橋梁畢業(yè)設(shè)計(jì)外文翻譯--大跨度橋梁

1、<p><b>　　大跨度橋梁</b></p><p><b>　　懸索橋</b></p><p>　　懸索橋是現(xiàn)行的跨徑超過600m大橋的唯一解決方案，而且對(duì)跨徑在300m以上的橋梁它也是被認(rèn)為是一種很有競(jìng)爭(zhēng)力的方案?，F(xiàn)在世界上最大跨徑的橋梁是紐約的威拉查諾（Verrazano）海峽大橋，另一個(gè)是英國(guó)的塞溫（Savern）大橋。<

2、;/p><p>　　懸索橋的組成部分有：柔性，主塔，錨碇，吊索（掛索），橋面板和加勁桁架。主纜是有一組平行的單根高強(qiáng)鋼絲在現(xiàn)場(chǎng)扭在一起并綁扎成型的鋼絲束組成的。每根鋼絲都是 經(jīng)過渡鋅處理的，并且整個(gè)用保護(hù)層覆蓋著。所用的鋼絲應(yīng)該是冷拔鋼絲而不是經(jīng)過熱處理的各種鋼絲。在進(jìn)行主塔設(shè)計(jì)時(shí)應(yīng)該特別注意其在美學(xué)上的要求。主塔很高而且具有足夠的柔性，使其每一座塔頂都可認(rèn)為是與主纜鉸接。主纜的兩端很安全的錨固在非常堅(jiān)實(shí)的錨碇上。吊

3、索把橋面板上的荷載傳遞到主主纜上。吊索也是有高強(qiáng)鋼絲制成的而且通常是豎直的。橋面板通常是有加勁鋼板，肋或槽型板，橫梁制成的異性結(jié)構(gòu)。提供一些加勁梁連接在其主塔之間，能夠起到控制空氣動(dòng)力運(yùn)動(dòng)并限制橋面板局部?jī)A角變化。如果加勁系統(tǒng)不適當(dāng)，由于風(fēng)引起的豎向振動(dòng)也許會(huì)導(dǎo)致結(jié)構(gòu)傾斜，就像塔科瑪（Tacoma）海峽大橋的悲劇性的破壞所表明的那樣。</p><p>　　邊跨與主跨的跨徑比的變化范圍是0.17~0.50。 在現(xiàn)有

4、的采用加勁梁的橋梁上， 當(dāng)跨徑高大 1000米時(shí)跨徑與橋梁的建筑高度之比為85與100之間?，F(xiàn)有的橋梁的跨徑與橋面板寬度之比約為20~56。橋梁結(jié)構(gòu)的空氣動(dòng)力穩(wěn)定性必須得通過對(duì)其模型的風(fēng)洞試驗(yàn)及細(xì)部分析進(jìn)行全面的研究。</p><p><b>　　斜拉橋體系 </b></p><p>　　在過去的十年間，斜拉橋得以廣泛的應(yīng)用，尤其實(shí)在歐洲，而在世界其它地區(qū)，應(yīng)用相對(duì)少

5、一些。</p><p>　　在現(xiàn)代橋梁工程中，斜拉橋體系的重新興旺起來(lái)是由于歐洲（主要是德國(guó)）的橋梁工程師有一種趨勢(shì)，即從因?yàn)閼?zhàn)爭(zhēng)而短缺的材料上獲得最佳的結(jié)構(gòu)性能。斜拉橋是有按各向異性橋面板和由吊索支撐的連續(xù)梁構(gòu)成的體系建造起來(lái)的，這些吊索是一些穿過或固定的位于主橋墩的索塔頂上的傾斜主纜。</p><p>　　用主纜來(lái)支撐橋跨并不是一種新思想，在很早以前就有大量此類結(jié)構(gòu)的的記載。不幸的是這

