桥梁工程本科毕业设计外文翻译

本科毕业设计外文翻译混凝土桥梁的结构形式院（系、部）名称：专业名称:学生姓名：学生学号：指导教师:The Ｓｔｒｕｃture of Ｃoncrete BｒidｇePre-stｒｅsｓed cｏｎｃretｅhas ｐrovedｔｏbｅtｅcｈnicａlｌｙadvａntageouｓ, ecｏnomically cｏmpetiｔiｖｅ, ａnd estheticaｌｌy supeｒioｒbridgｅs，ｆrｏm very shｏrt span strｕcｔurｅs usinｇstanｄard cｏmｐoneｎts ｔo cablｅ－sｔayｅd ｇｉrders anｄcontinuous box ｇiｒders wｉtｈcｌｅar ｓpanｓｏf ｎearly 1００aft ．Ｎeａrlｙall concrete bridges, even tｈose oｆｒeｌatiｖely short span, aｒe now pｒe-ｓtｒesseｄ．Pｒe-castinｇ, ｃast-in-pｌacｅcｏnstruｃtion, or a ｃomｂｉnaｔion ｏf ｔhｅｔｗo mｅｔｈods ｍay be used ．Bｏｔh pre-ｔensi ｏning ａnd posｔteｎｓioｎing arｅeｍployed, ｏfｔen on theｓame project.In tｈe Uｎited Staｔes，highｗay ｂridgeｓgｅｎeｒａlly must-ｍｅｅt loading ，dｅsign ，and cｏnｓtｒuctｉon rｅquireｍｅnｔｓｏf the AASHTＯS ｐeｃificaｔｉｏn ．Design rｅquiｒemeｎtｓfｏｒpedesｔrian crossinｇs and br ｉdges servｉnｇotｈeｒpｕrposｅsｍay ｂe estaｂｌｉshｅｄby local or ｒeｇionａl coｄesａnd speｃifｉcations．ACI Ｃode prｏvisｉｏns areｏftenｉnｃｏrｐorated by reｆｅｒence.Brｉｄges spanｓto abｏuｔ10０ft oｆtｅｎｃonｓist ｏf pｒｅ-caｓt ｉnt ｅgrａl－ｄeck uｎits ,which offer lｏw ｉniｔiaｌｃost ,miniｍum ,mａｉnｔenance ,ａnd fａst eaｓy ｃonstruction ,wiｔh mｉnｉmum traffic iｎterruｐtｉｏｎ.Ｓucｈgi ｒｄers arｅgeneｒａlly pre－teｎｓioned .Theｕniｔs aｒｅｐlaｃedｓide by side ,and are oｆtｅｎpoｓt-tensｉonｅd lateｒａlly at iｎteｒmeｄiａte dｉaphｒagm locatiｏnｓ,after ｗhich ｓhｅaｒｋeys bｅtween adｊacent unitｓare fｉlleｄw ｉtｈnon-ｓhｒｉnkinｇｍorｔａr .Fｏr hiｇhｗay spans ,an aspｈaltｗeariｎg surｆace ｍay bｅapplied dｉrｅctly to ｔhｅtoｐｏｆｔhe pｒｅ-ｃast cｏncretｅ.In ｓome ｃａses ,a caｓt－ｉｎ-ｐｌacｅｓｌａb is plａceｄtｏpｒovｉdｅｃompｏsite acｔiｏn .Tｈｅvoｉdｅd sｌabs are comｍonｌy ａvaｉｌaｂlｅｉｎdeｐtｈｓfroｍ１5tｏ21 in.ａnd widthsｏf 3 tｏ 4 ft .Ｆor a staｎｄard ｈigｈway HS20 loadｉng, ｔhey ａreｓuitａble for spａｎs to aｂouｔ50fｔ, Standarｄchanｎｅl secｔｉons are avaiｌaｂle in depｔｈs froｍ21ｔｏ35 ｉｎ a vaｒiｅty ｏｆｗidths, and arｅｕsed foｒsｐans ｂetween about 20 anｄ6０ｆt ．Theｈollow bｏx beａms-ａｎd ｓingｌe-teｅgiｒdeｒs aｒe ｉnteｎdｅd for lｏnger ｓpans up to abｏｕt１0０ft.Foｒmediｕｍ-spａn highｗａｙbｒiｄges ,ｔo ａbouｔ1２0ft ,ＡＡSHTＯstaｎdaｒd I beaｍs are ｇeneraｌlｙuｓed .Tｈey are iｎtenｄed for use witｈa com ｐoｓｉte cast-in-pｌａce roadｗay sｌａb .Suｃh girdｅrｓoften combine pｒｅ－tensiｏｎｉnｇoｆthe ｐrｅ－caｓt member wｉth posｔ-tｅｎsiｏniｎgｏf the compｏsitｅbｅam ａfter tｈｅｄｅck is ｐｌａcｅｄ.Iｎaｎefｆｏｒt to ｏb ｔain ｉmproved ｅconomｙ，some sｔatｅs havｅadoptｅd ｍore reｆｉneｄdesｉｇns ,such as ｔhｅＳtate of Ｗashington stａｎdard girders.The specｉallｙdesigned ｐｒe－cａst gｉrdeｒs ｍａy be useｄｔｏcaｒryａmonoｒａｉl ｔranｓit system ．Ｔhe fｉｎisｈｅd guｉde way of Walt Diｓney WｏrlｄＭonorail ｆeatｕreｓaｓeriｅs ｏf sｅｇments, eacｈconsistｉnｇof ｓｉxｓiｍply supporｔed ｐre-ｔensioｎed ｂeａms ,ｔｏgether tｏｆｒom a conｔｉnuouｓsｔructure ．Ｔｙｐｉcaｌｓｐaｎs are １００ｔｏ1１０ft .Ap ｐroximａｔelｙhalｆof tｈe337 ｂeamsｕsed ｈａve some cｏmbiｎaｔion of ｖerticaｌａnd horｉzｏntaｌcurｖatｕrｅs ａnd variａｂle suｐer elevaｔion .Aｌl ｂeａms are hollｏw, a ｆeatｕre acｈｉｅｖed bｙinserting a sｔyrｏ－foam voｉd in ｔhe ｃuｒｖｅdｂeａms aｎd bｙa moｖing mandrelｉnｓtｒaｉghtｂea ｍproｄuctｉon.Ｐrｅ－cａｓt girders maｙnot be usｅd foｒspaｎs mｕｃｈin exｃeｓｓoｆ120 ft ｂecaｕse ｏf tｈｅproｂｌems oｆtraｎsportiｎg ａnd ereｃting laｒｇｅ, ｈeavy unｉts.On the other hanｄ,theｒe is a ｃlｅａｒtrend toward thｅusｅof ｌonｇer sｐａns foｒbriｄgｅs .For eleｖａtｅd urban expｒｅssways,lｏng ｓｐans facilitａｔe aｃcesｓａnｄminimize oｂｓtｒｕctioｎto aｃｔｉvities ｂelow .Concｅrn f ｏr environmenｔａlｄamaｇe haｓｌed ｔｏｔhｅcｈoice of lonｇspans for contiｎuous viadｕcts. For rｉver crosｓｉngｓ, ｉｎtｅrｍeｄiａte pｉerｓmａy be impｏssible becａuｓｅｏf requｉrementｓof nａvigational cleaｒancｅ.Ｉn typｉcal cｏnstrucｔion ｏf tｈis ｔyｐe, piers ａre cast-in-placｅ, often using the slip-fｏｒming teｃｈｎｉquｅ．A “hammerｈeaｄ” sectiｏn ｏf boｘgｉrd ｅr iｓofｔｅn caｓt ａt the top of tｈe pier,and consｔrｕction pｒoｃeeds in ｅach ｄｉrection by tｈe bａlaｎcｅｄcａntileveｒmethｏd．Ｆｉｎally, aftｅr th ｅcｌｏｓinｇcasｔ－in-place joint is made ａt ｍid-spａn, ｔhe stｒucture ｉs further post-ｔeｎｓｉoneｄfor fuｌlｃonｔｉnuity ．Shｅａr kｅys may bｅu ｓed on tｈe verｔiｃａｌfaces ｂetｗｅen segments, and pre-ｃaｓｔaｒe gｌｕed ｗｉtｈｅpoxy rｅsin.Theｉmａｇｉｎatｉve engiｎeｅrinｇdｅｍonsｔraｔeｄbｙｍany speｃial ｔechｎｉqｕes hａs ｅxtendｅd the rangeｏf coｎcreｔe conｓtrｕｃｔion ｆor brｉｄges far beyoｎｄaｎytｈinｇｔhａt could be coｎｃｅiｖeｄjuｓｔ a fewｙears aｇｏ.In the UnitｅｄStaｔes,twin ｃurvｅｄcast-in –place seｇmｅｎtal boｘgirｄers haｖe rｅcｅnｔｌy been ｃomｐlｅted ｆｏr oｆspaｎof 310ft ovｅr the Eel Riveｒin ｎorthｅrn Califｏrnｉa .Ｐrelimiｎary design has ｂeen complｅted for t ｗiｎｃoｎtinuous bｏx girdeｒs coｎｓistingｏfｃentraｌ550ft sｐans fｌank ｅd bｙ３90ｆt sｉｄe spans.Aｎｏtｈｅr foｒm oｆｐre－stressed coｎcrｅte bridｇeｗell suiｔed to lｏｎｇspans ｉs the ｃａbｌe-stayed bｏｘgiｒder .Ａnotａble ｅxamplｅis ｔｈe Ｃｈａco－Cｏrｒientes Bridge in Argeｎtiｎa .The ｂridgeｓｍain sｐａn of 80４fｔis ｓupｐorted by two A-ｆｒamｅｔowｅrｓ, witｈcａｂle staｙs stｒeｔｃｈinｇｆrom tｏwer topｓto pｏints alｏng thｅｄeck .Ｔhe deｃｋitｓｅlfｃonsiｓts of ｔwｏｐａrallｅl boｘgiｒｄers made oｆｐrｅ-cast secｔｉonｓerect ｅd ｕsing thｅcaｎtｉlｅveｒmethod ．Tｈe ｔenｓioneｄcaｂles notｏnly provideａｖeｒticaｌreaction ｃomｐoｎｅｎｔto suｐｐｏrt the dｅｃk,buｔａlso introｄuce hoｒizontal compｒession toｔhe box ｇirderｓ，adding ｔo thｅｐosｔ-tensioniｎｇforce in thｏｓe ｍeｍbers .Strｅsｓ-rｉbboｎBriｄge ｐｉoneｅｒｅdｍａｎy yｅａrs ago ｂy thｅＧerman engｉｎeｅｒUｌｒｉｃｈFinｓterwalder.Thｅｓｔress－riｂbｏn bridｇe cａrries a ｐｉpelｉne and pedestｒians ｏｖer tｈe Rhｉne Rivｅr wiｔh ａｓpan of 446 fｔ.The superstrucｔｕre erection seqｕeｎｃe wａs to (a)erect two paiｒs o ｆcａblｅｓ, (b)plaｃｅｐrｅ-cast slaｂs ｆorminｇ a sidewａlk decｋand a U uｎder each of tｈe setｓof cａbｌes, and (c)ｃａｓt-ｉn-place cｏncrete within tｈeｔwｏＵs. The pipeｌinｅisｐlaced atｏp sｕpｐｏrts ａｔraｉling heigｈｔ，off to ｏnｅside,which greatly increasesｔhe wind speeｄｏｆthe struｃｔur ｅ．It is appｒopｒiate in diｓｃｕssing briｄｇe fｏrms toｍｅｎtiｏn structurａl estheｔics .The tｉme iｓpast wheｎstrucｔurｅs coulｄbe deｓiｇned on the basis ｏｆminｉmuｍcost and technical advantagｅs ａloｎｅ．Bridｇe sｔｒuctures inｐａrticulaｒare exposed for all ｔo see .To prodｕcｅa structuｒe ｔhat ｉｓviｓualｌｙoffｅnsｉve ，ａs ｈaｓoccurrｅd ａll ｔｏo oｆtｅn in the past, iｓan aｃt prｏfessional irrespｏnsｉbiｌity.Particularｌy for major spａns,ｂｕｔａlｓo for more ｏrdiｎaｒｙstrｕcｔureｓ，architectｕｒal aｄvicｅshｏuld be sｏught early inｃoncepｔuａlｓtaｇe of the deｓiｇn prｏcess.混凝土梁桥的结构形式事实证明，预应力混凝土结构是在技术上先进、经济上有竞争力、符合审美学的一种先进技术。

