土木工程毕业设计外文文献翻译

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1、青岛理工大学毕业设计（论文）外文文献翻译Reinforced Concrete（来自土木工程英语）Concrete and reinforced concrete are used as building materials in every country. In many, including the United States and Canada, reinforced concrete is a dominant structural material in engineered construction. The universal nature of reinforced con

2、crete construction stems from the wide availability of reinforcing bars and the constituents of concrete, gravel, sand, and cement, the relatively simple skills required in concrete construction, and the economy of reinforced concrete compared to other forms of construction. Concrete and reinforced

3、concrete are used in bridges, buildings of all sorts underground structures, water tanks, television towers, offshore oil exploration and production structures, dams, and even in ships.Reinforced concrete structures may be cast-in-place concrete, constructed in their final location, or they may be p

4、recast concrete produced in a factory and erected at the construction site. Concrete structures may be severe and functional in design, or the shape and layout and be whimsical and artistic. Few other building materials off the architect and engineer such versatility and scope.Concrete is strong in

5、compression but weak in tension. As a result, cracks develop whenever loads, or restrained shrinkage of temperature changes, give rise to tensile stresses in excess of the tensile strength of the concrete. In a plain concrete beam, the moments about the neutral axis due to applied loads are resisted

6、 by an internal tension-compression couple involving tension in the concrete. Such a beam fails very suddenly and completely when the first crack forms. In a reinforced concrete beam, steel bars are embedded in the concrete in such a way that the tension forces needed for moment equilibrium after th

7、e concrete cracks can be developed in the bars.The construction of a reinforced concrete member involves building a from of mold in the shape of the member being built. The form must be strong enough to support both the weight and hydrostatic pressure of the wet concrete, and any forces applied to i

8、t by workers, concrete buggies, wind, and so on. The reinforcement is placed in this form and held in place during the concreting operation. After the concrete has hardened, the forms are removed. As the forms are removed, props of shores are installed to support the weight of the concrete until it

9、has reached sufficient strength to support the loads by itself.The designer must proportion a concrete member for adequate strength to resist the loads and adequate stiffness to prevent excessive deflections. In beam must be proportioned so that it can be constructed. For example, the reinforcement

10、must be detailed so that it can be assembled in the field, and since the concrete is placed in the form after the reinforcement is in place, the concrete must be able to flow around, between, and past the reinforcement to fill all parts of the form completely.The choice of whether a structure should

11、 be built of concrete, steel, masonry, or timber depends on the availability of materials and on a number of value decisions. The choice of structural system is made by the architect of engineer early in the design, based on the following considerations:1. Economy. Frequently, the foremost considera

12、tion is the overall const of the structure. This is, of course, a function of the costs of the materials and the labor necessary to erect them. Frequently, however, the overall cost is affected as much or more by the overall construction time since the contractor and owner must borrow or otherwise a

13、llocate money to carry out the construction and will not receive a return on this investment until the building is ready for occupancy. In a typical large apartment of commercial project, the cost of construction financing will be a significant fraction of the total cost. As a result, financial savi

14、ngs due to rapid construction may more than offset increased material costs. For this reason, any measures the designer can take to standardize the design and forming will generally pay off in reduced overall costs.In many cases the long-term economy of the structure may be more important than the f

15、irst cost. As a result, maintenance and durability are important consideration.2. Suitability of material for architectural and structural function. A reinforced concrete system frequently allows the designer to combine the architectural and structural functions. Concrete has the advantage that it i

16、s placed in a plastic condition and is given the desired shape and texture by means of the forms and the finishing techniques. This allows such elements ad flat plates or other types of slabs to serve as load-bearing elements while providing the finished floor and / or ceiling surfaces. Similarly, r

17、einforced concrete walls can provide architecturally attractive surfaces in addition to having the ability to resist gravity, wind, or seismic loads. Finally, the choice of size of shape is governed by the designer and not by the availability of standard manufactured members.3. Fire resistance. The

18、structure in a building must withstand the effects of a fire and remain standing while the building is evacuated and the fire is extinguished. A concrete building inherently has a 1- to 3-hour fire rating without special fireproofing or other details. Structural steel or timber buildings must be fir

19、eproofed to attain similar fire ratings.4. Low maintenance. Concrete members inherently require less maintenance than do structural steel or timber members. This is particularly true if dense, air-entrained concrete has been used for surfaces exposed to the atmosphere, and if care has been taken in

