预应力混凝土连续梁毕业设计含外文翻译
土木工程结构设计专业毕业设计英语翻译
XXXXXXXXX学院学士学位毕业设计（论文）英语翻译课题名称英语翻译学号学生专业、年级所在院系指导教师选题时间目录1、第一篇 (3)2、第二篇 (6)3、第三篇 (9)Concrete, Reinforced Concrete, and PrestressedConcreteConcrete is a stone like material obtained by permitting a carefully proportioned mixture of cement, sand and gravel or other aggregate, and water to harden in forms of the shape and dimensions of the desired structure. The bulk of the material consists of fine and coarse aggregate. Cement and water interact chemically to bind the aggregate particles into a solid mass. Additional water, over and above that needed for this chemical reaction, is necessary to give the mixture workability that enables it to fill the forms and surround the embedded reinforcing steel prior to hardening. Concretes with a wide range of properties can be obtained by appropriates adjustment of the proportions of the constituent materials. Special cements, special aggregates, and special curing methods permit an even wider variety of properties to be obtained.These properties depend to a very substantial degree on the proportions of the mix, on the thoroughness with which the various constituents are intermixed, and on the conditions of humidity and temperature in which the mix is maintained from the moment it is placed in the forms of humidity and hardened. The process of controlling conditions after placement is known as curing. To protect against the unintentional production of substandard concrete, a high degree of skillful control and supervision is necessary throughout the process, from the proportioning by weight of the individual components, trough mixing and placing, until the completion of curing.The factors that make concrete a universal building material are so pronounced that it has been used, in more primitive kinds and ways than at present, for thousands of years, starting with lime mortars from 12,000 to 600 B.C. in Crete, Cyprus, Greece, and the Middle East. The facility with which , while plastic, it can be deposited and made to fill forms or molds of almost any practical shape is one of these factors. Its high fire and weather resistance are evident advantages. Most of the constituent materials, with the exception of cement and additives, are usually available at low cost locally or at small distances from the construction site. Its compressive strength, like that of natural stones, is high, which makes it suitable for members primarily subject to compression, such as columns and arches. On the other hand, again as in natural stones, it is a relatively brittle material whose tensile strength is small compared with its compressive strength. This prevents its economical use in structural members that ate subject to tension either entirely or over part of their cross sections.To offset this limitation, it was found possible, in the second half of thenineteenth century, to use steel with its high tensile strength to reinforce concrete, chiefly in those places where its low tensile strength would limit the carrying capacity of the member. The reinforcement, usually round steel rods with appropriate surface deformations to provide interlocking, is places in the forms in advance of the concrete. When completely surrounded by the hardened concrete mass, it forms an integral part of the member. The resulting combination of two materials, known as reinforced concrete, combines many of the advantages of each: the relatively low cost , good weather and fire resistance, good compressive strength, and excellent formability of concrete and the high tensile strength and much greater ductility and toughness of steel. It is this combination that allows the almost unlimited range of uses and possibilities of reinforced concrete in the construction of buildings, bridges, dams, tanks, reservoirs, and a host of other structures.In more recent times, it has been found possible to produce steels, at relatively low cost, whose yield strength is 3 to 4 times and more that of ordinary reinforcing steels. Likewise, it is possible to produce concrete 4 to 5 times as strong in compression as the more ordinary concrete. These high-strength materials offer many advantages, including smaller member cross sections, reduced dead load, and longer spans. However, there are limits to the strengths of the constituent materials beyond which certain problems arise. To be sure, the strength of such a member would increase roughly in proportion to those of the materials. However, the high strains that result from the high stresses that would otherwise be permissible would lead to large deformations and consequently large deflections of such member under ordinary loading conditions. Equally important, the large strains in such high-strength reinforcing steel would induce large cracks in the surrounding low tensile strength concrete, cracks that would not only be unsightly but that could significantly reduce the durability of the structure. This limits the useful yield strength of high-strength reinforcing steel to 80 ksi according to many codes and specifications; 60 ksi steel is most commonly used.A special way has been found, however, to use steels and concrete of very high strength in combination. This type of construction is known as prestressed concrete. The steel, in the form of wires, strands, or bars, is embedded in the concrete under high tension that is held in equilibrium by compressive stresses in the concrete after hardening, Because of this precompression, the concrete in a flexural member will crack on the tension side at a much larger load than when not so precompressed. Prestressing greatly reduces both the deflections and the tensile cracks at ordinaryloads in such structures, and thereby enables these high-strength materials to be used effectively. Prestressed concrete has extended, to a very significant extent, the range of spans of structural concrete and the types of structures for which it is suited.混凝土，钢筋混凝土和预应力混凝土混凝土是一种经过水泥，沙子和砂砾或其他材料聚合得到经过细致配比的混合物，在液体变硬使材料石化后可以得到理想的形状和结构尺寸。
预应力混凝土Prestressed-Concrete大学毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：预应力混凝土文献、资料英文题目：Prestressed Concrete文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14毕业设计（论文）外文资料翻译外文出处：The Concrete structure附件：1、外文原文；2、外文资料翻译译文。
1、外文资料原文Prestressed ConcreteConcrete is strong in compression, but weak in tension: Its tensile strength varies from 8 to 14 percent of its compressive strength. Due tosuch a Iow tensile capacity, fiexural cracks develop at early stages ofloading. In order to reduce or prevent such cracks from developing, aconcentric or eccentric force is imposed in the longitudinal direction of the structural element. This force prevents the cracks from developing by eliminating or considerably reducing the tensile stresses at thecritical midspan and support sections at service load, thereby raising the bending, shear, and torsional capacities of the sections. The sections are then able to behave elastically, and almost the full capacity of the concrete in compression can be efficiently utilized across the entire depth of the concrete sections when all loads act on the structure.Such an imposed longitudinal force is called a prestressing force,i.e., a compressive force that prestresses the sections along the span ofthe structural elementprior to the application of the transverse gravitydead and live loads or transient horizontal live loads. The type ofprestressing force involved, together with its magnitude, are determined mainly on the basis of the type of system to be constructed and the span length and slenderness desired.~ Since the prestressing force is applied longitudinally along or parallel to the axis of the member, the prestressing principle involved is commonly known as linear prestressing.Circular prestressing, used in liquid containment tanks, pipes,and pressure reactor vessels, essentially follows the same basic principles as does linear prestressing. The circumferential hoop, or "hugging" stress on the cylindrical or spherical structure, neutralizes the tensile stresses at the outer fibers of the curvilinear surface caused by the internal contained pressure.Figure 1.2.1 illustrates, in a basic fashion, the prestressing action in both types of structural systems and the resulting stress response. In(a), the individual concrete blocks act together as a beam due to the large compressive prestressing force P. Although it might appear that the blocks will slip and vertically simulate shear slip failure, in fact they will not because of the longitudinal force P. Similarly, the wooden staves in (c) might appear to be capable of separating as a result of the high internal radial pressure exerted on them. But again, because of the compressive prestress imposed by the metal bands as a form of circular prestressing, they will remain in place.From the preceding discussion, it is plain that permanent stresses in the prestressed structural member are created before the full dead and live loads are applied in order to eliminate or considerably reduce the net tensile stresses caused by these loads. With reinforced concrete,it is assumed that the tensile strength of the concrete is negligible and disregarded. This is because the tensile forces resulting from the bending moments are resisted bythe bond created in the reinforcement process. Cracking and deflection are therefore essentially irrecoverable in reinforced concrete once the member has reached its limit state at service load.The reinforcement in the reinforced concrete member does not exert any force of its own on the member, contrary to the action of prestressing steel. The steel required to produce the prestressing force in the prestressed member actively preloads the member, permitting a relatively high controlled recovery of cracking and deflection. Once the flexural tensile strength of the concrete is exceeded, the prestressed member starts to act like a reinforced concrete element.Prestressed members are shallower in depth than their reinforced concrete counterparts for the same span and loading conditions. In general, the depth of a prestressed concrete member is usually about 65 to 80 percent of the depth of the equivalent reinforced concrete member. Hence, the prestressed member requires less concrete, and,about 20 to 35 percent of the amount of reinforcement. Unfortunately, this saving in material weight is balanced by the higher cost of the higher quality materials needed in prestressing. Also, regardless of the system used, prestressing operations themselves result in an added cost: Formwork is more complex, since the geometry of prestressed sections is usually composed of. flanged sections with thin-webs.In spite of these additional costs, if a large enough number of precast units are manufactured, the difference between at least the initial costs of prestressed and reinforced concrete systems is usually not very large.~ And the indirect long-term savings are quite substantial, because less maintenance is needed; a longer working life is possible due to better quality control of the concrete, and lighter foundations are achieved due to the smaller cumulative weight of the superstructure.Once the beam span of reinforced concrete exceeds 70 to 90 feet (21.3 to 27.4m), the dead weight of the beam becomes excessive, resulting in heavier members and, consequently, greater long-term deflection and cracking. Thus, for larger spans, prestressed concrete becomes mandatory since arches are expensive to construct and do not perform as well due to the severe long-term shrinkage and creep they undergo.