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道路与桥梁专业外文翻译中英对照

道路与桥梁专业外文翻译中英对照Jenny was compiled in January 2021本科毕业设计（论文）专业名称：土木工程专业（道路与桥梁）年级班级：道桥08-5班学生姓名：指导教师：二○一二年五月十八日专业外文翻译Geometric Design of HighwaysThe road is one kind of linear construction used for travel. It is made of the roadbed, the road surface, the bridge, the culvert and the tunnel. In addition, it also has the crossingof lines, the protective project and the traffic engineeringand the route facility.The roadbed is the base of road surface, road shoulder,side slope, side ditch foundations. It is stone material structure, which is designed according to route's planeposition .The roadbed, as the base of travel, must guaranteethat it has the enough intensity and the stability that can prevent the water and other natural disaster from corroding.The road surface is the surface of road. It is single or complex structure built with mixture. The road surface require being smooth, having enough intensity, good stability and anti-slippery function. The quality of road surface directly affects the safe, comfort and the traffic.Highway geometry designs to consider Highway Horizontal Alignment, Vertical Alignment two kinds of linear and cross-sectional composition of coordination, but also pay attentionto the smooth flow of the line of sight, etc. Determine theroad geometry, consider the topography, surface features,rational use of land and environmental protection factors, to make full use of the highway geometric components of reasonable size and the linear combination.DesignThe alignment of a road is shown on the plane view and is a series of straight lines called tangents connected by circular. In modern practice it is common to interpose transition orspiral curves between tangents and circular curves.Alignment must be consistent. Sudden changes from flat to sharp curves and long tangents followed by sharp curves must be avoided; otherwise, accident hazards will be created. Likewise, placing circular curves of different radii end to end (compound curves) or having a short tangent between two curves is poor practice unless suitable transitions between them are provided. Long, flat curves are preferable at all times, as they are pleasing in appearance and decrease possibility of future obsolescence. However, alignment without tangents is undesirable on two-lane roads because some drivers hesitate to pass on curves. Long, flat curves should be used for small changes in dir ection, as short curves appear as “kink”. Also horizontal and vertical alignment must be considered together, not separately. For example, a sharp horizontal curve beginning near a crest can create a serious accident hazard.A vehicle traveling in a curved path is subject to centrifugal force. This is balanced by an equal and opposite force developed through cannot exceed certain maximums, and these controls place limits on the sharpness of curves that can be used with a design speed. Usually the sharpness of a given circular curve is indicated by its radius. However, for alignment design, sharpness is commonly expressed in terms of degree of curve, which is the central angle subtended by a 100-ft length of curve. Degree of curve is inversely proportional to the radius.Tangent sections of highways carry normal cross slope; curved sections are super elevated. Provision must be made for gradual change from one to the other. This usually involves maintaining the center line of each individual roadway at profile grade while raising the outer edge and lowering theinner edge to produce the desired super elevation is attained some distance beyond the point of curve.If a vehicle travels at high speed on a carefullyrestricted path made up of tangents connected by sharp circular curve, riding is extremely uncomfortable. As the car approaches a curve, super elevation begins and the vehicle is tilted inward, but the passenger must remain vertical since there is on centrifugal force requiring compensation. When the vehicle reaches the curve, full centrifugal force develops at once, and pulls the rider outward from his vertical position. To achieve a position of equilibrium he must force his body far inward. As the remaining super elevation takes effect, further adjustment in position is required. This process is repeated in reverse order as the vehicle leaves the curve. When easement curves are introduced, the change in radius from infinity on the tangent to that of the circular curve is effected gradually so that centrifugal force also develops gradually. By careful application of super elevation along the spiral, a smooth and gradual application of centrifugal force can be had and the roughness avoided.Easement curves have been used by the railroads for many years, but their adoption by highway agencies has come only recently. This is understandable. Railroad trains must follow the precise alignment of the tracks, and the discomfort described here can be avoided only by adopting easement curves. On the other hand, the motor-vehicle operator is free to alter his lateral position on the road and can provide his own easement curves by steering into circular curves gradually. However, this weaving within a traffic lane (but sometimes into other lanes) is dangerous. Properly designed easement curves make weaving unnecessary. It is largely for safety reasons,then, that easement curves have been widely adopted by highway agencies.For the same radius circular curve, the addition ofeasement curves at the ends changes the location of the curve with relation to its tangents; hence the decision regardingtheir use should be made before the final location survey. They point of beginning of an ordinary circular curve is usually labeled the PC (point of curve) or BC (beginning of curve). Its end is marked the PT (point of tangent) or EC (end of curve).For curves that include easements, the common notation is, as stationing increases: TS (tangent to spiral), SC (spiral to circular curve), CS (circular curve to spiral), and ST (spiralgo tangent).On two-lane pavements provision of a wilder roadway is advisable on sharp curves. This will allow for such factors as(1) the tendency for drivers to shy away from the pavement edge,(2) increased effective transverse vehicle width because thefront and rear wheels do not track, and (3) added width because of the slanted position of the front of the vehicle to the roadway centerline. For 24-ft roadways, the added width is so small that it can be neglected. Only for 30mph design speedsand curves sharper than 22°does the added width reach 2 ft.For narrower pavements, however, widening assumes importance even on fairly flat curves. Recommended amounts of and procedures for curve widening are given in Geometric Design for Highways.2. GradesThe vertical alignment of the roadway and its effect on the safe and economical operation of the motor vehicle constituteone of the most important features of road design. The vertical alignment, which consists of a series of straight linesconnected by vertical parabolic or circular curves, is known as the “grade line.” When the grade line is increasing from the horizontal it is known as a “plus grade,” and when it is decreasing from the horizontal it is known as a “minusgrade.” In analyzing grade and grade controls, the designer usually studies the effect of change in grade on the centerline profile.In the establishment of a grade, an ideal situation is onein which the cut is balanced against the fill without a great deal of borrow or an excess of cut to be wasted. All haulsshould be downhill if possible and not too long. The gradeshould follow the general terrain and rise and fall in the direction of the existing drainage. In mountainous country the grade may be set to balance excavation against embankment as a clue toward least overall cost. In flat or prairie country itwill be approximately parallel to the ground surface but sufficiently above it to allow surface drainage and, where necessary, to permit the wind to clear drifting snow. Where the road approaches or follows along streams, the height of thegrade line may be dictated by the expected level of flood water. Under all conditions, smooth, flowing grade lines arepreferable to choppy ones of many short straight sections connected with short vertical curves.Changes of grade from plus to minus should be placed in cuts, and changes from a minus grade to a plus grade should be placed in fills. This will generally give a good design, and many times it will avoid the appearance of building hills and producing depressions contrary to the general existing contours of the land. Other considerations for determining the gradeline may be of more importance than the balancing of cuts and fills.Urban projects usually require a more detailed study of the controls and finer adjustment of elevations than do rural projects. It is often best to adjust the grade to meet existing conditions because of the additional expense of doing otherwise.In the analysis of grade and grade control, one of the most important considerations is the effect of grades on the operating costs of the motor vehicle. An increase in gasoline consumption and a reduction in speed are apparent when grades are increase in gasoline consumption and a reduction in speedis apparent when grades are increased. An economical approach would be to balance the added annual cost of grade reduction against the added annual cost of vehicle operation withoutgrade reduction. An accurate solution to the problem depends on the knowledge of traffic volume and type, which can be obtained only by means of a traffic survey.While maximum grades vary a great deal in various states, AASHTO recommendations make maximum grades dependent on design speed and topography. Present practice limits grades to 5 percent of a design speed of 70 mph. For a design speed of 30 mph, maximum grades typically range from 7 to 12 percent, depending on topography. Wherever long sustained grades are used, the designer should not substantially exceed the critical length of grade without the provision of climbing lanes forslow-moving vehicles. Critical grade lengths vary from 1700 ft for a 3 percent grade to 500 ft for an 8 percent grade.Long sustained grades should be less than the maximum grade on any particular section of a highway. It is often preferredto break the long sustained uniform grade by placing steeper grades at the bottom and lightening the grade near the top of the ascent. Dips in the profile grade in which vehicles may be hidden from view should also be avoided. Maximum grade forhighway is 9 percent. Standards setting minimum grades are of importance only when surface drainage is a problem as when water must be carried away in a gutter or roadside ditch. In such instances the AASHTO suggests a minimum of %.3. Sight DistanceFor safe vehicle operation, highway must be designed to give drivers a sufficient distance or clear version ahead so that they can avoid unexpected obstacles and can pass slowervehicles without danger. Sight distance is the length of highway visible ahead to the driver of a vehicle. The conceptof safe sight distance has two facets: “stopping” (or “no passing”) and “passing”.At times large objects may drop into a roadway and will do serious damage to a motor vehicle that strikes them. Again a car or truck may be forced to stop in the traffic lane in the path of following vehicles. In dither instance, proper design requires that such hazards become visible at distances great enough that drivers can stop before hitting them. Further more, it is unsafe to assume that one oncoming vehicle may avoid trouble by leaving the lane in which it is traveling, for this might result in loss of control or collision with another vehicle.Stopping sight distance is made up of two elements. Thefirst is the distance traveled after the obstruction comes into view but before the driver applies his brakes. During this period of perception and reaction, the vehicle travels at its initial velocity. The second distance is consumed while the driver brakes the vehicle to a stop. The first of these two distances is dependent on the speed of the vehicle and the perception time and brake-reaction time of the operator. The second distance depends on the speed of the vehicle; thecondition of brakes, times, and roadway surface; and the alignment and grade of the highway.On two-lane highways, opportunity to pass slow-moving vehicles must be provided at intervals. Otherwise capacity decreases and accidents increase as impatient drivers risk head-on collisions by passing when it is unsafe to do so. The minimum distance ahead that must be clear to permit safe passing is called the passing sight distance. In deciding whether or not to pass another vehicle, the driver must weigh the clear distance available to him against the distance required to carry out the sequence of events that make up the passing maneuver. Among the factors that will influence his decision are the degree of caution that he exercises and the accelerating ability of his vehicle. Because humans differ markedly, passing practices, which depend largely on human judgment and behavior rather than on the laws of mechanics, vary considerably among drivers.The geometric design is to ensure highway traffic safety foundation, the highway construction projects around the other highway on geometric design, therefore, in the geometry of the highway design process, if appear any unsafe potential factors, or low levels of combination of design, will affect the whole highway geometric design quality, and the safety of the traffic to bring adverse impact. So, on the geometry of the highway design must be focus on.公路几何设计公路是供汽车或其他车辆行驶的一种线形带状结构体。

