混凝土专业毕业论文_外文翻译
混凝土毕业设计外文翻译--保护,预防,修复,改造和升级
外文文献翻译Protection,prevention,repair,renovation and upgrading（摘自《Management of Deteriorating Concrete Structures》Chapter 7作者George Somerville ）7.1 IntroductionThe need to repair concrete structure is not new. Much of the early work involved making good via patch repairs and crack filling, for aesthetic and serviceability reasons[7.1]. As the concrete infrastructure of the mid-20th century matured, there was also a demand to strengthen or upgrade to meet changes in use or increase in loadings. The need to treat cases of corrosion emerged in the 1950s with post-war prefabricated reinforced concrete housing,and many of the references to Chapter 2 detail examples of corrosion in highway structures as the use of de-icing salts increased rapidly in the early 1960s.Reference[7.2] gives some details of this ,and reference [7.3] is a detailed review of the situation in the UK and France with regard to post-tesioned concrete bridges.As durability concerns became more widespread, and consequences of failure more critical, repair became a growth industry, and options available on the market increased significantly in term of principles and approaches, and the individual solutions within each basic approach. This taining over 200 short papers on all aspects of the problem.The literature is full of individual case studies, describing what has been physically done and giving some reasons for selecting a particular option; it is often diffcult to draw general conclusions from these. Such articles, which are also helpful since they provide website addressers,appear most frequently in concrete-related journals such as Concrete from the Concrete Society in the UK. In North America, the various journals of the American Concrete Institute (ACI) do a similar job, and focus on repair is provided by the International Concrete Repair Institute (ICRI),which publishs a bimonthly Bulletin, and whose website gives details of available publications in the USA; generally, these are either guidance documents, or complications of articles on particular topics.There are aslo guidance documents available on individual repair, protection and upgrading methods, which explain the principles involved and are strong on the “how to …” aspects of the problem. Some examples of these can be obtained from the ICRIwebsite for North America, and reference[7.4-7.9] are similar publications available from the Concrete Society in the UK. The Concrete Society portfolio is augmented by other reports on test methods and diagnosis,and on how to enhance durability in new constructions; Technical Report 61 [7.10] is an example of the latter, where much of the detailed information is transferable to the repair and renovation situation. The Concrete RepairAssocication in the UK also has a website.The above brief rewiew is intended to show that there is quite a lot of information available on repair and renovation methods and also to indicate the nature of that information. It can become dated quite quickly however, as the technology is improved and new techniques are introduced. Moreover,, the nature and format of the information make it difficult to compare the technical and economic merits of alternative approaches- essential information to the owner when making a choice. This situation is now changing, with serious attempts being made to develop a systematic scientific basis for classifying repair and renovation methods, supported by sound specification and test methods. The emergence of EN 1504 is a prime example of that, and will be referred to strongly in later sections of this chapter.The final major missing link from the data bases is the lack of indepth feedback on real performation in the field over relevant periods of time. How does this compare with claims and expectations? Again this is changing, as typified by Figures 2.13-2.16 ,taken from the paper by Tilly [7.11]. Tilly's paper comes from the activities of a European network CONREPNET, which has examined well over 100 case studies in some detail and, apart from providing field data, has forced on developing criteria to permit alterative options to be evaluated to a common base. This information will also be used extensively later in this chapter.Repair and renovation is a huge subject, deserving several books in its own right.This book is about assessment, management and maintenance, and repair is an integral part of that. The emphasis in this chapter is on how it fits into the overall scheme of things, in moving forward from the assessment phase to taking effective action in selecting optimum solutions. This approach leads to the following sequence of subsection.7.2 Performance requirements for repaired structures7.3 Classification of protection, repair,renovation and upgrading options7.4 Performance requirements for repair and remedial measures7.5 Engineering specifications7.6 Moving towards the selection process7.7 Performance of repairs in sevice7.8 Timing of an intervention7.9 Selection a repair option-general7.10 The role of EN 1504 in selection7.11 Selecting a repair option in practice7.12 Concluding remarks Appendix 7.1 and 7.2 Reference7.2 Performance requirements for repaired structuresIn simple terms, the performance requirements for repaired structures are no different from those for new construction. Structurally, the focus will be on the factors listed in Table 4.12. Progressive assessment will have led to a performance time graph, such as that in Figure 3.13, for all relevant Table 4.12 factors. This paints a picture of how the present condition relates both to the performance levels provided in the original design and to the owner's perception of what constitutes minimum acceptable performance, bearing in mind that much more is now known about the structure (the Table 6.2 issue).Complicating the situation is the fact different owners may wish to manage the rehabilitation process differently. Figure 3.3 shows two viable options emanating from the asset management procedures associated with bridge in the UK . The different strategies involved intervention on different timescales, and,most probably, different solutions. Some owners may also wish to take a conservative approach,involving early preventative measures. There are no definitive general rules here, but a need to be aware of what the options are , linked to confidence in their effectiveness.In moving forward, however, it is essential to be clear about the required performance levels. While the basic structural factors in Table 4.12 will remain, there