~ Very large spans such as segmental bridges or cable-stayed bridges can only be constructed through the use of prestressing.Prestressd concrete is not a new concept, dating back to 1872, when P. H. Jackson, an engineer from California, patented a prestressing system that used a tie rod to construct beams or arches from individual blocks [see Figure 1.2.1 (a)]. After a long lapse of time during which little progress was made because of the unavailability of high-strength steel to overcome prestress losses, R. E. Dill of Alexandria, Nebraska, recognized the effect of the shrinkage and creep (transverse material flow) of concrete on the loss of prestress. He subsequently developed the idea that successive post-tensioning of unbonded rods would compensate for the time-dependent loss of stress in the rods due to the decrease in the length of the member because of creep and shrinkage. In the early 1920s,W. H. Hewett of Minneapolis developed the principles of circular prestressing. He hoop-stressed horizontal reinforcement around walls of concrete tanks through the use of turnbuckles to prevent cracking due to internalliquid pressure, thereby achieving watertightness. Thereafter, prestressing of tanks and pipes developed at an accelerated pace in the United States, with thousands of tanks for water, liquid, and gas storage built and much mileage of prestressed pressure pipe laid in the two to three decades that followed.Linear prestressing continued to develop in Europe and in France, in particular through the ingenuity of Eugene Freyssinet, who proposed in 1926--1928 methods to overcome prestress losses through the use of high-strength and high-ductility steels. In 1940, he introduced thenow well-known and well-accepted Freyssinet system.P. W. Abeles of England introduced and developed the concept of partial prestressing between the 1930s and 1960s. F. Leonhardt of Germany, V. Mikhailov of Russia, and T. Y. Lin of the United States also contributed a great deal to the art and science of the design of prestressed concrete. Lin's load-balancing method deserves particular mention in this regard, as it considerably simplified the design process, particularly in continuous structures. These twentieth-century developments have led to the extensive use of prestressing throughoutthe world, and in the United States in particular.Today, prestressed concrete is used in buildings, underground structures, TV towers, floating storage and offshore structures, power stations, nuclear reactor vessels, and numerous types of bridge systems including segn~ental and cable-stayed bridges, they demonstrate the versatility of the prestressing concept and its all-encompassing application. The success in the development and construction of all these structures has been due in no small measures to the advances in the technology of materials, particularly prestressing steel, and the accumulated knowledge in estimating the short-and long-term losses in the prestressing forces.~2、外文资料翻译译文预应力混凝土混凝土的力学特性是抗压不抗拉：它的抗拉强度是抗压强度的8％一14％。
预应力混凝土梁桥设计外文文献翻译
预应力混凝土梁桥设计外文文献翻译(文档含中英文对照即英文原文和中文翻译)原文：Analysis of Con tin uous Prestressed Concrete BeamsChris Burgoyne1、IntroductionThis conference is devoted to the development of structural analysis rather than the strength of materials, but the effective use of prestressed concrete relies on an appropriate combination of structural analysis techniques with knowledge of the material behaviour. Design of prestressed concrete structures is usually left to specialists; the unwary will either make mistakes or spend inordinate time trying to extract a solution from the various equations.There are a number of fundamental differences between the behaviour of prestressed concrete and that of other materials. Structures are not unstressed when unloaded; the design space of feasible solutions is totally bounded；in hyperstatic structures, various states of self-stress can be induced by altering the cable profile, and all of these factors get influenced by creep and thermal effects. How were these problemsrecognised and how have they been tackled?Ever since the development of reinforced concrete by Hennebique at the end of the 19th century (Cusack 1984), it was recognised that steel and concrete could be more effectively combined if the steel was pretensioned, putting the concrete into compression. Cracking could be reduced, if not prevented altogether, which would increase stiffness and improve durability. Early attempts all failed because the initial prestress soon vanished, leaving the structure to be- have as though it was reinforced; good descriptions of these attempts are given by Leonhardt (1964) and Abeles (1964).It was Freyssineti’s observations of the sagging o f the shallow arches on three bridges that he had just completed in 1927 over the River Allier near Vichy which led directly to prestressed concrete (Freyssinet 1956). Only the bridge at Boutiron survived WWII (Fig 1). Hitherto, it had been assumed that concrete had a Young’s modulus which remained fixed, but he recognised that the de- ferred strains due to creep explained why the prestress had been lost in the early trials. Freyssinet (Fig. 2) also correctly reasoned that high tensile steel had to be used, so that some prestress would remain after the creep had occurred, and also that high quality concrete should be used, since this minimised the total amount of creep. The history of Freyssineti’s early prestressed concrete work is written elsewhereFigure1:Boutiron Bridge,Vic h yFigure 2: Eugen FreyssinetAt about the same time work was underway on creep at the BRE laboratory in England ((Glanville 1930) and (1933)). It is debatable which man should be given credit for the discovery of creep but Freyssinet clearly gets the credit for successfully using the knowledge to prestress concrete.There are still problems associated with understanding how prestressed concrete works, partly because there is more than one way of thinking about it. These different philosophies are to some extent contradictory, and certainly confusing to the young engineer. It is also reflected, to a certain extent, in the various codes of practice.Permissible stress design philosophy sees prestressed concrete as a way of avoiding cracking by eliminating tensile stresses; the objective is for sufficient compression to remain after creep losses. Untensioned reinforcement, which attracts prestress due to creep, is anathema. This philosophy derives directly from Freyssinet’s logic and is primarily a working stress concept.Ultimate strength philosophy sees prestressing as a way of utilising high tensile steel as reinforcement. High strength steels have high elastic strain capacity, which could not be utilised when used as reinforcement; if the steel is pretensioned, much of that strain capacity is taken out before bonding the steel to the concrete. Structures designed this way are normally designed to be in compression everywhere under permanent loads, but allowed to crack under high live load. The idea derives directly from the work of Dischinger (1936) and his work on the bridge at Aue in 1939 (Schonberg and Fichter 1939), as well as that of Finsterwalder (1939). It is primarily an ultimate load concept. The idea of partial prestressingderives from these ideas.The Load-Balancing philosophy, introduced by T.Y. Lin, uses prestressing to counter the effect of the permanent loads (Lin 1963). The sag of the cables causes an upward force on the beam, which counteracts the load on the beam. Clearly, only one load can be balanced, but if this is taken as the total dead weight, then under that load the beam will perceive only the net axial prestress and will have no tendency to creep up or down.These three philosophies all have their champions, and heated debates take place between them as to which is the most fundamental.2、Section designFrom the outset it was recognised that prestressed concrete has to be checked at both the working load and the ultimate load. For steel structures, and those made from reinforced concrete, there is a fairly direct relationship between the load capacity under an allowable stress design, and that at the ultimate load under an ultimate strength design. Older codes were based on permissible stresses at the working load; new codes use moment capacities at the ultimate load. Different load factors are used in the two codes, but a structure which passes one code is likely to be acceptable under the other.For prestressed concrete, those ideas do not hold, since the structure is highly stressed, even when unloaded. A small increase of load can cause some stress limits to be breached, while a large increase in load might be needed to cross other limits. The designer has considerable freedom to vary both the working load and ultimate load capacities independently; both need to be checked.A designer normally has to check the tensile and compressive stresses, in both the top and bottom fibre of the section, for every load case. The critical sections are normally, but not always, the mid-span and the sections over piers but other sections may become critical ，when the cable profile has to be determined.The stresses at any position are made up of three components, one of which normally has a different sign from the other two; consistency of sign convention is essential.If P is the prestressing force and e its eccentricity, A and Z are the area of the cross-section and its elastic section modulus, while M is the applied moment, then where ft and fc are the permissible stresses in tension and compression.c e t f ZM Z P A P f ≤-+≤Thus, for any combination of P and M , the designer already has four in- equalities to deal with.The prestressing force differs over time, due to creep losses, and a designer is usually faced with at least three combinations of prestressing force and moment;• the applied moment at the time the prestress is first applied, before creep losses occur,• the maximum applied moment after creep losses, and• the minimum applied moment after creep losses.Figure 4: Gustave MagnelOther combinations may be needed in more complex cases. There are at least twelve inequalities that have to be satisfied at any cross-section, but since an I-section can be defined by six variables, and two are needed to define the prestress, the problem is over-specified and it is not immediately obvious which conditions are superfluous. In the hands of inexperienced engineers, the design process can be very long-winded. However, it is possible to separate out the design of the cross-section from the design of the prestress. By considering pairs of stress limits on the same fibre, but for different load cases, the effects of the prestress can be eliminated, leaving expressions of the form:rangestress e Permissibl Range Moment ≤Z These inequalities, which can be evaluated exhaustively with little difficulty, allow the minimum size of the cross-section to be determined.Once a suitable cross-section has been found, the prestress can be designed using a construction due to Magnel (Fig.4). The stress limits can all be rearranged into the form:()M fZ P A Z e ++-≤1By plotting these on a diagram of eccentricity versus the reciprocal of the prestressing force, a series of bound lines will be formed. Provided the inequalities (2) are satisfied, these bound lines will always leave a zone showing all feasible combinations of P and e. The most economical design, using the minimum prestress, usually lies on the right hand side of the diagram, where the design is limited by the permissible tensile stresses.Plotting the eccentricity on the vertical axis allows direct comparison with the crosssection, as shown in Fig. 5. Inequalities (3) make no reference to the physical dimensions of the structure, but these practical cover limits can be shown as wellA good designer knows how changes to the design and the