6、一體系只有很少成功的例子，這是由于人們對(duì)靜力學(xué)的原理沒有完全弄明白，并且還沒有構(gòu)成傾斜支撐或吊索的適當(dāng)?shù)牟牧?，例如主纜和鋼鏈等。這種吊索在它們能夠按計(jì)劃承擔(dān)拉力之前不能完全被拉緊，而應(yīng)處于允許橋面板產(chǎn)生較大變形的松弛狀態(tài)。</p><p>　　斜拉體系的廣泛的成功的應(yīng)用只在近年來(lái)，隨著高強(qiáng)鋼，各種異性橋面板的引入、焊接技術(shù)的發(fā)展和結(jié)構(gòu)分析方法的進(jìn)步才得以實(shí)現(xiàn)。電子計(jì)算機(jī)的發(fā)展和應(yīng)用，導(dǎo)致了解決高次超靜定體系的精確

7、值及它們的三維空間性能的精確靜力分析的新的無(wú)實(shí)際限制的可能性。</p><p>　　現(xiàn)有的斜拉橋提供了許多關(guān)于設(shè)計(jì)、制造、安裝和維修的有用的數(shù)據(jù)。隨著這些橋梁的建造，許多工程中遇到的基本問題已表明的到了成功的解決。然而這些重要的數(shù)據(jù)很顯然在這以前決沒有被系統(tǒng)的揭示出來(lái)。</p><p>　　斜吊索的應(yīng)用對(duì)大型橋梁建造帶來(lái)了一個(gè)新刺激。斜拉橋的重要性迅速增加起來(lái)，并且在僅三十年間這種橋梁類型

8、就變的這樣成功，已使其在古典橋梁體系中取得了它應(yīng)有的地位。如果我們注意到這種橋梁建造帶來(lái)如此徹底的變革的發(fā)展是怎樣發(fā)生的話，我們都會(huì)感興趣的，因?yàn)檫@一發(fā)展事實(shí)上并沒有什么任何新發(fā)現(xiàn)。</p><p>　　這一體系的開始也許可以追溯到人們開始認(rèn)識(shí)到通過三角形連接在一起能夠構(gòu)成剛性結(jié)構(gòu)的時(shí)代。</p><p>　　盡管大多數(shù)這種設(shè)計(jì)是基于結(jié)構(gòu)堅(jiān)固的原理和假定的，但斜拉加勁梁還是遭受各種各樣的不

9、幸事故，而最終令人遺憾的導(dǎo)致了這一體系被放棄。盡管這樣，這一體系并不是完全不適應(yīng)，只是問題的解決被不幸的應(yīng)用錯(cuò)誤的方式去嘗試。</p><p>　　然而，斜拉體系的復(fù)興只是在近十年來(lái)才最終獲得成功。</p><p>　　現(xiàn)代的斜拉橋提出了加勁梁、橫向及縱向聯(lián)系梁、各項(xiàng)異性橋面板和支撐部分（例如處于受壓狀態(tài)的索塔及受拉狀態(tài)的斜吊索）組成的三維空間體系。象這種空間三維結(jié)構(gòu)的重要特征是橫向結(jié)構(gòu)全

10、部參與主要縱向結(jié)構(gòu)的工作狀態(tài)。這就意味著結(jié)構(gòu)的慣性矩大大增加，這使的橋的建筑高度可以減少，并且使用鋼材是最經(jīng)濟(jì)的。</p><p>　　大跨度橋梁經(jīng)常是連續(xù)梁形式或懸臂梁形式的預(yù)應(yīng)力混凝土橋梁。以前許多的施工方法已發(fā)展為連續(xù)梁橋的施工方法。如果模板和地面之間的距離較小并且土質(zhì)堅(jiān)硬，橋梁的上部結(jié)構(gòu)可以使用支架施工方法。不過這種施工方法已經(jīng)越來(lái)越過時(shí)了。目前，自由懸臂法和移動(dòng)模架法的應(yīng)用漸廣并能節(jié)省時(shí)間和提高安全性。