are broader strategies issues involved, some non-technical,which will influence the course which individual owners may choose to follow. Different owners will have different strategic goals, depending, for example, on:•type of ownership – whether private or public sector;•changing statutory requirements;•the type of structure and its function;•future plans for the structure, independent of its current physicall state, due, say, to – a possible change in use;-- improved performance requirements arising from higher user expectations;-- increases in imposed loadings;• a greater emphasis on whole life costing, linked to budgetary plans;•s desire for improved sustainability.In a follow-up project to CONTECVET, a group of parters containing a high proportion of owners from Spain, Sweden and the UK, set out to establish a strategy for the maitenance and rehabilition of concrete structures. As part of this project, acronym REHABCON, a list of general performance requirements was developed. Table 7.1, taken from a REHABCON deliverable [7.12] ,givesdetails. While the majority of the requirements relate to the structure as a whole, some also relate to the selected rehabilitation option and to the renovation process itself.Table 7.1 General performance requirements for rehabilitated structures.Rehabcon [7.12]General performance requirements__________________________________________________________________ Structural safety Ultimate limit state design (same expectations as for newstructures)•Strength•Stability•Robustness•Fatigue•Fire resistance•Earthquake resistanceServiceability Serviceability limit state design (same expectations as fornew structures)•Deformation•Displacement•Vibrations•Watertightness•Slip resistance/roughness•Drainage•Visibility during inclement weather•Comfort/convenience to userOperation and function•Availability, functionability•Minimisation of downtime. While this is important for a rehabilitated structure, it is also important to minimise inconvenience to users during the rehabilitation action,i.e,low low impact on users during operation, maintenance and repair.Aesthetics•Inspectability•Colour•Texture of surface•Durability of aesthetics•Safe-lookingSustainabilityand environmentalfactors•Materials for rehabilitation works tobe sustainable, and environmentally friendlyduring•Manufacture•Construction works•Use•Damage•Demolition•Impact on recycling and reuse•Deposition•Acoustics, noise control•Energy consumption•Harmful effects, such as spillage, leakage, dust or the emission of toxic fumes, either spontaneously or due to situiations such as fire, both duringthe rehabilitation works and afterwardsHeath andSafety•Public safety•Health for humans and nature during all phases in the life-cycle•Evacuation, emergency escape routesDurability•Durability of the original structure and the rehabilitated parts of the structure. Dependability•Reliability of the repair methods•Maitainability•Maintenance supportabilityFlexibility•Ensure that it is possible to meet future requirementEconomy•Reduce or limit whole life costs•Operational costs•Maintenance, repair and rehabilitation costs•Improvement/strengthening costs•Demolition and deposition costs•User cost•Limit loss of income due to insufficient functionality etc Cultureheritage•Structure having cultural or historic value require special treatment保护，预防，修复，改造和升级（摘自《混凝土结构腐蚀恶化的管理》第7章作者乔治·萨默维尔）7.1简介混凝土结构需要修复对我们来说并不陌生。
混凝土工艺中英文对照外文翻译文献
混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献(文档含英文原文和中文翻译) Concrete technology and developmentPortland cement concrete has clearly emerged as the material of choice for the construction of a large number and variety of structures in the world today. This is attributed mainly to low cost of materials and construction for concrete structures as well as low cost of maintenance.Therefore, it is not surprising that many advancements in concrete technology have occurred as a result of two driving forces, namely the speed of construction and the durability of concrete.During the period 1940-1970, the availability of high early strength portland cements enabled the use of high water content in concrete mixtures that were easy to handle. This approach, however, led to serious problems with durability of structures, especially those subjected to severe environmental exposures.With us lightweight concrete is a development mainly of the last twenty years.Concrete technology is the making of plentiful good concrete cheaply. It includes the correct choice of the cement and the water, and the right treatment of the aggregates. Those which are dug near by and therefore cheap, must be sized, washed free of clay or silt, and recombined in the correct proportions so as to make a cheap concrete which is workable at a low water/cement ratio, thus easily comoacted to a high density and therefore strong.It hardens with age and the process of hardening continues for a long time after the concrete has attained sufficient strength.Abrams’law, perhaps the oldest law of concrete technology, states that the strength of a concrete varies inversely with its water cement ratio. This means that the sand content (particularly the fine sand which needs much water) must be reduced so far as possible. The fact that the sand “drinks” large quantities of water can easily be established by mixing several batches of x kg of cement with y kg of stone and the same amount of water but increasing amounts of sand. However if there is no sand the concrete will be so stiff that it will be unworkable thereforw porous and weak. The same will be true if the sand is too coarse. Therefore for each set of aggregates, the correct mix must not be changed without good reason. This applied particularly to the water content.Any drinkable and many undrinkable waters can be used for making concrete, including most clear waters from the sea or rivers. It is important that clay should be kept out of the concrete. The cement if fresh can usually be chosen on the basis of the maker’s certificates of tensile or crushing tests, but these are always made with fresh cement. Where strength is important , and the cement at the site is old, it should be tested.This stress , causing breakage,will be a tension since concretes are from 9 to 11times as strong in compression as in tension, This stress, the modulus of rupture, will be roughly double the direct tensile breaking stress obtained in a tensile testing machine,so a very rough guess at the conpressive strength can be made by multiplying the modulus of rupture by 4.5. The method can be used in combination