土木工程專業(yè)畢業(yè)設(shè)計外文翻譯

1、High-Rise BuildingsIntroductionIt is difficult to define a high-rise building . One may say that a low-rise building ranges from 1 to 2 stories . A medium-rise building probably ranges between 3 or 4 stories up to 10 or 20 stories or more . Although the basic principles of vertical and horizontal su

2、bsystem design remain the same for low- , medium- , or high-rise buildings , when a building gets high the vertical subsystems become a controlling problem for two reasons . Higher vertical loads will require larger columns , walls , and shafts . But , more significantly , the overturning moment and

3、 the shear deflections produced by lateral forces are much larger and must be carefully provided for .The vertical subsystems in a high-rise building transmit accumulated gravity load from story to story , thus requiring larger column or wall sections to support such loading . In addition these same

4、 vertical subsystems must transmit lateral loads , such as wind or seismic loads , to the foundations. However , in contrast to vertical load , lateral load effects on buildings are not linear and increase rapidly with increase in height . For example under wind load , the overturning moment at the

5、base of buildings varies approximately as the square of a buildings may vary as the fourth power of buildings height , other things being equal. Earthquake produces an even more pronounced effect.When the structure for a low-or medium-rise building is designed for dead and live load , it is almost a

6、n inherent property that the columns , walls , and stair or elevator shafts can carry most of the horizontal forces . The problem is primarily one of shear resistance . Moderate addition bracing for rigid frames in“short”buildings can easily be provided by filling certain panels ( or even all panels

7、 ) without increasing the sizes of the columns and girders otherwise required for vertical loads.Unfortunately , this is not is for high-rise buildings because the problem is primarily resistance to moment and deflection rather than shear alone . Special structural arrangements will often have to be

8、 made and additional structural material is always required for the columns , girders , walls , and slabs in order to made a high-rise buildings sufficiently resistant to much higher lateral deformations . As previously mentioned , the quantity of structural material required per square foot of floo

9、r of a high-rise buildings is in excess of that required for low-rise buildings . The vertical components carrying the gravity load , such as walls , columns , and shafts , will need to be strengthened over the full height of the buildings . But quantity of material required for resisting lateral fo

10、rces is even more significant . With reinforced concrete , the quantity of material also increases as the number of stories increases . But here it should be noted that the increase in the weight of material added for gravity load is much more sizable than steel , whereas for wind load the increase

11、for lateral force resistance is not that much more since the weight of a concrete buildings helps to resist overturn . On the other hand , the problem of design for earthquake forces . Additional mass in the upper floors will give rise to a greater overall lateral force under the of seismic effects

12、. In the case of either concrete or steel design , there are certain basic principles for providing additional resistance to lateral to lateral forces and deflections in high-rise buildings without too much sacrifire in economy . 1. Increase the effective width of the moment-resisting subsystems . T

13、his is very useful because increasing the width will cut down the overturn force directly and will reduce deflection by the third power of the width increase , other things remaining cinstant . However , this does require that vertical components of the widened subsystem be suitably connected to act

14、ually gain this benefit.2. Design subsystems such that the components are made to interact in the most efficient manner . For example , use truss systems with chords and diagonals efficiently stressed , place reinforcing for walls at critical locations , and optimize stiffness ratios for rigid frame

15、s . 3. Increase the material in the most effective resisting components . For example , materials added in the lower floors to the flanges of columns and connecting girders will directly decrease the overall deflection and increase the moment resistance without contributing mass in the upper floors

16、where the earthquake problem is aggravated . 4. Arrange to have the greater part of vertical loads be carried directly on the primary moment-resisting components . This will help stabilize the buildings against tensile overturning forces by precompressing the major overturn-resisting components . 5.

17、 The local shear in each story can be best resisted by strategic placement if solid walls or the use of diagonal members in a vertical subsystem . Resisting these shears solely by vertical members in bending is usually less economical , since achieving sufficient bending resistance in the columns an

18、d connecting girders will require more material and construction energy than using walls or diagonal members . 6. Sufficient horizontal diaphragm action should be provided floor . This will help to bring the various resisting elements to work together instead of separately . 7. Create mega-frames by

19、 joining large vertical and horizontal components such as two or more elevator shafts at multistory intervals with a heavy floor subsystems , or by use of very deep girder trusses . Remember that all high-rise buildings are essentially vertical cantilevers which are supported at the ground . When th

20、e above principles are judiciously applied , structurally desirable schemes can be obtained by walls , cores , rigid frames, tubular construction , and other vertical subsystems to achieve horizontal strength and rigidity . Some of these applications will now be described in subsequent sections in t

21、he following . Shear-Wall Systems When shear walls are compatible with other functional requirements , they can be economically utilized to resist lateral forces in high-rise buildings . For example , apartment buildings naturally require many separation walls . When some of these are designed to be

22、 solid , they can act as shear walls to resist lateral forces and to carry the vertical load as well . For buildings up to some 20storise , the use of shear walls is common . If given sufficient length ,such walls can economically resist lateral forces up to 30 to 40 stories or more . However , shea