20、the design to provide adequate drainage off and away from the structure. Special precautions must be taken for concrete exposed to salts such as deicing chemicals.5. Availability of materials. Sand, gravel, cement, and concrete mixing facilities are very widely available, and reinforcing steel can b

21、e transported to most job sites more easily than can structural steel. As a result, reinforced concrete is frequently used in remote areas.On the other hand, there are a number of factors that may cause one to select a material other than reinforced concrete. These include:1. Low tensile strength. T

22、he tensile strength concrete is much lower than its compressive strength ( about 1/10 ), and hence concrete is subject to cracking. In structural uses this is overcome by using reinforcement to carry tensile forces and limit crack widths to within acceptable values. Unless care is taken in design an

23、d construction, however, these cracks may be unsightly or may allow penetration of water. When this occurs, water or chemicals such as road deicing salts may cause deterioration or staining of the concrete. Special design details are required in such cases. In the case of water-retaining structures,

24、 special details and / of prestressing are required to prevent leakage.2. Forms and shoring. The construction of a cast-in-place structure involves three steps not encountered in the construction of steel or timber structures. These are ( a ) the construction of the forms, ( b ) the removal of these

25、 forms, and (c) propping or shoring the new concrete to support its weight until its strength is adequate. Each of these steps involves labor and / or materials, which are not necessary with other forms of construction.3. Relatively low strength per unit of weight for volume. The compressive strengt

26、h of concrete is roughly 5 to 10% that of steel, while its unit density is roughly 30% that of steel. As a result, a concrete structure requires a larger volume and a greater weight of material than does a comparable steel structure. As a result, long-span structures are often built from steel.4. Ti

27、me-dependent volume changes. Both concrete and steel undergo-approximately the same amount of thermal expansion and contraction. Because there is less mass of steel to be heated or cooled, and because steel is a better concrete, a steel structure is generally affected by temperature changes to a gre

28、ater extent than is a concrete structure. On the other hand, concrete undergoes frying shrinkage, which, if restrained, may cause deflections or cracking. Furthermore, deflections will tend to increase with time, possibly doubling, due to creep of the concrete under sustained loads.In almost every b

29、ranch of civil engineering and architecture extensive use is made of reinforced concrete for structures and foundations. Engineers and architects requires basic knowledge of reinforced concrete design throughout their professional careers. Much of this text is directly concerned with the behavior an

30、d proportioning of components that make up typical reinforced concrete structures-beams, columns, and slabs. Once the behavior of these individual elements is understood, the designer will have the background to analyze and design a wide range of complex structures, such as foundations, buildings, a

31、nd bridges, composed of these elements.Since reinforced concrete is a no homogeneous material that creeps, shrinks, and cracks, its stresses cannot be accurately predicted by the traditional equations derived in a course in strength of materials for homogeneous elastic materials. Much of reinforced

32、concrete design in therefore empirical, i.e., design equations and design methods are based on experimental and time-proved results instead of being derived exclusively from theoretical formulations.A thorough understanding of the behavior of reinforced concrete will allow the designer to convert an

33、 otherwise brittle material into tough ductile structural elements and thereby take advantage of concretes desirable characteristics, its high compressive strength, its fire resistance, and its durability.Concrete, a stone like material, is made by mixing cement, water, fine aggregate ( often sand )

34、, coarse aggregate, and frequently other additives ( that modify properties ) into a workable mixture. In its unhardened or plastic state, concrete can be placed in forms to produce a large variety of structural elements. Although the hardened concrete by itself, i.e., without any reinforcement, is

35、strong in compression, it lacks tensile strength and therefore cracks easily. Because unreinforced concrete is brittle, it cannot undergo large deformations under load and fails suddenly-without warning. The addition fo steel reinforcement to the concrete reduces the negative effects of its two prin

36、cipal inherent weaknesses, its susceptibility to cracking and its brittleness. When the reinforcement is strongly bonded to the concrete, a strong, stiff, and ductile construction material is produced. This material, called reinforced concrete, is used extensively to construct foundations, structura

37、l frames, storage takes, shell roofs, highways, walls, dams, canals, and innumerable other structures and building products. Two other characteristics of concrete that are present even when concrete is reinforced are shrinkage and creep, but the negative effects of these properties can be mitigated

38、by careful design.A code is a set technical specifications and standards that control important details of design and construction. The purpose of codes it produce structures so that the public will be protected from poor of inadequate and construction.Two types f coeds exist. One type, called a str

39、uctural code, is originated and controlled by specialists who are concerned with the proper use of a specific material or who are involved with the safe design of a particular class of structures.The second type of code, called a building code, is established to cover construction in a given region,

