土木工程毕业设计外文翻译-高层建筑结构.doc

1、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 largely for comm

2、ercial 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 landmarks, tall

3、 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 of the urban

4、 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 buildings upw

5、ard.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 servicing. A c

6、ompromise between conflicting demands will be almost inevitable. In all but the very tallest structures, however, the structural arrangement will be subservient to the architectural requirements of space arrangement and aesthetics.The two primary types of vertical load-resisting elements of tall bui

7、ldings are columns and walls, the latter acting either independently as shear walls or in assemblies as shear wall cores. The building function will lead naturally to the provision of walls to divide and enclose space, and of cores to contain and convey services such as elevators. Columns will be pr

8、ovided, in otherwise unsupported regions, to transmit gravity loads and, in some types of structure, horizontal loads also.The inevitable primary function of the structural elements is to resist the gravity loading from the weight of the building and its contents. Since the loading on different floo

9、rs tends to be similar, the weight of the floor system per unit floor area is approximately constant, regardless of the building height. Because the gravity load on the columns increases down the height of a building, the weight of columns per unit area increases approximately linearly with the buil

10、ding height.The highly probable second function of the vertical structural elements is to resist also the parasitic load caused by wind and possibly earthquakes, whose magnitudes will be obtained from National Building Codes or wind tunnel studies. The bending moments on the building caused by these

11、 lateral forces increase with at least the square of the height, and their effects will become progressively more important as the building height increases.Once the functional layout of the structure has been decided, the design process generally follows a well defined iterative procedure. Prelimin

12、ary calculations for member sizes are usually based on gravity loading augmented by an arbitrary increment to account for wind forces. The cross-sectional areas of the vertical members will be based on the accumulated loadings from their associated tributary areas, with reductions to account for the

13、 probability that not all floors will be subjected simultaneously to their maximum live loading. The initial sizes of beams and slabs are normally based on moments and shears obtained from some simple method of gravity load analysis, or from codified mid and end span values. A check is then made on

14、the maximum horizontal deflection, and the forces in the major structural members, using some rapid approximate analysis technique. If the deflection is excessive, or some of the members are inadequate, adjustments are made to the member sizes or the structural arrangement. If certain members attrac

15、t excessive loads, the engineer may reduce their stiffness to redistribute the load to less heavily stressed components. The procedure of preliminary analysis, checking, and adjustment is repeated until a satisfactory solution is obtained.Invariably, alterations to the initial layout of the building

16、 will be required as the clients and architects ideas of the building evolve. This will call for structural modifications, or perhaps a radical rearrangement, which necessitates a complete review of the structural design. The various preliminary stages may therefore have to be repeated a number of t

17、imes before a final solution is reached.Speed of erection is a vital factor in obtaining a return on the investment involved in such large-scale projects. Most tall buildings are constructed in congested city sites, with difficult access; therefore careful planning and organization of the constructi

18、on sequence become essential. The story-to-story uniformity of most multistory buildings encourages construction through repetitive operations and prefabrication techniques. Progress in the ability to build tall has gone hand in hand with the development of more efficient equipment and improved meth

19、ods of construction.Earthquake FaultsThe origin of an earthquakeAn earthquake originates on a plane of weakness or a fracture in the earths crust, termed a fault. The earth on one side of the fault slides or slips horizontally and /or vertically with respect to the earth on the opposite side, and th

20、is generates a vibration that is transmitted outward in all directions. This vibration constitutes the earthquake.The earthquake generally originates deep within the earth at a point on the fault where the stress that produces the slip is a maximum. This point is called the hypocenter or focus and t

21、he point on the earths surface directly above this point is called the epicenter. The main or greatest shock is usually followed by numerous smaller aftershocks. These aftershocks are produced by slippage at other points on the fault or in the fault zone.Types of earthquake faultsFaults are classifi

22、ed in accordance with the direction and nature of the relative displacement of the earth at the fault plane. Probably the most common type is the strike-slip fault in which the relative fault displacement is mainly horizontal across an essentially vertical fault plane. The great San Andreas fault in

23、 California is of the type. Another type is termed a normal fault when the relative movement is in an upward an downward direction on a nearly vertical fault plane. The great Alaskan earthquake of 1964 was apparently of this type. A less common type is the thrust fault when the earth is under compre

24、ssive stress across the fault and the slippage is in an upward and downward direction along an inclined fault plane. The San Fernando earthquake was generated on what has usually been classified as a thrust fault, although there was about as much lateral slippage as up and down slippage due to thrus

25、t across the inclined fault plane. Some authorities refer to this combined action as lateral thrust faulting. The compressive strain in the earth of the San Fernando Valley floor just south of the thrust fault was evidenced in many places by buckled sidewalks and asphalt paving.Forces exerted by an

26、earthquakeSlippage along the fault occurs suddenly. It is a release of stress that has gradually built-up in the rocks of the earths crust. Although the vibrational movement of the earth during an earthquake is in all directions, the horizontal components are of chief importance to the structural en