桥梁毕业设计外文翻译5

附录附录A 外文翻译第一部分英文原文4.2.2 Model that Failed in Punching ShearIt was realized that complete restraint in both the longitudinal and transversedirections is necessary for the development of the internal arching system in the deck slab. With this realization,another half-scale model of a two-girder bridge was built. This model also had a deck slab reinforced only by polypropylene fibres, and was very similar to the previous one, the main difference being that the top flangesof the girders were now interconnected by transverse steel straps lying outside the deck slab. A view of the steel work of this model can be seen in Fig. 4.7.These straps were provided so as to serve as transverse ties to the internal arch in the slab.The 100 mm thick slab of the model with transverse straps failed under a central load of 418 kN in a punching-shear failure mode. As can be seen in Fig. 4.8, the damaged area of the slab was highly localized. It can be appreciated that with such a high failure load, the thin deck slab of the half-scale model could have easily withstood the weights of even the heaviest wheel load of commercial vehicles.The model tests described above and in sub-section 4.2.1 clearly demonstrate that an internal arching action will indeed develop in a deck slab, but only if it is suitably restrained.4.2.3 Edge StiffeningA further appreciation of the deck slab arching action is provided by tests on a scale model of a skew slab-on-girder bridge. As will be discussed in sub-section 4.4.2, one transverse free edge of the deck slab of this model was stiffened by a composite steel channel with its web in the vertical plane. The other free edge was stiffened by a steel channel diaphragm with its web horizontal and connected to the deck slab through shear connectors. The deck slab near the former transverse edge failed in a mode that was a hybrid between punching shear and flexure. Tests near the composite diaphragm led to failure at a much higher load in punching shear (Bakht and Agarwal, 1993).The above tests confirmed yet again that the presence of the internal arching action in deck slabs induces high in-plane force effects which in turn demand stiffer restraint in the plane of the deck than in the out-of-plane direction.4.3 INTERNALLY RESTRAINED DECK SLABSDeck slabs which require embedded reinforcement for strength will now be referred to as internally restrained deck slabs. The state-of-art up to 1986 relating to the quantification and utilization of the beneficial internal arching action in deck slabs with steel reinforcement has been provided by Bakht and Markovic (1986). Their conclusions complemented with up-to-date information are presented in this chapter in a generally chronological order which, however, cannot be adhered to rigidlybecause of the simultaneous occurrence of some developments.4.3.1 Static Tests on Scale ModelsAbout three decades ago, the Structures Research Office of the Ministry of Transportation of Ontario (MTO), Canada, sponsored an extensive laboratory-based research program into the load carrying capacity of deck slabs; this research program was carried out at Queen's University, Kingston, Ontario. Most of this research was conducted through static tests on scale models of slab-on-girder bridges. This pioneering work is reported by Hewitt and Batchelor (1975) and later by Batchelor et al. (1985), and is summarized in the following.The inability of the concrete to sustain tensile strains, which leads to cracking, has been shown to be the main attribute which causes the compressive membrane forces to develop. This phenomenon is illustrated in Fig. 4.9 (a) which shows the part cross-section of slab-on-girder bridge under the action of a concentrated load.The cracking of the concrete, as shown in the figure, results in a net compressive force near the bottom face of the slab at each of the two girder locations. Midway between the girders, the net compressive force moves towards the top of the slab. It can be readily visualized that the transition of the net compressive force from near the top in the middle region, to near the bottom at the supports corresponds to the familiar arching action. Because of this internal arching action, the failure mode of a deck slab under a concentrated load becomes that of punching shear.If the material of the deck slab has the same stress-strain characteristics in both tension and compression, the slab will not crack and, as shown in Fig. 4.9 (b), will not develop the net compressive force and hence the arching action.In the punching shear type of failure, a frustum separates from the rest of the slab, as shown in schematically in Fig. 4.10. It is noted that in most failure tests, the diameter of the lower end of the frustrum extends to the vicinity of the girders.From analytical and confirmatory laboratory studies, it was established that the most significant factor influencing the failure load of a concrete deck slab is the confinement of the panel under consideration. It was concluded that this confinement is provided by the expanse of the slab beyond the loaded area; its degree was founddifficult to assess analytically. A restraint factor, η, was used as an empirical measure of the confinement; its value is equal to zero for the case of no confinement and 1.0 for full confinement.The effect of various parameters on the failure load can be seen in Table 4.1, which lists the theoretical failure loads for various cases. It can be seen that an increase of the restraint factor from 0.0 to 0.5 results in a very large increase in the failure load. The table also emphasizes the fact that neglect of the restraint factor causes a gross underestimation of the failure load.It was concluded that design for flexure leads to the inclusion of large amounts of unnecessary steel reinforcement in the deck slabs, and that even the minimum amount of steel required for crack control against volumetric changes in concrete is adequate to sustain modern-day, and even future, highway vehicles of North America.It was recommended that for new construction, the reinforcement in a deck slab should be in two layers, with each layer consisting of an orthogonal mesh having the same area of reinforcement in each direction. The area of steel reinforcement in each direction of a mesh was suggested to be 0.2% of the effective area of cross-section of the slab. This empirical method of design was recommended for deck slabs with certain constraints.4.3.2 Pulsating Load Tests on Scale ModelsTo study the fatigue strength of deck slabs with reduced reinforcement, five small scale models with different reinforcement ratios in different panels were tested at the Queen's University at Kingston. Details of this study are reported by Batchelor et al. (1978).Experimental investigation confirmed that for loads normally encountered in North America deck slabs with both conventional and recommended reducedreinforcement have large reserve strengths against failure by fatigue. It was confirmed that the reinforcement in the deck slab should be as noted in sub-section 4.3.1. It is recalled that the 0.2% reinforcement requires that the deck slab must have a minimum restraint factor of 0.5.The work of Okada, et al. (1978) also deals with fatigue tests on full scale models of deck slabs and segments of severely cracked slab removed from eight to ten year old bridges. The application of these test results to deck slabs of actual bridges is open to question because test specimens were removed from the original structures in such a way that they did not retain the confinement necessary for the development of the arching action.4.3.3 Field TestingAlong with the studies described in the preceding sub-section, a program of field testing of the deck slabs of in-service bridges was undertaken by the Structures Research Office of the MTO. The testing consisted of subjecting deck slabs to single concentrated loads, simulating wheel loads, and monitoring the load-deflection characteristics of the slab. The testing is reported by Csagoly et al. (1978) and details of the testing equipment are given by Bakht and Csagoly (1979).Values of the restraint factor, η, were back-calculated from measured deflections.A summary of test results, given in Table 4.2, shows that the average value of η in composite bridges is greater than 0.75, while that for non-composite bridges is 0.42. It was concluded that for new construction, the restraint factor, η, can be assumed to have a minimum value of 0.5.Bakht (1981) reports that after the first application of a test load of high magnitude on deck slabs of existing bridges, a small residual deflection was observed in most cases. Subsequent applications of the same load did not result in further residual deflections. It is postulated that the residual deflections are caused by cracking of the concrete which, as discussed earlier, accompanies the development of the internal arching action. The residual deflections after the first cycle of loading suggest that either the slab was never subjected to loads high enough to cause cracking, or the cracks have 'healed' with time.第二部分汉语翻译4.2.2 在冲切剪应力下的实效模型我们已经知道在桥面板内部拱形系统的形成中，不仅纵向而且横向也被完全约束限制是完全必要的。

桥梁工程本科毕业设计外文翻译---混凝土桥梁的结构形式

本科毕业设计外文翻译混凝土桥梁的结构形式院（系、部）名称：专业名称：学生姓名：学生学号：指导教师：The 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 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.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 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 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-place 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 of 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-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 placed .In an effort to obtain improved economy ,some states have adopted more refined designs ,such as the State of Washington standard girders.The specially 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 . Approximately half of the 337 beams used have some combination of vertical and horizontal curvatures and variable super elevation .Allbeams 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 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 below .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-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, after 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.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 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 form 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 deck 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 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-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 to mention structural esthetics .The time ispast 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, 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.混凝土梁桥的结构形式事实证明，预应力混凝土结构是在技术上先进、经济上有竞争力、符合审美学的一种先进技术。

桥梁工程毕业设计外文翻译

Review of assessment and repair of fire-damaged RChighway bridgesAbstract：This paper presents a review of the progress of the research and engineering practice of assessment and repair of fire-damaged RC highway bridges，based on which existing and pressing problems of the evaluation method are pointed out．At last，Prospect for the development of assessment and repair of fire-damaged highway bridges is also proposed．Key words：fire damage；assessment；repair techniques；RC structure；bridge 1 PrefaceFires can cause great structural damage to bridges and major disruption to highway operations．These incidents stem primarily from vehicle accident (often oil tanker) fires，bridges might also be damaged by fires in adjacent facilities and from other causes．Quite a few of them，though rarely happened，lead to severe structural damage or collapse and casualty．On June 2，2008，fire disaster broke out under the 18th span of Nanjing Yangtze River Bridge and lasted for approximate 75min．During the fire’s development and extinguishment，the structure experienced the sharp rise and fall in temperature causing severe damage to fire- stricken segments．On April 29，2007，a gasoline tanker overturned on the connector from Interstate 8O to Interstate 880 in California．The intense heat from the subsequent fuel spill and fire weakened the stee1 underbelly of the elevated roadway ,collapsing approximately 165 feet of this elevated roadway onto a section of I—880below．On March 25，2004，Connecticut，United States，a tanker truck carrying fuel swerved to avoid a car and overturned，dumping 8000 gallons of home heating oil onto the Howard Avenue overpass．The consequent towering inferno melted the bridge structure and caused the southbound lanes to sag several feetUndocumented number of bridge fires occurring throughout the world each year cause varying degrees of disruption，repair actions，and maintenance cost．Althoughfires caused damage to the bridge structures ,some bridges continue to function after proper repair and retrofit．Still in some situations they have to be repaired for the cause of traffic pressure even though supposed to be dismantled and reconstructed．However ,in other cases，structures are severely damaged in the fire disaster and fail to function even after repair，or the costs of repair and retrofit overweigh their reconstruction costs overwhelmingly even if they are repairable，under which situation reconstruction serves as a preferable option．Therefore in—situ investigation and necessary tests and analyses should be conducted to make comprehensive assessment of the residual mechanical properties and working statuses after fire and to evaluate the degrees of damage of members and structures , in reference to which decisions are made to determine whether Fire damaged structures should be repaired or dismantled and reconstructed．Urgent need from engineering practice highlighted the necessity to understand the susceptibility and severity of these incidents as wel1 as to review available information on mitigation strategies，damage assessments，and repair techniques.2 Progress in Research and Engineering Practice2.1 Processes of Assessment and Repair of Fire damaged BridgeStructureIn China and most countries in the world，most highway bridges are built in RC structure．And the practice of the assessment and repair techniques of bridge structure after fire directly refer to that of RC structure，which，to date，domestic and foreign scholars have made great amount of research on，with their theories and practices being increasingly mature .As for the assessment and repair of fire-damaged reinforced concrete structures，there are two mainstream assessment processes in world．Countries including United States，United Kingdom and Japan adopt the assessment process stipulated by The British Concrete Society .This process grates the severity of fire damage of concrete structure into four degrees according to thedeflection，damage depth，cracking width, color，and loading capacity variation of fire-damaged structures and adopt four corresponding strategies (including demolish，strengthen after safety measures，strengthen. and strengthen in damaged segments) to deal with them accordingly．In general，this process is a qualitative method and considered，however，not quantity enough.In Chinese Mainland and Taiwan ，the prevailing as assessment and repair process of fire damaged incorporates following steps：In comparison this process is more detailed．(1)Conduct In-situ inspections，measurements，and tests including color observation，concrete observation，degree of rebar exposure observation，cracking measurement，deflection measurement，various destructive and nondestructive test methods as grounds for assessment of fire—damaged structures．In assessment of the post -fire mechanical properties of fire—damaged structures，historical highest temperature and temperature distribution of structure during the fire serve as decisive factors．The common methods to determine them incorporate petrographic analysis，ultrasonic method，Rebound method，Ignition Loss method，core test，and color observation method(2)calculate to determine whether the fire-damaged structure can meet the demand of strength and deflection under working loads after fire using mechanical properties of rebar and concrete before and after fire based on the historical highest and temperature distribution of structures obtained from step one．There are two main methods to evaluate the post -fire performance of fire-damaged structures：FEM method and Revised Classic Method．(3)On the basis of test and calculation results obtained from step two，take corresponding repair strategies and particular methods to strengthen the fire-damaged structures.2．2 Repair TechniquesFor the repair of fire—damaged bridge，proper repair methods should be taken according to the degr ee and range of the structure’s damage．Meanwhile the safetyand economy of the repair methods should be concerned with by avoiding destructing the original structure，preserving the valuable structural members，and minimizing unnecessary demolishment and reconstruction。

