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

2、stem design remainthe same for low- , medium- , or high-rise buildings , when a building gets high thevertical subsystems becomea controlling problem for two reasons . Higher verticalloads will require larger columns , walls , and shafts . But , more significantly , theoverturning moment and the she

3、ar deflections produced by lateral forces aremuchlarger and must be carefully provided for .The vertical subsystems in a high-rise building transmit accumulated gravity loadfrom story to story , thus requiring larger column or wall sections to support suchloading . In addition these same vertical su

4、bsystems must transmit lateral loads , suchas 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 inheight . For example under wind load , the overturning moment at the base of buildin

5、gsvaries approximately as the square of a buildings may vary as the fourth power ofbuildings height , other things being equal. Earthquake produces an even morepronounced effect.When the structure for a low-or medium-rise building is designed for dead and liveload , it is almost an inherent property

6、 that the columns , walls , and stair or elevatorshafts can carry most of the horizontal forces . The problem is primarily one of shearresistance . Moderate addition bracing for rigid frames in“short”buildings caneasily beprovided by filling certain panels ( or even all panels ) without increasing t

7、he sizes ofthe columns and girders otherwise required for vertical loads.Unfortunately , this is not is for high-rise buildings because the problem is primarilyresistance to momentand deflection rather than shear alone . Special structuralarrangements will often have to be made and additional struct

8、ural material is alwaysrequired for the columns , girders , walls , and slabs in order to made a high-risebuildings sufficiently resistant to much higher lateral deformations .As previously mentioned , the quantity of structural material required per square footof floor of a high-rise buildings is i

9、n excess of that required for low-rise buildings . Thevertical components carrying the gravity load , such as walls , columns , and shafts ,will need to bestrengthened over the full height of the buildings . But quantity of material required forresisting lateral forces is even more significant .With

10、 reinforced concrete , the quantity of material also increases as the number ofstories increases . But here it should be noted that the increase in the weight ofmaterial added for gravity load is much more sizable than steel , whereas for wind loadthe increase for lateral force resistance is not tha

11、t muchmore since the weight of aconcrete buildings helps to resist overturn . On the other hand , the problem of designfor earthquake forces . Additional mass in the upper floors will give rise to a greateroverall lateral force under the of seismic effects .In the case of either concrete or steel de

12、sign , there are certain basic principles forproviding additional resistance to lateral to lateral forces and deflections in high-risebuildings without too muchsacrifire in economy .1.Increase the effective width of the moment-resisting subsystems . This isvery useful because increasing the width wi

13、ll cut down the overturn forcedirectly and will reduce deflection by the third power of the width increase ,other things remaining cinstant . However , this does require that verticalcomponents of the widened subsystem be suitably connected to actuallygain this benefit.2.Design subsystems such that

14、the components are madeto interact in themost efficient manner . For example , use truss systems with chords anddiagonals efficiently stressed , place reinforcing for walls at criticallocations , and optimize stiffness ratios for rigid frames .3.Increase the material in the most effective resisting

15、components . Forexample , materials added in the lower floors to the flanges of columns andconnecting girders will directly decrease the overall deflection and increasethe moment resistance without contributing mass in the upper floors wherethe earthquake problem is aggravated .4.Arrange to have the

16、 greater part of vertical loads be carried directly on theprimary moment-resisting components . This will help stabilize the buildingsagainst tensile overturning forces by precompressing the majoroverturn-resisting components .5.The local shear in each story can be best resisted by strategic placeme

17、nt ifsolid walls or the use of diagonal members in a vertical subsystem .Resisting these shears solely by vertical membersin bending is usually lesseconomical , since achieving sufficient bending resistance in the columnsand connecting girders will require more material and construction energythan u

18、sing 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 insteadof separately .7.Create mega-frames by joining large vertical and horizontal componentssuch as two or more elevator shafts

19、 at multistory intervals with a heavy floorsubsystems , or by use of very deep girder trusses .Remember that all high-rise buildings are essentially vertical cantilevers which aresupported at the ground . Whenthe above principles are judiciously applied ,structurally desirable schemes can be obtaine

