土木工程外文文獻翻譯---鋼筋混凝土

1、<p><b>　　外文文獻翻譯</b></p><p>　　Reinforced Concrete</p><p>　　（來自《土木工程英語》）</p><p>　　Concrete and reinforced concrete are used as building materials in every country. In

2、 many, including the United States and Canada, reinforced concrete is a dominant structural material in engineered construction. The universal nature of reinforced concrete construction stems from the wide availability o

3、f 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 ot</p><p>　　R

4、einforced concrete structures may be cast-in-place concrete, constructed in their final location, or they may be precast concrete produced in a factory and erected at the construction site. Concrete structures may be sev

5、ere 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.</p><p>　　Concrete is strong in com

6、pression 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 concre

7、te beam, the moments about the neutral axis due to applied loads are resisted by an internal tension-compression couple involving tension in the concrete. Such a beam fails very suddenly and completely when the first cra

8、ck forms. In a reinforced concrete </p><p>　　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 suppor

9、t both the weight and hydrostatic pressure of the wet concrete, and any forces applied to it by workers, concrete buggies, wind, and so on. The reinforcement is placed in this form and held in place during the concreting

10、 operation. After the concrete has hardened, the forms are removed. As the forms are removed, props of shores are inst</p><p>　　The designer must proportion a concrete member for adequate strength to resist

11、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 that it can be assembled in the field, and

12、 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.</p><p>　

13、　The choice of whether a structure should 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 archit

14、ect of engineer early in the design, based on the following considerations:</p><p>　　1. Economy. Frequently, the foremost consideration is the overall const of the structure. This is, of course, a function o

15、f 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 otherwi

16、se allocate 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</p><p>　　In many cases the long-term economy of

17、the structure may be more important than the first cost. As a result, maintenance and durability are important consideration.</p><p>　　2. Suitability of material for architectural and structural function. A

18、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 condition and is given the desired shape and text

19、ure 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 s</p>

20、<p>　　3. Fire resistance. The 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

21、 3-hour fire rating without special fireproofing or other details. Structural steel or timber buildings must be fireproofed to attain similar fire ratings.</p><p>　　4. Low maintenance. Concrete members inher

22、ently 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 th

23、e 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.</p><p>　　5. Availability of materials. Sand,

24、gravel, cement, and concrete mixing facilities are very widely available, and reinforcing steel can be transported to most job sites more easily than can structural steel. As a result, reinforced concrete is frequently u

25、sed in remote areas.</p><p>　　On the other hand, there are a number of factors that may cause one to select a material other than reinforced concrete. These include:</p><p>　　1. Low tensile stre

26、ngth. The 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 force

27、s and limit crack widths to within acceptable values. Unless care is taken in design and construction, however, these cracks may be unsightly or may allow penetration of water. When this occurs, water or chemicals such a

28、s road deicing salts may cause deteriorat</p><p>　　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.

29、These are ( a ) the construction of the forms, ( b ) the removal of these 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 /

30、 or materials, which are not necessary with other forms of construction.</p><p>　　3. Relatively low strength per unit of weight for volume. The compressive strength of concrete is roughly 5 to 10% that of st

31、eel, 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 structu

32、res are often built from steel.</p><p>　　4. Time-dependent volume changes. Both concrete and steel undergo-approximately the same amount of thermal expansion and contraction. Because there is less mass of s

33、teel to be heated or cooled, and because steel is a better concrete, a steel structure is generally affected by temperature changes to a greater extent than is a concrete structure. On the other hand, concrete undergoes

34、frying shrinkage, which, if restrained, may cause deflections or cracking. Furthermore, deflections will tend to i</p><p>　　In almost every branch of civil engineering and architecture extensive use is made

35、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 t

36、he behavior and 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</p><p>　　

37、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 homogeneo

38、us elastic materials. Much of reinforced 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 theo

39、retical formulations.</p><p>　　A thorough understanding of the behavior of reinforced concrete will allow the designer to convert an otherwise brittle material into tough ductile structural elements and ther

40、eby take advantage of concrete’s desirable characteristics, its high compressive strength, its fire resistance, and its durability.</p><p>　　Concrete, a stone like material, is made by mixing cement, water,

41、fine aggregate ( often sand ), 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 v

42、ariety of structural elements. Although the hardened concrete by itself, i.e., without any reinforcement, is strong in compression, it lacks tensile strength and therefore cracks easily. Because unreinforced concre</p

43、><p>　　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

44、 of inadequate and construction.</p><p>　　Two types f coeds exist. One type, called a structural code, is originated and controlled by specialists who are concerned with the proper use of a specific material