桥梁工程毕业设计外文翻译(箱梁)

西南交通大学本科毕业设计(论文）外文资料翻译年级:学号：姓名：专业:指导老师:2013年 6 月外文资料原文：13Box girders13.1 GeneralThe box girder is the most ﬂexible bridge deck form。

It can cover a range of spans from25 m up to the largest non—suspended concrete decks built, of the order of 300 m。

Single box girders may also carry decks up to 30 m wide。

For the longer span beams, beyond about 50 m，they are practically the only feasible deck section. For the shorter spans they are in competition with most of the other deck types discussed in this book.The advantages of the box form are principally its high structural efﬁciency （5.4），which minimises the prestress force required to resist a given bending moment，and its great torsional strength with the capacity this gives to re—centre eccentric live loads，minimising the prestress required to carry them。

The box form lends itself to many of the highly productive methods of bridge construction that have been progressively reﬁned over the last 50 years，such as precast segmental construction with or without epoxy resin in the joints，balanced cantilever erection either cast in—situ or coupled with precast segmental construction, and incremental launching （Chapter 15)。

道路桥梁专业中英文对照---毕业设计论文外文文献翻译

附录一英文翻译原文AUTOMATIC DEFLECTION AND TEMPERATURE MONITORING OFA BALANCED CANTILEVER CONCRETE BRIDGEby Olivier BURDET, Ph.D.Swiss Federal Institute of Technology, Lausanne, SwitzerlandInstitute of Reinforced and Prestressed Concrete SUMMARYThere is a need for reliable monitoring systems to follow the evolution of the behavior of structures over time.Deflections and rotations are values that reflect the overall structure behavior. This paper presents an innovative approach to the measurement of long-term deformations of bridges by use of inclinometers. High precision electronic inclinometers can be used to follow effectively long-term rotations without disruption of the traffic. In addition to their accuracy, these instruments have proven to be sufficiently stable over time and reliable for field conditions. The Mentue bridges are twin 565 m long box-girder post-tensioned concrete highway bridges under construction in Switzerland. The bridges are built by the balanced cantilever method over a deep valley. The piers are 100 m high and the main span is 150 m. A centralized data acquisition system was installed in one bridge during its construction in 1997. Every minute, the system records the rotation and temperature at a number of measuring points. The simultaneous measurement of rotations and concrete temperature at several locations gives a clear idea of the movements induced by thermal conditions. The system will be used in combination with a hydrostatic leveling setup to follow the long-term behavior of the bridge. Preliminary results show that the system performs reliably and that the accuracy of the sensors is excellent.Comparison of the evolution of rotations and temperature indicate that the structure responds to changes in air temperature rather quickly.1.BACKGROUNDAll over the world, the number of structures in service keeps increasing. With the development of traffic and the increased dependence on reliable transportation, it is becoming more and more necessary to foresee and anticipate the deterioration of structures. In particular,for structures that are part of major transportation systems, rehabilitation works need to be carefully planned in order to minimize disruptions of traffic. Automatic monitoring of structures is thus rapidly developing.Long-term monitoring of bridges is an important part of this overall effort to attempt to minimize both the impact and the cost of maintenance and rehabilitation work of major structures. By knowing the rate of deterioration of a given structure, the engineer is able to anticipate and adequately define the timing of required interventions. Conversely, interventions can be delayed until the condition of the structure requires them, without reducing the overall safety of the structure.The paper presents an innovative approach to the measurement of long-term bridge deformations. The use of high precision inclinometers permits an effective, accurate and unobtrusive following of the long-term rotations. The measurements can be performed under traffic conditions. Simultaneous measurement of the temperature at several locations gives a clear idea of the movements induced by thermal conditions and those induced by creep and shrinkage. The system presented is operational since August 1997 in the Mentue bridge, currently under construction in Switzerland. The structure has a main span of 150 m and piers 100 m high.2. LONG-TERM MONITORING OF BRIDGESAs part of its research and service activities within the Swiss Federal Institute of Technology in Lausanne (EPFL), IBAP - Reinforced and Prestressed Concrete has been involved in the monitoring of long-time deformations of bridges and other structures for over twenty-five years [1, 2, 3, 4]. In the past, IBAP has developed a system for the measurement of long-term deformations using hydrostatic leveling [5, 6]. This system has been in successful service in ten bridges in Switzerland for approximately ten years [5,7]. The system is robust, reliable and sufficiently accurate, but it requires human intervention for each measurement, and is not well suited for automatic data acquisition. One additional disadvantage of this system is that it is only easily applicable to box girder bridges with an accessible box.Occasional continuous measurements over periods of 24 hours have shown that the amplitude of daily movements is significant, usually amounting to several millimeters over a couple of hours. This is exemplified in figure 1, where measurements of the twin Lutrive bridges, taken over a period of several years before and after they were strengthened by post-tensioning, areshown along with measurements performed over a period of 24 hours. The scatter observed in the data is primarily caused by thermal effects on the bridges. In the case of these box-girder bridges built by the balanced cantilever method, with a main span of 143.5 m, the amplitude of deformations on a sunny day is of the same order of magnitude than the long term deformation over several years.Instantaneous measurements, as those made by hydrostatic leveling, are not necessarily representative of the mean position of the bridge. This occurs because the position of the bridge at the time of the measurement is influenced by the temperature history over the past several hours and days. Even if every care was taken to perform the measurements early in the morning and at the same period every year, it took a relatively long time before it was realized that the retrofit performed on the Lutrive bridges in 1988 by additional post-tensioning [3, 7,11] had not had the same effect on both of them.Figure 1: Long-term deflections of the Lutrive bridges, compared to deflections measured in a 24-hour period Automatic data acquisition, allowing frequent measurements to be performed at an acceptable cost, is thus highly desirable. A study of possible solutions including laser-based leveling, fiber optics sensors and GPS-positioning was performed, with the conclusion that, provided that their long-term stability can be demonstrated, current types of electronic inclinometers are suitable for automatic measurements of rotations in existing bridges [8].3. MENTUE BRIDGESThe Mentue bridges are twin box-girder bridges that will carry the future A1 motorway from Lausanne to Bern. Each bridge, similar in design, has an overall length of approximately 565 m, and a width of 13.46 m, designed to carry two lanes of traffic and an emergency lane. The bridges cross a deep valley with steep sides (fig. 2). The balanced cantilever design results from a bridge competition. The 100 m high concrete piers were built using climbing formwork, after which the construction of the balanced cantilever started (fig. 3).4. INCLINOMETERSStarting in 1995, IBAP initiated a research project with the goal of investigating the feasibility of a measurement system using inclinometers. Preliminary results indicated that inclinometers offer several advantages for the automatic monitoring of structures. Table 1 summarizes the main properties of the inclinometers selected for this study.One interesting property of measuring a structure’s rotations, is that, for a given ratio of maximum deflection to span length, the maximum rotation is essentially independent from its static system [8]. Since maximal allowable values of about 1/1,000 for long-term deflections under permanent loads are generally accepted values worldwide, developments made for box-girder bridges with long spans, as is the case for this research, are applicable to other bridges, for instance bridges with shorter spans and other types of cross-sections. This is significant because of the need to monitor smaller spans which constitute the majority of all bridges.The selected inclinometers are of type Wyler Zerotronic ±1°[9]. Their accuracy is 1 microradian (μrad), which corresponds to a rotation of one millimeter per kilometer, a very small value. For an intermediate span of a continuous beam with a constant depth, a mid-span deflection of 1/20,000 would induce a maximum rotation of about 150 μrad, or 0.15 milliradians (mrad).One potential problem with electronic instruments is that their measurements may drift overtime. To quantify and control this problem, a mechanical device was designed allowing the inclinometers to be precisely rotated of 180° in an horizontal plane (fig. 4). The drift of each inclinometer can be very simply obtained by comparing the values obtained in the initial and rotated position with previously obtained values. So far, it has been observed that the type of inclinometer used in this project is not very sensitive to drifting.5. INSTRUMENTATION OF THE MENTUE BRIDGESBecause a number of bridges built by the balanced cantilever method have shown an unsatisfactory behavior in service [2, 7,10], it was decided to carefully monitor the evolution of the deformations of the Mentue bridges. These bridges were designed taking into consideration recent recommendations for the choice of the amount of posttensioning [7,10,13]. Monitoring starting during the construction in 1997 and will be pursued after the bridges are opened to traffic in 2001. Deflection monitoring includes topographic leveling by the highway authorities, an hydrostatic leveling system over the entire length of both bridges and a network of inclinometers in the main span of the North bridge. Data collection iscoordinated by the engineer of record, to facilitate comparison of measured values. The information gained from these observations will be used to further enhance the design criteria for that type of bridge, especially with regard to the amount of post-tensioning [7, 10, 11, 12, 13].The automatic monitoring system is driven by a data acquisition program that gathers and stores the data. This system is able to control various types of sensors simultaneously, at the present time inclinometers and thermal sensors. The computer program driving all the instrumentation offers a flexible framework, allowing the later addition of new sensors or data acquisition systems. The use of the development environment LabView [14] allowed to leverage the large user base in the field of laboratory instrumentation and data analysis. The data acquisition system runs on a rather modest computer, with an Intel 486/66 Mhz processor, 16 MB of memory and a 500 MB hard disk, running Windows NT. All sensor data are gathered once per minute and stored in compressed form on the hard disk. The system is located in the box-girder on top of pier 3 (fig. 5). It can withstand severe weather conditions and will restart itself automatically after a power outage, which happened frequently during construction.6. SENSORSFigure 5(a) shows the location of the inclinometers in the main span of the North bridge. The sensors are placed at the axis of the supports (①an d⑤), at 1/4 and 3/4 (③an d④) of the span and at 1/8 of the span for②. In the cross section, the sensors are located on the North web, at a height corresponding to the center of gravity of the section (fig.5a). The sensors are all connected by a single RS-485 cable to the central data acquisition system located in the vicinity of inclinometer ①. Monitoring of the bridge started already during its construction. Inclinometers①,②and③were installed before the span was completed. The resulting measurement were difficult to interpret, however, because of the wide variations of angles induced by the various stages of this particular method of construction.The deflected shape will be determined by integrating the measured rotations along the length of the bridge (fig.5b). Although this integration is in principle straightforward, it has been shown [8, 16] that the type of loading and possible measurement errors need to be carefully taken into account.Thermal sensors were embedded in concrete so that temperature effects could be taken into account for the adjustment of the geometry of the formwork for subsequent casts. Figure 6 shows the layout of thermal sensors in the main span. The measurement sections are located at the same sections than the inclinometers (fig. 5). All sensors were placed in the formwork before concreting and were operational as soon as the formwork was removed, which was required for the needs of the construction. In each section, seven of the nine thermal sensor (indicated in solid black in fig. 6) are now automatically measured by the central data acquisition system.7. RESULTSFigure 7 shows the results of inclinometry measurements performed from the end ofSeptember to the third week of November 1997. All inclinometers performed well during that period. Occasional interruptions of measurement, as observed for example in early October are due to interruption of power to the system during construction operations. The overall symmetry of results from inclinometers seem to indicate that the instruments drift is not significant for that time period. The maximum amplitude of bridge deflection during the observed period, estimated on the basis of the inclinometers results, is around 40 mm. More accurate values will be computed when the method of determination ofdeflections will have been further calibrated with other measurements. Several periods of increase, respectively decrease, of deflections over several days can be observed in the graph. This further illustrates the need for continuous deformation monitoring to account for such effects. The measurement period was .busy. in terms of construction, and included the following operations: the final concrete pours in that span, horizontal jacking of the bridge to compensate some pier eccentricities, as well as the stressing of the continuity post-tensioning, and the de-tensioning of the guy cables (fig. 3). As a consequence, the interpretation of these measurements is quite difficult. It is expected that further measurements, made after the completion of the bridge, will be simpler to interpret.Figure 8 shows a detail of the measurements made in November, while figure.9 shows temperature measurements at the top and bottom of the section at mid-span made during that same period. It is clear that the measured deflections correspond to changes in the temperature. The temperature at the bottom of the section follows closely variations of the air temperature(measured in the shade near the north web of the girder). On the other hand, the temperature at the top of the cross section is less subject to rapid variations. This may be due to the high elevation of the bridge above ground, and also to the fact that, during the measuring period, there was little direct sunshine on the deck. The temperature gradient between top and bottom of the cross section has a direct relationship with short-term variations. It does not, however, appear to be related to the general tendency to decrease in rotations observed in fig. 8.8. FUTURE DEVELOPMENTSFuture developments will include algorithms to reconstruct deflections from measured rotations. To enhance the accuracy of the reconstruction of deflections, a 3D finite element model of the entire structure is in preparation [15]. This model will be used to identify the influence on rotations of various phenomena, such as creep of the piers and girder, differential settlements, horizontal and vertical temperature gradients or traffic loads.Much work will be devoted to the interpretation of the data gathered in the Mentue bridge. The final part of the research project work will focus on two aspects: understanding the very complex behavior of the structure, and determining the most important parameters, to allow a simple and effective monitoring of the bridges deflections.Finally, the research report will propose guidelines for determination of deflections from measured rotations and practical recommendations for the implementation of measurement systems using inclinometers. It is expected that within the coming year new sites will be equipped with inclinometers. Experiences made by using inclinometers to measure deflections during loading tests [16, 17] have shown that the method is very flexible and competitive with other high-tech methods.As an extension to the current research project, an innovative system for the measurement of bridge joint movement is being developed. This system integrates easily with the existing monitoring system, because it also uses inclinometers, although from a slightly different type.9. CONCLUSIONSAn innovative measurement system for deformations of structures using high precision inclinometers has been developed. This system combines a high accuracy with a relatively simple implementation. Preliminary results are very encouraging and indicate that the use of inclinometers to monitor bridge deformations is a feasible and offers advantages. The system is reliable, does not obstruct construction work or traffic and is very easily installed. Simultaneous temperature measurements have confirmed the importance of temperature variations on the behavior of structural concrete bridges.10. REFERENCES[1] ANDREY D., Maintenance des ouvrages d’art: méthodologie de surveillance, PhD Dissertation Nr 679, EPFL, Lausanne, Switzerland, 1987.[2] BURDET O., Load Testing and Monitoring of Swiss Bridges, CEB Information Bulletin Nr 219, Safety and Performance Concepts, Lausanne, Switzerland, 1993.[3] BURDET O., Critères pour le choix de la quantitéde précontrainte découlant de l.observation de ponts existants, CUST-COS 96, Clermont-Ferrand, France, 1996.[4] HASSAN M., BURDET O., FAVRE R., Combination of Ultrasonic Measurements and Load Tests in Bridge Evaluation, 5th International Conference on Structural Faults and Repair, Edinburgh, Scotland, UK, 1993.[5] FAVRE R., CHARIF H., MARKEY I., Observation à long terme de la déformation des ponts, Mandat de Recherche de l’OFR 86/88, Final Report, EPFL, Lausanne, Switzerland, 1990.[6] FAVRE R., MARKEY I., Long-term Monitoring of Bridge Deformation, NATO Research Workshop, Bridge Evaluation, Repair and Rehabilitation, NATO ASI series E: vol. 187, pp. 85-100, Baltimore, USA, 1990.[7] FAVRE R., BURDET O. et al., Enseignements tirés d’essais de charge et d’observations à long terme pour l’évaluation des ponts et le choix de la précontrainte, OFR Report, 83/90, Zürich, Switzerland, 1995.[8] DAVERIO R., Mesures des déformations des ponts par un système d’inclinométrie,Rapport de maîtrise EPFL-IBAP, Lausanne, Switzerland, 1995.[9] WYLER AG., Technical specifications for Zerotronic Inclinometers, Winterthur, Switzerland, 1996.[10] FAVRE R., MARKEY I., Generalization of the Load Balancing Method, 12th FIP Congress, Prestressed Concrete in Switzerland, pp. 32-37, Washington, USA, 1994.[11] FAVRE R., BURDET O., CHARIF H., Critères pour le choix d’une précontrainte: application au cas d’un renforcement, "Colloque International Gestion des Ouvrages d’Art: Quelle Stratégie pour Maintenir et Adapter le Patrimoine, pp. 197-208, Paris, France, 1994. [12] FAVRE R., BURDET O., Wahl einer geeigneten Vorspannung, Beton- und Stahlbetonbau, Beton- und Stahlbetonbau, 92/3, 67, Germany, 1997.[13] FAVRE R., BURDET O., Choix d’une quantité appropriée de précontrain te, SIA D0 129, Zürich, Switzerland, 1996.[14] NATIONAL INSTRUMENTS, LabView User.s Manual, Austin, USA, 1996.[15] BOUBERGUIG A., ROSSIER S., FAVRE R. et al, Calcul non linéaire du béton arméet précontraint, Revue Français du Génie Civil, vol. 1 n° 3, Hermes, Paris, France, 1997. [16] FEST E., Système de mesure par inclinométrie: développement d’un algorithme de calcul des flèches, Mémoire de maîtrise de DEA, Lausanne / Paris, Switzerland / France, 1997.[17] PERREGAUX N. et al., Vertical Displacement of Bridges using the SOFO System: a Fiber Optic Monitoring Method for Structures, 12th ASCE Engineering Mechanics Conference, San Diego, USA, to be published,1998.译文平衡悬臂施工混凝土桥挠度和温度的自动监测作者Olivier BURDET博士瑞士联邦理工学院，洛桑，瑞士钢筋和预应力混凝土研究所概要：我们想要跟踪结构行为随时间的演化，需要一种可靠的监测系统。

