土木工程毕业设计外文翻译-高层建筑结构(共10页).doc

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1、精选优质文档-倾情为你奉上Tall Building StructureTall buildings have fascinated mankind from the beginning of civilization, their construction being initially for defense and subsequently for ecclesiastical purposes. The growth in modern tall building construction, however, which began in the 1880s, has been lar

2、gely for commercial and residential purposes.Tall commercial buildings are primarily a response to the demand by business activities to be as close to each other, and to the city center, as possible, thereby putting intense pressure on the available land space. Also, because they form distinctive la

3、ndmarks, tall commercial buildings are frequently developed in city centers as prestige symbols for corporate organizations.Further, the business and tourist community, with its increasing mobility, has fuelled a need for more, frequently high-rise, city center hotel accommodations.The rapid growth

4、of the urban population and the consequent pressure on limited space have considerably influenced city residential development. The high cost of land, the desire to avoid a continuous urban sprawl, and the need to preserve important agricultural production have all contributed to drive residential b

5、uildings upward.Ideally, in the early stages of planning a building, the entire design team, including the architect, structural engineer, and services engineer, should collaborate to agree on a form of structure to satisfy their respective requirements of function, safety and serviceability, and se

6、rvicing.It 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 subsystem design remain t

7、he 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 the shear deflections

8、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 vertical subsystems mu

9、st 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 base of buildings varie

10、s 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 an inherent property tha

11、t 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 without increasing the sizes of the columns

12、 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 made and additional structural material is al

13、ways 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 floor of a high-rise buildings is in excess of tha

14、t 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 forces is even more significant .With reinforced

15、 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 for lateral force resistance is not that much m

16、ore 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 . In the case of either concrete or steel desig

17、n , 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 . Increase the effective width of the moment-resisting subsystems . This is very useful because increasing the width wi

18、ll 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 actually gain this benefit.Design subsystems such tha

19、t 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 frames . Increase the material in the most effective resis

20、ting 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 where the earthquake problem is aggravated . Arrange to

21、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 . The local shear in each story can be best resisted by strateg

22、ic 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 and connecting girders will require more material and constructi

23、on energy than using walls or diagonal members . Sufficient horizontal diaphragm action should be provided floor . This will help to bring the various resisting elements to work together instead of separately . Create mega-frames by joining large vertical and horizontal components such as two or mor

24、e 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 the above principles are judiciously applied , structurally desirable s

25、chemes 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 the following . Shear-Wall SystemsWhen shear walls are compatible with

26、 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 solid , they can act as shear walls to resist lateral forces and to c

27、arry 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 , shear walls can resist lateral load only the plane of the walls ( i.e.not i

28、n 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 . In addition , that wall layout should reflect consideration of any torsi

29、onal 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 forces very efficiently . If all external shear walls are continuously conne

30、cted , 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 solid type with openings when necessary , steel shear walls are usually ma

31、de 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 opportunity and deflection-limitation point of view , and they offer some

32、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 . As stated above , the walls of elevator , staircase ,and utility shaft

33、s 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 shear in all directions due to tube structural action . But a problem in

34、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 .In steel construction , heavier and more rigid connections are required

35、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 desirable that the stiffness offered these subsystems be more-or-less symmertr

36、ical in all directions .Rigid-Frame SystemsIn 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 . They are employed for low-and medium means for designing buildings .

37、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 stiffness in beams and columns that are required for the buildings in any

38、 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 may produce excessive deflections for the more slender high-rise building

39、s 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 stressing occurs at certain portions of a steel rigid frame ( i.e.,near th

40、e 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 considered by some to be a “best”seismic-resisting type for high-rise st

41、eel 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 designed in the conventional manner , without special care to produce higher

42、 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 possessed by steel rigid frames . But modern research and experience has ind

43、icated 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 . However , at present , these codes often require excessive reinforcemen

44、t 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 construction with shear-wall systems in one buildings ，For example , the bu

45、ildings 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 process, should the economy practical choose the reasonable form as far as po