45、 or who are involved with the safe design of a particular class of structures.</p><p>　　The second type of code, called a building code, is established to cover construction in a given region, often a city o

46、r 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 provi

47、sions to account for such regional conditions as earthquake, heavy snow, or tornados. National structural codes genrally are incorporated into local building cod</p><p>　　The American Concrete Institute ( AC

48、I ) 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 m

49、aterials, details on mixing and placing concrete, design assumptions for the analysis of continuous structures, and equations for proportioning members for design forces.</p><p>　　All structures must be prop

50、ortioned so they will not fail or deform excessively 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

51、subjected during its lifetime. </p><p>　　Although the design of most members is controlled typically by dead and live load acting simultaneously, consideration must also be given to the forces produced by wi

52、nd, impact, shrinkage, temperature change, creep and support settlements, earthquake, and so forth.</p><p>　　The load associated with the weight of the structure itself and its permanent components is called

53、 the dead load. The dead load of concrete 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

54、 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 members sized, and</p><p>　　Live loads asso

55、ciated 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.</p><p>　　After the

56、structure has been sized for vertical load, it is checked for wind 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 sto

57、ries, but for tall buildings wind loads become significant and cause large forces to develop in the structures. Under these conditions economy can be achieved only by selecting a structural system that is able to transfe

58、r horizontal loads into the ground efficiently.</p><p><b>　　鋼筋混凝土</b></p><p>　　在每一個國家，混凝土及鋼筋混凝土都被用來作為建筑材料。很多地區(qū)，包括美國和加拿大，鋼筋混凝土在工程建設中是主要的結構材料。鋼筋混凝土建筑的普遍性源于鋼筋的廣泛供應和混凝土的組成成分，礫石，沙子，水泥等，混凝

59、土施工所需的技能相對簡單，與其他形式的建設相比，鋼筋混凝土更加經(jīng)濟?；炷良颁摻罨炷劣糜跇蛄骸⒏鞣N地下結構建筑、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)。 </p><p>　　鋼筋混凝土結構可能是現(xiàn)澆混凝土結構，在其最后位置建造，或者他們可能是在一家工廠生產(chǎn)混凝土預制件，再在施工現(xiàn)場安裝?；炷两Y構在設計上可能是普通的和多功能的，或形狀和布局是奇想和藝術的。其他很少幾種建材能夠提供建筑和

60、結構如此的通用性和廣泛適用性。</p><p>　　混凝土有較強的抗壓力但抗拉力很弱。因此，混凝土，每當承受荷載時，或約束收縮或溫度變化，引起拉應力，在超過抗拉強度時，裂縫開始發(fā)展。在素混凝土梁中，中和軸的彎矩是由在混凝土內(nèi)部拉壓力偶來抵抗作用荷載之后的值。這種梁當出現(xiàn)第一道裂縫時就突然完全地斷裂了。在鋼筋混凝土梁中，鋼筋是那樣埋置于混凝土中，以至于當混凝土開裂后彎矩平衡所需的拉力由綱筋中產(chǎn)生。</p>

61、;<p>　　鋼筋混凝土構件的建造包括以被建構件的形狀支摸板。模型必須足夠強大，以至于能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，風壓力，等等。在混凝土的運作過程中，鋼筋將被放置在摸板中。在混凝土硬化后，模板都將被移走。當模板被移走時，支撐將被安裝來承受混凝土的重量直到它達到足夠的強度來承受自重。</p><p>　　設計師必須使混凝土構件有足夠的強度來抵抗荷、載和

62、足夠的剛度來防止過度的撓度變形。除此之外，梁必須設計合理以便它能夠被建造。例如，鋼筋必須按構造設計，以便能在現(xiàn)場裝配。由于當鋼筋放入摸板后才澆筑混凝土，因此混凝土必須能夠流過鋼筋及摸板并完全充滿摸板的每個角落。</p><p>　　被建成的結構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值決策。結構體系的選擇是由建筑師或工程師早在設計的基礎上決定的，考慮到下列因素：</p>

63、<p>　　1.經(jīng)濟。常常首要考慮的是結構的總造價。當然，這是隨著材料的成本和安裝構件的必需勞動力改變的。然而，總投資常常更受總工期的影響，因為承包商和業(yè)主必須借款或貸款以便完成建設，在建筑物竣工前他們從此項投資中將得不到任何回報。在一個典型的大型公寓或商業(yè)項目中，建筑成本的融資將是總費用的一個重要部分。因此，金融儲蓄，由于快速施工可能多于抵消增加材料成本?；谶@個原因，設計師可以采取任何措施規(guī)范設計來減輕削減的成本。<