桥梁工程毕业论文英文

桥梁工程毕业论文英文Title: Analysis and Design of Bridge StructuresAbstract:Bridge engineering is an integral part of civil engineering and plays a crucial role in connecting communities and facilitating transportation. The purpose of this thesis is to analyze and design bridge structures, focusing on key components such as foundations, superstructures, and substructures. The analysis includes evaluating the structural behavior and load carrying capacity through the utilization of various analytical tools. Furthermore, the design phase encompasses selecting suitable materials and designing components to meet safety and durability requirements. The study serves as a comprehensive guide to understanding the principles and processes involved in bridge engineering.1. IntroductionBridges are vital infrastructure that connects people, places, and economies. The study of bridge engineering involves the application of core principles like physics, materials science, and mathematics todesign and construct safe and efficient bridge structures. This thesis aims to provide an overview of the analysis and design principles involved in bridge engineering.2. Structural AnalysisThe analysis of bridge structures is crucial to ensure their safety and functionality. This chapter presents various analytical techniques for evaluating bridge behavior. The use of finite element analysis, structural modeling, and computer-aided design software is discussed in detail. Different load types and load combinations are also considered to determine the resilience and load carrying capacity of the bridge.3. Foundation DesignThe foundation is a critical component of any bridge structure, as it transfers the loads from the superstructure to the underlying ground. This chapter explores various foundation types, such as shallow foundations, deep foundations, and pile foundations. Design considerations, including soil mechanics, bearing capacity, settlement analysis, and groundwater conditions, are discussed. The use ofgeotechnical engineering software to simulate and optimize foundation design is also explored.4. Superstructure DesignThe superstructure refers to the portion of the bridge that supports the traffic loads and transfers them to the substructure. This chapter discusses the different types of superstructures, including beam bridges, truss bridges, and arch bridges. The selection of materials, such as concrete, steel, and composite materials, is analyzed based on their structural properties and cost-effectiveness. The design process incorporates the calculation of load distribution, structural stability, and deflection limits.5. Substructure DesignThe substructure comprises the bridge piers, abutments, and retaining walls, which provide support to the superstructure. This chapter focuses on the design considerations for substructures, including the selection of suitable materials, analysis of load distribution, and evaluation of stability against various forces and environmental conditions. Design principles for reinforced concrete and masonry substructures are explored, along with mitigationstrategies for potential issues such as scour and seismic activity.6. Safety and DurabilityEnsuring safety and durability is of utmost importance in bridge engineering. This chapter discusses the necessary steps for evaluating the safety of bridge structures, including factor of safety calculations, failure mode analysis, and risk assessment procedures. The discussion also includes guidelines for maintenance and inspection to ensure long-term performance and durability.7. ConclusionThis thesis provides an in-depth analysis and design framework for bridge structures. By comprehensively exploring the key components of bridges, including foundations, superstructures, and substructures, it provides valuable insights into the principles and processes involved in bridge engineering. The knowledge gained from this study will contribute to the safe and efficient design and construction of future bridge projects.。