46、ssible.高层建筑结构高楼大厦已经着迷，从人类文明的开始，其建设是国防和最初其后教会的目的。现代高层建筑的增长，然而，这在19世纪80年代开始，在很大程度上是为商业和住宅用途。高商业楼宇，主要是对商业活动的需求响应作为彼此接近，并到城市中心，如可能，从而使在现有的土地空间的巨大压力。此外，因为它们形成鲜明的标志性建筑，高商业楼宇，经常制定了促进企业组织的威信的象征的城市中心。此外，商业和旅游界与流动性日益增加，已促使更多的，经常的高层需要，市中心酒店住宿。城镇人口的迅速增长和随之而来的压力有限的空间大大影响了城市住宅发展。土地成本高，为了避免出现连续的城市扩张以及需要维护重要的农业生产都有

47、助于推动住宅楼宇向上。理想情况下，在规划建设的初期阶段，整个设计团队，包括建筑师，结构工程师，服务工程师，应互相合作，在商定的结构形式，以满足功能，安全性和可维护性各自的需求，并提供服务。高层建筑的定义很难确定。可以说2-3层的建筑物为底层建筑，而从3-4层地10层或20层的建筑物为中层建筑，高层建筑至少为10层或者更多。尽管在原理上，高层建筑的竖向和水平构件的设计同低层及多层建筑的设计没什么区别，但使竖向构件的设计成为高层设计有两个控制性的因素：首先，高层建筑需要较大的柱体、墙体和井筒；更重要的是侧向里所产生的倾覆力矩和剪力变形要大的多，必要谨慎设计来保证。高层建筑的竖向构件从上到下逐层对累

48、积的重力和荷载进行传递，这就要有较大尺寸的墙体或者柱体来进行承载。同时，这些构件还要将风荷载及地震荷载等侧向荷载传给基础。但是，侧向荷载的分布不同于竖向荷载，它们是非线性的，并且沿着建筑物高度的增加而迅速地增加。例如，在其他条件都相同时，风荷载在建筑物底部引起的倾覆力矩随建筑物高度近似地成平方规律变化，而在顶部的侧向位移与其高度的四次方成正比。地震荷载的效应更为明显。对于低层和多层建筑物设计只需考虑恒荷载和部分动荷载时，建筑物的柱、墙、楼梯或电梯等就自然能承受大部分水平力。所考虑的问题主要是抗剪问题。对于现代的钢架系统支撑设计，如无特殊承载需要，无需加大柱和梁的尺寸，而通过增加板就可以实现。不

49、幸的是，对于高层建筑首先要解决的不仅仅是抗剪问题，还有抵抗力矩和抵抗变形问题。高层建筑中的柱、梁、墙及板等经常需要采用特殊的结构布置和特殊的材料，以抵抗相当高的侧向荷载以及变形。如前所述，在高层建筑中每平方英尺建筑面积结构材料的用量要高于低层建筑。支撑重力荷载的竖向构件，如墙、柱及井筒，在沿建筑物整个高度方向上都应予以加强。用于抵抗侧向荷载的材料要求更多。对于钢筋混凝土建筑，虽着建筑物层数的增加，对材料的要求也随着增加。应当注意的是，因混凝土材料的质量增加而带来的建筑物自重增加，要比钢结构增加得多，而为抵抗风荷载的能力而增加的材料用量却不是呢么多，因为混凝土自身的重量可以抵抗倾覆力矩。不过不利的一面是混凝土建筑自重的增加，将会加大抗震设计的难度。在地震荷载作用下，顶部质量的增加将会使侧向荷载剧增。无论对于混凝土结构设计，还是对于钢结构设计，下面这些基本的原则都有助于在不需要增加太多成本的前提下增强建筑物抵抗侧向荷载的能力。1、增加抗弯构件的有效宽度。由于当其他条件不变时能够直接减小扭矩，并以宽度增量的三次幂形式减小变形，因此这一措施非常有效