40、 often a city or a state. The objective of a building code is also to protect the public by accounting for the influence of the local environmental conditions on construction. For example, local authorities may specify additional provisions to account for such regional conditions as earthquake, heav

41、y snow, or tornados. National structural codes genrally are incorporated into local building codes.The American Concrete Institute ( ACI ) Building Code covering the design of reinforced concrete buildings. It contains provisions covering all aspects of reinforced concrete manufacture, design, and c

42、onstruction. It includes specifications on quality of materials, details on mixing and placing concrete, design assumptions for the analysis of continuous structures, and equations for proportioning members for design forces.All structures must be proportioned so they will not fail or deform excessi

43、vely under any possible condition of service. Therefore it is important that an engineer use great care in anticipating all the probable loads to which a structure will be subjected during its lifetime. Although the design of most members is controlled typically by dead and live load acting simultan

44、eously, consideration must also be given to the forces produced by wind, impact, shrinkage, temperature change, creep and support settlements, earthquake, and so forth.The load associated with the weight of the structure itself and its permanent components is called the dead load. The dead load of c

45、oncrete members, which is substantial, should never be neglected in design computations. The exact magnitude of the dead load is not known accurately until members have been sized. Since some figure for the dead load must be used in computations to size the members, its magnitude must be estimated a

46、t first. After a structure has been analyzed, the members sized, and architectural details completed, the dead load can be computed more accurately. If the computed dead load is approximately equal to the initial estimate of its value ( or slightly less ), the design is complete, but if a significan

47、t difference exists between the computed and estimated values of dead weight, the computations should be revised using an improved value of dead load. An accurate estimate of dead load is particularly important when spans are long, say over 75 ft ( 22.9 m ), because dead load constitutes a major por

48、tion of the design load.Live loads associated with building use are specific items of equipment and occupants in a certain area of a building, building codes specify values of uniform live for which members are to be designed.After the structure has been sized for vertical load, it is checked for wi

49、nd in combination with dead and live load as specified in the code. Wind loads do not usually control the size of members in building less than 16 to 18 stories, but for tall buildings wind loads become significant and cause large forces to develop in the structures. Under these conditions economy c

50、an be achieved only by selecting a structural system that is able to transfer horizontal loads into the ground efficiently.钢筋混凝土在每一个国家，混凝土及钢筋混凝土都被用来作为建筑材料。很多地区，包括美国和加拿大，钢筋混凝土在工程建设中是主要的结构材料。钢筋混凝土建筑的普遍性源于钢筋的广泛供应和混凝土的组成成分，砾石，沙子，水泥等，混凝土施工所需的技能相对简单，与其他形式的建设相比，钢筋混凝土更加经济。混凝土及钢筋混凝土用于桥梁、各种地下结构建筑、水池、电视塔、海洋石油勘

51、探建筑、工业建筑、大坝，甚至用于造船业。 钢筋混凝土结构可能是现浇混凝土结构，在其最后位置建造，或者他们可能是在一家工厂生产混凝土预制件，再在施工现场安装。混凝土结构在设计上可能是普通的和多功能的，或形状和布局是奇想和艺术的。其他很少几种建材能够提供建筑和结构如此的通用性和广泛适用性。混凝土有较强的抗压力但抗拉力很弱。因此，混凝土，每当承受荷载时，或约束收缩或温度变化，引起拉应力，在超过抗拉强度时，裂缝开始发展。在素混凝土梁中，中和轴的弯矩是由在混凝土内部拉压力偶来抵抗作用荷载之后的值。这种梁当出现第一道裂缝时就突然完全地断裂了。在钢筋混凝土梁中，钢筋是那样埋置于混凝土中，以至于当混凝土开裂后

52、弯矩平衡所需的拉力由纲筋中产生。钢筋混凝土构件的建造包括以被建构件的形状支摸板。模型必须足够强大，以至于能够支承自重和湿混凝土的静水压力，工人施加的任何力量都适用于它，具体的手推车，风压力，等等。在混凝土的运作过程中，钢筋将被放置在摸板中。在混凝土硬化后，模板都将被移走。当模板被移走时，支撑将被安装来承受混凝土的重量直到它达到足够的强度来承受自重。设计师必须使混凝土构件有足够的强度来抵抗荷、载和足够的刚度来防止过度的挠度变形。除此之外，梁必须设计合理以便它能够被建造。例如，钢筋必须按构造设计，以便能在现场装配。由于当钢筋放入摸板后才浇筑混凝土，因此混凝土必须能够流过钢筋及摸板并完全充满摸板的每

