Components of A Building and Tall Buildings
1. Abstract
Materials and structural forms are combined to make up the various parts of a building, including the load-carrying frame, skin, floors, and partitions. The building also has mechanical and electrical systems, such as elevators, heating and cooling systems, and lighting systems. The superstructure is that part of a building above ground, and the substructure and foundation is that part of a building below ground.
The skyscraper owes its existence to two developments of the 19th century: steel skeleton construction and the passenger elevator. Steel as a construction material dates from the introduction of the Bessemer converter in 1885.Gustave Eiffel (1832-1932) introduced steel construction in France. His designs for the Galerie des Machines and the Tower for the Paris Exposition of 1889 expressed the lightness of the steel framework. The Eiffel Tower, 984 feet (300 meters) high, was the tallest structure built by man and was not surpassed until 40 years later by a series of American skyscrapers.
Elisha Otis installed the first elevator in a department store in New York in 1857.In 1889, Eiffel installed the first elevators on a grand scale in the Eiffel Tower, whose hydraulic elevators could transport 2,350 passengers to the summit every hour.
2. Load-Carrying Frame
Until the late 19th century, the exterior walls of a building were used as bearing walls to support the floors. This construction is essentially a post and lintel type, and it is still used in frame construction for houses. Bearing-wall construction limited the height of building because of the enormous wall thickness required；for instance, the 16-story Monadnock Building built in the 1880’s in Chicago had walls 5 feet (1.5 meters) thick at the lower floors. In 1883, William Le Baron Jenney (1832-1907) supported floors on cast-iron columns to form a cage-like construction. Skeleton construction, consisting of steel beams and columns, was first used in 1889. As a consequence of skeleton construction, the enclosing walls become a “curtain wall” rather than serving a supporting function. Masonry was the curtain wall material until the 1930’s, when light metal and glass curtain walls were used. After the introduction of buildings continued to increase rapidly.
All tall buildings were built with a skeleton of steel until World War Ⅱ. After the war, the shortage of steel and the improved quality of concrete led to tall building being built of reinforced concrete. Marina Tower (1962) in Chicago is the tallest concrete building in the United States； its height—588 feet (179 meters)—is exceeded by the 650-foot (198-meter) Post Office Tower in London and by other towers.
A change in attitude about skyscraper construction has brought a return to the use of the bearing wall. In New York City, the Columbia Broadcasting System Building, designed by Eero Saarinen in 1962,has a perimeter wall consisting of 5-foot (1.5meter) wide concrete columns spaced 10 feet (3 meters) from column center to center. This perimeter wall, in effect, constitutes a bearing wall. One reason for this trend is that stiffness against the action of wind can be economically obtained by using the walls of the building as a tube； the World Trade Center building is another example of this tube approach. In contrast, rigid frames or vertical trusses are usually provided to give lateral stability.
3. Skin
The skin of a building consists of both transparent elements (windows) and opaque elements (walls). Windows are traditionally glass, although plastics are being used, especially in schools where breakage creates a maintenance problem. The wall elements, which are used to cover the structure and are supported by it, are built of a variety of materials: brick, precast concrete, stone, opaque glass, plastics, steel, and aluminum. Wood is used mainly in house construction； it is not generally used for commercial, industrial, or public building because of the fire hazard.
4. Floors
The construction of the floors in a building depends on the basic structural frame that is used. In steel skeleton construction, floors are either slabs of concrete resting on steel beams or a deck consisting of corrugated steel with a concrete topping. In concrete construction, the floors are either slabs of concrete on concrete beams or a series of closely spaced concrete beams (ribs) in two directions topped with a thin concrete slab, giving the appearance of a waffle on its underside. The kind of floor that is used depends on the span between supporting columns or walls and the function of the space. In an apartment building, for instance, where walls and columns are spaced at 12 to 18 feet (3.7 to 5.5 meters), the most popular construction is a solid concrete slab with no beams. The underside of the slab serves as the ceiling for the space below it. Corrugated steel decks are often used in office buildings because the corrugations, when enclosed by another sheet of metal, form ducts for telephone and electrical lines.