11、</p><p>　　移動(dòng)模架法是利用固定在鋼制臺(tái)架上的移動(dòng)系統(tǒng)而形成，這種系統(tǒng)能夠達(dá)到一跨長(zhǎng)并支承在一端支承在橋墩上并借助于第二根鋼導(dǎo)梁逐跨移動(dòng)的鋼梁上。</p><p>　　一種經(jīng)濟(jì)的施工方法是被廣泛知曉的由Baur-leonhard團(tuán)隊(duì)所發(fā)展的使用廣泛的頂推法。整個(gè)的連續(xù)梁被劃分成10-30米長(zhǎng)度的節(jié)段，這種劃分主要依據(jù)跨徑和能夠利用的施工時(shí)間。每個(gè)節(jié)段在橋臺(tái)后面的鋼模上能夠快速澆注

12、，鋼?？梢灾苻D(zhuǎn)使用而澆注所有的節(jié)段。這樣設(shè)計(jì)模板是為了能夠橫向移動(dòng)或在鉸上轉(zhuǎn)動(dòng)，以便在混凝土充分硬化后脫模。在第一節(jié)段的頂端安裝上一個(gè)由輕型桁架組成的鋼導(dǎo)梁，以實(shí)現(xiàn)第一節(jié)段以后的節(jié)段順利架設(shè)而防止在施工出現(xiàn)過大的懸臂部分。第二節(jié)段及以后的節(jié)段可以直接在第一節(jié)段的硬化面上澆注并在施工過程中將節(jié)段連接起來(lái)。頂推是通過支承在橋臺(tái)上的液壓千斤頂實(shí)現(xiàn)的，由于聚四氟乙烯的滑塊的摩擦系數(shù)只有0.02，低效能的千斤頂就足夠完成長(zhǎng)度甚至達(dá)數(shù)百米的橋梁的頂

13、推。這種方法可以應(yīng)用在長(zhǎng)度在120米左右的直線橋梁或曲線橋梁上。</p><p>　　自由懸臂法是由法國(guó)的Dyckerhoff和Willmann所創(chuàng)始。這種施工方法中，橋梁的上部結(jié)構(gòu)是通過節(jié)段長(zhǎng)度基本在3.5米的懸臂機(jī)上施工，懸臂機(jī)的費(fèi)用相對(duì)比較低并且固定在橋梁承重結(jié)構(gòu)上，由于它的重復(fù)利用性使它能在長(zhǎng)橋上使用。由于施工速度的加快和時(shí)間的節(jié)省使得這種施工方法的費(fèi)用比較低從而避免了使用臺(tái)架施工，自由懸臂法比較適用于橋

14、墩較高并且懸臂能伸到跨徑中部的橋梁上。</p><p>　　另一種施工方法是整體沉箱法。沉箱是一種底邊有刃腳的大型圓筒，其刃腳可以切入水底。當(dāng)壓縮空氣進(jìn)入沉箱內(nèi)部時(shí)水就會(huì)被排出。沉箱的利用必須嚴(yán)加注意。首先，工人們只能在這種壓縮空氣的空間里呆很短的時(shí)間；另一方面，如果工人們從沉箱進(jìn)入正常的大氣壓條件下過于迅速，他們將比較容易患上潛水?。ㄒ脖环Q作沉箱?。?，這在能使人致殘的甚至致命的環(huán)境中由于血液中氧氣過多所引起的一

15、種病。當(dāng)St.louis市的密西西比河Eads上的橋在1867-1874年施工時(shí)，由于人們對(duì)在壓縮空氣中工作的危險(xiǎn)性認(rèn)識(shí)不足，最后由于患潛水病而導(dǎo)致14人死亡。</p><p>　　當(dāng)在橋墩上有外力作用時(shí)，基樁經(jīng)常需要嵌入基巖，也就是說(shuō)它們的下部一直延伸到基巖。這種方法曾經(jīng)用來(lái)建造位于強(qiáng)風(fēng)和地震區(qū)域的舊金山金門大橋的橋墩。鉆孔是在水下由深水潛水員進(jìn)行的。在不能到達(dá)基巖的地方，樁通常被打進(jìn)河床。今天，在施工的基樁基

