土木工程畢業(yè)設(shè)計(jì)外文文獻(xiàn)翻譯

1、外文文獻(xiàn)翻譯Reinforced Concrete來(lái)自?土木工程英語(yǔ)? 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 concrete constru

2、ction stems from the wide availabilityof reinforcingbars 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 concrete are us

3、ed 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 intheir final location, or they may be precast concrete

4、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 compression but

5、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 momentsabout the neutral axis due to applied loads are resisted by an internal t

6、ension-compression couple involving tension in the concrete. Such a beamfails very suddenly and completely whenthe first crack forms. In a reinforced concrete beam, steel bars are embeddedin the concrete in such a way that the tension forces needed for moment equilibrium after the concrete cracks ca

7、n be developed in the bars.The construction of a reinforced concrete member involves building a from ofmold in the shape of the memberbeing built. The form must be strong enough to support both the weight and hydrostatic pressure of the wet concrete, and any forces applied to it by workers, concrete

8、 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 has reached sufficient

9、 strength to support the loads by itself.The designer must proportion a concrete memberfor 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 must be detailed so tha

10、t 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 be built of concrete,

11、steel, masonry, or timber depends on the availabilityof 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 consideration is the overall const

12、 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 allocate moneyto carry out

13、 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 savings due to rapid construct

14、ion 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 manycases the long-term economyof the structure maybe more important than the first cost. As a result, maint

15、enance 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 is placed in a plastic conditi

16、on 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 thefinished floor and / or ceiling surfaces. Similarly, reinforced concrete walls can p

17、rovide 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 structure in a building must w

18、ithstand 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 fireproofed to attain similar fir

19、e ratings.4. Low maintenance. Concrete membersinherently 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 the design to provide adequate

20、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 facilitiesare very widely available, and reinforcing steelcan be transported tomost job sites mo

21、re 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 selecta material other than reinforced concrete. These include:1. Low tensile strength.The tensile strength concrete is much

22、 lower than itscompressive 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 and construction, however, thesecracks m

23、ay be unsightly or may allow penetrationof water. Whenthis occurs, water or chemicals such as road deicing salts maycause deterioration or staining ofthe concrete. Special design details are required insuch cases. In the case of water-retaining structures, special details and / of prestressing are r

24、equired 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 forms, and (c) propping or shoring the new

25、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 compressivestrength of concrete is roughly 5 to 10% that of stee

26、l, 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. Time-dependent volume changes. Both concrete and

27、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 changesto a greater extent than is a concrete structure. On the o

28、ther hand, concrete undergoes frying shrinkage, which, if restrained, maycause 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 branch of civil engineering and architectureextensiv

29、e use ismade 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 and proportioning of components that make up typical re

30、inforced 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, and bridges, composed of these elements.Since reinforc

31、ed 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. Muchof reinforced concrete design in therefore empirical, i.e., design e

32、quations 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 otherwise brittle material into tough ductile structu

33、ral elements and thereby take advantage of concrete s desirable characteristics, its high compressive strength, its fire resistance, and its durability.Concrete, a stone like material, is madeby mixing cement, water, fine aggregate ( often sand ), coarse aggregate, and frequently other additives ( t

34、hat 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 strong in compression, it lacks tensile strength and t

35、herefore 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 principal inherent weaknesses, its susceptibility to crack

36、ing 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, structural frames, storage takes, shell roofs, highways, walls,

37、 dams, canals, and innumerable other structures and building products. Two other characteristics of concrete that are present even whenconcrete is reinforced are shrinkage and creep, but the negative effects of these properties can be mitigated by careful design.A code is a set technical specificati

38、ons and standards thatcontrol importantdetails 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 structural code, is originated and controlled by specialists

39、 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, often a city or a state. The objective of a building cod

40、e 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, heavy snow, or tornados. National structural codes genrally a

41、re 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 construction. It includes specifications on quality of mat

42、erials, 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 excessively under any possible condition of service. Therefore i

43、t 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 simultaneously, consideration must also be given to the forces pro

44、duced 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 concrete members, which is substantial, should never be neg

45、lected in design computations. The exact magnitude of the dead load is not known accurately until membershave been sized. Since some figure for the dead load must be used in computations to size the members, its magnitude must be estimated at first. After a structure has been analyzed, the memberssi

46、zed, 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 significant difference exists between the computed and estimated value

47、s 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 portion of the design load.Live loads associated with building

48、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 wind in combination with dead and live load as specified inthe

49、 code. Wind loads do notusually control the size of members in building less than 16 to 18 stories, but for tall buildings wind loads becomesignificant and cause large forces to develop in the structures. Under these conditions economycan be achieved only by selecting a structural system that is abl