with the strength results of machine-crushed cubes or cylinders or tensile test pieces but cannot otherwise be regarded as reliable. With these comparisons,however, it is suitable for comparing concretes on the same site made from the same aggregates and cement, with beams cast and tested in the same way.Extreme care is necessary for preparation,transport,plating and finish of concrete in construction works.It is important to note that only a bit of care and supervision make a great difference between good and bad concrete.The following factors may be kept in mind in concreting works.MixingThe mixing of ingredients shall be done in a mixer as specified in the contract.Handling and ConveyingThe handling&conveying of concrete from the mixer to the place of final deposit shall be done as rapidly as practicable and without any objectionable separation or loss of ingredients.Whenever the length of haul from the mixing plant to the place of deposit is such that the concrete unduly compacts or segregates,suitable agitators shall be installed in the conveying system.Where concrete is being conveyed on chutes or on belts,the free fall or drop shall be limited to 5ft.(or 150cm.) unless otherwise permitted.The concrete shall be placed in position within 30 minutes of its removal from the mixer.Placing ConcreteNo concrete shall be placed until the place of deposit has been thoroughly inspected and approved,all reinforcement,inserts and embedded metal properly security in position and checked,and forms thoroughly wetted(expect in freezing weather)or oiled.Placing shall be continued without avoidable interruption while the section is completed or satisfactory construction joint made.Within FormsConcrete shall be systematically deposited in shallow layers and at such rate as to maintain,until the completion of the unit,a plastic surface approximately horizontal throughout.Each layer shall be thoroughly compacted before placing the succeeding layer.CompactingMethod. Concrete shall be thoroughly compacted by means of suitable tools during and immediately after depositing.The concrete shall be worked around all reinforcement,embedded fixtures,and into the comers of the forms.Every precaution shall be taken to keep the reinforcement and embedded metal in proper position and to prevent distortion.Vibrating. Wherever practicable,concrete shall be internally vibrated within the forms,or in the mass,in order to increase the plasticity as to compact effectively to improve the surface texture and appearance,and to facilitate placing of the concrete.Vibration shall be continued the entire batch melts to a uniform appearance and the surface just starts to glisten.A minute film of cement paste shall be discernible between the concrete and the form and around the reinforcement.Over vibration causing segregation,unnecessary bleeding or formation of laitance shall be avoided.The effect spent on careful grading, mixing and compaction of concrete will be largely wasted if the concrete is badly cured. Curing means keeping the concretethoroughly damp for some time, usually a week, until it has reached the desired strength. So long as concrete is kept wet it will continue to gain strength, though more slowly as it grows older.Admixtures or additives to concrete are materials arematerials which are added to it or to the cement so as to improve one or more of the properties of the concrete. The main types are:1. Accelerators of set or hardening,2. Retarders of set or hardening,3. Air-entraining agents, including frothing or foaming agents,4. Gassing agents,5. Pozzolanas, blast-furnace slag cement, pulverized coal ash,6. Inhibitors of the chemical reaction between cement and aggregate, which might cause the aggregate to expand7. Agents for damp-proofing a concrete or reducing its permeability to water,8. Workability agents, often called plasticizers,9. Grouting agents and expanding cements.Wherever possible, admixtures should be avouded, particularly those that are added on site. Small variations in the quantity added may greatly affect the concrete properties in an undesiraale way. An accelerator can often be avoided by using a rapid-hardening cement or a richer mix with ordinary cement, or for very rapid gain of strength, high-alumina cement, though this is very much more expensive, in Britain about three times as costly as ordinary Portland cement. But in twenty-four hours its strength is equal to that reached with ordinary Portland cement in thirty days.A retarder may have to be used in warm weather when a large quantity of concrete has to be cast in one piece of formwork, and it is important that the concrete cast early in the day does not set before the last concrete. This occurs with bridges when they are cast in place, and the formwork necessarily bends underthe heavy load of the wet concrete. Some retarders permanently weaken the concrete and should not be used without good technical advice.A somewhat similar effect,milder than that of retarders, is obtained with low-heat cement. These may be sold by the cement maker or mixed by the civil engineering contractor. They give out less heat on setting and hardening, partly because they harden more slowly, and they are used in large casts such as gravity dams, where the concrete may take years to cool down to the temperature of the surrounding air. In countries like Britain or France, where pulverized coal is burnt in the power stations, the ash, which is very fine, has been mixed with cement to reduce its production of heat and its cost without reducing its long-term strength. Up to about 20 per cent ash by weight of the cement has been successfully used, with considerable savings in cement costs.In countries where air-entraining cement cement can be bought from the cement maker, no air-entraining agent needs to be mixed in .When air-entraining agents draw into the wet cement and concrete some 3-8 percent of air in the form of very small bubbles, they plasticize the concrete, making it more easily workable and therefore enable the water |cement ratio to be reduced. They reduce the strength of the concrete slightly but so little that in the United States their use is now standard practice in road-building where heavy frost occur. They greatly improve the frost resistance of the concrete.Pozzolane is a volcanic ash found near the Italian town of Puzzuoli, which is a natural cement. The name has been given to all natural mineral cements, as well as to the ash from coal or the slag from blast furnaces, both of which may become cementswhen ground and mixed with