外文翻譯---混凝土梁橋的結(jié)構(gòu)形式

1、<p>　　混凝土梁橋的結(jié)構(gòu)形式</p><p>　　事實證明，預應力混凝土結(jié)構(gòu)是在技術上先進、經(jīng)濟上有競爭力、符合審美學的一種先進技術。從使用標準組成的小跨徑橋梁到吊梁和跨徑將近100英尺的連續(xù)箱梁橋，幾乎所有的混凝土橋梁，甚至于相對短時間的橋梁都是預應力結(jié)構(gòu)的。采用預制、現(xiàn)場澆筑或兩種方法并用。在同一工程中經(jīng)常同時使用先張法和后張法。</p><p>　　在美國，公路橋一般情

2、況下必須滿足荷載、設計和AASHTO規(guī)定的建設的要求。對于服務于其它目的步行街和橋梁的設計要求由當?shù)氐幕虻胤降拇a建立。ACI代碼的備注也被納入?yún)⒖肌?lt;/p><p>　　伴隨最小交通中斷的大約100英尺的跨徑的橋梁由提供低的初級預算，最小量維修和養(yǎng)護費用和快速的簡易的預制板組成。這種梁一般是用先張法。預制板一塊挨一塊的放置并且在相鄰的預制板間受剪的縫隙填滿不收縮的灰泥之后，經(jīng)常在中間橫膈膜的位置后張拉。對于公路

3、，用瀝青鋪設的表面可以直接用在預制混凝土的上面。在某些情況下，一塊放置在正確位置的現(xiàn)澆板提供復合作用。</p><p>　　空心板一般用于深度15英尺到21英尺，寬度3英尺或4英尺。對于一個標準HS20的公路，空心板適合于大約50 英尺的跨徑。標準渠化區(qū)段在多種寬度，深度從21英尺到35英尺時是有利的，可用于大約20英尺到60英尺的跨徑。中空的箱形梁和T形梁用于大約100英尺的長跨徑。</p>&l

4、t;p>　　對于中等跨徑的大約120英尺的公路橋，一般使用AASHTO 標準梁。它們和一種復合現(xiàn)場預制行車道板一起使用。在板被安置之后，這樣的梁經(jīng)常在預澆梁的先張拉 與合成梁的后張拉后結(jié)合。試圖獲得改進經(jīng)濟，一些國家已經(jīng)采用更精煉的設計，例如華盛頓州標準梁。 </p><p>　　經(jīng)過特別設計預制建筑梁可以用來攜帶一個單軌鐵路系統(tǒng)。完成的沃爾特迪斯尼樂園單軌鐵

5、路的一系列的特征, 每個包括六個單獨支持的預拉梁，一起形成連續(xù)結(jié)構(gòu)。典型的跨距是100到110英尺。被使用的337根梁，大約一半有垂直與水平曲率和易變超級升高的一些結(jié)合。所有的梁是中空的，它的特征是通過在曲梁中插入泡沫和在直梁制作中移動形心軸獲得。</p><p>　　由于運輸問題和構(gòu)件垂直的大而重的問題，預制梁不能用于跨徑超過120英尺的橋梁。另一方面，橋梁有一種向大跨徑發(fā)展的明顯趨勢。對于提高的都市高速道路來

6、說，大跨徑促進通路而且將對下面的活動妨礙減到最少。對環(huán)境的損害問題的關心，導致連續(xù)高架橋大跨徑的選擇。對于跨河橋，因為航行間隙的需求，中間可能不可以搭設橋墩。 </p><p>　　在這一個類型的典型建筑中，橋墩（臺）采用現(xiàn)場預制, 經(jīng)常使用滑動的技術。一個箱梁的" 錘頭"澆筑在橋墩的頂端, 并且通過平衡的懸臂方法控制每個方向的建筑進行。最后,在完成跨中結(jié)合處的澆筑之后, 這種結(jié)構(gòu)對于完全連續(xù)