23、r walls can resist lateral load only the plane of the walls ( i.e.not in a diretion perpendicular to them ) . There fore ,it is always necessary to provide shear walls in two perpendicular directions can be at least in sufficient orientation so that lateral force in any direction can be resisted . I

24、n addition , that wall layout should reflect consideration of any torsional effect . In design progress , two or more shear walls can be connected to from L-shaped or channel-shaped subsystems . Indeed , internal shear walls can be connected to from a rectangular shaft that will resist lateral force

25、s very efficiently . If all external shear walls are continuously connected , then the whole buildings acts as tube , and connected , then the whole buildings acts as a tube , and is excellent Shear-Wall Seystems resisting lateral loads and torsion . Whereas concrete shear walls are generally of sol

26、id type with openings when necessary , steel shear walls are usually made of trusses . These trusses can have single diagonals , “X”diagonals , or“K”arrangements . A trussed wall will have its members act essentially in direct tension or compression under the action of view , and they offer some opp

27、ortunity and deflection-limitation point of view , and they offer some opportunity for penetration between members . Of course , the inclined members of trusses must be suitable placed so as not to interfere with requirements for wiondows and for circulation service penetrations though these walls .

28、 As stated above , the walls of elevator , staircase ,and utility shafts form natural tubes and are commonly employed to resist both vertical and lateral forces . Since these shafts are normally rectangular or circular in cross-section , they can offer an efficient means for resisting moments and sh

29、ear in all directions due to tube structural action . But a problem in the design of these shafts is provided sufficient strength around door openings and other penetrations through these elements . For reinforced concrete construction , special steel reinforcements are placed around such opening .I

30、n steel construction , heavier and more rigid connections are required to resist racking at the openings . In many high-rise buildings , a combination of walls and shafts can offer excellent resistance to lateral forces when they are suitably located ant connected to one another . It is also desirab

31、le that the stiffness offered these subsystems be more-or-less symmertrical in all directions .Rigid-Frame Systems In the design of architectural buildings , rigid-frame systems for resisting vertical and lateral loads have long been accepted as an important and standard means for designing building

32、 . They are employed for low-and medium means for designing buildings . They are employed for low- and medium up to high-rise building perhaps 70 or 100 stories high . When compared to shear-wall systems , these rigid frames both within and at the outside of a buildings . They also make use of the s

33、tiffness in beams and columns that are required for the buildings in any case , but the columns are made stronger when rigidly connected to resist the lateral as well as vertical forces though frame bending . Frequently , rigid frames will not be as stiff as shear-wall construction , and therefore m

34、ay produce excessive deflections for the more slender high-rise buildings designs . But because of this flexibility , they are often considered as being more ductile and thus less susceptible to catastrophic earthquake failure when compared with ( some ) shear-wall designs . For example , if over st

35、ressing occurs at certain portions of a steel rigid frame ( i.e.,near the joint ) , ductility will allow the structure as a whole to deflect a little more , but it will by no means collapse even under a much larger force than expected on the structure . For this reason , rigid-frame construction is

36、considered by some to be a “best”seismic-resisting type for high-rise steel buildings . On the other hand ,it is also unlikely that a well-designed share-wall system would collapse. In the case of concrete rigid frames ,there is a divergence of opinion . It true that if a concrete rigid frame is des

37、igned in the conventional manner , without special care to produce higher ductility , it will not be able to withstand a catastrophic earthquake that can produce forces several times lerger than the code design earthquake forces . therefore , some believe that it may not have additional capacity pos

38、sessed by steel rigid frames . But modern research and experience has indicated that concrete frames can be designed to be ductile , when sufficient stirrups and joinery reinforcement are designed in to the frame . Modern buildings codes have specifications for the so-called ductile concrete frames

39、. However , at present , these codes often require excessive reinforcement at certain points in the frame so as to cause congestion and result in construction difficulties 。Even so , concrete frame design can be both effective and economical 。 Of course , it is also possible to combine rigid-frame c

40、onstruction with shear-wall systems in one buildings ，F(xiàn)or example , the buildings geometry may be such that rigid frames can be used in one direction while shear walls may be used in the other direction。SummaryAbove states is the high-rise construction ordinariest structural style. In the design pro

41、cess, should the economy practical choose the reasonable form as far as possible.外文資料翻譯（譯文）高層建筑前 沿高層建筑的定義很難確定?？梢哉f2-3層的建筑物為底層建筑，而從3-4層地10層或20層的建筑物為中層建筑，高層建筑至少為10層或者更多。盡管在原理上，高層建筑的豎向和水平構(gòu)件的設(shè)計同低層及多層建筑的設(shè)計沒什么區(qū)別，但使豎向構(gòu)件的設(shè)計成為高層設(shè)計有兩個控制性的因素：首先，高層建筑需要較大的柱體、墻體和井筒；更重要的是側(cè)向里所產(chǎn)生的傾覆力矩和剪力變形要大的多，必要謹(jǐn)慎設(shè)計來保證。高層建筑的豎向構(gòu)件從上到下