50、e to transfer horizontal loads into the ground efficiently.鋼筋混凝土在每一個(gè)國(guó)家，混凝土及鋼筋混凝土都被用來(lái)作為建筑材料。很多地區(qū)，包括美國(guó)和 加拿大，鋼筋混凝土在工程建設(shè)中是主要的結(jié)構(gòu)材料。鋼筋混凝土建筑的普遍性源于鋼筋 的廣泛供給和混凝土的組成成分，礫石，沙子，水泥等，混凝土施工所需的技能相對(duì)簡(jiǎn)單， 與其他形式的建設(shè)相比，鋼筋混凝土更加經(jīng)濟(jì)?；炷良颁摻罨炷劣糜跇蛄?、各種地下 結(jié)構(gòu)建筑、水池、電視塔、海洋石油勘探建筑、工業(yè)建筑、大壩，甚至用于造船業(yè)。鋼筋混凝土結(jié)構(gòu)可能是現(xiàn)澆混凝土結(jié)構(gòu)，在其最后位置建造，或者他們可能是在一家 工廠

51、生產(chǎn)混凝土預(yù)制件，再在施工現(xiàn)場(chǎng)安裝?；炷两Y(jié)構(gòu)在設(shè)計(jì)上可能是普通的和多功能 的，或形狀和布局是奇想和藝術(shù)的。其他很少幾種建材能夠提供建筑和結(jié)構(gòu)如此的通用性 和廣泛適用性。混凝土有較強(qiáng)的抗壓力但抗拉力很弱。因此，混凝土，每當(dāng)承受荷載時(shí)，或約束收縮 或溫度變化，引起拉應(yīng)力，在超過(guò)抗拉強(qiáng)度時(shí)，裂縫開(kāi)始開(kāi)展。在素混凝土梁中，中和軸 的彎矩是由在混凝土內(nèi)部拉壓力偶來(lái)抵抗作用荷載之后的值。這種梁當(dāng)出現(xiàn)第一道裂縫時(shí) 就突然完全地?cái)嗔蚜?。在鋼筋混凝土梁中，鋼筋是那樣埋置于混凝土中，以至于?dāng)混凝土 開(kāi)裂后彎矩平衡所需的拉力由綱筋中產(chǎn)生。鋼筋混凝土構(gòu)件的建造包括以被建構(gòu)件的形狀支摸板。模型必須足夠強(qiáng)大，以至于能

52、夠支承自重和濕混凝土的靜水壓力，工人施加的任何力量都適用于它，具體的手推車(chē)，風(fēng) 壓力，等等。在混凝土的運(yùn)作過(guò)程中，鋼筋將被放置在摸板中。在混凝土硬化后，模板都 將被移走。當(dāng)模板被移走時(shí)，支撐將被安裝來(lái)承受混凝土的重量直到它到達(dá)足夠的強(qiáng)度來(lái) 承受自重。設(shè)計(jì)師必須使混凝土構(gòu)件有足夠的強(qiáng)度來(lái)抵抗荷、載和足夠的剛度來(lái)防止過(guò)度的撓度 變形。除此之外，梁必須設(shè)計(jì)合理以便它能夠被建造。例如，鋼筋必須按構(gòu)造設(shè)計(jì)，以便 能在現(xiàn)場(chǎng)裝配。由于當(dāng)鋼筋放入摸板后才澆筑混凝土，因此混凝土必須能夠流過(guò)鋼筋及摸 板并完全充滿(mǎn)摸板的每個(gè)角落。被建成的結(jié)構(gòu)材料的選擇是混凝土，還是鋼材、砌體，或木材，取決于是否有材料和 一些價(jià)值決

53、策。結(jié)構(gòu)體系的選擇是由建筑師或工程師早在設(shè)計(jì)的根底上決定的，考慮到下 列因素：1.經(jīng)濟(jì)。常常首要考慮的是結(jié)構(gòu)的總造價(jià)。當(dāng)然，這是隨著材料的本錢(qián)和安裝構(gòu)件的 必需勞動(dòng)力改變的。然而，總投資常常更受總工期的影響，因?yàn)槌邪毯蜆I(yè)主必須借款或 貸款以便完成建設(shè)，在建筑物竣工前他們從此項(xiàng)投資中將得不到任何回報(bào)。在一個(gè)典型的 大型公寓或商業(yè)工程中，建筑本錢(qián)的融資將是總費(fèi)用的一個(gè)重要局部。因此，金融儲(chǔ)蓄， 由于快速施工可能多于抵消增加材料本錢(qián)?；谶@個(gè)原因，設(shè)計(jì)師可以采取任何措施標(biāo)準(zhǔn) 設(shè)計(jì)來(lái)減輕削減的本錢(qián)。在許多情況下，長(zhǎng)期的經(jīng)濟(jì)結(jié)構(gòu)可能比第一本錢(qián)更重要。因此，維修和耐久性是重要 的考慮因素。2 . 用于建

