城市综合体 浅谈城市综合体 26 原文

四川大学本科毕业论文浅谈城市综合体26 原文：Design Criteria for Tall Building The construction of tall buildings is the result of urbanization as seen in America since the late nineteenth century when the fist skyscrapers were built. The industrialized society attracts more people to the cities, requiring more space for offices as well as for habitation. Tall buildings, however, require two basic technical ingredients. First, economic method of building a tall building must be found and second, a reliable and economic method of transporting people vertically through the building must be available. Even though the Otis elevator in the late 19th century provided the logical answer to vertical transportation, the structure still remained a very significant deterrent to building very tall buildings. The pioneering Chicago School of Architecture refined the use of beam-column frames, but still required high “premium for height” for buildings taller than say 20 stories. As a result, buildings built up to 1920s were mostly below stories. A heroic step was taken in 1930 when the Empire State Building was built with more or less conventional method of construction. This was no example of any economic breakthrough. From the time of Depression in the30’s hardly any high rise construction was undertaken. After World War II the socioeconomic needs in the U.S. opened the way for more taller office and apartment buildings. But , these buildings could no longer be designed in the same manner and proportion as the earlier buildings, simply because the concept of uncluttered column-free space, the concept of climate control and communication in the buildings have drastically changed. All these changes in attitudes brought the era of a new architecture. The new demand and challenge was to create total urban environments. Within the last few years, research on building materials such as reinforced concrete and structural steel have made great strides and opened horizons for more efficient use of these materials. The structural engineers and architects also have met the challenge to find efficient and economical new structural systems for various ranges and heights of buildings going all the way to well over 100stories. Consequently, the process of selecting a structural system for a tall building has become more complicated than it ever was. Structural system approach used for the total design of a building. The process of choosing the structural system for a tall building depends on many criteria which are not always structural. Without the understanding of all of these significant criteria, the structural engineer would feel frustrated in his efforts. The process of designing a building is multi-discipline, and since structure is an integral part of the total scheme, the successful adoption of an innovation in concept will have a much harder time of for acceptance if the engineer does not have an understanding of these criteria, The following is a brief discussion of these design criteria.. 1. Environmental Planning Consideration. In any environment the addition of a tall building will certainly influence the operation of the traffic system, as well as the flow of people in the entire neighborhood. Therefore, a tall building project must be resolved in terms of pedestrian, auto and other traffic, and also resolve the overall need for space at the ground level. While an open plaza may be a viable solution 四川大学本科毕业论文浅谈城市综合体27 under certain climatic and planning conditions, it may not be a reasonable solution where weather conditions are extreme either for winter or for summer. In such cases alternate to open plazas must be considered as a pan of the total solution, and the structural system must respond to it. 2. The Overall Proportions of the Tower. The relationship of the building to the surrounding environment and other existing buildings and plazas may dictate the proportions of the tower itself. It is, of course, obvious that a flat narrow tower will