外文翻譯——預應力混凝土建筑

1、<p><b>　　外文資料：</b></p><p>　　Prestressed Concrete Buildings</p><p>　　Prestressed concrete has been widely and successfully applied to building construction of all types. Both pre

2、cast pretensioned members and cast-tensioned structures are extensively employed, sometimes in competition with one another, most effectively in combination wit each other.</p><p>　　Prestressed concrete offe

3、rs great advantages for incorporation in a total building. It is perhaps the “integrative”aspects of these, that is, structure plus other functions, which have made possible the present growth in use of prestressed concr

4、ete buildings. These advantages include the following: Structural strength; Structure rigidity; Durability; Mold ability, into desired forms and shapes; Fire resistance; Architectural treatment of surfaces; Sound insulat

5、ion; Heat insulation; Economy; Avai</p><p>　　Most of the above are also properties of conventionally reinforced concrete. Presrressing, however, makes the structural system more effective by enabling elimina

6、tion of the technical of difficulty, e.g., cracks that spoil the architectural treatment. Prestressing greatly enhance the structure efficiency and economy permitting longer spans and thinner elements. Above all, it give

7、s to the architect-engineer a freedom for variation and an ability to control behavior under service conditions.</p><p>　　Although prestressed concrete construction involves essentially the same consideratio

8、n and practices as for all structures, a number of special points require emphasis or elaboration.</p><p>　　The construction engineer is involved in design only to a limited extent. First, he muse be able to

9、 furnish advice to the architect and engineer on what can he done. Because of his specialized knowledge of techniques relating to prestressed concrete construction, he supplies a very needed service to the architect-engi

10、neer.</p><p>　　Second, the construction engineer may be made contractually responsible for the working drawings; that is, the layout of tendons, anchorage details, etc. It is particularly important that he g

11、ives careful attention to the mild steel and concrete details to ensure these are compatible with his presressing details.</p><p>　　Third, the construction engineer is concerned with temporary stresses, stre

12、sses at release, stresses in picking, handling and erection, and temporary condition prior to final completion of the structure, such as the need of propping for a composite pour.</p><p>　　Fourth, although t

13、he responsibility for design rests with the design engineer, nevertheless the construction engineer is also vitally concerned that the structure be successful form the point of view of structural integrity and service be

14、havior. Therefore he will want to look at the bearing and connection details, camber, creep, shrinkage, thermal movements, durability provisions, etc., and advise the design engineer of any deficiencies he encounters.<

15、;/p><p>　　Information on new techniques and especially application of prestressing to buildings are extensively available in the current technical literature of national and international societies. The Interna

16、tional Federation of Prestressing(I.F.P)has attempted to facilitate the dissemination of this information by establishing a Literature Exchange Service, in which the prestressing journals of some thirty countries are reg

17、ularly exchanged. In addition, an Abstract is published intermittently by I.F.P </p><p>　　With regard to working drawings, the construction engineer must endeavor to translate the design requirements into th

18、e most practicable and economical details of accomplishment, in such a way that the completed element or structure fully complies with the design requirement; for example, the design may indicate only the center of gravi

19、ty of prestressing and the effective prestress force. The working drawing will have to translate this into tendons having finite physical properties and dimensions</p><p>　　The computation of pre-stress loss

20、es, form transfer stress to effective stress, must reflect the actual manufacturing and construction process used, as well as thorough knowledge of the properties of the particular aggregates and concrete mix to be emplo

21、yed.</p><p>　　With post-tensioning, anchorages and their bearing plates must be laid out in their physical dimension. It is useful in the preparation of complex anchorage detail layouts to use full-scale dra

22、wings, so as to better appreciate the congestion of mild steel and anchorages at the end of the member. Tendons and reinforcing bars should be shown in full size rather than as dotted lines. This will permit consideratio

23、n to be given as to how the concrete can be placed and consolidated.</p><p>　　The end zone of both pre-tensioned and post-tensioned concrete members subject to high transverse or bursting stresses. These str