5. Mechanical and Electrical Systems
A modern building not only contains the space for which it is intended (office, classroom, apartment) but also contains ancillary space for mechanical and electrical systems that help to provide a comfortable environment. These ancillary spaces in a skyscraper office building may constitute 25% of the total building area. The importance of heating, ventilating, electrical, and plumbing systems in an office building is shown by the fact that 40% of the construction budget is allocated to them. Because of the increased use of sealed building with windows that cannot be opened, elaborate mechanical systems are provided for ventilation and air conditioning. Ducts and pipes carry fresh air from central fan rooms and air conditioning machinery. The ceiling, which is suspended below the upper floor construction, conceals the ductwork and contains the lighting units. Electrical wiring for power and for telephone communication may also be located in this ceiling space or may be buried in the floor construction in pipes or conduits.
There have been attempts to incorporate the mechanical and electrical systems into the architecture of building by frankly expressing them； for example, the American Republic Insurance Company Building(1965) in Des Moines, Iowa, exposes both the ducts and the floor structure in an organized and elegant pattern and dispenses with the suspended ceiling. This type of approach makes it possible to reduce the cost of the building and permits innovations, such as in the span of the structure.
6. Soils and Foundations
All building are supported on the ground, and therefore the nature of the soil becomes an extremely important consideration in the design of any building. The design of a foundation depends on many soil factors, such as type of soil, soil stratification, thickness of soil lavers and their compaction, and groundwater conditions. Soils rarely have a single composition； they generally are mixtures in layers of varying thickness. For evaluation, soils are graded according to particle size, which increases from silt to clay to sand to gravel to rock. In general, the larger particle soils will support heavier loads than the smaller ones. The hardest rock can support loads up to 100 tons per square foot(976.5 metric tons/sq meter), but the softest silt can support a load of only 0.25 ton per square foot(2.44 metric tons/sq meter). All soils beneath the surface are in a state of compaction； that is, they are under a pressure that is equal to the weight of the soil column above it. Many soils (except for most sands and gavels) exhibit elastic properties—they deform when compressed under load and rebound when the load is removed. The elasticity of soils is often time-dependent, that is, deformations of the soil occur over a length of time which may vary from minutes to years after a load is imposed. Over a period of time, a building may settle if it imposes a load on the soil greater than the natural compaction weight of the soil. Conversely, a building may heave if it imposes loads on the soil smaller than the natural compaction weight. The soil may also flow under the weight of a building； that is, it tends to be squeezed out.
Due to both the compaction and flow effects, buildings tend settle. Uneven settlements, exemplified by the leaning towers in Pisa and Bologna, can have damaging effects—the building may lean, walls and partitions may crack, windows and doors may become inoperative, and, in the extreme, a building may collapse. Uniform settlements are not so serious, although extreme conditions, such as those in Mexico City, can have serious consequences. Over the past 100 years, a change in the groundwater level there has caused some buildings to settle more than 10 feet (3 meters). Because such movements can occur during and after construction, careful analysis of the behavior of soils under a building is vital.
The great variability of soils has led to a variety of solutions to the foundation problem. Where
firm soil exists close to the surface, the simplest solution is to rest columns on a small slab of concrete(spread footing). Where the soil is softer, it is necessary to spread the column load over a greater area；in this case, a continuous slab of concrete(raft or mat) under the whole building is used. In cases where the soil near the surface is unable to support the weight of the building, piles of wood, steel, or concrete are driven down to firm soil.
The construction of a building proceeds naturally from the foundation up to the superstructure. The design process, however, proceeds from the roof down to the foundation (in the direction of gravity). In the past, the foundation was not subject to systematic investigation. A scientific approach to the design of foundations has been developed in the 20th century. Karl Terzaghi of the United States pioneered studies that made it possible to make accurate predictions of the behavior of foundations, using the science of soil mechanics coupled with exploration and testing procedures. Foundation failures of the past, such as the classical example of the leaning tower in Pisa, have become almost nonexistent. Foundations still are a hidden but costly part of many buildings.