42、逐層對累積的重力和荷載進(jìn)行傳遞，這就要有較大尺寸的墻體或者柱體來進(jìn)行承載。同時，這些構(gòu)件還要將風(fēng)荷載及地震荷載等側(cè)向荷載傳給基礎(chǔ)。但是，側(cè)向荷載的分布不同于豎向荷載，它們是非線性的，并且沿著建筑物高度的增加而迅速地增加。例如，在其他條件都相同時，風(fēng)荷載在建筑物底部引起的傾覆力矩隨建筑物高度近似地成平方規(guī)律變化，而在頂部的側(cè)向位移與其高度的四次方成正比。地震荷載的效應(yīng)更為明顯。對于低層和多層建筑物設(shè)計只需考慮恒荷載和部分動荷載時，建筑物的柱、墻、樓梯或電梯等就自然能承受大部分水平力。所考慮的問題主要是抗剪問題。對于現(xiàn)代的鋼架系統(tǒng)支撐設(shè)計，如無特殊承載需要，無需加大柱和梁的尺寸，而通過增加板就可以

43、實(shí)現(xiàn)。不幸的是，對于高層建筑首先要解決的不僅僅是抗剪問題，還有抵抗力矩和抵抗變形問題。高層建筑中的柱、梁、墻及板等經(jīng)常需要采用特殊的結(jié)構(gòu)布置和特殊的材料，以抵抗相當(dāng)高的側(cè)向荷載以及變形。如前所述，在高層建筑中每平方英尺建筑面積結(jié)構(gòu)材料的用量要高于低層建筑。支撐重力荷載的豎向構(gòu)件，如墻、柱及井筒，在沿建筑物整個高度方向上都應(yīng)予以加強(qiáng)。用于抵抗側(cè)向荷載的材料要求更多。對于鋼筋混凝土建筑，雖著建筑物層數(shù)的增加，對材料的要求也隨著增加。應(yīng)當(dāng)注意的是，因混凝土材料的質(zhì)量增加而帶來的建筑物自重增加，要比鋼結(jié)構(gòu)增加得多，而為抵抗風(fēng)荷載的能力而增加的材料用量卻不是呢么多，因?yàn)榛炷磷陨淼闹亓靠梢缘挚箖A覆力矩。

44、不過不利的一面是混凝土建筑自重的增加，將會加大抗震設(shè)計的難度。在地震荷載作用下，頂部質(zhì)量的增加將會使側(cè)向荷載劇增。無論對于混凝土結(jié)構(gòu)設(shè)計，還是對于鋼結(jié)構(gòu)設(shè)計，下面這些基本的原則都有助于在不需要增加太多成本的前提下增強(qiáng)建筑物抵抗側(cè)向荷載的能力。1. 增加抗彎構(gòu)件的有效寬度。由于當(dāng)其他條件不變時能夠直接減小扭矩，并以寬度增量的三次冪形式減小變形，因此這一措施非常有效。但是必須保證加寬后的豎向承重構(gòu)件非常有效地連接。2. 在設(shè)計構(gòu)件時，盡可能有效地使其加強(qiáng)相互作用力。例如，可以采用具有有效應(yīng)力狀態(tài)的弦桿和桁架體系；也可在墻的關(guān)鍵位置加置鋼筋；以及最優(yōu)化鋼架的剛度比等措施。3. 增加最有效的抗彎構(gòu)件的

45、截面。例如，增加較低層柱以及連接大梁的翼緣截面，將可直接減少側(cè)向位移和增加抗彎能力，而不會加大上層樓面的質(zhì)量，否則，地震問題將更加嚴(yán)重。4. 通過設(shè)計使大部分豎向荷載，直接作用于主要的抗彎構(gòu)件。這樣通過預(yù)壓主要的抗傾覆構(gòu)件，可以使建筑物在傾覆拉力的作用下保持穩(wěn)定。5. 通過合理地放置實(shí)心墻體及在豎向構(gòu)件中使用斜撐構(gòu)件，可以有效地抵抗每層的局部剪力。但僅僅通過豎向構(gòu)件進(jìn)行抗剪是不經(jīng)濟(jì)的，因?yàn)槭怪傲河凶銐虻目箯澞芰Γ扔脡蛐睋涡枰嗖牧虾褪┕すぷ髁俊?. 每層應(yīng)加設(shè)充足的水平隔板。這樣就會使各種抗力構(gòu)件更好地在一起工作，而不是單獨(dú)工作。7. 在中間轉(zhuǎn)換層通過大型豎向和水平構(gòu)件及重樓板形成大框架，或者采用深梁體系。應(yīng)當(dāng)注意的是，所有高層建筑的本質(zhì)都是地面支撐的懸臂結(jié)構(gòu)。如何合理地運(yùn)用上面所提到的原則，就可以利用合理地布置墻體、核心筒、框架、筒式結(jié)構(gòu)和其他豎向結(jié)構(gòu)分體系，使建筑物取得足夠的水