24、esses are also influenced by minor concrete details, such as chamfers. Provision of a grid of small bars (sometimes heavy wire mesh is used), as close to the end of a girder as possible, will help to confine and distribu

25、te the concentrated forces. Closely spaced stirrups and/or tightly spaced spiral are usually needed at the end of heavily stressed members. Recent test</p><p>　　Additional mild-steel stirrups may also be req

26、uired at hold-down points to resist the shear. This is also true wherever post-tensioned tendons make sharp bends. Practical consideration of concretion dictates the spacing of tendons and ducts. The general rules are th

27、at the clear spacing small be one-and-one-half times the maximum size of coarse aggregate. In the overall section, provision must be made for the vibrator stinger. Thus pre-stressing tendons must either be spaced apart i

28、n the horizont</p><p>　　In the vertical plane close contact between tendons is quite common. With post-tensioned ducts, however, in intimate vertical contact, careful consideration has to be given to prevent

29、 one tendon form squeezing into the adjacent duct during stressing. This depends on the size of duct and the material used for the duct. A full-scale layout of this critical cross section should be made. Usually, the bes

30、t solution is to increase the thickness ( and transverse strength ) of the duct, so that it will </p><p>　　As a last rest\ort it may be necessary to stress and grout one duct before stressing the adjacent on

31、e. This is time-consuming and runs the risks of grout blockage due to leaks from one duct to the other. Therefore the author recommends the use of heavier duct material, or else the respacing of the ducts. The latter, of

32、 course, may increase the prestressing force required.</p><p><b>　　中文翻譯：</b></p><p><b>　　預應力混凝土建筑</b></p><p>　　預應力混凝土已經(jīng)廣泛并成功地用于各種類型的建筑。無論預制先拉構(gòu)件，還是現(xiàn)澆后張構(gòu)件都已大量應

33、用，在應用二者時會相互競爭，但結(jié)合應用效率更高。在</p><p>　　預應力混凝土為一棟建筑物的總體結(jié)合提供了方便?；蛟S正是因為其在建筑結(jié)構(gòu)及其他功能結(jié)合上所起的作用，才使得預應力混凝土應用得以推廣。其優(yōu)點體系在下述各項；結(jié)構(gòu)強度；結(jié)構(gòu)港督；耐久性；可塑性，可制成所需求的方式和形狀；抗火性；表面的建筑處理；隔聲；絕熱；經(jīng)濟性；可行性，可通過使用本地原料和勞動力達到較高的程度。</p><p&

34、gt;　　上面大都是傳統(tǒng)鋼筋混凝土具有的特點。然而，預應力通過對建筑有破壞作用的裂縫等缺陷源的消除，而使結(jié)構(gòu)系統(tǒng)更加有效。由于允許采用較長和較薄構(gòu)件，預應力大大提高了結(jié)構(gòu)的效率和經(jīng)濟性。更重要的是，它為建筑師提供了一種變化的自由，以及在各種服務條件下的行為控制能力。</p><p>　　盡管預應力混凝土結(jié)構(gòu)在本質(zhì)上有著和所有結(jié)構(gòu)一樣的設(shè)計考慮和操作，但應重視和推敲一下特殊點。</p><p&g

35、t;　　施工工程師在設(shè)計中參與的工作是有限的。首先，他必須能夠向建筑師和工程師提供可行性的建議。由于其具有預應力混凝土施工方面的專業(yè)技術(shù)知識，他將為建筑師和工程師提供非常必要的服務。</p><p>　　其次，施工工程師應通曉施工圖。例如鋼筋的放置及錨定細節(jié)的等。尤為重要的是他應對鋼筋和混凝土細節(jié)給予足夠重視，以使其能夠與預應力細節(jié)相一致。</p><p>　　第三，施工工程師應該在結(jié)構(gòu)完