27、gineer. These movements exert forces on a structure because they accelerate. This acceleration is simply a change in the velocity of the earth movement. Since the ground motion in an earthquake is vibratory, the acceleration and force that it exerts on a structure reverses in direction periodically,

28、 at short intervals of time.The structural engineer is interested in the force exerted on a body by the movement of the earth. This may be determined from Newtons second law of motion which may be stated in the following form:F=MaIn which F is a force that produces an acceleration a when acting on a

29、 body of mass M. This equation is nondimensional. For calculations M is set equal to W/g, then:F=W/g*a (1)In which F is in pounds, a is in feet per second per second, W is the weight of the body also in pounds and g is the acceleration of gravity, which is 32.2 feet per second per second.Equation (1

30、) is empirical. It simply states the experimental fact that for a free falling body the acceleration a is equal to g and the acceleration force F is then equal to the weight W.For convenience, the acceleration of an earthquake is generally expressed as a ratio to the acceleration of gravity. This ra

31、tio is called a seismic coefficient. The advantage of this system is that the force exerted on a body by acceleration is simply the corresponding seismic coefficient multiplied by the weight of the body. This is in accordance with Equation (1) in which a/g is the seismic coefficient.Activity of faul

32、tsAll faults are not considered to present the same hazard. Some are classified as active since it is believed that these faults may undergo movement from time to time in the immediate geologic future. Unfortunately in the present state-of-the-art there is a good deal of uncertainty in the identific

33、ation of potentially active faults. For example, the fault that generated the San Fernando earthquake did not even appear on any published geological maps of the area. This fault was discovered to be active only when it actually slipped and ruptured the ground surface. Accordingly the identification

34、 of active faults and geologically hazardous areas for land use criteria and for hazard reduction by special engineering may be of questionable value.Only in very recent years have geologists begun to try to evaluate the potential activity of faults that have no historical record of activity. By clo

35、se inspection of a fault, visible in the side walls of a trench that cuts across the fault, it is sometimes possible to determine if it has been active in recent times. For example, if the trace of the fault extends through a recent alluvial material, then there must have been slippage since that ma

36、terial was deposited. However fault ruptures may be very difficult or impossible to see in imbedded material such as sand and gravel. Also of course the location of the fault must be known and it must reach the surface of the ground in order to inspect it by trenching.Evidence of the historical acti

37、vity of a fault may sometimes be obtained by observing the faulting of geologically young deposits exposed in a trench. Such deposits are generally bedded and well consolidated so that fault rupture can easily be seen.The approximate time of formation of a fault rupture or scarp has in some cases be

38、en determined by radiocarbon analysis of pieces of wood found in the rupture or scarp.In addition to evidence of young fault activity obtained by trenching, there also may be topographic evidence of young faulting such as is obvious along the San Andreas fault. Vertical aerial photographs are one of

39、 the most important methods for finding topographic evidence of active faults. This evidence, which includes scarps, offset channels, depressions, and elongated ridges and valleys, is produced by fault activity. The age of these topographic features and therefore the time of the fault activity, can

40、be estimated by the extent to which they are weathered and eroded.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

41、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。冲突的要求之间的妥协将是不可避免的。但在所有的结构非常最高，但结构安排将服从安排和空间美学的建筑要求。两个垂直荷载抗高层建筑元素的主要类型列和墙壁，后者代理或者作为剪力墙或剪力墙作为核心组件独立。该大楼的功能将导致自然提供的墙壁围分裂和空间，和内核，以遏制和传达，如电梯服务。专栏将提供，在每单

42、不支持的地区，否则，传输重力负荷，并在某些类型的结构，水平荷载也。不可避免的结构因素的主要功能是抵抗建筑物及其内容的重力负荷重量。由于不同的楼层负荷往往是相似的，该系统每单位楼面面积重量约不断，不论建筑物的高度。由于对降低建筑物的高度，重量面积和重力负荷的增加而增加约与建筑的高度成正比。在极有可能垂直结构构件的第二个功能是抵制也是寄生风荷载和可能的地震，其震级将由国家建筑守则或风洞研究取得造成的。对这些侧向力的增加造成的建设的弯矩至少高度广场，和其效果会变得越来越重要，因为建筑物高度的增加。一旦结构功能布局已经确定，设计过程中普遍遵循明确的迭代过程。会员规模初步测算，通常根据一个任意扩充增量占

43、风力重力负荷。的跨垂直截面面积的成员将根据其相关地区的支流与积累负荷削减，以考虑到，并非所有的楼层将同时受到其最大的活荷载的概率。最初的梁，板的尺寸通常为基础，在时刻剪一些简单的我获得需氧量重力负载分析，或从编纂中和年底跨度值。进行检查，然后做出的最高水平偏转，并在主要结构构件的力量，使用一些快速近似性能分析技术。如果变形过大，或部分成员不足，调整，是为成员的大小或结构安排。如果行政长官成员吸引过度劳累，工程师可减少其刚度重新分配负载量较低强调组件。初步分析程序，检查和调整，直到满意的解决办法，得到重复。总是以建筑物的初步布局的改动需作为客户端的建设和发展的建筑师的想法。这将调用结构的修改，或