16、本上是預(yù)應(yīng)力混凝土結(jié)構(gòu)。在建造紐約哈德遜河上的泰平.吉橋時(shí)所采用的一種巧妙技術(shù)是將一個(gè)空心混凝土箱置于橋樁層上，當(dāng)它里面的水被抽干時(shí)，它的浮力足夠支承橋梁重力的一大部分。</p><p>　　每一種類型的橋梁實(shí)際上代表了特殊的問題。許多桁架橋的施工是先將橋上桁架運(yùn)到已施工完畢的基樁位置，然后在利用千斤頂或起重機(jī)架設(shè)到適當(dāng)位置。拱橋是在腳手架或臨時(shí)腳手架上施工的，這種方法通常用于預(yù)應(yīng)力混凝土拱橋。然而對(duì)鋼拱橋來(lái)說(shuō)已

17、發(fā)展了一種技術(shù)，用這種技術(shù)將已裝好的部分借助起支承作用的主纜控制就位（鋼拱在安裝過程中還沒有合攏前，是兩個(gè)懸臂，需要用主纜拉住兩個(gè)懸臂以免傾倒）。當(dāng)主纜中的拉力增加時(shí)，起重機(jī)就沿著拱橋的頂部移動(dòng)以架設(shè)新的鋼拱。</p><p>　　對(duì)懸索橋來(lái)說(shuō)，需要首先施工基礎(chǔ)和索塔。這時(shí)主纜從錨碇（一個(gè)固定主纜的大混凝土塊）穿過直至索塔并且通過另一索塔而錨固在錨碇上，然后從卷線盤上放松主纜的輪子沿著主纜運(yùn)動(dòng)，當(dāng)卷線盤到達(dá)另一面

18、時(shí)，另一根鋼絲又裝進(jìn)卷線盤并最終到達(dá)它的原位置。當(dāng)所有的主纜被放在固定的位置后，另一臺(tái)機(jī)器沿著主纜移動(dòng)并對(duì)其進(jìn)行張拉錨固。當(dāng)主纜施工完畢時(shí)，逐漸開始在支架上從兩端向中間施工。</p><p>　　在橋梁下部結(jié)構(gòu)和基礎(chǔ)設(shè)計(jì)中要考慮的荷載包括：從上部結(jié)構(gòu)傳下來(lái)的荷載和直接作用于下部結(jié)構(gòu)的基礎(chǔ)的荷載。</p><p>　　AASHTO荷載。 AASHTO規(guī)范第三部分總結(jié)了橋梁設(shè)計(jì)（上、下部結(jié)構(gòu)）

19、要考慮的荷載和作用力。主要有：恒載、活載、活載沖擊力或動(dòng)力作用、風(fēng)荷載以及其他荷載——如縱向力、離心力、溫度力、土壓力、浮力、收縮及徐變、拱肋縮短、安裝應(yīng)力、冰及水流壓力、沖撞力及地震應(yīng)力。除了這些通常能夠量化大的典型荷載外，AASHTO同樣認(rèn)識(shí)到諸如活動(dòng)支座處產(chǎn)生的摩擦以及由于橋梁的沉降差而產(chǎn)生的應(yīng)力等間接荷載效應(yīng)。</p><p>　　Large Span Bridge</p><p>

20、;　　Suspension Bridge</p><p>　　The suspension bridge is currently the only solution in excess of 600 m, and is regarded as competitive for down to 300. The world’s longest bridge at present is the Verrazano N

