外文翻譯tallbuildingstructure外文翻譯-文庫吧
2024-11-16 05:18 本頁面
【正文】 ilding caused by these lateral forces increase with at least the square of the height, and their effects will bee 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. Preliminary calculations for member sizes are usually based on gravity loading augmented by an arbitrary increment to account for wind forces. The crosssectional areas of the vertical members will be based on the accumulated loadings from their associated tributary areas, with reductions to account for the 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 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 attract excessive loads, the engineer may reduce their stiffness to redistribute the load to less heavily stressed ponents. 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 will be required as the client39。s and architect39。s ideas of the building evolve. This will call for structural modifications, or perhaps a radical rearrangement, which necessitates a plete review of the structural design. The various preliminary stages may therefore have to be repeated a number of times before a final solution is reached. Speed of erection is a vital factor in obtaining a return on the investment involved in such largescale projects. Most tall buildings are constructed in congested city sites, with difficult access。 therefore careful planning and anization of the construction sequence bee essential. The storytostory 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 methods of construction. Earthquake Faults The origin of an earthquake An earthquake originates on a plane of weakness or a fracture in the earth39。s 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 this 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 the point on the earth39。
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