44、者可能是激进的重新安排，因此必须对结构性的设计进行全面审查。各种初级阶段，因此可能要重复最终解决之前，多次到达。勃起速度是在获得在这样大规模的项目涉及投资回报的重要因素。大多数高层建筑都建在拥挤的城市用地，难以利用，因此仔细的规划和施工顺序组织是至关重要的。这个故事对大多数高层建筑的故事，鼓励通过反复的统一行动和预制技术建设。在高大的能力建设已经取得进展的同时更高效的设备和施工方法的改进发展手。地震断层地震的起源据我国地震台起源于软弱的飞机或在地壳断裂，称为“错误”。关于一个断层的一侧地球幻灯片或单就在地球对面横向和/或垂直，这会生成一个向各个方向传播向外震动。这构成了地震震动。这次地震深度一

45、般起源于对故障点的地球内部的压力下产生的支路是最长的。这一点被称为震源或重点和地球表面的点上方这一点称为震中。主要的或最大的震动，随后通常是由众多小的余震。这些余震在其他生产点的过失或在断裂带的延误。地震断层类型故障归类按照方向和在断层面上的地球相对位移的性质。可能是最常见的类型是走滑断层，其中相对断层位移主要是在本质上平面垂直断层水平。伟大的圣安德烈亚斯断层是在加利福尼亚州的类型。另一种是称为正断层-相对运动时，在一个向上向下的方向，是一个几乎垂直于断层面上。在1964年阿拉斯加大地震显然是属于这一类。一个不太常见的类型是逆冲断层-当地球上的断层下压应力和滑移有上升和下跌态势发展的方向沿倾斜

46、断层面。圣费尔南多地震产生什么通常也被作为一个逆冲断层机密，虽然没有像过去那样向上和向下滑动，由于整个飞机倾斜断层侧向推力延误。有些机关是指一个断层侧向推力联合行动。中的圣费尔南多谷楼土压应变南边的逆冲断层是由反手表现在人行道和沥青铺路很多地方。由地震产生力量沿断层滑动突然发生。这是一个强调的是，逐渐形成，在地球的地壳岩石释放。虽然地球发生地震的振动，在所有的运动方向的，水平组成部分是行政的重要性结构工程师。这些运动在结构上施加的力量，因为他们加快。这种加速仅仅是在地球运动速度的变化。自地震地面运动的振动，加速度和力，它在结构上施加定期方向逆转，在很短的时间间隔。结构工程师有兴趣的机构施加的地

47、球运动的力量。这可能是决定从牛顿第二运动定律可在下列表格中：F=ma在这F是一种力量，产生一种加速度1时1米的大机构担任这个方程无量纲。对于M是设置为等于为W计算/克，则：F =瓦/克* 1（1）其中F在磅，使每英尺每秒第二位，W是体重也磅，g是重力加速度，即三十二点二英尺每秒每秒。方程（1）经验。它只是国家的实验事实，即自由落体加速度a等于克和加速度力F然后等于体重总统为方便起见，地震加速度一般表现为对重力加速度的比例。这个比例被称为地震系数。该系统的优点是，该部队由加速人体产生仅仅是相应的地震系数由体重成倍增加。这是在1 /克，是地震系数与方程（1）条。活动断层所有的错误是没有考虑到目前相

48、同的危险。有些被列为“积极的”，因为它相信，这些错误可能会经历不时在不久的将来地质运动。可惜在目前状况的最先进的有一个潜在的活断层识别大量的不确定性。例如，的过错产生的圣费尔南多地震甚至没有出现在任何地区出版的地质图。这种故障是要积极发现只有在实际上下降和地表破裂。据此，确定活断层和土地使用准则地质危险区和危险的特殊工程的减少可能是令人怀疑的。只有在非常近年来地质学家开始尝试评估故障，没有活动的历史记录潜在活性。通过仔细观察，当出现故障，在一个战壕的跨越断层削减，有时可能以确定它是否已被近来活跃侧壁可见。例如，如果跟踪的故障已延长到最近的冲积物质，那么一定有延误，因为这些材料沉积。但是断层破裂

49、可能很困难或不可能看到嵌、材料，如砂石。另外当然是故障定位必须知道而且必须到达地面，以检查它的挖坑。对出现故障的历史活动的证据，有时会获得通过观察断裂在一个战壕暴露，地质年轻的存款。这类存款一般层状和良好的综合，使断层破裂可以很容易地看到。在出现故障破裂或形成陡坎近似的时间已经被放射性碳在破裂或悬崖发现木头分析确定在某些情况下。除了年轻的过失所取得的挖沟，但也可能是地形的证据年轻断层活动的证据是显而易见的，如沿圣安德烈斯断层。垂直空中拍摄的照片是最重要的方法之一发现活断层地形证据。这些证据包括削壁，抵消渠道，洼地，修长，山脊和山谷，是由断层活动。这些地形特点的年龄，因此断层的活动时间，可以通过他们被风化侵蚀的程度估计。.