loadings alter the Magnel diagram. Changing both the maximum and minimum bending moments, but keeping the range the same, raises and lowers the feasible region. If the moments become more sagging the feasible region gets lower in the beam.In general, as spans increase, the dead load moments increase in proportion to the live load. A stage will be reached where the economic point (A on Fig.5) moves outside the physical limits of the beam; Guyon (1951a) denoted the limiting condition as the critical span. Shorter spans will be governed by tensile stresses in the two extreme fibres, while longer spanswill be governed by the limiting eccentricity and tensile stresses in the bottom fibre. However, it does not take a large increase in moment ，at which point compressive stresses will govern in the bottom fibre under maximum moment.Only when much longer spans are required, and the feasible region moves as far down as possible, does the structure become governed by compressive stresses in both fibres.3、Continuous beamsThe design of statically determinate beams is relatively straightforward; the engineer can work on the basis of the design of individual cross-sections, as outlined above. A number of complications arise when the structure is indeterminate which means that the designer has to consider, not only a critical section,but also the behaviour of the beam as a whole. These are due to the interaction of a number of factors, such as Creep, Temperature effects and Construction Sequence effects. It is the development of these ideas which forms the core of this paper. The problems of continuity were addressed at a conference in London (Andrew and Witt 1951). The basic principles, and nomenclature, were already in use, but to modern eyes concentration on hand analysis techniques was unusual, and one of the principle concerns seems to have been the difficulty of estimating losses of prestressing force.3.1 Secondary MomentsA prestressing cable in a beam causes the structure to deflect. Unlike the statically determinate beam, where this motion is unrestrained, the movement causes a redistribution of the support reactions which in turn induces additional moments. These are often termed Secondary Moments, but they are not always small, or Parasitic Moments, but they are not always bad.Freyssinet’s bridge across the Marne at Luzancy, started in 1941 but not completed until 1946, is often thought of as a simply supported beam, but it was actually built as a two-hinged arch (Harris 1986), with support reactions adjusted by means of flat jacks and wedges which were later grouted-in (Fig.6). The same principles were applied in the later and larger beams built over the same river.Magnel built the first indeterminate beam bridge at Sclayn, in Belgium (Fig.7) in 1946. The cables are virtually straight, but he adjusted the deck profile so that the cables were close to the soffit near mid-span. Even with straight cables the sagging secondary momentsare large; about 50% of the hogging moment at the central support caused by dead and live load.The secondary moments cannot be found until the profile is known but the cable cannot be designed until the secondary moments are known. Guyon (1951b) introduced the concept of the concordant profile, which is a profile that causes no secondary moments; es and ep thus coincide. Any line of thrust is itself a concordant profile.The designer is then faced with a slightly simpler problem; a cable profile has to be chosen which not only satisfies the eccentricity limits (3) but isalso concordant. That in itself is not a trivial operation, but is helped by the fact that the bending moment diagram that results from any load applied to a beam will itself be a concordant profile for a cable of constant force. Such loads are termed notional loads to distinguish them from the real loads on the structure. Superposition can be used to progressively build up a set of notional loads whose bending moment diagram gives the desired concordant profile.3.2 Temperature effectsTemperature variations apply to all structures but the effect on prestressed concrete beams can be more pronounced than in other structures. The temperature profile through the depth of a beam (Emerson 1973) can be split into three components for the purposes of calculation (Hambly 1991). The first causes a longitudinal expansion, which is normally released by the articulation of the structure; the second causes curvature which leads to deflection in all beams and reactant moments in continuous beams, while the third causes a set of self-equilibrating set of stresses across the cross-section.The reactant moments can be calculated and allowed-for, but it is the self- equilibrating stresses that cause the main problems for prestressed concrete beams. These beams normally have high thermal mass which means that daily temperature variations do not penetrate to the core of the structure. The result is a very non-uniform temperature distribution across the depth which in turn leads to significant self-equilibrating stresses. If the core of the structure is warm, while the surface is cool, such as at night, then quite large tensile stresses can be developed on the top and bottom surfaces. However, they only penetrate a very short distance into the concrete and the potential crack width is very small. It can be very expensive to overcome the tensile stress by changing the section or the prestress。
外文翻译中英文——预应力混凝土建筑
外文资料：Prestressed Concrete BuildingsPrestressed concrete has been widely and successfully applied to building construction of all types.Both precast pretensioned members and cast-tensioned structures are extensively employed,sometimes in competition with one another, most effectively in combination wit each other.Prestressed concrete offers great advantages for incorporation in a totalaspects of these, that is, structure plus other building. It is perhaps the “integrative”functions,which have made possible the present growth in use of prestressed concrete buildings.These advantages include the following:Structural strength; Structure rigidity;Durability;Mold ability,into desired forms and shapes;Fire resistance;Architectural treatment of surfaces;Sound insulation;Heat insulation; Economy; Availability, through use of local materials and labor to a high degree.Most of the above are also properties of conventionally reinforced concrete. Presrressing,however,makes the structural system more effective by enabling elimination of the technical of difficulty,e.g.,cracks that spoil the architectural treatment.Prestressing greatly enhance the structure efficiency and economy permitting longer spans and thinner elements.Above all,it gives to the architect-engineer a freedom for variation and an ability to control behavior under service conditions.Although prestressed concrete construction involves essentially the same consideration and practices as for all structures, a number of special points require emphasis or elaboration.The construction engineer is involved in design only to a limited extent. First,he muse be able to furnish advice to the architect and engineer on what can he done. Because of his specialized knowledge of techniques relating to prestressed concrete construction, he supplies a very needed service to the architect-engineer.Second, the construction engineer may be made contractually responsible for the working drawings;that is,the layout of tendons,anchorage details,etc.It is particularly important that he gives careful attention to the mild steel and concrete details to ensure these are compatible with his presressing details.Third, the construction engineer is concerned with temporary stresses, stresses at release, stresses in picking, handling and erection, and temporary condition prior to final completion of the structure, such as the need of propping for a composite pour.Fourth,although the responsibility for design rests with the design engineer, nevertheless the construction engineer is also vitally concerned that the structure be successful form the point of view of structural integrity and service behavior. Therefore he will want to look at the bearing and connection details, camber, creep, shrinkage,thermal movements,durability provisions,etc.,and advise the design engineer of any deficiencies he encounters.Information on new techniques and especially application of prestressing to buildings are extensively available in the current technical literature of national and international societies.The International Federation of Prestressing(I.F.P)has attempted to facilitate the dissemination of this information by establishing a Literature Exchange Service,in which the prestressing journals of some thirty countries are regularly exchanged.In addition,an Abstract is published intermittently by I.F.P The Prestressed Concrete Institute(USA)regularly publishes a number of journals and pamphlets on techniques and applications, and proceduresare set up for their dissemination to architects and engineers as well as directly to the construction engineer. It is important that he keep abreast of these national and worldwide developments, so as to be able to recommend the latest and best that is available in the art,and to encourage the engineer to make the fullest and most effective use of prestressed concrete in their buildings.With regard to working drawings, the construction engineer must endeavor to translate the design requirements into the most practicable and economical details of accomplishment,in such a way that the completed element or structure fully complies with the design requirement;for example, the design may indicate only the center of gravity of prestressing and the effective prestress force. The working drawing will have to translate this into tendons having finite physical properties and dimensions.If the center of gravity of pre-stressing is a parabolic path then,for pre-tensioning,and approximation by chords is required,with hold-down points suitably located.The computation of pre-stress losses,form transfer stress to effective stress, must reflect the actual manufacturing and construction process used,as well as thorough knowledge of the properties of the particular aggregates and concrete mix to be employed.With post-tensioning, anchorages and their bearing plates must be laid out in their physical dimension. It is useful in the preparation of complex anchorage detail layouts to use full-scale drawings, so as to better appreciate the congestion of mild steel and anchorages at the end of the member. Tendons and reinforcing bars should be shown in full size rather than as dotted lines. This will permit consideration to be given as to how the concrete can be placed and consolidated.The end zone of both pre-tensioned and post-tensioned concrete memberssubject to high transverse or bursting stresses. These stresses are also influenced by minor concrete details,such as chamfers.Provision of a grid of small bars (sometimes heavy wire mesh is used), as close to the end of a girder as possible, will help to confine and distribute the concentrated forces. Closely spaced stirrups and/or tightly spaced spiral are usually needed at the end of heavily stressed members.Recent tests have confirmed that closeness of spacing is much more effective than increase in the size of bars. Numerous small bars, closely spaced, are thus the best solution.Additional mild-steel stirrups may also be required at hold-down points to resist the shear. This is also true wherever post-tensioned tendons make sharp bends. Practical consideration of concretion dictates the spacing of tendons and ducts. The general rules are that the clear spacing small be one-and-one-half times the maximum size of coarse aggregate. In the overall section, provision must be made for the vibrator stinger.Thus pre-stressing tendons must either be spaced apart in the horizontal plane, or, in special cases, bundled.In the vertical plane close contact between tendons is quite common.With post-tensioned ducts,however,in intimate vertical contact,careful consideration has to be given to prevent one tendon form squeezing into the adjacent duct during stressing.This depends on the size of duct and the material used for the duct.A full-scale layout of this critical cross section should be ually,the best solution is to increase the thickness ( and transverse strength ) of the duct, so that it will span between the supporting shoulders of concrete.As a last rest\ort it may be necessary to stress and grout one duct before stressing the adjacent one.This is time-consuming and runs the risks of grout blockage due to leaks from one duct to the other. Therefore the author recommendsthe use of heavier duct material,or else the respacing of the ducts.The latter,of course, may increase the prestressing force required.中文翻译：预应力混凝土建筑预应力混凝土已经广泛并成功地用于各种类型的建筑。
