ratios of self-an- chored bridges are around 1:6—considerably greater than the sag:span ratios of externally anchored

41、 suspension bridges, which typically are around 1:10.ANALYSIS OF SELF-ANCHORED SUSPENSION BRIDGESTwo theories have dominated suspension bridge analysis over the last century—the elastic theory and the deflection theory.

42、The elastic theory did not account for the stiffening effect of the main cable under tension, and thus gave higher moments in the stiffening girder. The deflection theory (or ex- act theory) accounted for the second-orde

43、r effects of cable stiffness and correctly reduced the moment carried by the stiff- ening girder (Melan 1913). By the 1930s, suspension bridge designers were aware of the economy offered by the deflection theory, and reg

44、arded the elastic theory to be obsolete (Stein- man 1929). The elastic theory gives the moment at any point in the deck girder asM = M? ? hy (1)where M? = live-load moment of unsuspended girder; h = horizontal component

45、of cable tension produced by live load; and y = ordinate of main span cable curve at location of de- sired moment. Thus, the live load moment produced in the girder is reduced by the effect of the horizontal component of

46、 live load tension in the cable. However, the elastic theory does not account for the addi- tional relieving moment provided by the horizontal component of total cable tension (dead plus live load) when the bridge deflec

47、ts a distance v, under the live load. The deflection theory accounts for this cable stiffness and reduces the moment in the girder by an additional amount (H ? h)v. Thus the de- flection theory is an extension of the ela

48、stic theory and is writ- tenM = M? ? hy ? (H ? h)v (2)where (H ? h) = horizontal component of tension in cable due to dead and live load. By accounting for cable stiffness, the deflection theory reduces the required gird

49、er stiffness and provides considerable economy over the elastic theory (Stein- man 1929). Accounting for the large axial force in the deck of self- anchored suspension bridges requires an adaptation in tradi- tional susp

50、ension bridge analysis. Because the deck carries the entire horizontal force component of the cable, the axial force in the deck is equal to the quantity (H ? h). Under a down- ward deflection v, the axial force will pro

51、duce an additional positive moment (H ? h)v if the bridge deck is considered to be initially horizontal.J. Bridge Eng. 1999.4:151-156.Downloaded from ascelibrary.org by Tongji University on 07/22/13. Copyright ASCE. For