21、arrows bridge in New York. Another modern example is the Severn Bridge in England. </p><p>　　The components of a suspension bridge are: (a) flexible cables, (b) towers, (c) anchorages, (d) suspenders, (e) de

22、ck and ，(f) stiffening trusses. The cable normally consists of parallel wires of high tensile steel individually spun at site and bound into one unit .Each wire is galvanized and the cable is cover with a protective coat

23、ing. The wire for the cable should be cold-drawn and not of the heat-treated variety. Special attention should be paid to aesthetics in the design of the rowers. The </p><p>　　The side span to main span rati

24、o varies from 0.17 to 0.50 .The span to depth ratio for the stiffening truss in existing bridge lies between 85 and 100 for spans up to 1,000m and rises rather steeply to 177. The ratio of span to width of deck for exist

25、ing bridges ranges from 20 to 56. The aerodynamic stability will have be to be investigated thoroughly by detailed analysis as well as wind tunnel tests on models.</p><p>　　The cable-stayed bridge</p>

26、<p>　　During the past decade cable-stayed bridges have found wide application, s\especially in Western Europe, and to a lesser extent in other parts of the world.</p><p>　　The renewal of the cable-stay

27、ed system in modern bridge engineering was due to the tendency of bridge engineering in Europe, primarily Germany, to obtain optimum structural performance from material which was in short supply-during the post-war year

28、s.</p><p>　　Cable-stayed bridges are constructed along a structural system which comprises an orthotropic deck and continuous girders which are supported by stays, i.e. inclined cables passing over or attach

29、ed to towers located at the main piers. </p><p>　　The idea of using cables to support bridge span bridge span is by no means new, and a number of examples of this type of construction were recorded a long ti

30、me ago. Unfortunately the system in general met with little success, due to the fact that the statics were not fully understood and that unsuitable materials such as bars and chains were used to form the inclined support

31、s or stays. Stays made in this manner could not be fully tensioned and in a slack condition allowed large deformations of t</p><p>　　Wide and successful application of cable-stayed systems was realized only

32、recently, with the introduction of high-strength steels, orthotropic decks, development of welding techniques and progress in structural analysis. The development and application of electronic computers opened up new and

33、 practically unlimited possibilities for exact solution of these highly statically indeterminate systems and for precise stoical analysis of their three-dimensional performance.</p><p>　　Existing cable-staye

34、d bridges provide useful data regarding design, fabrication, erection and maintenance of the mew system. With the construction of these bridges many basic problems encountered in their engineering are shown to have been

35、successfully solved. However, these important data have apparently never before been systematically presented.</p><p>　　The application of inclined cable gave a new stimulus to construction of large bridges.

36、 The importance of cable-stayed bridges increased rapidly and within only one decade they have become so successful that they have taken their rightful place among classical bridge system. It is interesting to note now h

37、ow this development which has so revolutionized bridge construction, but which in fact is no new discovery, came about.</p><p>　　The beginning of this system, probably, may be traced back to the time when it

38、 was realized that rigid structures could be formed by joining triangles together. Although most of these earlier designs were based on sound principles and assumptions, the girder stiffened by inclined cables suffered v

39、arious misfortunes which regrettably resulted in abandonment of the system. Nevertheless, the system in itself was not at all unsuitable. The solution of the problem had unfortunately been attempted in </p><p&

40、gt;　　The renaissance of the cable-stayed, however, was finally successfully achieved only during the last decade. </p><p>　　Modern cable-stayed present a three-dimensional system consisting of stiffening gir

41、ders, transverse and longitudinal bracings, orthotropic-type deck and supporting parts such as towers in compression and inclined cables in tension. The important characteristics of such a three-dimensional structure is

42、the full participation of the transverse construction in the work of the main longitudinal structure. This means a considerable increase in the moment of inertia of the construction which permits a</p><p>　　

43、Long span concrete bridges are usually of post-tensioned concrete and constructed either as conditions beams types or as free versatile structures. Many methods have been developed for continuous deck construction. If th