Although there have been many advancements in building construction technology in general, spectacular achievements have been made in the design and construction of ultrahigh-rise buildings.
The early development of high-rise buildings began with structural steel framing. Reinforced concrete and stressed-skin tube systems have since been economically and competitively used in a number of structures for both residential and commercial purposes. The high-rise buildings ranging from 50 to 110 stories that are being built all over the United States are the result of innovations and development of new structural systems.
Greater height entails increased column and beam sizes to make buildings more rigid so that under wind load they will not sway beyond an acceptable limit. Excessive lateral sway may cause serious recurring damage to partitions, ceilings, and other architectural details. In addition, excessive sway may cause discomfort to the occupants of the building because of their perception of such motion. Structural systems of reinforced concrete, as well as steel, take full advantage of the inherent potential stiffness of the total building and therefore do not require additional stiffening to limit the sway.
In a steel structure, for example, the economy can be defined in terms of the total average quantity of steel per square foot of floor area of the building. Curve A in Fig.1 represents the average unit weight of a conventional frame with increasing numbers of stories. Curve B represents the average steel weight if the frame is protected from all lateral loads. The gap between the upper boundary and the lower boundary represents the premium for all lateral loads. The gap between the upper boundary and the lower boundary represents the premium for height for the traditional column-and-beam frame. Structural engineers have developed structural systems with a view to eliminating this premium.
7. Tube in tube