64、/p><p>　　在許多情況下，長期的經(jīng)濟結構可能比第一成本更重要。因此，維修和耐久性是重要的考慮因素。 </p><p>　　2 .用于建筑與結構功能適宜的材料。鋼筋混凝土體系經(jīng)常讓設計師將建筑與結構的功能相結合?；炷帘环胖迷谒苄詶l件下借助于模板和表面加工來造出想要的形狀和結構，這是它具有的優(yōu)勢。在提供成品樓或天花板表面時，這使得平板或其他形式的板作為受力構件。同樣，鋼筋混凝土墻壁能提供有

65、吸引力的建筑表面，還有能力抵御重力、風力，或地震荷載。最后，大小和形狀的選擇是由設計師而不是由提供構件的標準決定的。</p><p>　　3 .耐火性。建筑結構必須經(jīng)受得住火災的襲擊，并且當人員疏散及大火撲滅之時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造措施情況下，自身具有1-3個小時的耐火極限。鋼結構或木結構必須采取防火措施才能達到類似的耐火極限。</p><p>　　4

66、 .低維護。混凝土構件本身比結構鋼或木材構件需要更少的維修。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表面，如果在設計中已經(jīng)采取謹慎措施，以提供足夠的排水和遠離的結構。必須采取的特別預防措施是讓混凝土接觸到鹽，如除冰化學品。</p><p>　　5 .材料的供應。砂、碎石、水泥和混凝土攪拌設備是被非常廣泛使用的，以及鋼筋比結構鋼更容易運到多數(shù)工地。因此，鋼筋混凝土在偏遠地區(qū)經(jīng)常使用。</p>

67、;<p>　　另一方面，有一些因素可能會導致選擇鋼筋混凝土以外的材料。這些措施包括： </p><p>　　1 .低抗拉強度?；炷恋目估瓘姸仁沁h低于其抗壓強度（約1 / 10 ） ，因此，混凝土易經(jīng)受裂縫。在結構用途時，用鋼筋承受拉力，并限制裂縫寬度在允許的范圍內(nèi)來克服。不過，在設計和施工中如果不采取措施，這些裂縫可能會有礙觀瞻，或可允許水的浸入。發(fā)生這種情況時，水或化學物質(zhì)如道路除冰鹽可能會導致

68、混凝土的惡化或污染。這種情況下，需要特別設計的措施。在水支擋結構這種情況下，需要特別的措施和/或預應力，以防止泄漏。</p><p>　　2 .支摸。建造一個現(xiàn)澆結構包括三個步驟，在鋼或木結構的施工中是遇不到的。這些都是（a）支摸 （b）拆摸（ c ） 安裝支撐，直至其達到足夠的強度以支承其重量。上述每個步驟，涉及勞動力和/或材料，在其他結構形式中，這是沒有必要的。</p><p>　　3

69、 . 每單位重量或量的相對低強度。該混凝土抗壓強度大約是鋼材抗壓強度5至10 ％ ，，而其單位密度大約是鋼材密度的30 ％。因此，一個混凝土結構，與鋼結構相比，需要較大的體積和較大重量的材料。因此，大跨度結構，往往建成鋼結構。</p><p>　　4 .時間依賴的量的變化?；炷僚c鋼進行大約同樣數(shù)量的熱膨脹和收縮時，有比較少量的鋼材加熱或冷卻，因為鋼與混凝土相比是一個較好的導體，鋼結構比混凝土結構在更大程度上更易

70、受溫度變化。另一方面，混凝土經(jīng)歷了干縮，如果被抑制，可能會導致變形或開裂。此外，變形隨著時間的推移將趨于增加，由于混凝土在持續(xù)的負荷下的徐變，可能會增加一倍。</p><p>　　幾乎在土木工程和建筑的每一個分支中，鋼筋混凝土在結構和基礎領域內(nèi)都得到了廣泛的使用。因此，工程師及建筑師在其整個職業(yè)生涯中需要鋼筋混凝土設計的基本知識。文章的大部分是直接關于組成典型的鋼筋混凝土結構的部件如梁、柱和板他們之間的作用、協(xié)調(diào)

71、。一旦這些個別要素的作用被理解，設計師將有能力分析和設計這些元素組成的各種各樣的復雜結構，例如地基，建筑物和橋梁。</p><p>　　由于鋼筋混凝土是一個徐變、收縮，并出現(xiàn)裂縫的非勻質(zhì)材料，它的應力不能由適用于材料強度均勻彈性材料的傳統(tǒng)方程推導出的方程準確預測。因此，許多鋼筋混凝土的設計基于實證，即設計方程和設計方法是基于實驗和費時的證明，而不是從理論的提法被完全導出的結果。</p><p&