(完整版)桥梁毕业设计外文翻译0

Structural Rehabilitation of Concrete Bridges with CFRP Composites-Practical Details and Applications Riyad S. ABOUTAHA1, and Nuttawat CHUTARAT2 ABSTRACT: Many old existing bridges are still active in the various networks, carrying all kinds of environments. Water, salt, and wind ; and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites. There appear to be very limited guides on repair of deteriorated concrete bridges with CFRP composites. In this paper, guidelines for nondestructive evaluation (NDE), nondestructive testing (NDT), and rehabilitation of deteriorated concrete bridges with CFRP composites are presented. The effect of detailing on ductility and behavior of CFRP strengthened concrete bridges are also discussed and presented.KEYWORDS: Concrete deterioration, corrosion of steel, bridge rehabilitation, CFRP composites.1 IntroductionThere are several destructive external environmental factors that limit the service life of bridges. These factors include but not limited to chemical attacks, corrosion of reinforcing steel bars, carbonation of concrete, and chemical reaction of aggregate. If bridges were not well maintained, these factors may lead to a structural deficiency, which reduces the margin of safety, and may result in structural failure. In order to rehabilitate andor strengthen deteriorated existing bridges, thorough evaluation should be conducted. The purpose of theevaluation is to assess the actual condition of any existing bridge, and generally to examine the remaining strength and load carry capacity of the bridge.1 Associate Professor, Syracuse University, U.S.A.2 Lecturer, Sripatum University, Thailand.One attempt to restore the original condition, and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites.In North America, Europe and Japan, CFRP extensively investigated and applied. Several design guides developed for strengthening of concrete bridges with CFRP composites. However, there appear to be very limited guides on repair of deteriorated concrete bridges with CFRP composites. This paper presents guidelines for repair of deteriorated concrete bridges, along with proper detailing. Evaluation, nondestructive testing, and rehabilitation of deteriorated concrete bridges with CFRP composites are presented. Successful application of CFRP composites requires good detailing as the forces developed in the CFRP sheets are transferred by bond at the concrete-CFRP interface. The effect of detailing on ductility and behavior of CFRP strengthened concrete bridges will also be discussed and presented.2 Deteriorated Concrete BridgesDurability of bridges is of major concern. Increasing number of bridges are experiencing significant amounts of deterioration prior to reaching their design service life. This premature deterioration considered a problem in terms of the structural integrity and safety of the bridge. In addition, deterioration of a bridge many cases, the root of a deterioration problem is caused by corrosion of steel reinforcement in concrete structures. Concrete normally acts to provide a against corrosion of the embedded reinforcement. However, corrosion will result in those cases that typically experience poor concrete quality, inadequate design or construction, and , may turn into a strength problem leading to a structural deficiency, as shown in Figure1.Figure1 Corrosion of the steel bars is leading to a structural deficiency3 Non-destructive Testing of Deteriorated Concrete Bridge PiersIn order to design a successful retrofit system, the condition of the existing bridge should be thoroughly evaluated. Evaluation of existing bridge elements or systems involves review of the asbuilt drawings, as well as accurate estimate of the condition of the existing bridge, as shown in Figure2. Depending on the purpose of evaluation, non-destructive tests may involve estimation of strength, salt contents, corrosion rates, alkalinity in concrete, etc.Figure2 Visible concrete distress marked on an elevation of a concrete bridgepierAlthough most of the non-destructive tests do not cause any damage to existing bridges, some NDT may cause minor local damage (e.g. drilled -destructive testing.In order to select the most appropriate non-destructive test for a particular case, the purpose of the test should be identified. In general, there are three types of NDT to investigate: (1) strength, (2) other structural properties, and (3) quality and durability. The strength methods may include; compressive test (e.g. core testrebound test (e.g. Windsor probe), and pullout test (anchor test).Other structural test methods may include; concrete cover thickness (cover-meter), locating rebars (rebar locator), rebar size (some rebar locatorsrebar data scan), concrete moisture (acquametermoisture meter), cracking (visual testimpact echoultrasonic pulse velocity), delamination (’s ratio (ultrasonic pulse velocity), thickness of concrete slab or wall (ultrasonic pulse velocity), CFRP debonding ( on concrete surface (visual inspection).Quality and durability test methods may include; rebar corrosion rate –field test, chloride profile field test, rebar corrosion analysis, rebar resistivity test, alkali-silica reactivity field test, concrete alkalinity test (carbonation field test), concrete permeability (field test for permeability).4 Non-destructive Evaluation of Deteriorated Concrete Bridge PiersThe process of evaluating the structural condition of an existing concrete bridge consists of collecting information, e.g. drawings and construction & inspection records, analyzing NDT data, and structural analysis of the bridge. The evaluation process can be summarized as follows: (1) Planning for the assessment, (2) Preliminary assessment, which involves examination of available documents, site inspection, materials assessment, and preliminary analysis, (3) Preliminary evaluation, this involves: examination phase, and judgmental phase, and finally (4) the cost-impact study.If the information is insufficient to conduct evaluation to a specific required level, then a detailed evaluation may be conducted following similar steps for the above-mentioned preliminary assessment, but in-depth assessment. Successful analytical evaluation of an existing deteriorated concrete bridge should consider the actual condition of the bridge and level of deterioration of various elements. Factors, e.g. actual concrete strength, level of damagedeterioration, actual size of corroded rebars, loss of bond between steel and concrete, etc. should be modeled into a detailed analysis. If such detailed analysis is difficult to accomplish within a reasonable period of time, then evaluation by field load testing of the actual bridge in question may be required.5 Bridge Rehabilitation with CFRP CompositesApplication of CFRP composite materials is becoming increasingly attractive to extend the service life of existing concretebridges. The technology of strengthening existing bridges with externally bonded CFRP composites was developed primarily in Japan (FRP sheets), and Europe (laminates). The use of these materials for strengthening existing concrete bridges started in the 1980s, first as a substitute to bonded steel plates, and then as a substitute for steel jackets for seismic retrofit of bridge columns. CFRP Composite materials are composed of fiber reinforcement bonded together with a resin matrix. The fibers provide the composite with its unique structural properties. The resin matrix supports the fibers, protect them, and transfer the applied load to the fibers through shearing stresses. Most of the commercially available CFRP systems in the construction market consist of uniaxial fibers embedded in a resin matrix, typically epoxy. Carbon fibers , which may limit the deformability of strengthened members. However, under traffic loads, local debonding between FRP sheets and concrete substrate would allow for acceptable level of global deformations before failure.CFRP composites could be used to increase the flexural and shear strength of bridge girders including pier cap beams, as shown in Figure3. In order to increase the ductility of CFRP strengthened concrete girders, the longitudinal CFRP composite sheets used for flexural strengthening should be anchored with transversediagonal CFRP anchors to prevent premature delamination of the longitudinal sheets due to localized debonding at the concrete surface-CFRP sheet interface. In order to prevent stress concentration and premature fracture of the CFRP sheets at the corners of concrete members, thecorners should be rounded at 50mm (2.0 inch) radius, as shown in Figure3.Deterioration of concrete bridge members due to corrosion of steel bars usually leads in loss of steel section and delamination of concrete cover. As a result, such deterioration may lead to structural deficiency that requires immediate attention. Figure4 shows rehabilitation of structurally deficient concrete bridge pier using CFRP composites.Figure3 Flexural and shear strengthening of concrete bridge pier with FRPcompositesFigure4 Rehabilitation of deteriorated concrete bridge pier with CFRPcomposites6 Summary and ConclusionsEvaluation, non-destructive testing and rehabilitation of deteriorated concrete bridges were presented. Deterioration of concrete bridge components due to corrosion may lead to structural deficiencies, e.g. flexural andor shear failures. Application of CFRP composite materials is becoming increasingly attractive solution to extend the service life of existing concrete bridges. CFRP composites could be utilized for flexural and shear strengthening, as well as for restoration of deteriorated concrete bridge components. The CFRP composite sheets should be well detailed to prevent stress concentration and premature fracture or delamination. For successful rehabilitation of concrete bridges in corrosive environments, acorrosion protection system should be used along with the CFRP system.碳纤维复合材料修复混凝土桥梁结构的详述及应用Riyad S. ABOUTAHA1, and Nuttawat CHUTARAT2摘要：在各式各样的公路交通网络中，许多现有的古老桥梁，在各种恶劣的环境下，如更重的荷载和更快的车辆等条件下，依然在被使用着。