桥梁专业毕业设计-连续梁(含外文翻译)
二○一○届毕业设计雀鼠谷大桥设计书学院：公路学院专业：桥梁工程姓名：王萌学号：2102060133指导教师：陈峰完成时间：2010-6-12二〇一〇年六月毕业设计（论文）任务书课题名称雀鼠谷大桥设计学院(部) 公路学院桥梁系专业桥梁工程班级21020601学生姓名王萌学号21020601334月 26日至 6 月 18 日共 10 周指导教师(签字)教学院长(签字)年月日一、设计内容（论文阐述的问题）①根据已给设计资料，选择三至四种以上可行的桥型方案，拟定桥梁结构主要尺寸，根据技术经济比较，推荐最优方案进行全桥的纵、横、平面布置，并合理拟定上、下部结构的细部尺寸。
②根据推荐方案桥型确定桥梁施工方案。
③对推荐桥梁方案进行运营及施工阶段的内力计算，上部结构（束）设计；配筋（束）设计，并进行内力组合，强度、刚度、稳定性等验算。
④施工方案制定，施工验算。
⑤绘制上部结构的方案比选图，总体布置图，一般构造图、钢筋构造图及施工示意图。
⑥编写设计计算书。
二、设计原始资料（实验、研究方案）1、设计桥梁的桥位地型及地质图一份。
2、设计荷载：公路—Ⅰ级3、桥面宽度：：2×（0.5+净—11.5＋0.5）4、抗震烈度： 7级烈度设防5．风荷载：500Pa6、通航要求：无7、温度：最高月平均温度405º最低月平均温度0º施工温度22º 8．平曲线半径：7000米竖曲线半径： 4500米9．纵坡： <=3% 横坡：<=1.5%10．桥头引道填土高度：<=4米主要技术指标①设计依据：JTG D60-2004《公路桥涵设计通用规范》JTJ 022-85《公路砖石及混凝土桥涵设计规范》JTG D62-2004《公路钢筋混凝土及预应力混凝土桥涵设计规范》JTG D62-2004《公路钢筋混凝土及预应力混凝土桥涵设计规范》②材料：混凝土：50号；预应力钢筋：φj15钢绞线非预应力钢筋：直径≥12mm的用Ⅱ级螺纹钢筋，直径<12mm 的用Ⅰ级光圆钢筋；锚具：XM锚或OVM锚三、设计完成后提交的文件和图表（论文完成后提交的文件）1、计算说明书部分：(除附录的计算结果文本外，其余必须手写)设计计算书一套。
土木工程专业钢筋混凝土结构设计毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：钢筋混凝土结构设计文献、资料英文题目：DESIGN OF REINFORCED CONCRETE STRUCTURES 文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：土木工程班级：姓名：学号：指导教师：翻译日期： 2017.02.14毕业设计（论文）外文参考资料及译文译文题目：DESIGN OF REINFORCED CONCRETE STRUCTURES原文：DESIGN OF REINFORCED CONCRETESTRUCTURES1. BASIC CONCERPTS AND CHARACERACTERISTICS OF REINFORCED CONCRETEPlain concrete is formed from hardened mixture of cement, water , fine aggregate , coarse aggregate (crushed stone or gravel ) , air and often other admixtures . The plastic mix is placed and consolidated in the formwork, then cured to accelerate of the chemical hydration of hen cement mix and results in a hardened concrete. It is generally known that concrete has high compressive strength and low resistance to tension. Its tensile strength is approximatelyone-tenth of its compressive strength. Consequently, tensile reinforcement in the tension zone has to be provided to supplement the tensile strength of the reinforced concrete section.For example, a plain concrete beam under a uniformly distributed load q is shown in Fig .1.1(a), when the distributed load increases and reaches a value q=1.37KN/m , the tensile region at the mid-span will be cracked and the beam will fail suddenly . A reinforced concrete beam if the same size but has to steel reinforcing bars (2φ16) embedded at the bottom under a uniformly distributed load q is shown in Fig.1.1(b). The reinforcing bars take up the tension there after the concrete is cracked. When the load q is increased, the width of the cracks, the deflection and thestress of steel bars will increase . When the steel approaches the yielding stress ƒy , thedeflection and the cracked width are so large offering some warning that the compression zone . The failure load q=9.31KN/m, is approximately 6.8 times that for the plain concrete beam.Concrete and reinforcement can work together because there is a sufficiently strong bond between the two materials, there are no relative movements of the bars and the surrounding concrete cracking. The thermal expansion coefficients of the two materials are 1.2×10-5K-1 for steel and 1.0×10-5~1.5×10-5K-1 for concrete .Generally speaking, reinforced structure possess following features :Durability .With the reinforcing steel protected by the concrete , reinforced concreteFig.1.1Plain concrete beam and reinforced concrete beamIs perhaps one of the most durable materials for construction .It does not rot rust , and is not vulnerable to efflorescence .(2)Fire resistance .Both concrete an steel are not inflammable materials .They would not be affected by fire below the temperature of 200℃when there is a moderate amount of concrete cover giving sufficient thermal insulation to the embedded reinforcement bars.(3)High stiffness .Most reinforced concrete structures have comparatively large cross sections .As concrete has high modulus of elasticity, reinforced concrete structures are usuallystiffer than structures of other materials, thus they are less prone to large deformations, This property also makes the reinforced concrete less adaptable to situations requiring certainflexibility, such as high-rise buildings under seismic load, and particular provisions have to be made if reinforced concrete is used.(b)Reinfoced concrete beam(4)Locally available resources. It is always possible to make use of the local resources of labour and materials such as fine and coarse aggregates. Only cement and reinforcement need to be brought in from outside provinces.(5)Cost effective. Comparing with steel structures, reinforced concrete structures are cheaper.(6)Large dead mass, The density of reinforced concrete may reach2400~2500kg/pare with structures of other materials, reinforced concrete structures generally have a heavy dead mass. However, this may be not always disadvantageous, particularly for those structures which rely on heavy dead weight to maintain stability, such as gravity dam and other retaining structure. The development and use of light weight aggregate have to a certain extent make concrete structure lighter.(7)Long curing period.. It normally takes a curing period of 28 day under specified conditions for concrete to acquire its full nominal strength. This makes the progress of reinforced concrete structure construction subject to seasonal climate. The development of factory prefabricated members and investment in metal formwork also reduce the consumption of timber formwork materials.(8)Easily cracked. Concrete is weak in tension and is easily cracked in the tension zone. Reinforcing bars are provided not to prevent the concrete from cracking but to take up the tensile force. So most of the reinforced concrete structure in service is behaving in a cracked state. This is an inherent is subjected to a compressive force before working load is applied. Thus the compressed concrete can take up some tension from the load.2. HISTOEICAL DEVELPPMENT OF CONCRETE STRUCTUREAlthough concrete and its cementitious(volcanic) constituents, such as pozzolanic ash, have been used since the days of Greek, the Romans, and possibly earlier ancient civilization, the use of reinforced concrete for construction purpose is a relatively recent event, In 1801, F. Concrete published his statement of principles of construction, recognizing the weakness if concrete in tension, The beginning of reinforced concrete is generally attributed to Frenchman J. L. Lambot, who in 1850 constructed, for the first time, a small boat with concrete for exhibition in the 1855 World’s Fair in Paris. In England, W. B. Wilkinson registered a patent for reinforced concrete l=floor slab in 1854.J.Monier, a French gardener used metal frames as reinforcement to make garden plant containers in 1867. Before 1870, Monier had taken a series of patents to make reinforcedconcrete pipes, slabs, and arches. But Monier had no knowledge of the working principle of this new material, he placed the reinforcement at the mid-depth of his wares. Then little construction was done in reinforced concrete. It is until 1887, when the German engineers Wayss and Bauschinger proposed to place the reinforcement in the tension zone, the use of reinforced concrete as a material of construction began to spread rapidly. In1906, C. A. P. Turner developed the first flat slab without beams.Before the early twenties of 20th century, reinforced concrete went through the initial stage of its development, Considerable progress occurred in the field such that by 1910 the German Committee for Reinforced Concrete, the Austrian Concrete Committee, the American Concrete Institute, and the British Concrete Institute were established. Various structural elements, such as beams, slabs, columns, frames, arches, footings, etc. were developed using this material. However, the strength of concrete and that of reinforcing bars were still very low. The common strength of concrete at the beginning of 20th century was about 15MPa in compression, and the tensile strength of steel bars was about 200MPa. The elements were designed along the allowable stresses which was an extension of the principles in strength of materials.By the late twenties, reinforced concrete entered a new stage of development. Many buildings, bridges, liquid containers, thin shells and prefabricated members of reinforced concrete were concrete were constructed by 1920. The era of linear and circular prestressing began.. Reinforced concrete, because of its low cost and easy availability, has become the staple material of construction all over the world. Up to now, the quality of concrete has been greatly improved and the range of its utility has been expanded. The design approach has also been innovative to giving the new role for reinforced concrete is to play in the world of construction.The concrete commonly used today has a compressive strength of 20~40MPa. For concrete used in pre-stressed concrete the compressive strength may be as high as 60~80MPa. The reinforcing bars commonly used today has a tensile strength of 400MPa, and the ultimate tensile strength of prestressing wire may reach 1570~1860Pa. The development of high strength concrete makes it possible for reinforced concrete to be used in high-rise buildings, off-shore structures, pressure vessels, etc. In order to reduce the dead weight of concrete structures, various kinds of light concrete have been developed with a density of 1400~1800kg/m3. With a compressive strength of 50MPa, light weight concrete may be used in load bearing structures. One of the best examples is the gymnasium of the University of Illinois which has a span of 122m and is constructed of concrete with a density of 1700kg/m3. Another example is the two 20-story apartment houses at the Xi-Bian-Men in Beijing. The walls of these two buildings are light weight concrete with a density of 1800kg/m3.The tallest reinforced concrete building in the world today is the 76-story Water Tower Building in Chicago with a height of 262m. The tallest reinforced concrete building in China today is the 63-story International Trade Center in GuangZhou with a height a height of 200m. The tallest reinforced concrete construction in the world is the 549m high International Television Tower in Toronto, Canada. He prestressed concrete T-section simply supported beam bridge over the Yellow River in Luoyang has 67 spans and the standard span length is 50m.In the design of reinforced concrete structures, limit state design concept has replaced the old allowable stresses principle. Reliability analysis based on the probability theory has very recently been introduced putting the limit state design