Another system in reinforced concrete for office buildings combines the traditional shear wall construction with an exterior framed tube. The system consists of an outer framed tube of very closely spaced columns and an interior rigid shear wall tube enclosing the central service area. The system (Fig.2), known as the tube-in-tube system, made it possible to design the world’s present tallest (714 ft or 218 m) lightweight concrete building (the 52-story One Shell Plaza Building in Houston) for the unit price of a traditional shear wall structure of only 35 stories. /
Systems combining both concrete and steel have also been developed, an example of which is the composite system developed by Skidmore, Owings & Merrill in which an exterior closely spaced framed tube in concrete envelops an interior steel framing, thereby combining the advantages of both reinforced concrete and structural steel systems. The story One Shell Square Building in New Orleans is based on this system.
建筑的组成部分
1 摘要
材料和结构类型是构成建筑物各方面的组成部分，包括承重结构、围护结构、楼地面和隔墙。在建筑物内部还有机械和电气系统，例如电梯、供暖和冷却系统、照明系统等。高于地面的部分是建筑物的上部结构，地面以下部分为建筑物的基础和地基。
摩天大楼的出现应归功于19世纪的两个新发明：钢结构建筑和载人电梯。钢材作为结构材料是从1855年贝色麦炼钢法被首次介绍后开始应用的。古斯塔•艾菲尔（1832~1923）首次介绍钢结构建筑是在法国。他的设计是为1889年的巴黎国际博览会所设计的理想的建筑，表达了钢结构的轻巧。艾菲尔铁塔高300米，是当时人类建造的最高建筑物，直到40年后才由美国的摩天大楼超过其高度。
第一部电梯是1857年Elisha Otis给纽约的一家百货公司所安装的。1889年，艾菲尔在艾菲尔铁塔上安装了第一部大型液压电梯，它每小时可以运送2350位乘客到达塔顶。
2 承重框架
直到19世纪后期，建筑物的外墙被用做承重墙来支撑楼层，这种结构是基本的一种过梁类型，它还被用在框架结构房屋中。因为所需墙体的厚度很大，承重墙结构限制了建筑物的高度；例如，建于1880年的芝加哥16层高的Monadnock Building，在较低的楼层墙体厚度已达到1.5米。1883年，Willian Le Baron Jenney（1832~1907）用类似鸟笼形状的铁柱来支撑楼层。在1889年，框架结构首次由钢梁和钢柱构成。外墙成为了“幕墙”而不是被用做支撑结构是框架结构的一个成果。砖石一直是“幕墙”的主要材料，直到1930年轻金属和玻璃幕墙的问世为止。自从钢骨架首次推出，建筑物的高度一直在迅速增加。
直到第二次世界大战为止，所有的高层建筑都是由钢骨架建造的。战争结束以后，钢材的缺乏和混凝土品质的改进，促进了钢筋混凝土高层建筑的发展。芝加哥的Marina Towers（1962）是美国最高的混凝土建筑；它的高度是588英尺即179米，不久以后它将超出198米高的伦敦邮政塔和其它的塔。
在关于摩天大楼建筑中的承重墙的使用在看法上有了改变。在纽约，由Eero Saarinen于1962年设计的哥伦比亚广播公司大楼，四周的墙由1.5米宽的混凝土柱构成，柱与柱的中心间距为3米。这种围护墙有效地构成了建筑物的承重墙。这种趋势发展的原因是建筑物的墙像一个管道可以有利地抵抗风的强烈作用；世贸大楼是另一个管道法的例子。相比之下，坚固的框架或垂直支撑通常提供建筑的横向稳定。
3 围护结构
一个建筑的围护结构由透明的窗户和不透明的墙组成。窗户采用传统上的玻璃作为材料年，然而塑料也被使用，特别在破损严重和保养难的学校里。墙被用来覆盖结构和起支撑作用，它是由多样化的建筑材料组成：砖、现浇混凝土、石头、不透明的玻璃、塑料、钢材和铝材。木头是过去建造房屋的主要材料；因为它易着火，因而不常用于商业的、工业的和公共建筑。
4 楼地面
一幢建筑的楼地面结构取决于它所使用的基本结构框架。在钢框架建筑中，楼地面或者是钢梁上的混凝土楼板，或者是由波纹钢配有混凝土骨料组成的地板。在混凝土结构中，楼地面或者是混凝土梁上的混凝土楼板或者是一系列紧密分布于混凝土梁在方向上端的薄混凝土楼板，在它的下面抹一层抹面。楼层的种类取决于支撑柱之间的距离或者墙和空间的功能性。在一栋公寓大楼中，例如，墙和柱隔开3.7米到5.5米，最常见的结构是无梁实心混凝土楼盖。楼盖的下表面是楼盖以下空间的最高限度。办公大楼中常使用波纹钢地板，这是因为波纹钢地板的波纹当由另一块金属板盖上时，可以形成电话线和电线管道。
