High-rise buildings are closely related to the city; they are a natural response to dense population concentration,scarcity of land, and high land costs. The massing of the high-rise building evolves out of the designer‟s interpretation of the environmental context and his response to the purpose of the building. A high-rise building may be free standing—that is, vertical and slender or horizontal and bulky—or it may be placed directly adjacent to other tall buildings, thus forming a solid building block. In both approaches the building is basically an isolated object. However the tall building of the future may very well be an integral part of one large building organism, the city, where the buildings or activity cells are interconnected by multilevel movement systems.
High-rise buildings range in height from below 10 to more than 100 stories. A rather complex planning process is necessary to determine the height of a building. Some of the factors to be considered are the client‟s needs versus the land available and the location of the land as related to the facets of the environmental context, for example necessary services to support the building and its inhabitants or the ecological impact of the building or the scenic characteristic of the landscape.
The development of the high-rise buildings follows closely the growth of the city. The process of urbanization which started with the age of industrialization is still in progress in many parts of the world. In the United States this process began in the nineteenth century; people migrated from rural to urban areas, thereby forcing an increase in the density of cities. Technology responded to this pressure with the lightweight steel cage structure (轻钢骨架结构), the elevator, and the energy supply systems necessitated by the high density vertical city.
At the beginning of this century building blocks about 20 stories high were set opposite each other, separated only by dark narrow streets, forming urban canyons. Primary concern was the placement of maximum number of people on a minimum area of land. The resulting congestion (拥挤) and its impact on people and the city as an organic interaction system was hardly a design consideration. The needs for light, air, and open ground level for public activity spaces led to the evolution of the free-standing skyscraper. It is much taller, since it must provide a density at least equivalent to the building block it is replacing. Present technology is far enough advanced to allow construction of the single skyscraper at an economically feasible cost.
From a technological or material space point of view, the design of tall buildings is relatively well understood;however consideration of the behavioral space, that is, identification of human needs and space adaptability, is still in an early developmental stage. The isolation and lack of contact between people within the building, and the loss of contact with street life, are some of the problems designers are trying to overcome.
Although to some degree the density of tall buildings in cities is now controlled by zoning regulations (城市区域规划), this design is not based on the context of the total, dynamic urban fabrics. The consequences to the urban environment of close grouping of tall buildings are of utmost importance. The impact of scale of some of the super skyscrapers on the city, such as the 109 stories Sears Tower in Chicago, more than a quarter-mile high, is apparent. The building‟s electrical system can serve a city of 147000 people and its air conditioning complex can cool 6000 one-family houses. A total of 102 elevators are needed to distribute about 16500 daily users to the different parts of the building.