on a sound theoretical foundation. Elastic-plastic analysis of continuous beams is established and is accepted in most of the design codes. Finite element analysis is extensively used in the design of reinforced concrete structures and non-linear behavior of concrete is taken into consideration. Recent earthquake disasters prompted the research in the seismic resistant reinforced of concrete structures. Significant results have been accumulated.3. SPECIAL FEATURES OF THE COURSEReinforced concrete is a widely used material for construction. Hence, graduates of every civil engineering program must have, as a minimum requirement, a basic understanding of the fundamentals of reinforced concrete.The course of Reinforced Concrete Design requires the prerequisite of Engineering Mechanics, Strength of Materials, and some if not all, of Theory of Structures, In all these courses, with the exception of Strength of Materials to some extent, a structure is treated of in the abstract. For instance, in the theory of rigid frame analysis, all members have an abstract EI/l value, regardless of what the act value may be. But the theory of reinforced concrete is different, it deals with specific materials, concrete and steel. The values of most parameters must be determined by experiments and can no more be regarded as some abstract. Additionally, due to the low tensile strength of concrete, the reinforced concrete members usually work with cracks, some of the parameters such as the elastic modulus I of concrete and the inertia I of section are variable with the loads.The theory of reinforced concrete is relatively young. Although great progress has been made, the theory is still empirical in nature in stead of rational. Many formulas can not be derived from a few propositions, and may cause some difficulties for students. Besides, due to the difference in practice in different countries, most countries base their design methods on their own experience and experimental results. Consequently, what one learns in one country may be different in another country. Besides, the theory is still in a stage of rapid。
本科生毕业设计预应力混凝土连续梁桥设计开题报告
本科生毕业设计预应力混凝土连续梁桥设计开题报告一、课题来源、目的、意义，国内外基本研究概况（1）课题来源预应力混凝土连续梁桥是预应力桥梁中的一种，它具有整体性能好、结构刚度大、变形小、抗震性能好，特别是主梁变形挠曲线平缓，桥面伸缩缝少，行车舒适等优点。
故其在当今桥梁的应用中极其普遍[1]。
（2）目的及意义毕业设计是高等教学过程中一个重要的综合性教学实践环节，也是实现本科培养目标要求的重要阶段。
毕业设计是学生学完理论基础课、技术基础课、专业课以后，按照教学大纲的要求，在指导老师下独立完成一项设计或撰写一篇论文。
做好毕业设计可以使学生所学的基础理论知识与专业知识更加系统、巩固、延伸和拓展。
对工科院校而言，可使学生收到工程技术和科学技术的基本训练，以及工程技术人员所必需的综合训练，提高学生调查研究、理论分析、计算、绘图和外语翻译等各方面的能力特别是综合运用所学基本理论只是分析、解决工程实际问题的能力。
毕业设计是完成教学计划达到本科培养目标的重要环节。
此外，通过设计，还能够提高我们的综合能力：1）培养分析和解决问题的独立工作能力；2）提高计算、绘图、查阅文献、使用规范手册和编写技术及计算机辅助设计计算等基本技能，使学生了解生产设计的主要内容和要求；3）掌握大、中桥型的设计原则、设计方法和步骤；4）树立正确设计思想以及严谨负责、实事求是、刻苦钻研、勇于创新的作风，为桥梁建设事业服务。
（3）国内外基本研究情况由于悬臂施工方法的应用，连续梁在预应力混凝土结构中有了飞速的发展。
60年代初期在中等跨径预应力混凝土连续梁中，应用了逐跨架设法与顶推法；60年代中期在德国莱茵河建成的本多夫（Bendorf）桥，采用了悬臂浇筑法[2]。
随着悬臂浇筑施工法和悬臂拼装施工法的不断改进、完善和推广应用，在跨度为40—200米范围内的桥梁中，连续梁桥逐步占据了主要地位。
目前，无论是城市桥梁、高架道路、山谷高架栈桥，还是跨河大桥，预应力混凝土连续梁都发挥了其独特的优势，成为优胜方案[3]。
预应力混凝土连续梁桥的毕业设计
预应力混凝土连续梁桥的毕业设计北方工业大学本科毕业设计（论文）报告书题目：指导教师：专业班级：学号：姓名：日期：绪论预应力混凝土连续梁桥以结构受力性能好、变形小、伸缩缝少、行车平顺舒适、造型简洁美观、养护工程量小、抗震能力强等而成为最富有竞争力的主要桥型之一。
本章简介其发展：由于普通钢筋混凝土结构存在不少缺点：如过早地出现裂缝，使其不能有效地采用高强度材料，结构自重必然大，从而使其跨越能力差，并且使得材料利用率低。
为了解决这些问题，预应力混凝土结构应运而生，所谓预应力混凝土结构，就是在结构承担荷载之前，预先对混凝土施加压力。
这样就可以抵消外荷载作用下混凝土产生的拉应力。
自从预应力结构产生之后，很多普通钢筋混凝土结构被预应力结构所代替。
我国的预应力混凝土结构起步晚，但近年来得到了飞速发展。
现在，我国已经有了简支梁、带铰或带挂梁的T构、连续梁、桁架拱、桁架梁和斜拉桥等预应力混凝土结构体系。
虽然预应力混凝土桥梁的发展还不到80年。
但是，在桥梁结构中，随着预应力理论的不断成熟和实践的不断发展，预应力混凝土桥梁结构的运用必将越来越广泛。
然而，当跨度很大时，连续梁所需的巨型支座无论是在设计制造方面，还是在养护方面都成为一个难题；而T型刚构在这方面具有无支座的优点。
因此有人将两种结构结合起来，形成一种连续—刚构体系。
这种综合了上述两种体系各自优点的体系是连续梁体系的一个重要发展，也是未来连续梁发展的主要方向。
另外，由于连续梁体系的发展，预应力混凝土连续梁在中等跨径范围内形成了很多不同类型，无论在桥跨布置、梁、墩截面形式，或是在体系上都不断改进。
在城市预应力混凝土连续梁中，为充分利用空间，改善交通的分道行驶，甚至已建成不少双层桥面形式。
在设计预应力连续梁桥时，技术经济指针也是一个很关键的因素，它是设计方案合理性与经济性的标志。
目前，各国都以每平方米桥面的三材（混凝土、预应力钢筋、普通钢筋）用量与每平方米桥面造价来表示预应力混凝土桥梁的技术经济指针。
50+70+50m预应力混凝土连续梁桥毕业设计设计说明书.
在施工方面，结合其地形情况及起重设备等方面的考虑，采用满堂支架施工法。
2
2.1工程概况
1工程概况
本工程属于xxx到xxx的高速公路，桥梁全长1105m，宽26m，主桥为双塔三跨式斜拉桥（跨径布置为170m+425m+170m），两端引桥均为预应力混凝土连续箱型梁桥（跨径布置为50m+70m+50m）。设计标准为公路一级。本次设计为该工程中的引桥部分为主要设计对象进行其相关的设计计算。
The design process is as follows:
Size formulation、modeling by using Dr. bridge software、the calculation of dead load、the
calculation of secondary internal force、estimation of prestressed reinforcement、the combination of internal forces、the calculation of the prestressed loss、girder checking、deflection and camber setting、the summary of major engineering quantity.
预应力混凝土连续梁桥外文文献_pdf
DeformationAnalysisofPrestressedContinuousSteel-ConcreteCompositeBeamsJianguoNie 1;MuxuanTao 2;C.S.Cai 3;andShaojingLi 4Abstract:Deformationcalculationofprestressedcontinuoussteel-concretecompositebeamsaccountingfortheslipeffectbetweenthe steelandconcretein terfaceunderserviceloadsisanalyzed.Asimplifiedanalyticalmodelispresented.Basedonthismodel,formulasfor predictingthecrackingregionofconcreteslabneartheinteriorsupportsandtheincreaseoftheprestressingtendonforcearederived.Atable for calculating the midspan de flection of two-span prestressed continuous composite beams is also proposed. It is found that the internalforceoftheprestressingtendonunderserviceloadscanbeaccuratelycalculatedusingtheproposedformulas.Byignoringthe increaseofthetendonforce,thecalculateddeflectionareoverestimated,andconsideringtheincreaseofthetendonforcecansignificantly improvetheaccuracyofanalyticalpredictions.Asthecalculatedvaluesshowgoodagreementwiththetestresults,theproposedformulas can be reliably applied to the deformation analysis of prestressed continuous composite beams. Finally, based on the formulas for calculating the deformation of two-span prestressed continuous composite beams, a general method for deformation analysis of pre- stressedcontinuouscompositebeamsisproposed. DOI:10.1061/ASCE ST.1943-541X.0000067CEDatabasesubjectheadings:Prestressedconcrete;Compositebeams;Deformation;Deflection;Cracking;Concreteslabs;Con - tinuousbeams .Introduction2 increasing the ultimate loading capacity;3 decreasing the deformation under service loads;4 being favorable in crack-widthcontrol;5fullyusingthematerialsandthusreducingthestructural height and overall dead load; and 6 improving the fatigueandfracturebehavior. Continuous steel-concrete composite beams are widely used in buildingsa ndbridgesforhigherspan/depthratiosandlessdeflec -tionetc.,whichresultsinsuperioreconomicalperformancecom-pared with simply supported composite beams. For continuouscomposite beams, negative bending near interior supports will resultinearlycrackingofconcreteslabandreductionofstiffness.Whenbeamsaredesignedforspanlengthsandloadsgreaterthanusual, the requirement of serviceability limit state due to unac- ceptabledeflectionandcrackwidthwouldrequireusingprestress -ingtechnique.Since Szilard 1959 suggested a method for the design and analysisofprestressedsteel-concretecompositebeamsconsider-ingtheeffectsofconcreteshrinkageandcreep,manyresearchers have developed methods for analyzing the behavior of simply supportedprestressedcompositebeams Hoadley1963;Klaiberetal.1982;Dunkeretal.1986;Saadatmanesh1986;Saadatmanesh etal.1989a,b,c;Albrechtetal.1995,Nieetal.2007 .However, continuous prestressed composite beams have not been re-searched until the late 1980s Troitsky and Rabbani 1987; Troitsky 1990; Dall’Asta and Dezi 1998, Ayyub et al. 1990, 1992a,b;Dall’AstaandZona2005.Asaresult,prestressedcon-tinuouscompositebeamshavenotwidelybeenusedpartlyduetothelackofdesigntheory. In fact, the behavior of prestressed continuous composite beamsdependsontheinteractionbetweenfourmaincomponents: thereinforcedconcreteslab,thesteelprofileofbeams,theshearconnections, and the prestressing tendons, which makes pre- stressedcontinuouscompositebeamsmorecomplexthanconven-tional ones. Dall’Asta and Zona 2005 proposed a nonlinear finiteelementmodelsimulatingthebehaviorofprestressedcon- tinuouscompositebeamsaccurately.Thisnumericalapproachisa very powerful research tool for analyzing the externally pre- stressedstructures,butitperhapsistoocomplicatedforaroutine designpractice. Comparedwithconventionalsteel-concretecompositebeams, prestressedsteel-concretecompositebeamshaveafewmajorad- vantages: 1 extending the elastic range of structural behavior; 1Professor,Dept.ofCivilEngineering,KeyLaboratoryofStructural EngineeringandVibrationofChinaEducationMinistry,TsinghuaUniv., Beijing100084,China. 2Ph.D. Candidate, Dept. of Civil Engineering, Key Laboratory ofStructural Engineering and Vibration of China Education Ministry,Tsinghua Univ., Beijing 100084, China corresponding author . E-mail:dmh03@3AssociateProfessor,Dept.ofCivilandEnvironmentalEngineering,LouisianaStateUniv.,BatonRouge,LA,70803;presently,AdjunctPro-fessor,SchoolofCivilEngineeringandArchitecture,ChangshaUniv.ofScienceandTechnology,Changsha,China.4Formerly,GraduateStudent,Dept.ofCivilEngineering,KeyLabo-ratoryofStructuralEngineeringandVibrationofChinaEducationMin-istry,TsinghuaUniv.,Beijing100084,China.Note.ThismanuscriptwassubmittedonAugust10,2008;approved on April 20, 2009; published online on October 15, 2009. Discussion periodopenuntilApril1,2010;separatediscussionsmustbesubmitted for individual papers. This paper is part of the Journal of Structural Engineering ,Vol.135,No.11,November1,2009.©ASCE,ISSN0733- 9445/2009/11-1377–1389/$25.00.Asprestressingtechniqueisaneffectivewaytoreducedefor- mation and crack width under service loads, particular attention hastobepaidtothedeformationcalculationofprestressingcon- tinuouscompositebeams.Themainobjectiveofthisresearchis todevelopcalculationmethodsforthedeformationofprestress-ing continuous composite beams based on the reduced stiffnessJOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009/1377Thedownwardconcentratedforceappliedbytendonsattheinte-rior support is not shown in the figure as the force is applieddirectlyonthesupport.Therigidityalongthebeamcanbecon-sideredasunchangedinthisstagesincethecrackingofconcreteusually does not occur.The section properties can be calculatedby the transformed section method ignoring the slip effect be-tweensteelandconcreteinterfaceatthisstage.Itisassumedthatthedistributionofmomentalongthebeamduetotheprestressingforcekeepsunchanged.Oncealltheparametershavebeendeter-mined,deformationinthefirststage f1canbedirectlycalculatedbymethodsofstructuremechanics.Fig.1.Sketchoftwo-spanprestressedcontinuouscompositebeammethodthatwasdevelopedforconventionalcontinuouscompos-itebeams NieandCai2003.Theproposedmethod,verifiedbytestresults,issuitablefordesignpractice.In the second stage shown in Fig. 2b, application of theexternal force P results in the increase of downward deflection⌬f andachangeofprestressingtendonforce⌬T.Intheregionof2TheoreticalStudysaggingmoment,thereducedflexuralstiffness B=E1I11+ isusedduetotheslipeffects,whereisstiffnessreductioncoeffi-cient according to the reduced stiffness method Nie and Cai2003,andtheaxialstiffnessEAiscalculatedbythetransformedsectionmethod.IntheregionofhoggingmomentintherangeofnL neareachsideoftheinteriorsupports,concreteisconsideredno longer in service due to cracking. In this case the bendingrigidityE2I2 andaxialrigidityE2A2 canonlyincludethecontri-butionofthereinforcementandsteelmaterials,andparameter␣andaredefinedas␣=B E2I2,and=EA E2A2.Actually,inthesecondstage,concreteinthehoggingmomentmaystillcontributetostiffnessbecauseoftheprestressingforce.Therefore, the partial interaction between the steel and concreteshould be considered for a rational analysis. For simplicity, thiskind of interaction effect is considered in the present study byadjustingthevalueofnL insteadofactuallymodifyingthestiff-nessofcompositebeamsnearthesupports,whichresultsinonlysmallerrorsas willbeverifiedbytheexperimentsanddiscussedlater.AnalyticalModelPrestressed continuous composite beams discussed in