54、筑與結(jié)構(gòu)功能適宜的材料。鋼筋混凝土體系經(jīng)常讓設(shè)計(jì)師將建筑與結(jié)構(gòu)的功 能相結(jié)合?；炷帘环胖迷谒苄詶l件下借助于模板和外表加工來(lái)造出想要的形狀和結(jié)構(gòu)， 這是它具有的優(yōu)勢(shì)。在提供成品樓或天花板外表時(shí)，這使得平板或其他形式的板作為受力 構(gòu)件。同樣，鋼筋混凝土墻壁能提供有吸引力的建筑外表，還有能力抵御重力、風(fēng)力，或 地震荷載。最后，大小和形狀的選擇是由設(shè)計(jì)師而不是由提供構(gòu)件的標(biāo)準(zhǔn)決定的。3 . 耐火性。建筑結(jié)構(gòu)必須經(jīng)受得住火災(zāi)的襲擊，并且當(dāng)人員疏散及大火撲滅之時(shí)建筑 物仍然保持不倒。鋼筋混凝土建筑特殊的防火材料及其他構(gòu)造措施情況下，自身具有 1-3 個(gè)小時(shí)的耐火極限。鋼結(jié)構(gòu)或木結(jié)構(gòu)必須采取防火措施才能到

55、達(dá)類(lèi)似的耐火極限。4 . 低維護(hù)?；炷翗?gòu)件本身比結(jié)構(gòu)鋼或木材構(gòu)件需要更少的維修。如果致密，尤其如 此，加氣混凝土已經(jīng)被用于暴露于大氣中的外表，如果在設(shè)計(jì)中已經(jīng)采取謹(jǐn)慎措施，以提 供足夠的排水和遠(yuǎn)離的結(jié)構(gòu)。必須采取的特別預(yù)防措施是讓混凝土接觸到鹽，如除冰化學(xué) 品。5 . 材料的供給。砂、碎石、水泥和混凝土攪拌設(shè)備是被非常廣泛使用的，以及鋼筋比 結(jié)構(gòu)鋼更容易運(yùn)到多數(shù)工地。因此，鋼筋混凝土在偏遠(yuǎn)地區(qū)經(jīng)常使用。另一方面，有一些因素可能會(huì)導(dǎo)致選擇鋼筋混凝土以外的材料。這些措施包括：1 . 低抗拉強(qiáng)度。混凝土的抗拉強(qiáng)度是遠(yuǎn)低于其抗壓強(qiáng)度約 1 / 10 ，因此，混 凝土易經(jīng)受裂縫。在結(jié)構(gòu)用途時(shí)，用鋼筋承

56、受拉力，并限制裂縫寬度在允許的范圍內(nèi)來(lái)克 服。不過(guò)，在設(shè)計(jì)和施工中如果不采取措施，這些裂縫可能會(huì)有礙觀瞻，或可允許水的浸 入。發(fā)生這種情況時(shí)，水或化學(xué)物質(zhì)如道路除冰鹽可能會(huì)導(dǎo)致混凝土的惡化或污染。這種 情況下，需要特別設(shè)計(jì)的措施。在水支擋結(jié)構(gòu)這種情況下，需要特別的措施和/ 或預(yù)應(yīng)力，以防止泄漏。2 . 支摸。建造一個(gè)現(xiàn)澆結(jié)構(gòu)包括三個(gè)步驟，在鋼或木結(jié)構(gòu)的施工中是遇不到的。這些 都是a支摸b拆摸c 安裝支撐，直至其到達(dá)足夠的強(qiáng)度以支承其重量。上述每個(gè)步驟，涉及勞動(dòng)力和 / 或材料，在其他結(jié)構(gòu)形式中，這是沒(méi)有必要的3 . 每單位重量或量的相對(duì)低強(qiáng)度。該混凝土抗壓強(qiáng)度大約是鋼材抗壓強(qiáng)度5 至10 ，而其單位密度大約是鋼材密度的 30 。因此， 一個(gè)混凝土結(jié)構(gòu)， 與鋼結(jié)構(gòu)相比， 需要較大的體積和較大重量的材料。因此，大跨度結(jié)構(gòu)，往往建成鋼結(jié)構(gòu)。4 . 時(shí)間依賴(lài)的量的變化?；炷僚c鋼進(jìn)行大約同樣數(shù)量的熱膨脹和收縮時(shí)，有比擬少 量的鋼材加熱或冷卻，因?yàn)?/p>