建筑 橋梁工程 外文翻譯 外文文獻 英文文獻 混凝土梁橋的結(jié)構(gòu)形式

1、 出處：安瑞克混凝土橋梁結(jié)構(gòu)形式j(luò)建筑實錄(美)，2010，33(36)：3436the structure of concrete bridgepre-stressed concrete has proved to be technically advantageous, economically competitive, and esthetically superior bridges, from very short span structures using standard components to cable-stayed girders and continuous box

2、girders with clear spans of nearly 100aft .nearly all concrete bridges, even those of relatively short span, are now pre-stressed. pre-casting, cast-in-place construction, or a combination of the two methods may be used .both pre-tensioning and post tensioning are employed, often on the same project

3、.in the united states, highway bridges generally must-meet loading ,design ,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 provisions

4、 are often incorporated by reference .bridges spans to about 100ft often consist of pre-cast integral-deck units ,which offer low initial cost ,minimum ,maintenance ,and fast easy construction ,with minimum traffic interruption .such girders are generally pre-tensioned .the units are placed side by

5、side ,and are often post-tensioned laterally at intermediate diaphragm locations ,after which shear keys between adjacent units are filled with non-shrinking mortar .for highway spans ,an asphalt wearing surface may be applied directly to the top of the pre-cast concrete .in some cases ,a cast-in-pl

6、ace slab is placed to provide composite action .the voided slabs are commonly available in depths from 15 to 21 in .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 o

7、f widths, and are used for spans between about 20 and 60 ft .the hollow box beams-and single-tee girders are intended for longer spans up to about 100 ft.for medium-span highway bridges ,to about 120 ft ,aashto standard i beams are generally used .they are intended for use with a composite cast-in-p

8、lace roadway slab .such girders often combine pre-tensioning of the pre-cast member with post-tensioning of the composite beam after the deck is placed .in an effort to obtain improved economy ,some states have adopted more refined designs ,such as the state of washington standard girders.the specia

9、lly designed pre-cast girders may be used to carry 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 .typical spans are 100 to 110 ft . ap

10、proximately 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 styro-foam void in the curved beams and by a moving mandrel in straight beam production.pre-cast girders may not be

11、 used for spans much in excess of 120 ft because of the problems of transporting and erecting large, heavy units.on the other hand ,there is a clear trend toward the use of longer spans for bridges .for elevated urban expressways ,long spans facilitate access and minimize obstruction to activities b

12、elow .concern for environmental damage has led to the choice of long spans for continuous viaducts . for river crossings, intermediate piers may be impossible because of requirements of navigational clearance. in typical construction of this type, piers are cast-in-place, often using the slip-formin

13、g 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, after the closing cast-in-place joint is made at mid-span, the structure is further post-tensioned for full continuity .shea

14、r keys may be used on the vertical faces between segments, and pre-cast are glued with epoxy resin.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 the

15、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 box girders consisting of central 550 ft spans flanked by 390 ft side spans.another f

16、orm of pre-stressed concrete bridge well suited to long spans is the cable-stayed box girder .a notable example 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 d

17、eck itself consists of two parallel box girders made of pre-cast sections erected using the cantilever method .the tensioned cables not only provide a vertical reaction component to support the deck ,but also introduce horizontal compression to the box girders ,adding to the post-tensioning force in

18、 those members .stress-ribbon bridge pioneered many years 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 of cables, (b) place pre-

19、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 side, which greatly increases the wind speed of the structure.it is appropriate in discussing bridge forms

20、 to mention structural esthetics .the time is past when structures could be designed on the basis of minimum cost and technical advantages 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,

21、is an act professional irresponsibility .particularly for major spans ,but also for more ordinary structures ,architectural advice should be sought early in conceptual stage of the design process.混凝土梁橋的結(jié)構(gòu)形式事實證明，預(yù)應(yīng)力混凝土結(jié)構(gòu)是在技術(shù)上先進、經(jīng)濟上有競爭力、符合審美學的一種先進技術(shù)。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

22、的橋梁都是預(yù)應(yīng)力結(jié)構(gòu)的。采用預(yù)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。在美國，公路橋一般情況下必須滿足荷載、設(shè)計和aashto規(guī)定的建設(shè)的要求。對于服務(wù)于其它目的步行街和橋梁的設(shè)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０殡S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(yù)算，最小量維修和養(yǎng)護費用和快速的簡易的預(yù)制板組成。這種梁一般是用先張法。預(yù)制板一塊挨一塊的放置并且在相鄰的預(yù)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，用瀝青鋪設(shè)的表面可以直接用在預(yù)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

23、提供復合作用?？招陌逡话阌糜谏疃?5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。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(yù)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(yù)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(shè)計，例如華盛頓州標準梁。 經(jīng)過特別設(shè)計預(yù)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路的一系列的特征, 每個包括六個單獨支持的預(yù)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。由于運輸問題和構(gòu)件垂直的大而重的問題，預(yù)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(guān)心，導致連續(xù)高架橋大跨徑的選擇。對于跨河橋，因為