water. Pozzolanas of either the industrial or the mineral type are important to civil engineers because they have been added to oridinary Portland cement in proportions up to about 20 percent without loss of strength in the cement and with great savings in cement cost. Their main interest is in large dams, where they may reduce the heat given out by the cement during hardening. Some pozzolanas have been known to prevent the action between cement and certain aggregates which causes the aggregate to expand, and weaken or burst the concrete.The best way of waterproof a concrete is to reduce its permeability by careful mix design and manufacture of the concrete, with correct placing and tighr compaction in strong formwork ar a low water|cement ratio. Even an air-entraining agent can be used because the minute pores are discontinuous. Slow, careful curing of the concrete improves the hydration of the cement, which helps to block the capillary passages through the concrete mass. An asphalt or other waterproofing means the waterproofing of concrete by any method concerned with the quality of the concrete but not by a waterproof skin.Workability agents, water-reducing agents and plasticizers are three names for the same thing, mentioned under air-entraining agents. Their use can sometimes be avoided by adding more cement or fine sand, or even water, but of course only with great care.The rapid growth from 1945 onwards in the prestressing of concrete shows that there was a real need for this high-quality structural material. The quality must be high because the worst conditions of loading normally occur at the beginning of the life of the member, at the transfer of stress from the steel to theconcrete. Failure is therefore more likely then than later, when the concrete has become stronger and the stress in the steel has decreased because of creep in the steel and concrete, and shrinkage of the concrete. Faulty members are therefore observed and thrown out early, before they enter the structure, or at least before it The main advantages of prestressed concrete in comparison with reinforced concrete are :①The whole concrete cross-section resists load. In reinforced concrete about half the section, the cracked area below the neutral axis, does no useful work. Working deflections are smaller.②High working stresses are possible. In reinforced concrete they are not usually possible because they result in severe cracking which is always ugly and may be dangerous if it causes rusting of the steel.③Cracking is almost completely avoided in prestressed concrete.The main disadvantage of prestressed concrete is that much more care is needed to make it than reinforced concrete and it is therefore more expensive, but because it is of higher quality less of it needs to be needs to be used. It can therefore happen that a solution of a structural problem may be cheaper in prestressed concrete than in reinforced concrete, and it does often happen that a solution is possible with prestressing but impossible without it.Prestressing of the concrete means that it is placed under compression before it carries any working load. This means that the section can be designed so that it takes no tension or very little under the full design load. It therefore has theoretically no cracks and in practice very few. The prestress is usually applied by tensioning the steel before the concrete in which it isembedded has hardened. After the concrete has hardened enough to take the stress from the steel to the concrete. In a bridge with abutments able to resist thrust, the prestress can be applied without steel in the concrete. It is applied by jacks forcing the bridge inwards from the abutments. This methods has the advantage that the jacking force, or prestress, can be varied during the life of the structure as required.In the ten years from 1950 to 1960 prestressed concrete ceased to be an experinmental material and engineers won confidence in its use. With this confidence came an increase in the use of precast prestressed concrete particularly for long-span floors or the decks of motorways. Whereever the quantity to be made was large enough, for example in a motorway bridge 500 m kong , provided that most of the spans could be made the same and not much longer than 18m, it became economical to usefactory-precast prestressed beams, at least in industrial areas near a precasting factory prestressed beams, at least in industrial areas near a precasting factory. Most of these beams are heat-cured so as to free the forms quickly for re-use.In this period also, in the United States, precast prestressed roof beams and floor beams were used in many school buildings, occasionally 32 m long or more. Such long beams over a single span could not possibly be successful in reinforced concrete unless they were cast on site because they would have to be much deeper and much heavier than prestressed concrete beams. They would certainlly be less pleasing to the eye and often more expensive than the prestressed concrete beams. These school buildings have a strong, simple architectural appeal and will be a pleasure to look at for many years.The most important parts of a precast prestressed concrete beam are the tendons and the concrete. The tendons, as the name implies, are the cables, rods or wires of steel which are under tension in the concrete.Before the concrete has hardened (before transfer of stress), the tendons are either unstressed (post-tensioned prestressing) or are stressed and held by abutments outside the concrete ( pre-tensioned prestressing). While the concrete is hardening it grips each tendon more and more tightly by bond along its full length. End anchorages consisting of plates or blocks are placed on the ends of the tendons of post-tensioned prestressed units, and such tendons are stressed up at the time of transfer, when the concrete has hardened sufficiently. In the other type of pretressing, with pre-tensioned tendons, the tendons are released from external abutments at the moment of transfer, and act on the concrete through bond or archorage or both, shortening it by compression, and themselves also shortening and losing some tension.Further shortening of the concrete (and therefore of the steel) takes place with time. The concrete is said to creep. This means that it shortens permanently under load and spreads the stresses more uniformly and thus more safely across its section. Steel also creeps, but rather less. The result of these two effects ( and of the concrete shrinking when it dries ) is that prestressed concrete beams are never more highly stressed than at the moment of transfer.The factory precasting of long prestressed concrete beams is likely to become more and more popular in the future, but one difficulty will be road transport. As the length of the beam increases, the lorry becomes less and less manoeuvrable untileventually the only suitable time for it to travel is in the middle of the night when traffic in the district and the route, whether the roads are straight or curved. Precasting at the site avoids these difficulties; it may be expensive, but it has often been used for large bridge beams.混凝土工艺及发展波特兰水泥混凝土在当今世界已成为建造数量繁多、种类复杂结构的首选材料。