44、e clearance between the ground and bottom of the deck is small and the soil is firm, the superstructure can be built on staging. This method is becoming obsolete. Currently, free-cantilever and movable scaffold systems a

45、re increasingly used to save time and improve safety.</p><p>　　The movable scaffold system employs movable forms stiffened by steel frames. These forms extend one span length and are supported by steel girde

46、rs which rest on a pier at one end and can be moved from span to span on a second set of auxiliary steel girders.</p><p>　　An economical construction technique known as incremental push-launching method is d

47、eveloped by Baur-Leonhard team. The total continuous deck is subdivided longitudinally into segments of 10 to 30 m length depending on the length of spans and the time available for construction. Each of these segments i

48、s constructed immediately behind the abutment of the bridge in steel framed forms, which remain in the same place for concreting all segments .The forms are so designed as to be capable of being m</p><p>　　T

49、he free-cantilever system was pioneered by Dyckerhoff and Willmann in Germany .In this system , the superstructure is erected by means of cantilever truck in sections generally of 3.5 m .The cantilever truck ,whose cost

50、is relatively small and which is attached firmly to permanent construction , emits by repeated use the construction of large bridges . The avoidance of scaffold from below, the speed of work and the saving in labor cost

51、result in the construction being very economical. The free-</p><p>　　Another technique is the use of the pneumatic caisson .The caisson is a huge cylinder with a bottom edge that can cut into the water bed.

52、When compressed is pumped into it ,the water is forced out .Caissons must be used with extreme care .for one thing, workers can only stay in the compression chamber for short periods of time .For another , if they come u

53、p to normal atmospheric pressure too rapidly ,they are subject to the bends ,or caisson disease as it is also called , which is a crippling or</p><p>　　When extra strength is necessary in the piers, they som

54、etimes keyed into the bedrock-that is ,they are extended down into the bedrock .This method was used to build the piers for the Golden Gate Bridge in San Francisco ,which is subject to strong tidies and high winds ,and i

55、s located in an earthquake zone .The drilling was carried out under water by deep-sea divers .</p><p>　　Where bedrock cannot be reached ,piles are driven into the water bed .Today ,the piles in construction

56、are usually made of prestressed concrete beams .One ingenious technique ,used for the Tappan Zee Bridge across the Hudson River in New York ,is to rest a hollow concrete box on top of a layer of piles .When the box is pu

57、mped dry ,it becomes buoyant enough to support a large proportion of the weight of the bridge .</p><p>　　Each type of bridge indeed each individual bridge presents special construction problems. With some tr

58、uss bridges , the span is floated into position after the piers have been erected and then raised into place by means of jacks or cranes .Arch bridges can be constructed over a false work ,or temporary scaffolding. This

59、method is usually employed with reinforced concrete arch bridges .With steel arches ,however ,a technique has been developed whereby the finished sections are held in place by wi</p><p>　　With suspension bri

60、dges ,the foundations and the towers are built first .Then a cable is run from the anchorage-concrete block in which the cable is fastened-up to the tower and across to the opposite tower and anchorage .A wheel that unwi

61、nds wire from a reel puns along this cable .When the reel reaches the other side ,another wire is placed on it ,and the wheel returns to its original position .When all the wires have been put in place ,another machine m

62、oves along the cable to compact and to bi</p><p>　　The loads to be considered in the design of substructures and bridge foundations include loads and forces transmitted from the superstructure, and those act

63、ing directly on the substructure and foundation.</p><p>　　AASHTO loads .Section 3 of AASHTO specifications summarizes the loads and forces to be considered in the design of bridges (superstructure and substr

64、ucture). Briefly , these are dead load ,live load , impact or dynamic effect of live load , wind load , and other forces such as longitudinal forces , centrifugal force ,thermal forces , earth pressure , buoyancy , shrin