36、工之前，注重鋼筋的臨時應力、松弛應力、截取、加工和安裝階段的應力，以及臨時條件，如復合灌注時所需的支柱支撐。</p><p>　　第四，盡管設(shè)計任務是設(shè)計工程師的工作職責，不過施工工程師應該從結(jié)構(gòu)整體及使用功能上把握結(jié)構(gòu)的可行性。因此他會關(guān)注承載和連接細節(jié)、撓度、蠕變、收縮、熱運動及耐久性保證等，并向設(shè)計工程師提供相應的建議。</p><p>　　當今國內(nèi)外，新技術(shù)尤其是預應力在建筑物上的

37、應用技術(shù)，已經(jīng)廣泛使用。國際預應力聯(lián)盟試圖通過建立文化交流服務來散布這些信息，大約30多個國家的預應力雜志進行了交流。并且，該聯(lián)盟還定期發(fā)布一些摘要信息。美國的“預應力混凝土結(jié)構(gòu)”定期發(fā)布一些關(guān)于技術(shù)及應用的雜志和手冊，同時還建立了將其傳播給建筑師、工程師以及施工人員的程序。這種與國內(nèi)和國際發(fā)展接軌的工作有著很重要的意義，它能夠使技術(shù)保持最新和最好，并能使建筑師和是使設(shè)計工程師在建筑物設(shè)計中，最充分和有效地利用預應力混凝土。</p

38、><p>　　參照施工圖，施工工程師必須按照最實際和最經(jīng)濟的要求，盡力將設(shè)計進行細節(jié)化處理，這樣全部構(gòu)件或結(jié)構(gòu)就能和設(shè)計需求保持一致。例如，設(shè)計設(shè)計可能只提供應力重心及有效應力，這就需要將施工圖轉(zhuǎn)化為有明確性能的鋼筋束。如果預應力重心跡線是拋物線形的，為了預拉就需要一種弦近似，同時適當定位支撐點。</p><p>　　將預應力轉(zhuǎn)化為有效應力的過程中，計算預應力的損失時，必須能夠反映所采用的實際

39、施工過程、所用的特殊細節(jié)及混合物的性能。</p><p>　　采用后張法，錨具已經(jīng)它們的承載板，必須在其物理尺寸內(nèi)進行布置。在對復雜錨具進行布置準備時，采用全比例尺圖是非常有用的，這樣才能在構(gòu)件底部對鋼筋和錨具進行合理的布置。鋼筋束和加筋肋應給出全部尺寸，而不適應點線表示這樣有利于隊混凝土構(gòu)件進行放置和固結(jié)。</p><p>　　先張和后張混凝土構(gòu)件的端部受到較高的橫向應力或拉應力的作用，

40、這些應力經(jīng)常受到一些較小的混凝土細部如倒角的影響。采用梁或者較小的肋（有時采用較重的金屬網(wǎng)），且梁要盡可能的靠近端部，將有助于控制并分散集中力。在端部有較大應力的構(gòu)件，還經(jīng)常采用近距離箍筋或者較密的箍筋布置。 近來有實驗表明，采用較小的間距比增加尺寸更有效。這樣大量的下肋間隔分布式最好的解決辦法。</p><p>　　控制點處也可能設(shè)有附加鋼筋肋以抵抗剪力這種做法在后張預應力筋存在明顯的彎曲時也是正確的?；炷恋?/p>

41、補償作用提供了鋼筋束的間距，一般而言，間距是粗骨料最大尺寸的1.5倍。在全截面上，必須保證振子的通過。因此預應力筋即要在水平面內(nèi)間隔分布，又能在特殊情況下進行捆綁。</p><p>　　在垂直平面內(nèi)鋼筋的密集接觸實際其常見的。然而，在后張法過程中應考慮避免管道中的鋼筋因豎向間距過于緊密而相互擠壓。這取決于管道的尺寸和所用的材料，因此應該做出對控制截面進行布置的全比例草圖。通常，最后的辦法是增加管道的厚度，這樣就會