7、性的橋梁來說是進一步的受拉的 。修剪鑰匙可能被用在片段之間垂直面之上, 而且預制建筑與環(huán)氧基樹脂黏在一起。</p><p>　　想象的工程學藉著許多特別的技術示范已經(jīng)延長混凝土建筑的范圍，就橋梁而言，已經(jīng)遠遠超過幾年以前可以想象的到的任何事。在美國，雙向彎曲的現(xiàn)場澆鑄的部分箱梁已經(jīng)成功地完成 310 英尺 的跨距，跨越了北加州的鰻魚河。該橋的中間跨度550英尺，側(cè)跨跨度390英尺，初步設計已經(jīng)完成。</p&

8、gt;<p>　　預應力混凝土橋梁很適合于大跨徑的另一種形式是懸索箱梁。一個值得注意的例子是阿根廷境內(nèi)的Chaco-Corrientes橋。橋的主跨徑804英尺，由兩個A型構(gòu)架塔支撐，懸索從塔頂?shù)窖刂装迳煺?。受拉的懸索不僅提供一種垂直反應組成支撐底板，而且對于箱梁產(chǎn)生水平的壓縮，增加構(gòu)件中的張拉力。 </p><p>　　許多年以前德國工程師 Ulrich Finsterwalder 提出適合于負

9、擔荷載和大跨徑的一個結(jié)構(gòu)類型是壓帶式橋。壓帶是橋運輸跨越萊茵河的一個管道和人行道，跨徑446英尺。上部結(jié)構(gòu)的施工順序是（a）垂直的一對懸索，(b)在每個懸索的下面，安置預制板形成一人行道甲板和 一U型 的平臺, 并且 (c)在附近現(xiàn)場澆注混凝土。放置在頂部的管道支撐在扶手的頂部，向一邊傾斜， 大幅地增加結(jié)構(gòu)的主要風速。</p><p>　　討論橋梁形式應適當?shù)目紤]結(jié)構(gòu)的美學。當結(jié)構(gòu)可能根據(jù)最小的費用和技術設計的時

10、候，時間消逝了。特別是橋梁結(jié)構(gòu)到處可見。生產(chǎn)視覺上不愉快的結(jié)構(gòu) , 過去經(jīng)常發(fā)生, 是一種不負專業(yè)責任的行為。特別地對于主要的跨距，還有一些比較普通的結(jié)構(gòu)來說，應該在設計過程的概念階段尋找建筑的建議。</p><p><b>　　出處：</b></p><p>　　安瑞克．混凝土橋梁結(jié)構(gòu)形式[J]．建筑實錄(美)，2010，33(36)：34—36</p>

11、<p>　　The Structure of Concrete Bridge</p><p>　　Pre-stressed concrete has proved to be technically advantageous, economically competitive, and esthetically superior bridges, from very short span struc

12、tures using standard components to cable-stayed girders and continuous box girders with clear spans of nearly 100aft .Nearly all concrete bridges, even those of relatively short span, are now pre-stressed. Pre-casting, c

13、ast-in-place construction, or a combination of the two methods may be used .Both pre-tensioning and post tensioning are employed</p><p>　　In the United States, highway bridges generally must-meet loading ,de

14、sign ,and construction requirements of the AASHTO Specification .Design requirements for pedestrian crossings and bridges serving other purposes may be established by local or regional codes and specifications .ACI Code

15、provisions are often incorporated by reference .</p><p>　　Bridges spans to about 100ft often consist of pre-cast integral-deck units ,which offer low initial cost ,minimum ,maintenance ,and fast easy constru

16、ction ,with minimum traffic interruption .Such girders are generally pre-tensioned .The units are placed side by side ,and are often post-tensioned laterally at intermediate diaphragm locations ,after which shear keys be