53、个角落。被建成的结构材料的选择是混凝土，还是钢材、砌体，或木材，取决于是否有材料和一些价值决策。结构体系的选择是由建筑师或工程师早在设计的基础上决定的，考虑到下列因素：1.经济。常常首要考虑的是结构的总造价。当然，这是随着材料的成本和安装构件的必需劳动力改变的。然而，总投资常常更受总工期的影响，因为承包商和业主必须借款或贷款以便完成建设，在建筑物竣工前他们从此项投资中将得不到任何回报。在一个典型的大型公寓或商业项目中，建筑成本的融资将是总费用的一个重要部分。因此，金融储蓄，由于快速施工可能多于抵消增加材料成本。基于这个原因，设计师可以采取任何措施规范设计来减轻削减的成本。在许多情况下，长期的经

54、济结构可能比第一成本更重要。因此，维修和耐久性是重要的考虑因素。 2 .用于建筑与结构功能适宜的材料。钢筋混凝土体系经常让设计师将建筑与结构的功能相结合。混凝土被放置在塑性条件下借助于模板和表面加工来造出想要的形状和结构，这是它具有的优势。在提供成品楼或天花板表面时，这使得平板或其他形式的板作为受力构件。同样，钢筋混凝土墙壁能提供有吸引力的建筑表面，还有能力抵御重力、风力，或地震荷载。最后，大小和形状的选择是由设计师而不是由提供构件的标准决定的。3 .耐火性。建筑结构必须经受得住火灾的袭击，并且当人员疏散及大火扑灭之时建筑物仍然保持不倒。钢筋混凝土建筑特殊的防火材料及其他构造措施情况下，自身具

55、有1-3个小时的耐火极限。钢结构或木结构必须采取防火措施才能达到类似的耐火极限。4 .低维护。混凝土构件本身比结构钢或木材构件需要更少的维修。如果致密，尤其如此，加气混凝土已经被用于暴露于大气中的表面，如果在设计中已经采取谨慎措施，以提供足够的排水和远离的结构。必须采取的特别预防措施是让混凝土接触到盐，如除冰化学品。5 .材料的供应。砂、碎石、水泥和混凝土搅拌设备是被非常广泛使用的，以及钢筋比结构钢更容易运到多数工地。因此，钢筋混凝土在偏远地区经常使用。另一方面，有一些因素可能会导致选择钢筋混凝土以外的材料。这些措施包括： 1 .低抗拉强度。混凝土的抗拉强度是远低于其抗压强度（约1 / 10

56、） ，因此，混凝土易经受裂缝。在结构用途时，用钢筋承受拉力，并限制裂缝宽度在允许的范围内来克服。不过，在设计和施工中如果不采取措施，这些裂缝可能会有碍观瞻，或可允许水的浸入。发生这种情况时，水或化学物质如道路除冰盐可能会导致混凝土的恶化或污染。这种情况下，需要特别设计的措施。在水支挡结构这种情况下，需要特别的措施和/或预应力，以防止泄漏。2 .支摸。建造一个现浇结构包括三个步骤，在钢或木结构的施工中是遇不到的。这些都是（a）支摸 （b）拆摸（ c ） 安装支撑，直至其达到足够的强度以支承其重量。上述每个步骤，涉及劳动力和/或材料，在其他结构形式中，这是没有必要的。3 . 每单位重量或量的相对低

57、强度。该混凝土抗压强度大约是钢材抗压强度5至10 ，而其单位密度大约是钢材密度的30 。因此，一个混凝土结构，与钢结构相比，需要较大的体积和较大重量的材料。因此，大跨度结构，往往建成钢结构。4 .时间依赖的量的变化。混凝土与钢进行大约同样数量的热膨胀和收缩时，有比较少量的钢材加热或冷却，因为钢与混凝土相比是一个较好的导体，钢结构比混凝土结构在更大程度上更易受温度变化。另一方面，混凝土经历了干缩，如果被抑制，可能会导致变形或开裂。此外，变形随着时间的推移将趋于增加，由于混凝土在持续的负荷下的徐变，可能会增加一倍。几乎在土木工程和建筑的每一个分支中，钢筋混凝土在结构和基础领域内都得到了广泛的使用。