The durability of concrete 英文版混凝土论文
The durability of concreteIn civil engineering, concrete is the most widely used and the amount of one of the largest building materials. Over the past century, the concrete strength to continuously improve its main development trends. China's large population, the urgent need for housing.Structural Design not only to meet the requirements of safe and reliable indicators, but also consider the durability requirements.The durability of concrete issues, refers to the structure in the environment and cause long-term evolution of the structure due to internal or external reasons, the concrete has to lose the ability to use. That for durability failure, the durability of many reasons, have antifreeze failure, failure of alkali - aggregate reaction, chemical corrosion failure. Part of the concrete structure in the environment below freezing, water in the pores will freeze, resulting in volume expansion of cold water migration, the formation of various pressures, when the pressure reaches a certain level, resulting in the destruction of the concrete.Alkali - aggregate reaction of concrete chemical reactions that occur by the active component of the alkali in the concrete aggregates, causing the expansion of the concrete, cracking, or even destroy. Response factors in the concrete, and its harmful effects are often not the root of the rule is a big hidden in the concrete works. Concrete structures in aggressive media environment, will cause the cement paste to a series of chemical, physical, and materialized change gradually been eroded, cement strength to reduce serious, as well as destruction. In concrete engineering in order to meet the requirements of concrete construction work, that is, water consumption, water-cement ratio is high, resulting in high porosity of the concrete, durability reduce. Also, the lack of hydrate stability in the cement paste will have an impact on the durability.Therefore, to improve the durability of concrete, must reduce the porosity of the concrete, especially the capillary porosity, the most important method is to reduce the concrete mixing water. But if we simply reduce the amount of water, the concrete decreases, will lead to tamping forming a total of difficulties, the same result in the concrete structure is not dense, and even cellular and macroscopic defects such as, not only reduce the strength of concrete, and the durability of concrete also reduced. To improve the durability of concrete basic There are several ways: First, the strength of the material and engineering properties of cement cement is hardening formed by the condensation of the cement mortar, cement paste, once damaged, the durability of concrete is damaged, the choice of cement should pay attention to the specific performance of the varieties of cement, select alkali content, low heat of hydration, shrinkage of a small, heat resistance, water resistance, corrosion resistance, good frost resistance of cement and in the circumstances to choose . The strength of cement is not the sole criterion to determine the concrete strength and performance, such as lower grade cement can also be the preparation of high-grade concrete. Therefore, the project select the strength of cement at the same time, the need to consider the engineering performance, and sometimes, its engineering performance is more important than the strength. Aggregates and admixtures choice of the aggregate consideration should be given its alkali activity to prevent the harm caused by alkali-aggregate reaction, corrosion resistance and water absorption of the aggregate, reasonable choice of gradation, to improve the workability of the concrete mixture to increase concrete density; a large number of studies have shown that the doped fly ash, slag, silica fume, etc. the mixed caineng effectively improve the performance of the concrete, to improve the pore structure of concrete, filling the internal voids, and to increase the density, high-ash concrete can inhibition of alkali-aggregate reaction, and thus doped hybrid materials of concrete, is to improve the durability of concrete and effective measures. Development in recent years, high-performance concrete. Second, the rational design of concrete mix mix design meet the concrete strength, work should be considered to minimize the amount of cement and water consumption, lower heat of hydration, reduce shrinkage cracks, and to increase the density, and reasonable water reducer and air entraining agent, to improve the internal structure of concrete, mixed with a sufficient amount of mixture to improve concrete durability. Structural members shall use the environmental design of the concrete cover thickness, to prevent the outside media to penetrate the internal corrosion of reinforced. Node structural design of the structure should also be considered a component to the overallendurance capacity after partial damage. The structural design shall also control the crack width of concrete cracks. Third, the incorporation of an appropriate amount of admixtures, water-reducing agent such as: liquidity needed to ensure that concrete mixture at the same time, minimizing water consumption, reduce water-cement ratio, so that the total porosity of the concrete, in particular, the capillary porosity substantially reduced. 