5 机械电力系统
一个现代建筑不仅包括必要使用空间而且也包括机械、电力系统等的辅助空间，以便营造一个舒适的生活环境。这些辅助空间可能占摩天大楼总建筑面积的25%。在一个办公大楼中，供暖、通风、电力和卫生设备系统的预算额占实际建筑总预算额的40%，显示了它们在建筑中的重要性。因为许多建筑是密封的，窗户不能被打开，因而由机械系统提供了通风设备和空气调节设备。新鲜空气从中央换气室由空气调节器用管道输入。通风管和控制照明设备单元由悬挂在上面楼层结构下面的天花板遮住了。提供动力的电力线路和电话通讯线路也可能在天花板里或者也可能在楼地面结构层中的管道或导线管里。
我们曾尝试性地把机械、电力系统加入建筑物的建筑风格中去，让他们裸露在结构的外部；例如美国保险公司大楼in Des Morines ,衣阿华，管道和楼地面的结构层有组织的、优美的悬挂在天花板上。这类型的方法使得建筑物的花费尽可能的减少了并且使结构有了创新，例如在结构间距方面。
土地和地基
所有的建筑物都是靠土层支撑在地面上的，因而土的特性成为建筑设计时极其重要的考虑因素。基础的设计取决于土的许多因素，例如土的类型，土分层的情况，土层的厚度和它的密实度，以及地下水的情况等。土层很少有一个单一的性质；他们通常是厚度变化的混合状态土层。据评定，土层的等级是根据土分子的大小来划分，从小到大依次是淤泥、粘土、沙、石子、岩石。通常，较大分子的土支撑的荷载要大。最坚硬的岩石能够支撑的荷载大约是每平方米100吨，而最软的淤泥仅能够支撑的荷载大约是每平方米0.25吨。所有地表以下的土都处于受压状态，说得更精确些，这些土承受与作用在其上的土柱重量相等的压力。许多土显示出弹性的性质——他们或被重载压坏或卸载后又恢复。土的弹性常随时间而改变，更精确地说，土层的变形在恒载作用下随着时间的增长而不断地改变。过一段时间后，如果加于土层上的荷载大于土自然压紧状态下的重量，则建筑物不会产生沉降。建筑物的重量可能会使土产生流动；也就是说，经常会发生土被挤出。
由于土受压和流动的影响，使建筑物发生沉降。不均匀沉降例如比萨斜塔，损坏的结果是建筑物发生倾斜，墙和隔墙可能出现裂缝，窗户和门可能产生变形，或者甚至建筑可能倒塌。均匀沉降不会如此严重，尽管可能出现危险状况，例如墨西哥城的一些建筑，出现各种各样的后果，在过去的一年里，地下水位发生了改变，致使一些建筑下沉了3米多。因为类似的状况可能发生在建造时也可能是建造后，因此小心处理建筑物下的土层是极其重要的。
土层巨大的变化使得解决地基问题的办法多样化。如果表面土层下的土为坚硬土层，最简单的办法是采用混凝土基础。若是软弱土层，加大柱的面积；假如这样的话，整个建筑就可采用筏板基础。假设表面土层不能够支撑建筑物的重量，木结构建筑、钢结构建筑、或者混凝土建筑应建造在坚硬土层上。
建造一幢建筑物一般是从基础往上到上部结构。然而设计的过程是从屋顶开始到基础。在过去，地基处理不是一个系统的研究项目。在20世纪，一种科学的地基设计方法已经发展起来了。美国的Karl Teraghi不断创造研究，使土力学和土地勘测联合起来，让它尽可能准确地预测地基的活动状态。过去典型的地基破坏的例子——比萨斜塔现在变得几乎不存在了。而地基仍然是建筑物中不可见部分费用最大的一部分。
尽管大体上在建筑物的建造工艺上取得许多进步，但是在超高层建筑物的设计和建造上仍取得了惊人的成就。
早期的高层建筑的发展是以型钢结构开始的。钢筋混凝土和薄壳筒体体系已成为许多住宅和商业建筑以节俭和竟争为目的的结构。作为新结构体系的创新和发展的结果，美国到处都是50到110层的高层建筑。
巨大的高度需要增加柱和梁的尺寸来使建筑物更加坚固，为的是在风荷载作用下不致于使其倾斜度超过限值。反复地过多地侧向摆动可能引起隔墙天花板和其它建筑部件的损坏。另外，过度的摆动可能会给建筑物中的居住者带来不安和恐惧，因为会使他们有移动的感觉。钢筋混凝土结构体系和钢结构一样，内在的潜力使得建筑物非常坚硬因此不需要附加的强化摆动限制。
在一个钢结构中，例如，根据建筑物每平方米的楼层面积的总的平均用量表明其经济性。图中曲线A表示一般性的框架在不受水平荷载的作用下钢的平均重量。上边界和下边界之间的间距表示一般的梁—柱框架的重量。结构工程师以发展结构体系为目标。
7 框筒结构
另一种体系是钢筋混凝土外框筒结构的办公大楼结合传统的剪力墙建筑。该体系由间距很小的柱子构成的外框筒与围绕中心设备区的刚性剪力墙内筒组成。这就是有名的筒中筒体系，使用这种体系建造设计的建筑物可能是目前世界上最高的轻质混凝土大楼（52层的休斯敦的贝壳广场大厦）仅35层的传统简力墙结构。
混凝土与钢筋结合的结构体系已得到发展，这种复合体系发展的一个例子是Skidmore,Owings&Merrill,外部的混凝土框筒结构紧密地包住内部的钢结构，因此，它结合了钢混结构和钢结构体系的优点。