20、d by walls , cores , rigid frames, tubularconstruction , and other vertical subsystems to achieve horizontal strength and rigidity .Some of these applications will now be described in subsequent sections in thefollowing .Shear-Wall SystemsWhen shear walls are compatible with other functional require

21、ments , they can beeconomically utilized to resist lateral forces in high-rise buildings . For example ,apartment buildings naturally require many separation walls . Whensomeof these aredesigned to be solid , they can act as shear walls to resist lateral forces and to carry thevertical load as well

22、. For buildings up to some 20storise , the use of shear walls iscommon . If given sufficient length ,such walls can economically resist lateral forces upto 30 to 40 stories or more .However , shear walls can resist lateral load only the plane of the walls ( in a diretionperpendicular to them ) . The

23、re fore ,it is always necessary to provide shear walls intwo perpendicular directions can be at least in sufficient orientation so that lateral forcein any direction can be resisted . In addition , that wall layout should reflectconsideration of any torsional effect .In design progress , two or more

24、 shear walls can be connected to from L-shaped orchannel-shaped subsystems . Indeed , internal shear walls can be connected to from arectangular shaft that will resist lateral forces very efficiently . If all external shear wallsare continuously connected then the whole buildings acts as tube , and

25、connected ,then the whole buildings acts as a tube , and is excellent Shear-Wall Seystemsresisting lateral loads and torsion .Whereas concrete shear walls are generally of solid type with openings whennecessary , steel shear walls are usually made of trusses . These trusses can havesingle diagonals

26、,“X”diagonals , or“K”arrangements A trussed wall will have itsmembers act essentially in direct tension or compression under the action of view , andthey offer someopportunity and deflection-limitation point of view , and they offersomeopportunity for penetration between members . Of course , the in

27、clined membersof trusses must be suitable placed so as not to interfere with requirements forwiondows and for circulation service penetrations though these walls .As stated above , the walls of elevator , staircase ,and utility shafts form natural tubesand are commonly employed to resist both vertic

28、al and lateral forces . Since theseshafts are normally rectangular or circular in cross-section , they can offer an efficientmeansfor resisting moments and shear in all directions due to tube structural action .But a problem in the design of these shafts is provided sufficient strength around doorop

29、enings and other penetrations through these elements . For reinforced concreteconstruction , special steel reinforcements are placed around such opening .In steelconstruction , heavier and more rigid connections are required to resist racking at theopenings .In many high-rise buildings , a combinati

30、on of walls and shafts can offer excellentresistance to lateralforces when they are suitablylocated ant connected to one another . It is also desirable that the stiffness offeredthese subsystems be more-or-less symmertrical in all directions .Rigid-Frame SystemsIn the design of architectural buildin

31、gs , rigid-frame systems for resisting vertical andlateral loads have long been accepted as an important and standard means fordesigning building . They are employed for low-and mediummeansfor designingbuildings . They are employed for low- and mediumup to high-rise building perhaps 70or 100 stories

32、 high . Whencompared to shear-wall systems , these rigid frames bothwithin and at the outside of a buildings . They also make use of the stiffness in beamsand columns that are required for the buildings in any case , but the columns aremadestronger whenrigidly connected to resist the lateral as well

33、 as vertical forcesthough frame bending .Frequently , rigid frames will not be as stiff as shear-wall construction , and thereforemay 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

34、thusless susceptible to catastrophic earthquake failure when compared with ( some )shear-wall designs . For example , if over stressing occurs at certain portions of a steelrigid frame ( .,near the joint ) , ductility will allow the structure as a whole to deflect alittle more , but it will by no me

35、ans collapse even under a much larger force thanexpected on the structure . For this reason , rigid-frame construction is considered bysometo be a“best”seismic -resisting type for high-rise steel buildings . On the otherhand ,it is also unlikely that a well-designed share-wall system would collapse.