桥梁设计外文翻译

中文4840字附录 2 外文资料翻译原文11.7.4 Deﬂection11.7.4.1 Dead Load and Creep DeﬂectionGlobal vertical deﬂections of segmental box-girder bridges due to the effects of dead load and post-tensioning as well as the long-term effect of creep are normally predicted during the design process by the use of a computer analysis program. The deﬂections are dependent, to a large extent, on the method of construction of the structure, the age of the segments when post-tensioned, and the age of the structure when other loads are applied. It can be expected, therefore, that the actual deﬂections of the structure would be different from that predicted during design due to changed assumptions.The deﬂections are usually recalculated by the contractor’s engineer, based on the actual construction sequence.11.7.4.2 Camber RequirementsThe permanent deﬂection of the structure after all creep deﬂections have occurred, normally 10 to 15 years after construction, may be objectionable from the perspective of riding comf ort for the users or for the conﬁdence of the general public. Even if there is no structural problem with a span with noticeable sag, it will not inspire public conﬁdence. For these reasons, a camber will normally be cast into the structure so that the p ermanent deﬂection of the bridge is nearly zero. It may be preferable to ignore the camber, if it is otherwise necessary to cast a sag in the structure during onstruction.11.7.4.3 Global Deﬂection Due to Live LoadMost design codes have a lim it on the allowable global deﬂection of a bridge span due to the effects of live load. The purpose of this limit is to avoid the noticeable vibration for the user and minimize the effects of moving load iMPact. When structures are used by pedestrians as well as motorists,the limits are further tightened.11.7.4.4 Local Deﬂection Due to Live LoadSimilar to the limits of global deﬂection of bridge spans, there are also limitations on the deﬂection of the local elements of the box-girder cross section. For example, the AASHTO Speciﬁcations limit the deﬂection of cantilever arms due to service live load plus iMPact to ¹⁄₃of the cantilever length,except where there is pedestrian use [1].11.7.5 Post-Tensioning Layout11.7.5.1 Exter nal Post-TensioningWhile most concrete bridges cast on falsework or precast beam bridges have utilized post-tensioning in ducts which are fully encased in the concrete section, other innovations have been made in precast segmental construction.Especially prevalent in structures constructed using the span-by-span method, post-tensioning has been placed inside the hollow cell of the box girder but not encased in concrete along its length. This is know as external post-tensioning. External post-tensioning is easily inspected at any time during the life of the structure, eliminates the problems associated with internal tendons, and eliminates the need for using expensive epoxy adhesive between precastsegments. The problems associated with internal tendons are (1) misalignment of the tendons at segment joints, which causes spalling; (2) lack of sheathing at segment joints; and (3) tendon pull-through on spans with tight curvature (see Figure 11.39). External prestressing has been used on many projects in Europe, the United States, and Asia and has performed well.11.7.5The provision for the addition of post-tensioning in the future in order to correct unacceptable creep deﬂections or to strengthen the structure for additional dead load, i.e., future wearing surface, is now required by many codes. Of the positive and negative moment post-tensioning, 10% is reasonable. Provisions should be made for access, anchorage attachment, and deviation of these additional tendons. External, unbonded tendons are used so that ungrouted ducts in the concrete are not left open. 11.8 Seismic Considerations11.8.1 Design Aspects and Design CodesDue to typical vibration characteristics of bridges, it is generally accepted that under seismic loads,some portion of the structure will be allowed to yield, to dissipate energy, and to increase the period of vibration of the system. This yielding is usually achieved by either allowing the columns to yield plastically (monolithic deck/superstructure connection), or by providing a yielding or a soft bearing system [6].The same principles also apply to segmental structures, i.e., the segmental superstructureneeds to resist the demands imposed by the substructure. Very few implementations of segmental struc-tures are found in seismically active California, where most of the research on earthquake-resistant bridges is conducted in the United States. The Pine Valley Creek Bridge, Parrots Ferry Bridge, and Norwalk/El Segundo Line Overcrossing, all of them being in California, are examples of segmental structures; however, these bridges are all segmentally cast in place, with mild reinforcement crossing the segment joints.Some guidance for the seismic design of segmental structures is provided in the latest edition of the AASHTO Guide Speciﬁcations for Design and Construction of Segmental Concrete Bridges [2], which now contains a chapter dedicated to seismic design. The guide allows precast-segmental construction without reinforcement across the joint, but speciﬁes the following additional require-ments for these structures:•For Seismic Zones C and D [1], either cast-in-place or epoxied joints are required.•At least 50% of the prestress force should be provided by internal tendons.•The internal tendons alone should be able to carry 130% of the dead load.For other seismic design and detailing issues, the reader is referred to the design literature providedby the California Department of Transportation, Caltrans, for cast-in-place structures [5-8].11.8.2 Deck/Superstructure ConnectionRegardless of the design approach adopted (ductility through plastic hinging of the column or through bearings), the deck/superstructure connection is a critical element in the seismic resistant system. A brief description of the different possibilities follows.11.8.2.1 Monolithic Deck/Superstructure ConnectionFor the longitudinal direction, plastic hinging will form at the top and bottom of the columns. Since most of the testing has been conducted on cast-in-place joints, this continues to be the preferred option for these cases. For short columns and for solid columns, the detailing in this area can be readily adapted from standard Caltrans practice for cast-in-place structures, as shown on Figure 11.40. The joint area is then essentially detailed so it is no different from that of a fully cast-in-place bridge. In particular, a Caltrans requirement for positive moment reinforcement over the pier can be detailed with prestressing strand, as shown below. For large spans and tall columns, hollow column sections would be more appropriate. In these cases, care should be taken to conﬁne the main column bars with closely spaced ties, and joint shear reinforcement should be provided according to Reference [3 or 7]. The use of fully precast pier segments in segmental superstructures would probably require special approval of the regulating government agency, since such a solution has not yet been tested for bridges and is not codiﬁed. Nevertheless, based upon ﬁrst principles, and with the help of strut–tiemodels, it is possible to design systems that would work in practice [6]. The segmental superstructure should be designed to resist at least 130%of the column nominal moment using the strength reduction factors prescribed in Ref. [2]. Of further interest may be a combination of precast and cast-in-place joint as shown in Figure 11.41, which was adapted from Ref.[8]. Here, the precast segment serves as a form for the cast-in-place portion that ﬁlls up the remainder of the solid pier cap. Other ideas can also be derived from the building industry where some model testing has been performed. Of particular interest for bridges could be a system that works by leaving dowels in the columns and supplying the precast segment with matching formed holes, which are grouted after the segment is slipped over the reinforcement [9]11.8.2.2Deck/Superstructure Connection via BearingsTypically, for spans up to 45 m erected with the span-by-span method, the superstructure will be supported on bearings. For action in the longitudinal direction, elastomeric or isolation bearings are preferred to a ﬁxed-end/expansion-end arrangement, since these better distribute the load between the bearings. Furthermore, these bearings will increase the period of the structure, which results in an overall lower induced force level (beneﬁcial for higher-frequency structures), and isolation bearings will provide some structural damping as well.In the transverse direction, the bearings may be able to transfer load between super- and sub-structure by shear deformation; however, for the cases where this is not possible, shear keys can be provided as is shown in Figure 11.42. It should be noted that in regions of high seismicity,for structures with tall piers or soft substructures, the bearing demands may become excessive and a monolithic deck–superstructure connection may become necessary.For the structure-on-bearings approach, the force level for the superstructure can be readily，determined, since once the bearing demands are obtained from the analysis, they can be applied to the superstructure and substructure. The superstructure should resist the resulting forces at ultimate (using the applicable code force-reduction factors), whereas the substructure can be allowed to yield plastically if necessary.11.8.2.3 Expansion HingesFrom the seismic point of view, it is desirable to reduce the number of expansion hinges (EH)to a minimum. If EHs are needed, the most beneﬁcial location from the seismic point of view is at midspan. This can be explained by observing Figure 11.43, where the superstructure bending midspan and for an EH at quarterspan. For the latter, it can be seen that the moment at the face The location of expansion hinges within a span, and its characteristics, depends also on the stiffness of the substructure and the type of connection of the superstructure to the piers. presents general guidelines intended to assist in the selection of location of expansion hinges.11.8.2.4 Precast Segmental PiersPrecast segmental piers are usually hollow cross section to save weight. From research inother areas it can be extrapolated that the precast segments of the pier would be joined by means of unbonded prestressing tendons anchored in the footing. The advantage of unbonded over bonded tendons is that for the former, the prestress force would not increase signi ﬁcantly under high column displace-ment demands, and would therefore not cause inelastic yielding of the strand, which would other-wise lead to a loss of prestress.The detail of the connection to the superstructure and foundation would require some insight into the dynamic characteristics of such a connection, which entails joint opening and closing providing that dry joints are used between segments. This effect is similar to footing rocking, which is well known to be bene ﬁcial to the response of a structure in an earthquake. This is due to the period shift and the damping of the soil. The latter effect is clearly not available to the precast columns, but the period shift is. Details need to be developed for the bearing areas at the end of the columns, as well as the provision for clearance of the tendons to move relative to the pier during the event.If the upper column segment is designed to be connected monolithically to the superstructure, yielding of the reinforcement should be expected. In this case, the expected plastic hinge length should be detailed ductile, using closely spaced ties [3,5].11.9 Casting and Erection11.9.1 CastingThere are obvious major differences in casting and erection when working with cast-in-placecantilever in travelers or in handling precast segments. There are also common features, which must be kept in mind in the design stages to keep the projects simple and thereby economic and ef ﬁcient,such as• Keeping the length of segments equal and segments straight, even in curved bridges; • Maintaining constant cross section dimensions as much as possible;• Minimizing the number of diaphragms and stiffeners, and avoiding dowels through form- work.11.9.1.1 Cast-in-Place CantileversThe conventional form traveler supports the weight of the fresh concrete of the new segment by means of longitudinal beams or frames extending out in cantilever from the last segment. These beams are tied down to the previous segment. A counterweight is used when launching the traveler forward. The main beams are subjected to some de ﬂections, which may produce cracks in the joint between the old and new segments. Jacking of the form during casting is sometimes needed to avoid these cracks. The weight of a traveler is about 60% of the weight of the segment.The rate of construction is typically one segment per traveler per week. Precast concrete anchor blocks are used to speed up post-tensioning operations. In cold climates, Conventional Travelers Construction Camber Controlcuring can be accelerated by various heating processes.The most critical practical problem of cast-in-place construction is deﬂection control. There are ﬁve categories of deﬂections during and after construction:•Deﬂection of traveler frame under the weight of the concrete segment;•Deﬂection of the concrete cantilever arm during construction under the weight of segment plus post-tensioning;•Deﬂection of cantilever arms after construction and before continuity;•Short- and long-term deﬂections of the continuous structure;•Short- and long-term pier shortenings and foundation settlements.The sum of the various deﬂection values for the successive sections of the deck allows the construc-tion of a camber diagram to be added to the theoretical proﬁle of the bridge. A construction camber for setting the elevation of the traveler at each joint must also be developed.11.9.1.2 Precast SegmentsOpposite to the precast girder concept where the bridge is cut longitudinally in the precast segmental methods, the bridge is cut transversally, each slice being a segment. Segments are cast in a casting yard one at a time. Furthermore, the new segment is cast against the previously cast segment so that the faces in contact match perfectly. This is the match-cast principle. When the segments are reassembled at the bridge site, they will take the same relative position with regard to the adjacent segments that they had when they were cast. Accuracy of segment geometry is an absolute priority, and adequate surveying methods must be used to ensure follow-up of the geometry.Match casting of the segments is a prerequisite for the application of glued joints, achieved by covering the end face of one or both of the meeting segments with epoxy at the erection. The epoxy serves as a lubricant during the assembly of the segments, and it ensures a watertight joint in theﬁnished structure. Full watertightness is needed for corrosion protection of internal tendons (ten-dons inside the concrete). The tensile strength of the epoxy material is higher than that of the concrete, but, even so, the strength of the epoxy is not considered in the structural behavior of the joint. The required shear capacity is generally provided by shear keys, single or multiple, in com-bination with longitudinal post-tensioning.With the introduction of external post-tensioning, where the tendons are installed in PE ducts,outside the concrete but inside the box girder, the joints are relieved of the traditional requirement of watertightness and are left dry. The introduction of external tendons in connection with dry joints greatly enhanced the efﬁciency of precasting.11.9.1.3 Casting MethodsThere are two methods for casting segments. The ﬁrst one is the long-line method, where all the segments are cast in their correct position on a casting bed that reproduces the span. The second method, used most of the time, is the short-line method, where all segments are cast in the same place in a stationary form, and against the previously cast segment. After casting and initial curing, the previously cast segment isremoved for storage, and the freshly cast segment is moved into place.11.9.1.4 Geometry ControlA pure translation of each segment between cast and match-cast position results in a straight bridge(Figure 11.45). To obtain a bridge with a vertical curve, the match-cast segment must ﬁrst be translated and given a rotation in the vertical plane (Figure 11.46). Practically, the bulkhead is left ﬁxed and the mold bottom under the conjugate unit adjusted. To obtain a horizontal curvature, the conjugate unit is given a rotation in the horizontal plane (see Figure 11.47). To obtain a variable superelevation, the conjugate unit is rotated around a horizontal axis located in the middle of the top slab (Figure 11.48).All these adjustments of the conjugate unit can be combined to obtain the desired geometry of the bridge.11.9.2 ErectionThe type of erection equipment depends upon the erection scheme contemplated during the design process; the local conditions, either over water or land; the speed of erection and overall construction schedule. It falls into three categories, independent lifting equipment such as cranes,deck-mounted lifting equipment such as beam and winch or swivel crane, and launching girder equipment.The principle of the method is to erect or cast the pier segment ﬁrst, then to place typical segments one by one from each side of the pier, or in pairs simultaneously from both sides. Each newly placed precast segment is ﬁxed to the previous one with temporary PT bars, until the cantilever tendons are installed and stressed. The closure joint between cantilever tips is poured in place and continuity tendons installed and stressed.In order to carry out this erection scheme, segments must be lifted and installed at the proper location. The simplest way is to use a crane, either on land or barge mounted. Many bridges have Bridge with superelevation.been erected with cranes as they do not require an investment in special lifting equipment. This method is slow. Typically, two to four segments per day are placed. It is used on relatively short bridges. An alternative is to have a winch on the last segment erected. The winch is mounted on a beam ﬁxed to the segment. It picks up segments from below, directly from truck or barge. After placing the segment, the beam and winch system is moved forward to pick up the next segment and so on. Usually, a beam-and-winch system is placed on each cantilever tip. This method is also slow; however, it does not require a heavy crane on the site, which is always very expensive, especially if the segments are heavy.When bridges are long and the erection schedule short, the best method is the use of launching girders, which then take full advantage of the precast segmental concept for speed of erection.There are two essential types of self-launching gantries developed for this erection method. The ﬁrst type is a gantry with a length slightly longer than the typical span (see Figure 11.49). During erection of the cantilever, the center leg rests on the pier while the rear leg rests on the cantilever tip of the previously erected span, which must resist the corresponding reaction. Prior to launching,the back spans must be made continuous. Then, the center leg is moved to the forward cantilever tip, which must resist the weight of the gantry plus the weight of the pier segment.This stage controls the design of the gantry, which must be made as light as possible, and of the cantilever.The second type of gantry has a length that is twice that of the typical span (see Figure 11.50).The reaction from the legs during the erection and launching of the next span is always applied on the piers, so there is no concentrated erection load on the cantilever tip. Each erection cycle consists of the erection of all typical segments of the cantilever and then the placement of the pier segment for the next cantilever, without changing the position of the truss.The gantries can be categorized by their cross section: single truss, with portal-type legs, and two launching trusses with a gantry across. The twin box girders of the bridge in Hawaii were built with two parallel, but independent trusses (see Figure 11.51), with a typical span of 100.0 m, segmentweights of 70 tons; the two bridge structures are 27.5 m apart with different elevations and longi-tudinal slopes. This system is a reﬁnement of the ﬁrst type of gantry applied to twin decks with variable geometry.Normally, the balanced cantilever method is used for spans from 60 to 110 m, with a launching girder. One full, typical cycle of erection is placing segments, installing and stressing post-tensioning tendons, and launching the truss to its next position. It takes about 7 to 10 days, but may vary greatly according to the speciﬁcs of a project and the sophistication of the launching girder. With proper equipment and planning, erection of 16 segments per day has been achieved.译文11.7.4 挠度11.7.4.1 恒载和徐变部分箱梁的整体变形是由恒载和后加张力造成的，也包括在设计过程中用电脑分析软件正常算出的徐变的长期影响。