this paperareshowninFig.1wheretheprestressingtendonsarelaidoutasfold lines or straight lines for the convenience of construction.Thestraightlinescanbeconsideredasaspecialcaseofthefold-linetypewith=0incalculation.Thepositionoftendonscanbeeitherinternalorexternal,whichwillnotinfluencethemethodofanalysis.Thus,theresearchinterestinthispaperisconcentratedonatwo-spanprestressedcontinuouscompositebeamwithfold-line tendons as shown in Fig. 1, and the methodology can be appliedtootherkindsofprestressedcontinuouscompositebeams.Thecalculationmodelofprestressedsteel-concretecompositebeamsisshowninFig.2.Theprocessofloadingcanbedividedinto two st ages. In the first stage shown in Fig. 2a, beams areinitially prestressed by tendons and the equivalent loads appliedto the continuous beams by tendons are composed of two parts.Thefirstpartincludesaxialcompressionforce T andmomentT0e0atthebeamends,wheree0=distancefromthebeamanchortotheneutralaxisofthetransformedsection,positivebelowneu-tral axis. The second part includes vertical concentrated loadsappliedbytendons.ForceequilibriumshowninFig.3givesthevalueoftheequivalentconcentrateforceFappliedbythetendonsasT0sin,whichequalstoT0approximatelyasisverysmall.Inordertoobtainthedeflectionofthecompositebeamsinthisstage, the length of cracking region of concrete slab at interiorsupports, defined by n, should be determined first. For conven-tionalcontinuouscompositebeams,itisfoundinpreviousstudiesandexperimentsthattaking0.15forthenvaluewillbeaccurateenough for design Nie et al. 2004. However, for prestressedcontinuous composite beams, the length of cracking region ofconcreteslabissmallerthantheconventionones.Furthermore,nisrelatedtotheprestressingdegreedirectly,whichhasbeenveri-fied by tests. The other parameter ⌬T is also very essential forcalculatingthedeflection.Since the materials are generally linear elastic under serviceload conditions, the principle of superposition can be used toobtainthetotaldeflectionas f1+⌬f2,where f1canbecalculateddirectlybymethodsofstructuralmechanics.Inthisstudy,wearemore concerned about the increase of deflection under serviceloads, i.e., ⌬f2. Therefore, this paper will only investigate theincrease of deflection in the second stage, and for convenience,⌬f2 will be rewritten as f hereafter.According to the discussionmadeabove,thecoreofdeformationcalculationistodeterminethe values of n and ⌬T, which will be discussed further in thefollowingparts.Fig. 2. Calculation model of prestressed continuous steel-concretecompositebeam:afirstloadingstage;b secondloadingstageThecableslipatthesaddlepointsisacomplexbehavioroftheexternally prestressed composite beams. The slip friction at thesaddle points can influence the behavior of beams under serviceloads. Negligible friction occurs by using individually coatedsingle-strand tendons Conti et al. 1993 and the assumption ofnegligiblefrictioncanbefoundinthepreviousmodel Dall’Astaand Zona 2005. This assumption is also used in the followinganalyticalstudies.Fig.3.Equivalentloadappliedtothebeambytendons1378/JOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER200951M k =0.85M ek = m 1−m P k L640where M ek =moment due to P k ignoring the moment redistribu- tion.The relationship between the service load and the initial pre- stressingforcecanbederivedusingEqs.5and 6as40T 0 51m 1−m L 2 e W20T 0 17 0 P k =++ 7A Undertheapplicationofexternalforceandprestressingforce,thedistributionofmomentalongthebeamisshownasFigs.4 bandc , respectively. The tension stress at the top of concrete at the boundaryofthecrackingregionequalstozero,whichleadstoM T x=nL +M P x=nL −T=08W AFig.4.Theoreticalanalysisofthelengthofcrackingregionofcon-creteslab:a calculationmodeloftwo-spanprestressedcontinuouscompositebeams;b momentdistributionduetoprestressingtendon force;and c momentdistributionduetoexternalloadswhere T=tendon force under service load conditions. Compared withtheinitialprestressingforce,theincreaseoftendonforceisrelatively small, and T can be taken proximately as T 0; M T x =moment distribution along the beam due to the prestressing force,andM P x =momentdistributionalongthebeamduetothe serviceload.TheyarecalculatedasPredictionofCrackingRegionofConcreteSlabx =3Te 02 Lx −21Te 0+ −23m 2+32m+1 T x In this part, the length of cracking region of concrete slab overinteriorsupportswillbetheoreticallyanalyzedbasedonthecal- culation model shown in Fig. 4a . After the initial force T 0 is prestressed,astructuralanalysisgivesthesaggingmomentatthe interiorsupportasM T−23m 1−m T L 0Յx ՅnL95140 51 51 =T 0e 0 +32m 1−m T 0L M P x = m 2−40 m −1 P k x+ m 1−m P k L 0Յx ՅnLM T0140210Accordingly,theinitialcompressivestressatthetopofconcreteslabattheinteriorsupportiscalculatedasIntroducing Eqs. 7, 9, and 10 into Eq. 8 leads to theex-pressionofnasafunctionof pc =M T0+T 0= A T 0e 0+ 2W 3m 1−m T 0L 2W +TA 2A −1 0 n=B −CA 11Wwhere W=section modulus of transformed composite section at the top of concrete flange and A=cross-sectional area of trans-formedsection.Themomentneededtoeliminatethecompressivestressatthe interiorsupportisobtainedaswhereA,B,andCcanbecalculatedas1 W +321−m me 0L A=2+Ae 03 3 3 1 m L + m B=2 + − m+ 2 2 e 0 M 0=pc W=12T 0e 0+32m 1−m T 0L+TA 0W 3C=51m 2−51m −4051m 2−51mTheprestressingdegreeisdefinedas=MM 4From Eq. 11 we can see that the main factors influencing the rangeofconcretecrackingregionincludetheprestressingdegree ,theparameterW Ae 0,theparameterm L e 0,andtheloading positionm.TheireffectsonnareplottedinFigs.5–7.FromFigs.5–7 we can see that the length of concrete cracking region falls moreandmorequicklyastheprestressingdegreerises.Whenthe prestressingdegreeistakenas1,thelengthofconcretecrackingregion is zero, referred to as fully prestressed composite beams. Similarly,azerooftheprestressingdegreeresultsinthelengthof concrete cracking region being as 1C, which depends only on theloadingpositionmandcorrespondstoconventionalcomposite beams. Fig. 5 indicates how n varies within the usual range of parameter W Ae 0 when the other parameters are fixed. It iskwhereM k =momentattheinteriorsupportduetoserviceload P k excludingprestressingeffect .IntroducingEq.3intoEq.4givesM k =T20e 0+3m 1−m T 0L+T 0W 52 A It is found in experiments that the moment redistribution coeffi-cient ␣a attheinteriorsupportcanreachabout15%underservice loadconditions.Therefore,15%isusedtocalculatethemoment attheinteriorsupportunderserviceloadsapproximatelyasJOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009/1379Fig.5.Influenceofparameter W Ae0onn Fig. 8. Comparison among test results, theoretical results and sim-plifiedtheoreticalresultsfoundthattheinfluenceofparameter W Ae0onnisveryslightandcanbeignored.In most cases, the neutral axis in the region of positive mo-me ntisadjacenttothesteeltopflange,andtheprestressingten-dons are adjacent to the steel bottom flange. According to thesketchshowninFig.1,mLrepresentstheverticaldistancefromthebeamanchortothecenteroftendonstakenproximatelyasthepositionofthesteelbottomflange,leadingtothefollowing:gion,andinlowprestressingdegreeregionitvariesfrom0.15to0.20approximatelywhenmvarieswithintheusualrange.Sincetheactuallengthofconcretecrackingregionisslightlyshorter than the theoretical result due to the assumption that thetensile strength of concrete and the increase of tendon force arenegligible, Eq. 11should be modified to a certain extent. Fur-thermore, except for , the other three parameters all slightlyinfluencethe n value.Thus,Eq.11canbesimplifiedconsider-ingthefollowingfactors:mL+e0h s mL hs−1 12e0 e01. RelationshipformatbetweennandasdefinedbyEq.11is maintained by adjusting only the coefficient in the equa-tion.Sincetheheightofthesteelbeamh isabout4to8timesofthesanchoreccentricitye0,theparametermL e0variesfrom3to7.WithinthisrangewecanconcludefromFig.6thatthevariationofparametermL e0willnotsignificantlyinfluencethevalueofn.2.3.Thenewequationcanreducetoconventionalnonprestressedcase,i.e.,when=0,n =0.15.The parameter W Ae0 and mL e0 can be taken as theaveragevalueswithintheusualrange.Consequently,Eq.11issimplifiedas Fig. 7 shows how the loading position m influences the nvalue.The n approaches to unity in high prestressing degree re-n=143−−20113Thecomparisonbetweentestresults discussedlater ,theoreticalresults, and simplified modified theoretical results is shown inFig.8,whichprovesthatEq.13isreasonableandaccurateforthecalculation.PredictionofTendonForceTheincrementoftendonforceduetoexternalloadscanbepre-dicted by developing the equilibrium equation, the deformationcompatibilityequation,andthephysicalequationforthestructuresystem.Theexternalloadsmainlyresultinbeammomentswhosedistribution depends on the loading conditions. The change ofprestressing tendon forces mainly result in axial forces and mo-ments, which can be solved by a simple structural analysis asshowninFig.9.Fig.6.InfluenceofparameterL e0onnTheeffectofprestressingforceincrement⌬Tisresolvedintotwo parts in Fig. 9a, namely the equivalent vertical forces andhorizontalaxialforcesatbeamends.Thepositionchangeofneu-tralaxisintheregionofhoggingmomentneartheinteriorsupportinfluencesthemomentdistributionduetoprestressingforce.Asaresult,acoefficient=e02e0isdefinedheretodescribeit,wheree02representstheverticaldistancefromtheprestressingtendontotheelasticneutralaxisintheregionofhoggingmomentasshowninFig.9a withpositiveforbeingbelowtheneutralaxis.In order to solve the expression of R1 and R2 in Fig. 9a, Fig.7.Influenceofparameter monn1380/JOURNALOFSTRUCTURAL ENGINEERING©ASCE/NOVEMBER2009Fig.9.Distributionofinternalforcesduetoprestressingtendonforces:a distributionofmomentsduetotheincreaseofprestressingtendon forces;b distributionofaxialforcesduetotheincreaseofprestressingtendonforcesdeformation compatibility equations at Point 1 as shown in Fig. 9a underthetwoloadcasescanbedevelopedasfollowingEqs. 14and 15 ,respectively=⌬TL P⌬P19E A P Pwhere L P =length of the prestressing tendons; E P A P =axial stiff-nessoftheprestressingtendons;andYoung’smodulusoftendons E p canbetakenproximatelyasYoung’smodulusofsteelsb . Fortheconvenienceoffurtherderivations,thefollowingdefi- nitionsareintroduced:1 114⌬ =⌬ −2R 1⌬T 11=0 1 1,⌬T22R ⌬Te 0 11=0 2 21,⌬T 15⌬ =⌬ −1 L 11where ⌬ =actual vertical displacement of Point 1 under Load e 2 e=e 1,=e 1202Case 1;⌬ =actualverticaldisplacementofPoint1underLoad 1 Case 2;⌬1,1⌬T =verticaldisplacementofPoint1underLoadCase 21,⌬Twhere e 1 and e 2 are shown in Fig. 10a with a positive value beingforbelowtheneutralaxis.Accordingly,fold-lineoftendons hasanegative andstraight-lineapositive value.Intheregionofhoggingmoment,sinceonlythetopreinforce- mentbarsandthesteelbeamareconsideredinthecalculation,the slipeffectcanbeexcluded,whichresultsinthestrainofthesteel fiberattheheightleveloftendonsas1 with the interior support removed; ⌬ =vertical displace- ment of Point 1 under Load Case2 with the interior support removed; and 11=vertical displacement of Point 1 produced by unit vertical force applied on Point 1 with the interior support removed.SolvingEqs.14and 15givestheexpressionofR 1andR 2 inFig.9a asinthefollowing:R 1=−3␣−1n 2+6␣−1n −3m 2+3m+22␣−1n 3−6␣−1n 2+6␣−1n+216−3␣−1n 2+6␣−1n+3 2␣−1n 3−6␣−1n 2+6␣−1n+2R 2=17Theexternallyprestressedcompositebeamsdonotdeformcom-patiblywithprestressingtendonsatallsections.However,inad- ditiontothetwoendanchors,severalintermediateconnectionsor calleddeviatorsareprovidedfortheprestressingtendonssothat thedeformationcompatibilityatthesepointsismaintainedduring theloadingprocess,ensuringtheglobaldeformationcompatibil- ity between the prestressing tendons and the composite beam. From the global deformation compatibility conditions, the total deformationoftheprestressingtendonsequalstotheintegration ofthestrainofthesteelfiberattheheightleveloftendons,thus leadingtothedeformationcompatibilityequationas͵2L⌬P =b x dx 18where ⌬ =total deformation of the prestressing tendons and pFig. 10. Distribution of eccentricity of the tendons to the elastic neutralaxisoftransformedsectionalongthebeam:a positionofthe elasticneutralaxis;b actualdistributionofe x ;and c si mplified distributionofe xb x =strain of the steel fiber at the height level of tendons at sectionxfromthesidesupport.Thedeformationofprestressingtendonscanalsobecalculated asJOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009/1381Fig. 11. Analytical model for calculating the strain of steel beamundermomentinthesaggingmomentregions−= e x+N⌬T xEA␣M P x+M⌬T 21b BFig. 12. Calculation diagram of midspan deflection of prestressedcontinuouscompositebeamswhere M P x, M⌬T x, and N⌬T x represent the distribution of internalforcesalongthebeamduetoboththeexternalloadsandtheincreaseofprestressingtendonforces.In the region of sagging moment, the distribution of strainsacrosstheheightofacompositebeamsectionisshownasFig.11.Due to the slip effect, the slip strain which results in the addi-tional curvature exists in the adjacent fibers at the interface ofconcreteandthesteelbeam.Therefore,itisnecessarytomodifytheelasticresultsofthesteelstrains.ItcanbeseenfromFig.11that the strain of the steel fibers where the prestressing tendons arepositionedintheregionofsaggingmomentcanbecalculatedaseA␣,M,PB27⌬T=1 +Be C1L+C2e02LEA0where C1 and C2 are coefficients related to ␣, , m, n, and ,calculatedasfollows:C1=12␣−R1n2−␣−R1−1n− 21R1+m2−m−21+=be−⌬b2228 bwhere ⌬b=additional strain due to the slip effect and be=strain calculated by beam theory and the transformed sectionmethod29C2=21␣−R2n2−␣−R2−1n− R −1122whereA0=transformedsectionalareaofthecompositebeamand be=M P x+M⌬T x e prestressingtendons,calculatedas23B1+A P AA0=1−n+n A P+L P2L A 30 Assumingthatthesteelbeamandconcreteflangehavethesamecurvature and the distribution of stresses and strains across theheight of a section due to the slip effect is linear, the additionalstraincanbeobtainedasA␣external loads and the coordinate axis, multiplied by ␣ in thehoggingmomentand insaggingmoment,positiveforsagging,=areabetweenthegraphofmomentdistributionduetotheM,P⌬b=⌬y−e24momentandnegativeforhoggingmoment.FortheloadingcaseshowninFig.1,A␣,=2C PL2;thenputtingthisexpressionof Thereducedstiffnessmethod NieandCai2003gives M,P 1 kA␣,into Eq. 27, we can finally obtain the increase of tendonM,Pforce due to the two concentrated loads symmetric to the mid- ⌬=EIM =M P x+M⌬T x25span,asaspecialcaseofEq.27 ,asB 1+eC1P k L Basedontheanalysisaboveandconsideringthesteelstraindueto axial forces, the strain of the steel fiber at the height level ofsteeltendonsintheregionofsaggingmomentcanbederivedas⌬T= 31B+e C1L+C2e0EA01−The increase of tendon force due to other loading cases can beobtainedusingthesamemethodology.+=Be y x+N⌬T xM P x+M⌬Tb 1+ e EA=BeM P x+M⌬T x+N⌬T xEA26DeformationCalculationOncethelengthofconcretecrackingregionattheinteriorsupportandtheincreaseofprestressingtendonforcearedetermined,thedeformation can be obtained following the same procedure asconventional continuous composite beams Nie and Cai 2003.For the loading case shown as Fig. 1, the midspan deflection ofprestressed continuous composite beams can be calculated fromthecalculationdiagramasFig.12.where reflects the slip effect between steel and concrete inter-faceintheregionofsaggingmoment.Considering the equilibrium conditions, deformation compat-ibilityconditions,andphysicalconditionsaltogether,theincreaseof tendon force can be predicted from simultaneous equationsfromEq.18toEq.26as1382/JOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009M=M P +⌬T ·M ⌬¯T 34Finally,selecttherelatedformulasfromFig.12andthecalcula-tion diagram for conventional continuous beams Nie and Cai 2003,andobtainthemidspandeflectionsolutionsforthemidd le andsidespans.Inthedesignpractice,wealwayshopethattheintroductionofinternal moment by the prestressing tendons can act in opposite direction to that induced by the externally applied loads. As a result, the tendon profile is usually designed according t o the momentdiagramofexternalforcesassummarizedinFig.13a , inwhichtwoappliedloadscoincidewiththepointofchangeinangle in the prestressing tendons. In fact, the proposed general method for deformation calculation can also be used for the ap- plication of any given force at any arbitrary location along the beamspansinceEqs.33and 34donotcontainingtheassump- tionthatthediagramofM P andM ⌬¯T shouldsatisfysomecertain relationship.M P andM ⌬¯T canbeobtainedaccordingtotheactual load location and tendon profile, respecti vely, when using Eqs. 33and 34formoregeneralanalysis.Fig. 13. Deformation calculation of three-span prestressed continu- ouscompositebeam:a sketchofthree-spanprestressedcontinuouscomposite beams; b calculation model of three-span prestressed continuouscompositebeams;c M P graph;and d M ⌬¯T graphExperimentalProgram DescriptionofTestsInordertovalidatethedevelopedanalyticalprocedures,onenon-prestressed CCB-1 and six prestressed PCCB-1 to PCCB-6continuouscompositebeamsweretested Li2003.Thedetailsofthese seven specimens are given in Table 1 and the layout isshowninFig.14.Thetestedbeamsare8mlongwithtwoequalspans,andthecrosssection Fig.15consistsofasteelboxbeamandaconcreteslabof500 mm ϫ70 mm.Theexpressionforthemidspandeflectioncanbederivedas f=f 1+f 2+f 3+f 4 32 where f 1–4 canbecalculatedusingtheformulasinFig.12. GeneralMethodforDeformationCalculationCCB-1isaregularsteel-concretecontinuouscompositebeam without prestressing tendons. For PCCB series, the prestressingtendons were anchored at the two beam ends with two interme-diateconnectionswithineachspanandoneattheinteriorsupportsothattheycoulddeformcompatiblywiththesteelbeamattheseconnecting points during the loading process. The main factorsinfluencing the behavior of prestressed continuous c ompositebeams are the form of tendons, the number of tendons, and thepositionoftendons.Inordertomakeacomprehensiveinvestiga-tion on the prestressed continuous composite beams, the PCCBseriesweredesignedas Fig.14• PCCB -1:straight-line,one-tendon,internalprestressedbeam; • PCCB -2:straight-line,two-tendon,internalprestressedbeam; • PCCB -3:fold-line,one-tendon,internalprestressedbeam; • PCCB -4:fold-line,two-tendon,internalprestressedbeam;• PCCB -5:straight-line,two-tendon,externalprestressedbeam;and• PC CB-6:fold-line,two-tendon,externalprestressedbeam. Thespecimensweretestedwithtwoservocontrolledhydrau-licjacks,witheachforcebeingspreadintotwosymmetricpointloads as shown in Figs. 16 and 17.The test setup also included deflectionmeasurementsatthemidspanan dstrainmeasurements atcriticalsectionsbystraingaugesgluedonthelongitudinalre- inforcement,steelbeam,concreteslab,andprestressingtendons.Strains and deflections were measured automatically by a data acquisitionsystem IsolatedMeasurementPodsystem controlled byacomputer.Thearrangementofmeasuringdevicesissumma-rizedinFig.18indetail. Usingthedevelopedmethodologyforcalculatingthedeformationof two-span prestressed continuous composite beams, the defor-mationofprestressedcontinuouscompositebeamswithanynum-berofspansatserviceabilitylimitstatescanbeobtained.Asanexample Fig. 13a shows the sketch of a three-span prestressedcontinuouscompositebeam.First,thelengthofconcretecrackingregion at every support n i can be determined according to Eq.13, based on which the calculation model for prestressed con-tinuous composite beams can be developed as shown in Fig.13b . Second, the moment diagrams due to external loads M P andduetotheunitchangeofprestressingtendonforceM ⌬¯T can be solved as shown in Fig. 13c and Fig. 13d , respectively. Thenthechangeofprestressingtendonforcecanbecalculatedas A M,P,⌬T= 2LB 33 ␣,eEA 0−A M,⌬T ¯ whereA ␣,=areabetweenthediagramofM P andthecoordinate M,Paxis, multiplied by ␣ for the hogging moment and for thesagging moment, positive for the sagging moment and A ␣M,⌬,¯T =areabetweenthediagramofM ⌬¯T andthecoordinateaxis,mul- tipliedby ␣forthehoggingmomentand forsaggingmoment,positive for the sagging moment. The other parameters are the sameasthoseintheformulasfortwo-spanprestressedcontinuous compositebeams.The principle of superposition gives the moment distributionalongthebeamasThe height of beam supports was adjustable, hinged for the interioroneandslidingforthesideones.BeforethebeamswereJOURNALOFSTRUCTURALENGINEERING©ASCE/NO VEMBER2009/1383。
预应力混凝土连续梁桥设计设计
摘要： (2)Abstract： (3)1 引言 (4)第一章、设计资料及方案比选 (5)1.1设计概况 (5)1.1.1 桥梁概况 (5)1.1.2 技术标准 (5)1.1.3 工程地形地质 (6)1.2方案比选 (7)1.3推荐方案 (10)1.4设计规范 (11)第二章、方案简介及上部结构尺寸拟定 (12)2.1 主梁截面主要尺寸拟定 (12)2.2 本桥的主要材料 (13)第三章、单元的划分 (14)第四章、配筋设计及配筋结果计算 (15)4.1.预应力筋的估算 (15)4.1.1预应力筋的计算原理 (16)4.1.2 上、下缘布置预应力钢束的判别条件 (19)4.2 预应力钢束的布置 (20)4.3 配筋结果验算输出 (22)第五章、施工阶段描述 (23)5.1施工工艺概述 (23)5.2 施工阶段应力验算 (24)第六章、全桥内力验算 (28)6.1 正常使用极限状态应力验算 (28)6.1.1 短期效应组合 (29)6.1.2 长期效应组合 (35)6.1.3 基本组合 (40)6.2承载能力极限状态正截面强度验算 (46)结论 (49)谢辞 (50)[参考文献] (51)摘要：本设计主要是以某大桥作为工程背景，利用Dr.Bridge进行桥梁的结构设计。
设计总长为110m的公路直线预应力混凝土连续梁桥, 跨径组成30m+50m+30m，在设计中先用Dr.Bridge建立桥梁模型，然后按照实际情况和规范要求输入设计参数，按照过往工程经验进行预应力钢束布置；最后，调整至验算通过，经分析比较证明该桥设计计算正确，内力分布合理，达到预期的要求，符合设计任务要求。
关键词：预应力混凝土连续梁桥、有限元模型、配筋设计、内力Abstract：The design is under the engineering background of some bridge,using the Dr.Bridgesoftware to do the structure design.The Design is about a total length of 110m highwaylinear prestressed concrete continuous beam bridge composed of 30m+50m+30m. Firstly,using the Dr.Briage software to establish structural model, then according to the actualsituation and specification requirements to define some related parameters,，after that ,proceeded with the layouts of prestressed reinforcement.Finally, tinker up thereinforcement until the checking meets to the requirement. After calculation and checkingof the stress,distortion of model under dead load and living load ,the result show that thedesign is up to the demands。
【完整版】预应力混凝土连续梁桥毕业论文设计
【完整版】预应⼒混凝⼟连续梁桥毕业论⽂设计摘要预应⼒混凝⼟连续梁桥是⼀种桥⾯体系以梁受压或受弯为主的桥梁。
本⽂根据南京长江⼆桥北汊⼤桥的设计资料，使⽤桥梁博⼠建⽴平⾯杆系有限元分析模型，完成主桥成桥及施⼯状态下梁的⾃重、恒载、活载和温度内⼒分析及强度与应⼒验算，以及挠度、抗裂验算。
并初步了解了预应⼒混凝⼟连续梁的总体设计。
关键词预应⼒混凝⼟连续梁桥；梁、单元、节点；悬臂浇筑施⼯；内⼒分析；结构验算。
AbstractPrestressed concrete continuous bridges are constructed along a structural systEm which comprises continuous girders which are bent and crashed often .My thesis mainly combines with the building project of the North Part Bridge of the Second Nanjing Yangzi River Bridge, and analyses the whole structure. Firstly based upon acquainting myself with the structure, I established the plane finite element model, using the Dr.Bridge V3.0. Then I use the model to calculate the structure internal forces, which are caused by permanent load, live load and temperature changes. Then, I assembled the structure internal forces, and used the result to check the strength. The result is that they all meet the need of stress and strength. Through this bridge design, I acquaint myself with the load principle, the characteristic of bridge type and main elements of design about prestressed concrete continuous bridges.Key words Prestressed concrete continuous bridges; internal forces strength stress毕业设计（论⽂）原创性声明和使⽤授权说明原创性声明本⼈郑重承诺：所呈交的毕业设计（论⽂），是我个⼈在指导教师的指导下进⾏的研究⼯作及取得的成果。
预应力混凝土连续梁桥设计设计
摘要： (2)Abstract： (3)1 引言 (4)第一章、设计资料及方案比选 (5)1.1设计概况 (5)1.1.1 桥梁概况 (5)1.1.2 技术标准 (5)1.1.3 工程地形地质 (6)1.2方案比选 (7)1.3推荐方案 (10)1.4设计规范 (11)第二章、方案简介及上部结构尺寸拟定 (12)2.1 主梁截面主要尺寸拟定 (12)2.2 本桥的主要材料 (13)第三章、单元的划分 (14)第四章、配筋设计及配筋结果计算 (15)4.1.预应力筋的估算 (15)4.1.1预应力筋的计算原理 (16)4.1.2 上、下缘布置预应力钢束的判别条件 (19)4.2 预应力钢束的布置 (20)4.3 配筋结果验算输出 (22)第五章、施工阶段描述 (23)5.1施工工艺概述 (23)5.2 施工阶段应力验算 (24)第六章、全桥内力验算 (28)6.1 正常使用极限状态应力验算 (28)6.1.1 短期效应组合 (29)6.1.2 长期效应组合 (35)6.1.3 基本组合 (40)6.2承载能力极限状态正截面强度验算 (46)结论 (49)谢辞 (50)[参考文献] (51)摘要：本设计主要是以某大桥作为工程背景，利用Dr.Bridge进行桥梁的结构设计。