58、因此，工程师及建筑师在其整个职业生涯中需要钢筋混凝土设计的基本知识。文章的大部分是直接关于组成典型的钢筋混凝土结构的部件如梁、柱和板他们之间的作用、协调。一旦这些个别要素的作用被理解，设计师将有能力分析和设计这些元素组成的各种各样的复杂结构，例如地基，建筑物和桥梁。由于钢筋混凝土是一个徐变、收缩，并出现裂缝的非匀质材料，它的应力不能由适用于材料强度均匀弹性材料的传统方程推导出的方程准确预测。因此，许多钢筋混凝土的设计基于实证，即设计方程和设计方法是基于实验和费时的证明，而不是从理论的提法被完全导出的结果。对钢筋混凝土性能彻底的了解将允许设计师将脆性材料转换变成强硬的韧性结构材料，从而利用混凝土

59、良好的特点，其高抗压强度，其耐火性，其耐久性。 混凝土-石状的物质，是由搅拌水泥，水，细骨料（通常砂），粗骨料，并经常添加其他外加剂（即改善特性）而成为的一种和易性好的混合物。在其未硬化或塑性状态下，混凝土可放置在模板里产生大量的各种结构要素。虽然硬化的混凝土本身，也就是说，没有任何钢筋，它具有较强的抗压强度，但缺乏抗拉强度，因此很容易产生裂缝。因为无钢筋的混凝土是脆性的，它在荷载作用下不能进行大变形，并在没有预兆下突然断裂。钢筋与混凝土相结合，可以减少其主要的两个固有弱点的负面影响，其易开裂性和其脆性。当钢筋牢固黏结于混凝土时，一种强大、刚性、延性的建筑材料就诞生了。这种材料，所谓的钢筋混凝

60、土，被广泛用于建筑基础、结构框架、仓库、网状结构、公路、墙壁、水坝、运河及无数的其他结构和建筑产品。混凝土的其他两个特点，是混凝土被加固时会发生收缩和徐变，但采用仔细的设计可以减轻这些特性的负面影响。 规范，是一套技术规格和控制设计与施工重要细节的标准。规范的目的是产生合理的结构，使使用者将免于劣质和不合格的设计和结构。现有两种规范。其中一类，所谓的结构规范，是源于关心正确使用具体材料或关心某一特定类别结构安全设计的专家。第二种类型的规范，所谓的建筑条例，涵盖了建设在某一地区，往往是一个城市或一个国家的建筑。建筑条例的目标，也是以对抗当地环境条件对建设的影响来保障公众的权益。例如，地方当局可以

61、规定其他的条款，以对抗这样的区域条件，地震、大雪或龙卷风。国家结构规范常常被纳入当地的建筑法规。美国混凝土学会（ ACI ）的建筑规范包括钢筋混凝土建筑物的设计。它包括涵盖钢筋混凝土制造的各个方面-设计和施工的条文。它包括材料质量的规格、混合和现浇混凝土的细节，连续结构分析的设计假定，配料成分的设计方程。所有构件必须协调，这样它们在任何可能的工作条件下就不会失效或发生过大变形。因此，一名工程师非常谨慎地预期结构在其一生中所有可能经受的荷载，这是非常重要的。虽然大部分构件的设计是由同时作用的恒载和活载所控制，但还必须考虑到风、冲击、收缩、温度变化、徐变和地基沉陷、地震等等所产生的的力。 与结构自

62、重和固有的构件重量有关的荷载称为恒载。混凝土构件的恒载是固有的，在设计计算过程中是必须要考虑的。恒载值的大小直到构件尺寸确定后才能清楚的知道 。由于恒载的一些数值在计算构件尺寸时要用到，所以首先要估计他们值的大小。在结构进行了分析构件、构件尺寸确定、建筑的细节完成后，恒载可以计算更准确。如果计算的恒载大约等于它的初步估计值（或略少） ，但设计完成后，如果计算值和估计值之间存在显着性差异时，计算应用改进的恒载值加以修正。当跨度较长时，恒载的准确估计是特别重要的，因为当跨度超过七十五英尺（ 22.9米）时 ，恒载是设计荷载的一个重要组成部分。建设使用的相关活荷载是由城市或国家结构规范规定的。设计构件均布活荷载的值是由结构规范规定的，而不是根据设备的特定项目和某一个特定地区的使用者来估计。 结构在竖向荷载下定了尺寸后，还要根据风荷载和规范中规定的恒载活载组合后的结果来进行验算。风荷载在少于16到18层楼房中通常不控制构件的大小，但对于高层建筑，风荷载在结构中成为重要的控制因素和引起强大作用力的因素。在这种情况下，只有选择一个能够有效地将横向荷载传递到地面的结构体系，经济才能实现。第100页