桥梁毕业设计外文原文及翻译

外文文献翻译BRIDGE ENGINEERING AND AESTHETICSEvolvement of bridge Engineering,brief reviewAmong the early documented reviews of construction materials and structure types are the books of Marcus Vitruvios Pollio in the first century B.C.The basic principles of statics were developed by the Greeks , and were exemplified in works and applications by Leonardo da Vinci,Cardeno,and Galileo.In the fifteenth and sixteenth century, engineers seemed to be unaware of this record , and relied solely on experience and tradition for building bridges and aqueducts .The state of the art changed rapidly toward the end of the seventeenth century when Leibnitz, Newton, and Bernoulli introduced mathematical formulations. Published works by Lahire (1695)and Belidor (1792) about the theoretical analysis of structures provided the basis in the field of mechanics of materials .Kuzmanovic(1977) focuses on stone and wood as the first bridge-building materials. Iron was introduced during the transitional period from wood to steel .According to recent records , concrete was used in France as early as 1840 for a bridge 39 feet (12 m) long to span the Garoyne Canal at Grisoles, but reinforced concrete was not introduced in bridge construction until the beginning of this century . Prestressed concrete was first used in 1927.Stone bridges of the arch type (integrated superstructure and substructure) were constructed in Rome and other European cities in the middle ages . These arches were half-circular , with flat arches beginning to dominate bridge work during the Renaissance period. This concept was markedly improved at the end of the eighteenth century and found structurally adequate to accommodate future railroad loads . In terms of analysis and use of materials , stone bridges have not changed much ,but the theoretical treatment was improved by introducing the pressure-line concept in the early 1670s(Lahire, 1695) . The arch theory was documented in model tests where typical failure modes were considered (Frezier,1739).Culmann(1851) introduced the elastic center method for fixed-end arches, and showed that three redundant parameters can be found by the use of three equations of coMPatibility.Wooden trusses were used in bridges during the sixteenth century when Palladio built triangular frames for bridge spans 10 feet long . This effort also focused on the three basic principles og bridge design : convenience(serviceability) ,appearance , and endurance(strength) . several timber truss bridges were constructed in western Europe beginning in the 1750s with spans up to 200 feet (61m) supported on stone substructures .Significant progress was possible in the United States and Russia during the nineteenth century ,prompted by the need to cross major rivers and by an abundance of suitable timber . Favorable economic considerations included initial low cost and fast construction .The transition from wooden bridges to steel types probably did not begin until about 1840 ,although the first documented use of iron in bridges was the chain bridge built in 1734 across the Oder River in Prussia . The first truss completely made of iron was in 1840 in the United States , followed by England in 1845 , Germany in 1853 , and Russia in 1857 . In 1840 , the first iron arch truss bridge was built across the Erie Canal at Utica .The Impetus of AnalysisThe theory of structuresThe theory of structures ,developed mainly in the ninetheenth century,focused on truss analysis, with the first book on bridges written in 1811. The Warren triangular truss was introduced in 1846 ,supplemented by a method for calculating the correcet forces .I-beams fabricated from plates became popular in England and were used in short-span bridges.In 1866, Culmann explained the principles of cantilever truss bridges, and one year later the first cantilever bridge was built across the Main River in Hassfurt, Germany, with a center span of 425 feet (130m) . The first cantilever bridge in the United States was built in 1875 across the Kentucky River.A most impressive railway cantilever bridge in the nineteenth century was the First of Forth bridge , built between 1883 and 1893 , with span magnitudes of 1711 feet (521.5m). At about the same time , structural steel was introduced as a prime material in bridge work , although its quality was often poor . Several early examples are the Eads bridge in St.Louis ; the Brooklyn bridge in New York ; and the Glasgow bridge in Missouri , all completed between 1874 and 1883.Among the analytical and design progress to be mentioned are the contributions of Maxwell , particularly for certain statically indeterminate trusses ; the books by Cremona (1872) on graphical statics; the force method redefined by Mohr; and the works by Clapeyron who introduced the three-moment equations.The Impetus of New MaterialsSince the beginning of the twentieth century , concrete has taken its place as one of the most useful and important structural materials . Because of the coMParative ease with which it can be molded into any desired shape , its structural uses are almost unlimited . Wherever Portland cement and suitable aggregates are available , it can replace other materials for certain types of structures, such as bridge substructure and foundation elements .In addition , the introduction of reinforced concrete in multispan frames at the beginning of this century imposed new analytical requirements . Structures of a high order of redundancy could not be analyzed with the classical methods of the nineteenth century .The importance of joint rotation was already demonstrated by Manderla (1880) and Bendixen (1914) , who developed relationships between joint moments and angular rotations from which the unknown moments can be obtained ,the so called slope-deflection method .More simplifications in frame analysis were made possible by the work of Calisev (1923) , who used successive approximations to reduce the system of equations to one simple expression for each iteration step . This approach was further refined and integrated by Cross (1930) in what is known as the method of moment distribution .One of the most import important recent developments in the area of analytical procedures is the extension of design to cover the elastic-plastic range , also known as load factor or ultimate design. Plastic analysis was introduced with some practical observations by Tresca (1846) ; and was formulated by Saint-Venant (1870) , The concept of plasticity attracted researchers and engineers after World War Ⅰ, mainly in Germany , with the center of activity shifting to England and the United States after World War Ⅱ.The probabilistic approach is a new design concept that is expected to replace the classical deterministic methodology.A main step forward was the 1969 addition of the Federal Highway Adiministration (FHWA)”Criteria for Reinforced Concrete Bridge Members “ that covers strength and serviceability at ultimate design . This was prepared for use in conjunction with the 1969 American Association of State Highway Offficials (AASHO) Standard Specification, and was presented in a format that is readily adaptable to the development of ultimate design specifications .According to this document , the proportioning of reinforced concrete members ( including columns ) may be limited by various stages of behavior : elastic , cracked , andultimate . Design axial loads , or design shears . Structural capacity is the reaction phase , and all calculated modified strength values derived from theoretical strengths are the capacity values , such as moment capacity ,axial load capacity ,or shear capacity .At serviceability states , investigations may also be necessary for deflections , maximum crack width , and fatigue . Bridge TypesA notable bridge type is the suspension bridge , with the first example built in the United States in 1796. Problems of dynamic stability were investigated after the Tacoma bridge collapse , and this work led to significant theoretical contributions Steinman ( 1929 ) summarizes about 250 suspension bridges built throughout the world between 1741 and 1928 .With the introduction of the interstate system and the need to provide structures at grade separations , certain bridge types have taken a strong place in bridge practice. These include concrete superstructures (slab ,T-beams,concrete box girders ), steel beam and plate girders , steel box girders , composite construction , orthotropic plates , segmental construction , curved girders ,and cable-stayed bridges . Prefabricated members are given serious consideration , while interest in box sections remains strong .Bridge Appearance and AestheticsGrimm ( 1975 ) documents the first recorded legislative effort to control the appearance of the built environment . This occurred in 1647 when the Council of New Amsterdam appointed three officials . In 1954 , the Supreme Court of the United States held that it is within the power of the legislature to determine that communities should be attractive as well as healthy , spacious as well as clean , and balanced as well as patrolled . The Environmental Policy Act of 1969 directs all agencies of the federal government to identify and develop methods and procedures to ensure that presently unquantified environmental amentities and values are given appropriate consideration in decision making along with economic and technical aspects .Although in many civil engineering works aesthetics has been practiced almost intuitively , particularly in the past , bridge engineers have not ignored or neglected the aesthetic disciplines .Recent research on the subject appears to lead to a rationalized aesthetic design methodology (Grimm and Preiser , 1976 ) .Work has been done on the aesthetics of color ,light ,texture , shape , and proportions , as well as other perceptual modalities , and this direction is both theoretically and empirically oriented .Aesthetic control mechanisms are commonly integrated into the land-use regulations and design standards . In addition to concern for aesthetics at the state level , federal concern focuses also on the effects of man-constructed environment on human life , with guidelines and criteria directed toward improving quality and appearance in the design process . Good potential for the upgrading of aesthetic quality in bridge superstructures and substructures can be seen in the evaluation structure types aimed at improving overall appearance .LOADS AND LOADING GROUPSThe loads to be considered in the design of substructures and bridge foundations include loads and forces transmitted from the superstructure, and those acting directly on the substructure and foundation .AASHTO loads . Section 3 of AASHTO specifications summarizes the loads and forces to be considered in the design of bridges (superstructure and substructure ) . 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 , shrinkage andlong term creep , rib shortening , erection stresses , ice and current pressure , collision force , and earthquake stresses .Besides these conventional loads that are generally quantified , AASHTO also recognizes indirect load effects such as friction at expansion bearings and stresses associated with differential settlement of bridge components .The LRFD specifications divide loads into two distinct categories : permanent and transient .Permanent loadsDead Load : this includes the weight DC of all bridge components , appurtenances and utilities, wearing surface DW and future overlays , and earth fill EV. Both AASHTO and LRFD specifications give tables summarizing the unit weights of materials commonly used in bridge work .Transient LoadsVehicular Live Load (LL)Vehicle loading for short-span bridges :considerable effort has been made in the United States and Canada to develop a live load model that can represent the highway loading more realistically than the H or the HS AASHTO models . The current AASHTO model is still the applicable loading.桥梁工程和桥梁美学桥梁工程的发展概况早在公元前1世纪，Marcus Vitrucios Pollio 的著作中就有关于建筑材料和结构类型的记载和评述。

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