17、tween adjacent units are filled with non-shrinking mortar .For highway spans ,an asphalt wearing surface may be applied directly to</p><p>　　The voided slabs are commonly available in depths from 15 to 21 in

18、 .and widths of 3 to 4 ft .For a standard highway HS20 loading, they are suitable for spans to about 50 ft, Standard channel sections are available in depths from 21 to 35 in a variety of widths, and are used for spans b

19、etween about 20 and 60 ft .The hollow box beams-and single-tee girders are intended for longer spans up to about 100 ft.</p><p>　　For medium-span highway bridges ,to about 120 ft ,AASHTO standard I beams are

20、 generally used .They are intended for use with a composite cast-in-place roadway slab .Such girders often combine pre-tensioning of the pre-cast member with post-tensioning of the composite beam after the deck is plac

21、ed .In an effort to obtain improved economy ,some states have adopted more refined designs ,such as the State of Washington standard girders.</p><p>　　The specially designed pre-cast girders may be used to c

22、arry a monorail transit system .The finished guide way of Walt Disney World Monorail features a series of segments, each consisting of six simply supported pre-tensioned beams ,together to from a continuous structure .Ty

23、pical spans are 100 to 110 ft . Approximately half of the 337 beams used have some combination of vertical and horizontal curvatures and variable super elevation .All beams are hollow, a feature achieved by inserting a s

24、tyro</p><p>　　Pre-cast girders may not be used for spans much in excess of 120 ft because of the problems of transporting and erecting large, heavy units.</p><p>　　On the other hand ,there is a

25、clear trend toward the use of longer spans for bridges .For elevated urban expressways ,long spans facilitate access and minimize obstruction to activities below .Concern for environmental damage has led to the choice of

26、 long spans for continuous viaducts . For river crossings, intermediate piers may be impossible because of requirements of navigational clearance. </p><p>　　In typical construction of this type, piers are c

27、ast-in-place, often using the slip-forming technique .A “hammerhead” section of box girder is often cast at the top of the pier, and construction proceeds in each direction by the balanced cantilever method. Finally, aft

28、er the closing cast-in-place joint is made at mid-span, the structure is further post-tensioned for full continuity .Shear keys may be used on the vertical faces between segments, and pre-cast are glued with epoxy resin.

29、</p><p>　　The imaginative engineering demonstrated by many special techniques has extended the range of concrete construction for bridges far beyond anything that could be conceived just a few years ago .In

30、the United States, twin curved cast-in –place segmental box girders have recently been completed for of span of 310 ft over the Eel River in northern California .Preliminary design has been completed for twin continuous

31、box girders consisting of central 550 ft spans flanked by 390 ft side spans.</p><p>　　Another form of pre-stressed concrete bridge well suited to long spans is the cable-stayed box girder .A notable example

32、is the Chaco-Corrientes Bridge in Argentina .The bridges main span of 804 ft is supported by two A-frame towers, with cable stays stretching from tower tops to points along the deck .The deck itself consists of two paral

33、lel box girders made of pre-cast sections erected using the cantilever method .The tensioned cables not only provide a vertical reaction component to support t</p><p>　　Stress-ribbon Bridge pioneered many ye

34、ars ago by the German engineer Ulrich Finsterwalder. The stress-ribbon bridge carries a pipeline and pedestrians over the Rhine River with a span of 446 ft .The superstructure erection sequence was to (a) erect two pairs

35、 of cables, (b) place pre-cast slabs forming a sidewalk deck and a U under each of the sets of cables, and (c) cast-in-place concrete within the two Us. The pipeline is placed atop supports at railing height, off to one

36、side, which greatly in</p><p>　　It is appropriate in discussing bridge forms to mention structural esthetics .The time is past when structures could be designed on the basis of minimum cost and technical adv

37、antages alone .Bridge structures in particular are exposed for all to see .To produce a structure that is visually offensive ,as has occurred all too often in the past, is an act professional irresponsibility .Particular