36、In the case of concrete rigid frames ,there is a divergence of opinion . It true that if aconcrete rigid frame is designed in the conventional manner , without special care toproduce higher ductility , it will notbe able to withstand a catastrophic earthquake that can produce forces several timesler

37、ger than the code design earthquake forces . therefore , somebelieve that it may nothave additional capacity possessed by steel rigid frames . But modern research andexperience has indicated that concrete frames can be designed to be ductile , whensufficient stirrups and joinery reinforcement are de

38、signed in to the frame . Modernbuildings codes have specifications for the so-called ductile concrete frames .However , at present , these codes often require excessive reinforcement at certainpoints in the frame so as to cause congestion and result in construction difficulties。Even so , concrete fr

39、ame design can be botheffective and economical。Of course , it is also possible to combine rigid-frame construction with shear-wallsystems in one buildings，F(xiàn)or example , the buildingsgeometry maybe such that rigid frames can be used in one direction while shear wallsmay be used in the other direction

40、。SummaryAbove states is the high-rise construction ordinariest structural style. In the designprocess, should the economypractical 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f(shuō)2-3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(jì)同低層及多層建筑的設(shè)計(jì) 沒(méi)什么區(qū)別

41、， 但使豎向構(gòu)件的設(shè)計(jì)成為高層設(shè)計(jì)有兩個(gè)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(jì)來(lái)保證。高層建筑的豎向構(gòu)件從上到下逐層對(duì)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(lái)進(jìn)行承載。 同時(shí)，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(xiàn)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(shí)， 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

42、明顯。對(duì)于低層和多層建筑物設(shè)計(jì)只需考慮恒荷載和部分動(dòng)荷載時(shí)，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(wèn)題主要是抗剪問(wèn)題。對(duì)于現(xiàn)代的鋼架系統(tǒng)支撐設(shè)計(jì)， 如無(wú)特殊承載需要， 無(wú)需加大柱和梁的尺寸， 而 通過(guò)增加板就可以實(shí)現(xiàn)。不幸的是， 對(duì)于高層建筑首先要解決的不僅僅是抗剪問(wèn)題， 還有抵抗力矩和 抵抗變形問(wèn)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(gè)高度方向上都 應(yīng)予以加強(qiáng)。用于抵抗側(cè)向

43、荷載的材料要求更多。對(duì)于鋼筋混凝土建筑，雖著建筑物層數(shù)的增加，對(duì)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(lái)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?自身的重量可以抵抗傾覆力矩。 不過(guò)不利的一面是混凝土建筑自重的增加， 將會(huì) 加大抗震設(shè)計(jì)的難度。 在地震荷載作用下，頂部質(zhì)量的增加將會(huì)使側(cè)向荷載劇增。無(wú)論對(duì)于混凝土結(jié)構(gòu)設(shè)計(jì)， 還是對(duì)于鋼結(jié)構(gòu)設(shè)計(jì)， 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(shí)能夠直接減小扭 矩，并以寬度

44、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(jì)構(gòu)件時(shí)，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(huì)加大上層 樓面的質(zhì)量，否則，地震問(wèn)題將更加嚴(yán)重。4.通過(guò)設(shè)計(jì)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(guò) 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(guò)合理地放置實(shí)心墻體及在豎向構(gòu)件中使用斜

45、撐構(gòu)件， 可以有效地 抵抗每層的局部剪力。但僅僅通過(guò)豎向構(gòu)件進(jìn)行抗剪是不經(jīng)濟(jì)的，因 為使柱及梁有足夠的抗彎能力， 比用墻或斜撐需要更多材料和施工工作量。6.每層應(yīng)加設(shè)充足的水平隔板。 這樣就會(huì)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(guò)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平承載力和剛度。 本文后面將對(duì) 這些原理的應(yīng)用做介紹。剪力墻結(jié)構(gòu) 在能夠滿(mǎn)足其他功能需求時(shí)， 高層建筑中采用剪力墻可以經(jīng)濟(jì)地進(jìn)行高層建 筑的抗側(cè)向荷載設(shè)計(jì)。例如， 住宅樓需要很多隔墻，如