72、gt;　　對鋼筋混凝土性能徹底的了解將允許設計師將脆性材料轉換變成強硬的韌性結構材料，從而利用混凝土良好的特點，其高抗壓強度，其耐火性，其耐久性。 </p><p>　　混凝土--石狀的物質(zhì)，是由攪拌水泥，水，細骨料（通常砂），粗骨料，并經(jīng)常添加其他外加劑（即改善特性）而成為的一種和易性好的混合物。在其未硬化或塑性狀態(tài)下，混凝土可放置在模板里產(chǎn)生大量的各種結構要素。雖然硬化的混凝土本身，也就是說，沒有任何鋼筋，它

73、具有較強的抗壓強度，但缺乏抗拉強度，因此很容易產(chǎn)生裂縫。因為無鋼筋的混凝土是脆性的，它在荷載作用下不能進行大變形，并在沒有預兆下突然斷裂。鋼筋與混凝土相結合，可以減少其主要的兩個固有弱點的負面影響，其易開裂性和其脆性。當鋼筋牢固黏結于混凝土時，一種強大、剛性、延性的建筑材料就誕生了。這種材料，所謂的鋼筋混凝土，被廣泛用于建筑基礎、結構框架、倉庫、網(wǎng)狀結構、公路、墻壁、水壩、運河及無數(shù)的其他結構和建筑產(chǎn)品?；炷恋钠渌麅蓚€特點，是混凝土被

74、加固時會發(fā)生收縮和徐變，但采用仔細的設計可以減輕這些特性的負面影響。 </p><p>　　規(guī)范，是一套技術規(guī)格和控制設計與施工重要細節(jié)的標準。規(guī)范的目的是產(chǎn)生合理的結構，使使用者將免于劣質(zhì)和不合格的設計和結構。</p><p>　　現(xiàn)有兩種規(guī)范。其中一類，所謂的結構規(guī)范，是源于關心正確使用具體材料或關心某一特定類別結構安全設計的專家。</p><p>　　第二種類

75、型的規(guī)范，所謂的建筑條例，涵蓋了建設在某一地區(qū)，往往是一個城市或一個國家的建筑。建筑條例的目標，也是以對抗當?shù)丨h(huán)境條件對建設的影響來保障公眾的權益。例如，地方當局可以規(guī)定其他的條款，以對抗這樣的區(qū)域條件，地震、大雪或龍卷風。國家結構規(guī)范常常被納入當?shù)氐慕ㄖㄒ?guī)。</p><p>　　美國混凝土學會（ ACI ）的建筑規(guī)范包括鋼筋混凝土建筑物的設計。它包括涵蓋鋼筋混凝土制造的各個方面--設計和施工的條文。它包括材料

76、質(zhì)量的規(guī)格、混合和現(xiàn)澆混凝土的細節(jié)，連續(xù)結構分析的設計假定，配料成分的設計方程。</p><p>　　所有構件必須協(xié)調(diào)，這樣它們在任何可能的工作條件下就不會失效或發(fā)生過大變形。因此，一名工程師非常謹慎地預期結構在其一生中所有可能經(jīng)受的荷載，這是非常重要的。</p><p>　　雖然大部分構件的設計是由同時作用的恒載和活載所控制，但還必須考慮到風、沖擊、收縮、溫度變化、徐變和地基沉陷、地震等

77、等所產(chǎn)生的的力。 </p><p>　　與結構自重和固有的構件重量有關的荷載稱為恒載?；炷翗嫾暮爿d是固有的，在設計計算過程中是必須要考慮的。恒載值的大小直到構件尺寸確定后才能清楚的知道 。由于恒載的一些數(shù)值在計算構件尺寸時要用到，所以首先要估計他們值的大小。在結構進行了分析構件、構件尺寸確定、建筑的細節(jié)完成后，恒載可以計算更準確。如果計算的恒載大約等于它的初步估計值（或略少） ，但設計完成后，如果計算值和估計

78、值之間存在顯著性差異時，計算應用改進的恒載值加以修正。當跨度較長時，恒載的準確估計是特別重要的，因為當跨度超過七十五英尺（ 22.9米）時 ，恒載是設計荷載的一個重要組成部分。</p><p>　　建設使用的相關活荷載是由城市或國家結構規(guī)范規(guī)定的。設計構件均布活荷載的值是由結構規(guī)范規(guī)定的，而不是根據(jù)設備的特定項目和某一個特定地區(qū)的使用者來估計。 </p><p>　　結構在豎向荷載下定了尺