设计总长为110m的公路直线预应力混凝土连续梁桥, 跨径组成30m+50m+30m，在设计中先用Dr.Bridge建立桥梁模型，然后按照实际情况和规范要求输入设计参数，按照过往工程经验进行预应力钢束布置；最后，调整至验算通过，经分析比较证明该桥设计计算正确，内力分布合理，达到预期的要求，符合设计任务要求。
关键词：预应力混凝土连续梁桥、有限元模型、配筋设计、内力Abstract：The design is under the engineering background of some bridge,using the Dr.Bridgesoftware to do the structure design.The Design is about a total length of 110m highwaylinear prestressed concrete continuous beam bridge composed of 30m+50m+30m. Firstly,using the Dr.Briage software to establish structural model, then according to the actualsituation and specification requirements to define some related parameters,，after that ,proceeded with the layouts of prestressed reinforcement.Finally, tinker up thereinforcement until the checking meets to the requirement. After calculation and checkingof the stress,distortion of model under dead load and living load ,the result show that thedesign is up to the demands。
预应力混凝土连续梁的分析大学毕业论文外文文献翻译
毕业设计（论文）外文文献翻译文献、资料中文题目：预应力混凝土连续梁的分析文献、资料英文题目：文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14预应力混凝土连续梁的分析1 简介这次会议召开的主要目的是对结构的分析和开发，而不是讨论材料的强度，但是要想有效在使用预应力混凝土材料需要依靠适当的结构分析和对材料的性能的认识。
预应力混凝土结构的设计在没有专家参与的情况下，人们在进行设计时会出现很多错误或者会花费大量的时间进行方程式的推导求解。
预应力混凝土材料和其他材料的在基本性能上有很大的区别。
静定结构在不加荷载的情况下是不会有应力产生的，内力的解是在完全可行解内；在超静定结构当中，由于各种因素的影响，引起了缆绳的徐变和热效应从而导致出现各种自应力。
这些问题是如何被认识并且如何处理的呢?自从19世纪末钢筋混凝土开始被埃纳比克应用和发展以来（库萨克1984），它被人们认识到如果把预应力钢筋砼混凝土放在一起，它们能够很有效的结合起来。
如果它们能够结合在一起这样的话就会降低开裂的可能性，并且能够增加刚度和提高耐久性。
通过Leonhardt (1964) 和Abeles (1964)对这些尝试详细的介绍，我们可知早期尝试的失败是因为初始预应力的过早消失，残余的结构行为仿佛是被加强了。
1927年弗莱西奈在维希附近的阿列河上完成了对浅拱在三个桥梁上的下沉的观察，这直接导致了预应力混凝土的发展（Freyssinet 1956）。
第二次世界大战只有Boutiron桥幸存下来(图1)。
迄今为止它被人们认为是一个杨氏模数混凝土而被固定保留下来，但是他认为过度的变形会导致徐变的发生，这就解释了早期试验当中为什么预应力会消失。
由于弗莱西奈使高强钢筋能够被正确使用，因而一些预应力会在徐变后也将存在，这就导致高性能混凝土被使用，使得徐变的总变量达到最小。
弗莱西奈早期是在各个地方书写关于预应力混凝土的工作。
预应力混凝土连续梁桥外文文献_pdf
预应力钢-混凝土连续组合梁的变形分析摘要:对预应力钢-混凝土连续组合梁在正常使用极限状态下的变形计算进行分析。
分析考虑钢与混凝土之间的滑移效应，建立简化计算模型，并在辞基础上，提出混凝土支座开裂区的长度以及预应力筋内的筋内增量的计算公式。
给出两跨预应力连续组合梁跨中扰度的计算图表。
分析结果表明，两跨预应力连续组合梁变形计算公式计算正常使用极限状态预应力筋的内力值精度提高，不考虑预应力筋内力增量的变形计算值较实验值偏大，考虑预应力筋内力增量的变形计算值得精度有明显提高，与实验结果吻合较好，可供工程设计参考。
最后在两跨预应力连续组合梁变形计算公式的基础上提出预应力连续组合梁变形计算的通用方法引言：普通钢一混凝土连续组合梁由于中支座处混凝土过早开裂，刚度下降，当跨度或荷载较大时，变形和裂缝宽度可能无法满足正常使用极限状态的要求。
试验研究表明，使用预应力技术能较好地解决上述问题，同时还可增大梁的弹性工作范围，充分利用材料性能，从而降低结构高度、减轻自重、减小地震用，增加强度储备，延长使用期限。
在我国，组合的研究起步较晚，对于预应力钢一混凝土连续组梁更是缺乏系统的研究，本文以文献的试验结果为基础，参考了史纲Ⅲ、周安⋯以及段建中提出的变形计算方法，以结构力学的力法为主要分析手段，在聂建国提出的普通连续组合梁计算模型的基础上，提出了一种较为准确实用的预应力钢一混凝土连续组合梁在正常使用极限状态下的变形计算方法，供工程实践参考。
1计算模型预应力钢-混凝土连续组合梁按布筋形式不同，可分为直线布筋和折线布筋，按预应力筋的位置不同，可分体内预应力和体外预应力，其中直线布筋是折线布筋的特例(预应力筋折线处转角为零时即为直线布筋)，而体内预应力和体外预应力的变形分析方法在本文中没有本质的区别，因此本文以折线布筋的预应力两跨连续组合梁作为研究对象，如图l所示，计算方法及结果适用于不同类型的预应力连续组合梁。
C图，两跨预应力连续组合梁受力简图预应力钢一混凝土连续组合梁的变形计算模型如图2所示，图中m表示集中力(外荷载以及预应力筋等效荷载)作用点到相邻支座的距离和单跨跨度的比值，n表示中支座混凝土开裂区的单侧长度和单跨跨度的比值。
预应力混凝土连续梁毕业设计(含外文翻译)
石家庄铁道大学毕业设计（20+40+20）m预应力混凝土连续梁结构设计The Construction Design of the (20+40+20)m Prestressed concrete continuous beam2012 届高等技术学院专业道路桥梁工程技术学号20095116学生姓名 1 2 3指导教师 2 2完成日期2012年5月28日毕业设计任务书毕业设计开题报告摘要本设计主要是关于公路预应力混凝土连续梁桥上部结构的设计。
设计跨度(20+40+20)m。
本设计采用国内著名的有限元分析软件——迈达斯计算,全桥共分40个单元，41个截面，两个施工阶段。
因为连续梁的内力与其施工方法密切相关，本设计采用满堂支架法施工。
这种施工方法操作比较简单，相比其他方法从经济效益上讲也比其他方法更有优势，而且施工质量易得到保证。
计算过程中由于涉及到大量的数字运算，采用手算比较繁琐，并且准确性得不到保证，因此采用计算机辅助设计。
设计中使用了迈达斯来计算内力,并且初步估算配筋量和进行初步验算。
但为了提高设计可靠性，最终还会通过以Excel电子表格计算、AutoCAD辅助软件进行手算，使自己的设计能力有较大的提升。
关键词：预应力混凝土连续梁桥; 迈达斯; 满堂支架法ABSTRACTThis graduate design is mainly about the design of the superstructure of the road prestressed concrete continuous bridge. The span of the bridge is 20m+40m+20m.This design adopts the domestic famous analytical software—MIDAS.The bridge is divided totally into 40units、41 sections and 2 construction stages. Because of the internal force of the continuous girder bridge relating to the method of construction closely, the method of construction of this design adopts the full scaffold construction method. Compared with other methods, this method is quite easy to construct and has economic superiority and the quantity of this construction also could get the assurance easily.Because this design involving a great deal of numerical calculation, it's too tedious to work by hand and the accuracy assuranced hardly. So it restores to CAD. Many bridge specialized software are applied, such as MIDAS applied in calculation of internal forces. and the initial estimate amount of reinforcing steel and initial checking. However, in order to improve design reliability, this will eventually be calculated by the Excel, AutoCAD and other auxiliary software by hand, developing design capabilities with a great improvement at the same time.Key word: Prestressed Concrete Continuous Bridge, MIDAS , Full Scaffold Construction目录第1章绪论 (1)1.1引言 (1)1.2预应力混凝土连续梁桥的发展 (1)1.2.1 国内外预应力混凝土连续梁桥的发展状况 (1)1.2.2预应力混凝土结构的特点 (3)第2章桥梁的总体设计概况 (4)2.1设计基本资料 (4)2.1.1总体设计 (4)2.1.2 主要技术标准 (4)2.1.3 主要材料 (4)2.1.4 设计依据 (4)2.2桥型及纵横断面布置 (5)2.2.1桥型布置及孔径划分 (5)2.2.2截面形式与截面尺寸 (5)第3章模型建立及结果分析 (7)3.1MIDAS的建模说明 (7)3.1.1 MIDAS的介绍 (7)3.1.2 MIDAS的建模步骤 (7)3.2恒载内力计算 (11)3.2.1恒载内力计算 (11)3.2.2活载内力计算 (12)3.2.3钢束的布置与计算 (14)第4章预应力损失及有效应力的计算 (21)4.1预应力损失的计算 (21)4.1.1摩阻损失 (21)4.1.2锚具变形损失 (22)4.1.3混凝土的弹性压缩 (22)4.1.4钢束松弛损失 (22)4.1.5收缩徐变损失 (23)4.2有效预应力的计算 (23)第5章预加力产生的次内力及内力组合 (25)5.1原理 (25)5.2计算方法 (26)5.2.1等效荷载法 (26)第6章内力组合 (27)6.1承载能力极限状态下的效应组合 (27)6.2正常使用极限状态下的效应组合 (32)第7章主梁截面验算 (40)7.1正截面抗弯承载力验算 (40)7.2持久状况正常使用极限状态应力验算 (41)7.2.1 正截面抗裂验算（法向拉应力） (41)7.2.2 斜截面抗裂验算（主拉应力） (43)7.2.3 使用阶段预应力混凝土受压区混凝土最大压应力验算 (44)7.2.4 预应力钢筋中的拉应力验算 (45)7.2.5 混凝土的主压应力验算 (45)7.3短暂状况预应力混凝土受弯构件应力验算 (45)第8章结束语 (47)参考文献 (48)致谢 (49)附录 (50)外文翻译 (50)第1章绪论1.1引言随着经济建设的迅速发展，我国城市交通的桥梁建设也进入迅速发展时期。
混凝土毕业设计论文中英文对照资料外文翻译文献
外文文献及译文目录•1历史•2组成o水泥2.1o 2.2水o 2.3骨料o 2.4化学外加剂o 2.5掺合料和水泥混合o 2.6纤维•3搅拌混凝土•4个特点o 4.1和易o 4.2固化o 4.3强度o 4.4弹性o 4.5扩张和收缩o 4.6开裂▪ 4.6.1收缩裂缝▪ 4.6.2拉裂o 4.7蠕变•5损伤模式o 5.1火灾o 5.2总量扩张o 5.3海水效果o 5.4细菌腐蚀o 5.5化学武器袭击▪ 5.5.1碳化▪ 5.5.2氯化物▪ 5.5.3硫酸盐o 5.6浸出o 5.7人身损害•6种混凝土o 6.1普通混凝土o 6.2高强混凝土o 6.3高性能混凝土o 6.4自密实混凝土o 6.5喷浆o 6.6透水性混凝土o 6.7混凝土蜂窝o 6.8软木复合水泥o 6.9碾压混凝土o 6.10玻璃混凝土o 6.11沥青混凝土•7混凝土测试•8混凝土回收•9使用混凝土结构o9.1大体积混凝土结构o9.2钢筋混凝土结构o9.3预应力混凝土结构•10参见•11参考•12外部链接历史在塞尔维亚,仍然是一个小屋追溯到5600bce已经发现,同一个楼层发红色石灰,沙子和砾石。
金字塔陕西中建千多年前,含有石灰和火山灰.或粘土。
碎石水和泥浆僵硬和发展实力超过时间。
为了确保经济实用的解决方案,既罚款又粗骨料使用,以弥补大部分的混凝土混合物。
砂,天然砾石及碎石,主要用于这一目的。
不过,现在越来越普遍,再生骨料(由建筑,拆卸和挖掘废物)被用作局部代替天然骨料,而一些生产总量包括风冷高炉炉渣和粉煤灰也是不允许的。
装饰石材等石英岩,潆石块或玻璃破碎,有时添加到混凝土表面进行装饰性"的总暴露"完成,流行景观设计师。
化学外加剂化学外加剂现形式的材料粉末或液体,补充了混凝土给它的某些特性没有可与普通混凝土混合物。
在正常情况下使用,外加剂剂量均低于5%的大量水泥,并补充了混凝土当时的配料/混合.最常见的外加剂有:加速器加速水化(硬化)的混凝土。
(65m+115m+65m)公路预应力混凝土连续刚构梁桥设计--毕业设计
(二)材料规格
(1)梁体混凝土：C50级混凝土；
(2)桥面铺装及栏杆混凝土：C40级混凝土；
(3)预应力钢筋及锚具：
主梁纵向预应力钢筋可选用7-φj15.24、9-φj15.24、12-φj15.24或19-φj15.24高强度低松弛钢绞线(1-φj15.24公称断面面积为140.00mm2)， =1860MPa， =1488MPa；对应锚具分别为YM15-7、YM15-9、YM15-12或YM15-19；对应波纹管直径分别为(内径)φ70、φ80、φ85、φ100mm(外径比内径大7mm)。
(三)施工顺序及要点
(1)墩台基础施工：桥台采用明挖基础，桥墩采用钻孔桩基础。
(2)墩身：刚构桥下部结构的主墩墩身采用薄壁空心墩，墩高均为30m；
(3)主梁横截面：本桥为单箱单室的箱梁截面，梁底下缘及底板上缘均按二次抛物线规律变化，腹板、底板可根据要求变厚；
(4)在支架上施工中间墩顶0#段；
(5)在满堂支架上施工边跨靠近边支座梁段；
(65m+115m+65m)公路预应力混凝土连续刚构梁桥设计--毕业设计
(65m+115m+65m)公路预应力混凝土
连续刚构梁桥设计
毕业设计任务书
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学生姓名：
学 号：
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完成日期：
题 目：65+ 115 +65 m公路预应力混凝土双薄壁墩连续刚构桥设计
1、本论文的目的、意义根据教育部指示，毕业设计是高等工科院校本科培养计划中最后一个重要的教学环节，目的是使学生在学完培养计划所规定的基础课、技术基础课及各类必修课和选修专业课程之后，通过毕业设计这一环节，较为集中和专一地培养学生综合运用所学的基础理论、基本知识和基本技能以及分析和解决实际问题的能力。和以往的理论教学不同，毕业设计要求学生在老师的指导下，独立地、系统地完成一个工程设计，掌握一个工程设计的全过程。在巩固已学课程的基础上，学会考虑问题、分析问题和解决问题，并可以继续学习到一些新的专业知识，有所创新 。
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石家庄铁道大学毕业设计（20+40+20）m预应力混凝土连续梁结构设计The Construction Design of the (20+40+20)m Prestressed concrete continuous beam2012 届高等技术学院专业道路桥梁工程技术学号20095116学生姓名 1 2 3指导教师 2 2完成日期2012年5月28日毕业设计任务书毕业设计开题报告摘要本设计主要是关于公路预应力混凝土连续梁桥上部结构的设计。
设计跨度(20+40+20)m。
本设计采用国内著名的有限元分析软件——迈达斯计算,全桥共分40个单元，41个截面，两个施工阶段。
因为连续梁的内力与其施工方法密切相关，本设计采用满堂支架法施工。
这种施工方法操作比较简单，相比其他方法从经济效益上讲也比其他方法更有优势，而且施工质量易得到保证。
计算过程中由于涉及到大量的数字运算，采用手算比较繁琐，并且准确性得不到保证，因此采用计算机辅助设计。
设计中使用了迈达斯来计算内力,并且初步估算配筋量和进行初步验算。
但为了提高设计可靠性，最终还会通过以Excel电子表格计算、AutoCAD辅助软件进行手算，使自己的设计能力有较大的提升。
关键词：预应力混凝土连续梁桥; 迈达斯; 满堂支架法ABSTRACTThis graduate design is mainly about the design of the superstructure of the road prestressed concrete continuous bridge. The span of the bridge is 20m+40m+20m.This design adopts the domestic famous analytical software—MIDAS.The bridge is divided totally into 40units、41 sections and 2 construction stages. Because of the internal force of the continuous girder bridge relating to the method of construction closely, the method of construction of this design adopts the full scaffold construction method. Compared with other methods, this method is quite easy to construct and has economic superiority and the quantity of this construction also could get the assurance easily.Because this design involving a great deal of numerical calculation, it's too tedious to work by hand and the accuracy assuranced hardly. So it restores to CAD. Many bridge specialized software are applied, such as MIDAS applied in calculation of internal forces. and the initial estimate amount of reinforcing steel and initial checking. However, in order to improve design reliability, this will eventually be calculated by the Excel, AutoCAD and other auxiliary software by hand, developing design capabilities with a great improvement at the same time.Key word: Prestressed Concrete Continuous Bridge, MIDAS , Full Scaffold Construction目录第1章绪论 (1)1.1引言 (1)1.2预应力混凝土连续梁桥的发展 (1)1.2.1 国内外预应力混凝土连续梁桥的发展状况 (1)1.2.2预应力混凝土结构的特点 (3)第2章桥梁的总体设计概况 (4)2.1设计基本资料 (4)2.1.1总体设计 (4)2.1.2 主要技术标准 (4)2.1.3 主要材料 (4)2.1.4 设计依据 (4)2.2桥型及纵横断面布置 (5)2.2.1桥型布置及孔径划分 (5)2.2.2截面形式与截面尺寸 (5)第3章模型建立及结果分析 (6)3.1MIDAS的建模说明 (6)3.1.1 MIDAS的介绍 (6)3.1.2 MIDAS的建模步骤 (6)3.2恒载内力计算 (10)3.2.1恒载内力计算 (10)3.2.2活载内力计算 (11)3.2.3钢束的布置与计算 (12)第4章预应力损失及有效应力的计算 (20)4.1预应力损失的计算 (20)4.1.1摩阻损失 (20)4.1.2锚具变形损失 (21)4.1.3混凝土的弹性压缩 (21)4.1.4钢束松弛损失 (21)4.1.5收缩徐变损失 (22)4.2有效预应力的计算 (22)第5章预加力产生的次内力及内力组合 (24)5.1原理 (24)5.2计算方法 (25)5.2.1等效荷载法 (25)第6章内力组合 (26)6.1承载能力极限状态下的效应组合 (26)6.2正常使用极限状态下的效应组合 (31)第7章主梁截面验算 (39)7.1正截面抗弯承载力验算 (39)7.2持久状况正常使用极限状态应力验算 (40)7.2.1 正截面抗裂验算（法向拉应力） (40)7.2.2 斜截面抗裂验算（主拉应力） (42)7.2.3 使用阶段预应力混凝土受压区混凝土最大压应力验算 (43)7.2.4 预应力钢筋中的拉应力验算 (44)7.2.5 混凝土的主压应力验算 (44)7.3短暂状况预应力混凝土受弯构件应力验算 (44)第8章结束语 (46)参考文献 (47)致谢 (48)附录 (49)外文翻译 (49)第1章绪论1.1引言随着经济建设的迅速发展，我国城市交通的桥梁建设也进入迅速发展时期。
预应力混凝土连续梁优于普通钢筋混凝土连续梁的另一重要特点，就是它可以有效地避免混凝土开裂，特别是处于负弯矩区的桥面板的开裂。
与预应力混凝土T形刚构桥相比，连续梁桥的下部结构受力和构造简单，节省材料，加之它具有变形和缓、伸缩率小、刚度大、行车平稳、超载能力大、养护简便等优点，尤其是悬臂施工法、顶推法、逐跨施工法在连续梁桥中的应用，这种充分应用预应力技术的优点使施工设备机械化，生产工厂化，从而提高了施工质量，降低了施工费用。
所以在近代桥梁建筑中已得到越来越多的应用。
连续梁是超静定结构，基础不均匀沉降将在结构中产生附加内力，因此，对桥梁基础要求较高，通常宜用于地基较好的场合。
此外，箱梁截面局部温差，混凝土收缩、徐变及预加应力均会在结构中产生附加内力，增加了设计计算的复杂程度。
本桥段采用满堂支架法施工，满堂脚手架又称作满堂红脚手架，是一种搭建脚手架的施工工艺。
本桥段是一级公路上一座预应力混凝土等截面连续梁桥（跨径同设计题目），横桥向宽度为12.5m，单箱单室，下部结构采用实体墩，灌注桩基础。
桥梁设计基准期100年，结构设计安全等级一级，A类构件，可变荷载：汽车荷载：公路—Ⅰ。
1.2预应力混凝土连续梁桥的发展1.2.1国内外预应力混凝土连续梁桥的发展状况连续梁是一种古老的结构体系，它具有变形小，结构刚度好、行车平顺舒适，伸缩缝少，养护简易，抗震能力强等优点。
而在50年代前，预应力混凝土连续梁虽是常被采用的一种体系，但跨径均在百米以下。
当时主要采用满堂支架施工，费工费时，限材了它的发展。
50年代后，预应力混凝土桥梁应用悬臂施工方法后，加速了它的发展步伐。
预应力锚具结构的悬臂体系和悬臂施工方法相结合产生了T型刚构，在60年代，跨径100-200m范围内，几乎是大跨预应力混凝土梁桥中的优胜方案。
早期有典型意义的桥梁便是联邦德国1953年建造的胡尔姆斯桥和1954年建成的科布伦茨(Koblenz)桥。
然而，这种结构，由于中间带铰，并对混疑土徐变，收缩变形估计不足，又因温度影响等因素使结构在铰处形成明显折线变形状态，对行车不利。
因此，对行车条件有利的连续梁获得了新的发展。
对中跨预应力混凝土连续梁，在60年代初期，逐跨架设法与顶推法(F.Leonhardt所创建)的应用，对大跨预应力混凝土连续梁，各种更完善的悬针施工方法的应用，使连续梁废弃了昂贵的满堂的施工方法而代之以经济有效的高度机械化施工方法，从而使连续梁方案获得新的竞争力，逐步在40-200m范围内占主要地位。
如1962年在委内瑞拉的卡尼罗河上，用顶推法修建的6跨连续箱梁桥是顶推法的代表作，主跨为96m。
图1-1预应力混凝土连续梁桥无论是城市桥梁、高架道路、山谷高架栈桥，还是跨越宽阔河流的大桥，预应力混凝土连续梁都发挥了它的优势，往往取代其它体系而成为中选的优胜方案。
预应力混凝土连续梁在中等跨径范围，它更是千姿百态。
无论在桥跨布置、梁、墩赴面形式，或是在体系上(吸取其它结构的优点)不断改进桥型布置，例如V形墩的连续梁体系、双薄壁墩连续梁体系。
值得一提的是法国的SetubedLogoon桥，主跨130m 的五跨连续染，中间墩采用双薄壁结构，双壁相距10m，壁厚仅0.5m。
预应力混凝土连续梁在40-60m的范围，已可以说占绝对优势。
顶推法、移动模架法、逐孔架设法等施工方法经济快速，广泛应用也是关键因素。
如瑞士的Beckenried 高架桥，总长3048m，标准跨径55m。
连续梁的横截面形式在小跨径的城市高架桥中，为求最小建筑高度，常选用板式或肋板式截面，而在中、大跨径主要采用箱式截面。
但总的发展趋势是尽可能加长悬臂桥面板而选用单箱截面，以达到快速施工的目的。
在这种单箱截面的锚具结构中，往往采用三向预应力工艺。
预应力混凝土连续梁用干城市桥梁，为充分利用空间，并改善交通的分道行驶，已建成不少双层桥面的型式。
在这方面的一个突出例子是1980年在维也纳市多瑙河上新建的帝国(New Rei-chs)桥。