4, the incorporation of the hydrate stability, lack of efficient activity of mineral admixtures: ordinary Portland cement concrete, cement paste is another major factor in the concrete can not be super durable.To eliminate the structure of the concrete itself disruptive factor: In addition to concrete structural damage caused by environmental factors, some of the concrete itself, physical and chemical factors may also cause serious damage of the concrete structure, resulting in concrete failure. To ensure the strength of concrete: strength and durability is a different concept, but is closely related to the nature of links between them is based on the internal structure of the concrete with water-cement ratio, this factor is directly related.Concrete construction should also consider the durability of concrete mixing and maximize the use of the second mixing method, wrap the sand method, wrapped in the process of gravel law, improve the workability of the concrete mixing materials, water retention and improve the concrete strength, reduce water consumption; pouring mass concrete vibrators shall control the temperature of concrete cracks, shrinkage cracks, construction cracks, concrete pouring and vibrating system, to improve concrete density and impermeability, attention to the process of the surface after the concrete vibratorsand enhance the conservation, in order to reduce the concrete cracks. Concrete construction process control component appearance of cracks, construction cracks is essential and should strengthen the construction quality management, the special season of construction of concrete structures, there should be to take special measures.So, we want to develop the new concrete, such as high performance concrete.Therefore, to improve the durability of concrete is the inevitable trend of development of the concrete.。
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％。
混凝土的英文作文
混凝土的英文作文英文：Concrete is a versatile and durable building material that is widely used in construction. It is composed of a mixture of cement, water, and aggregates, such as sand, gravel, or crushed stone. The mixture is then poured into molds or forms and allowed to harden and cure.One of the key benefits of concrete is its strength and durability. It can withstand heavy loads and harsh weather conditions, making it ideal for use in foundations, walls, and floors. Additionally, concrete is fire-resistant and can help to prevent the spread of flames in the event of a fire.Another advantage of concrete is its versatility. It can be molded into various shapes and sizes, allowing for a wide range of design possibilities. It can also be colored or textured to create a unique look and feel.However, there are some drawbacks to using concrete. It can be expensive and time-consuming to install, and it is not always the most environmentally friendly option. Additionally, concrete can crack and deteriorate over time, requiring maintenance and repair.Overall, concrete is a reliable and durable building material that has been used for centuries. With proper installation and maintenance, it can last for many yearsand provide a solid foundation for any structure.中文：混凝土是一种多功能且耐用的建筑材料，在建筑中被广泛使用。
混凝土英文论文
Development of Green High Performance Concrete for SustainableDevelopment0706121 29 刘海庆Abstract: With the fast development of society and economy an important factor that affects social and economicdevelopment is environmental pollution. In face of reduction of the natural resources and the growing problem ofenvironmental pollution, the ordinary concrete has not been fit with the need of the social economy; the perfor-mances of concrete are required improvement. So the development of the concrete materials is generally considered with environmental protection, energy conservation, resource saving and the green high performance concrete is developed. The green high performance concrete that is developed in recent years is a new building material. The concept and features of green high performance concrete are introduced, then the categories and current application of it are analyzed and exist problems are proposed, finally it is concluded that the development of green high per-formance concrete is the only way for the sustainable development of the concrete materials.Keywords:green high performance concrete; environmental pollution; sustainable development CLC: TU528 Document code: A Article ID: 1672-2132(2010)Suppl.-0432-040 IntroductionConcrete is the most widely used and the greatest amount of building materials in the con-struction area. However, extensive use of concrete has destroyed unprecedented natural resources so that resources and energy appear crisis. Concrete in the 21st.century not only meets with the re-quirements of the structure, but also minimizes asmuch as possible the damage to the ecological envi-ronment to the need of sustainable development.So, developing the green high performance con-crete is the need of the sustainable develop-ment.1 Connotation and features of green high performance concretenWu Zongwei, academician of Chinese academy of engineering, first proposed the concept of con-crete and he pointed out the green high perfor-mance concrete was the direction of concrete devel-opment. Researchers consider the green high performance concrete should follow conditions as follows:(1) Cement used must be green cement. Sand and stone should be exploited orderly and withoutdamaging the environment.(2) Cement consumption should be saved tothe greatest extent in order to reduce by-products during the course of producing cement, for exam-ple, CO2, SO2, and NO2and so on.(3) Agricultural and industrial waste residueprocessed should be mixed more, such as, ground-ed slag, high-quality fly ash, silica fume and rice husk, to reduce cement, protect environment and improve concrete durability.(4) Industrial waste liquid should be used a lot, especially; water reducing agent made by black paper waste liquid and other composite addi-tive developed should be mixed to help dealing with other liquid.(5) Concrete should be mixed in the mixing station to reduce waste, dust and waster water of mixing concrete in site and waste and water recy-cling should be strengthened.(6) Through enhancing the strength, reduc-ing cross-sectional area or volume of structure, re-ducing concrete volume, cement, sand and stone can be saved. By improving durability of concrete,service life of structure can be lengthened and re-pair and reconstruction cost are further saved andthe indiscriminate use of natural resources will be reduced.(7) A lot of demolition waste should be recy-cled and recycled aggregate concrete should be de-veloped.The concept of green high performance con-crete is to strengthen people′s green awareness and to play an important role of energy saving and en-vironmental protection. It is concluded that the de-velopment of green high performance concrete is the only way for the sustainable development of concrete.2 Classification of the green high performance concrete2.1 Ecological environment-friendly concreteTo meet with the requirements of high strength and high durability, traditional concrete is always in pursuit of its compactness, which will cause concrete structures (lots of buildings and rigid pavement and so on) lack of permeability and permeability, exacerbate urban heat island effect,deteriorate human living environment. So rainwa-ter can not penetrate so that it lowers ground-wa-ter table in the city and affects growth of the sur-face plant, in a result, causes urban ecological sys-tem disorder. Because concrete color is gray, living space built in concrete gives a rough, hard, cold,dark feeling. So it is concluded that the develop-ment of ecological environment-friendly concrete is the only way to solve these problems. Another, e-cological environment-friendly concrete can be di-vided into plant concrete and water-permeability concrete according to different functions.2.2 Recycled aggregate concreteConcrete from the old buildings or structures can be divided into coarse and fine aggregate through breaking and this aggregate take place of some sand and gravel. So this is considered as re-cycled aggregate concrete. The use of recycled ag-gregate has been viewed as one of main measures in the development of green concrete.2.3 High-volume fly ash high performance con-creteFly ash mixed can improve concrete’s strength, impermeability and frost resistance,lower shrinkage; inhibit the effect of the alkali-ag-gregate reaction. High performance concrete which is mixed a great deal of fly ash and the morphologi-cal effects, micro-aggregate effects, volcanic ash effects of fly ash are used fully will lead to greater economic and environmental benefits.2.4 Environmentally mitigatable concrete(1) Environment-protecting concrete: the dif-ferences in composition between this concrete and traditional concrete are that a lot of solid waste,industrial waste residue, waste brick, concrete and solid rubbish and so on and additive produced through industrial waste liquid are mixed by taking certain technical measures to achieve all kinds of waste recycling and reduce environment pollution.(2) Energy-saving concrete: high temperature calcinations siliceous materials (clay or shale) and calcium raw material are needed in the course of ce-ment production, which will consume a large amount of energy. If concrete are prepared through non-burned cement, energy consumption can be reduced significantly.(3) Self-compacting concrete: self-compacting concrete is vibrated and compacted through self-weight. Because of this concrete has sufficient co-hesion so as to ensure disengagement in theprocess of pouring, a large amount of powder are required.3 Engineering application of green high performance concreteThe history of green high performance con-crete is not long, but it has obvious advantages and is paid attention to at home and abroad. Because concrete has been used widely as structural materi-al to date, appearance of green high performance concrete will become the main building structure materials in the 21st.century. Concrete strength in Chicago′s 311 South-walker Building in America with 295m height and 71 layers was C95. 40 mil-lion m3high performance concrete was used in both anchor piers of Akashi Kaikyo Bridge which was the longest suspension bridge at that time.The use of high green performance concretewas started late in China, especially the serious de-fects of the overpass in the Beijing and Tianjin re-gion arouse great concern in the engineering area.Research and application of green high perfor-mance concrete are increasing little by little.C80 high performance concrete are used in high-rise buildings and Jingan Center Building in Shang-hai.4 Existing problems of green high performance concrete4.1 Cost issuesThe cost of concrete is increased by 50% or more because used raw materials, the production and management level and production lines are raised. For example, collecting and preparing re-cycling aggregate must cost a certain machinery and equipment and manpower for recycled con-crete. From the point of economic indicators, the production of recycled aggregate is few profits, no profit, even deficit. If the production of recycled aggregate maintains a certain profit, its retail price will inevitably higher than the natural aggregate.Therefore, it is difficult to be accepted by users.4.2 Early crackingIn recent years cracking of concrete has be-come a hot topic at home and abroad and high per-formance concrete is no exception. That is, crackof concrete is very common. Many factors that in-fluence early cracking of concrete are as follows:self-shrinkage, drying shrinkage, earl y elastic modulus, tensile strength, ultimate tensile strain,creep, water evaporation rate, structural con-straint degree and so on.4.3 Mix problemThe same absolute volume is used with con-ventional concrete. After mixes of various compo-nents are determined, the performance require-ments are proved through experiments. The mix design of green high performance concrete is more difficult than that of common concrete. Comparing with mix design of conventional concrete, the mix design parameters of green high performance con-crete are smaller, such as, less than 0.4~0.42 water-cement ratio, less than 25mm the largest stone diameter (less than 20 mm or even 15 mm),2.6~3.0 sand fineness modulus, 42.5 concretes trength grade (ISO). So mix design will be sim-plified.5 ConclusionThe research of the green high performance technology in China is still in primary stage and the current research is not enough to conclude the laws that directly guide production. So the research and development of green high performance concrete should be increased greatly andquality standards and production specifications should be drawn up.In a word, we should attach great importance to green issues of concrete because these are related to our human survival and development. Through constant exploration and research, it is firmly be-lieved that the green high performance concrete is the only way for the sustainable development of the concrete materials.Reference:[1] CEB-FIP. Environment Design [R]. Lausanne: [s.n.],2004.[2]Malhotra V M. Introduction: Sustainable develop-ment and concrete technology [J].Concrete interna-tional,2002, 24(7):22.[3]吴中伟.绿色高性能混凝土——混凝土的发展方向[J].混凝土与水泥制品,1998,(1):3-6.[4]鄢朝勇.混凝土材料的可持续发展与粉煤灰绿色高性能混凝土[J].国外建材科技,2005,(4):5-7.[5] 王立久,汪振双,赵善宇.绿色生态混凝土技术的研究现状与发展[J].混凝土. 2009,(7):1-3.[6] Kumar M P. Reducing the environmental impact of concrete [J]. Concrete International,2001, 23(10):61-66.[7] Kumar M P. Greening of the concrete industry for sustainable development [J]. ConcreteInternational,2002, 24(7):23-28.[8] 王淑萍,王思远,张春,等.高性能混凝土的研究现状和发展应用[J].北方交通,2007,(4):47-50.[9]周士琼,李益进,尹健,等.复合超细粉煤灰与特种混凝土技术的开发与应用[J].铁道科学与工程学报,2004,(2):39-45.。
毕业论文外文翻译-混凝土的耐久性
Durability of concreteBesides its ability to sustain loads, concrete is also required to be durable .The durability of concrete can be defined as its resistance to deterioration resulting from external and internal causes. The external causes include the effects of environmental and service conditions to which concrete is subjected, such as weathering, particularly chlorides and sulphates, in the constituent materials, interaction between the constituent materials, such as alkali-aggregate reaction, volume changes, absorption and permeability.In order to produce a durable concrete, care should be taken to select suitable constituent materials. It is also important that mix contains adequate quantities of materials in proportions suitable for producing a homogeneous and fully compacted concrete mass.WeatheringDeterioration of concrete by weathering is usually brought about by the disruptive action of alternate freezing and thawing of free water within the concrete and expansion and contraction of the concrete, under restraint, resulting from variations in temperature and alternate wetting and drying.Damage to concrete from freezing and thawing arises from the expansion of pore water during freezing; in a condition of restraint, if repeated a sufficient number of times, this results in the development of hydraulic pressure capable of disrupting concrete. Road Krebs and slabs, dams and reservoirs are very susceptible are very susceptible to frost action.The resistance of concrete to freezing and thawing can be improved by increasing its impermeability. This can be achieved by using a mix with the lowest possible water-cement ratio compatible with sufficient workability for placing and compacting into a homogeneous mass. Durability can be further improved by using air entrainment, an air content of 3 to 6 per cent of the volume of concrete normally being adequate for most applications. The use of air entrained concrete is particularly useful for roads where salts are used for deicing.Chemical Attackin general, concrete has a low resistance to chemical attack.There are several chemical agents which react with concrete but the most common forms of attack are those associated with leaching, carbonation, chlorides and sulphates. Chemical agents essentially react with certain compounds of the hardened cement paste and the resistance of concrete to chemical attack therefore can be affected by the type of cement used. The resistance to chemical attack improves with increased impermeability.WearThe main causes of wear of concrete are the cavitation effects of fast-moving water, abrasive material in water, wind blasting and attrition and impact of traffic. Certain conditions of hydraulic flow result in the formation of cavities between the flowing water and the concrete surface .These cavities are usually filled with water vapor charged with extraordinarily high energy and repeated contact with the concrete surface results in the formation of pits and holes, Known an cavitation erosion. Since even a good-quality concrete will not be able to resist this kind of deterioration, the best remedy is therefore the elimination of cavitation by producing smooth hydraulic flow. Wherenecessary, the critical areas may be lined with materials having greater resistance to cavitation erosion.In general, the resistance of concrete to erosion and abrasion increases with increase in strength. The use of a hard and tough aggregate tends to improve concrete resistance to wear.Alkali-Aggregate ReactionsCertain natural aggregates react chemically with the alkalis present in Portland cement. When this happens these aggregates expand or swell resulting in cracking and disintegration of concrete.Volume ChangesPrincipal factors responsible for volume changes are the chemical combination of water and cement and the subsequent drying of concrete, variations in temperature and alternate wetting and drying. When a change in volume is resisted by internal or external forces this can produce cracking, The greater the imposed restraint, the more severe the cracking. The presence of cracks in concrete reduces its resistance to the action of leaching, corrosion of reinforcement, attack by sulphates and other chemicals, alkali-aggregate reaction and freezing and thawing, all of which may lead to disruption of concrete. Severe cracking can lead to complete disintegration of the concrete surface particularly when this is accompanied by alternate expansion and contraction.V olume changes can be minimized by using suitable constituent materials and mix proportions having due regard to the size of structure. Adequate moist curing is also essential to minimize the effects of any volume changes.Permeability and AbsorptionPermeability refers to the ease with which water can pass through the concrete. This should not be confused with the absorption property of concrete and the two are not necessarily related. Absorption may be defined as the ability of concrete to draw water into its voids. Low permeability is an important requirement for hydraulic structures and in some cases water tightness of concrete may be considered to be more significant than strength although, other conditions being equal, concrete of low permeability will also be strong and durable. A concrete which readily absorbs water is susceptible to deterioration. Concrete is inherently a porous material. This arises from the use of water in excess of that required for the purpose of hydration in order to make the mix sufficiently workable and the difficulty of completely removing all the air from the concrete during compaction. If the voids are interconnected concrete becomes pervious although with normal care concrete is sufficiently impermeable for most purposes. Concrete of low permeability can be obtained by suitable selection of its constituent materials and their proportions followed by careful placing, compaction and curing. In general for a fully compacted concrete, the permeability decreases with decreasing water-cement ratio. Permeability is affected by both the fineness and the chemical composition of cement. Aggregates of low porosity are preferable when concrete with a low permeability is required. Segregation of the constituent materials during placing can adversely affect the impermeability of concrete.混凝土的耐久性混凝土除了承受荷载之外，还需要有一定的耐久性。
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。