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1、外文翻译 Ahthor: Wentworth Miller 一 、原文 : Structural Systems to resist lateral loads Commonly Used structural Systems With loads measured in tens of thousands kips, there is little room in the design of high-rise buildings for excessively complex thoughts. Indeed, the better high-rise buildings carry th
2、e universal traits of simplicity of thought and clarity of expression. It does not follow that there is no room for grand thoughts. Indeed, it is with such grand thoughts that the new family of high-rise buildings has evolved. Perhaps more important, the new concepts of but a few years ago have beco
3、me commonplace in today s technology. Omitting some concepts that are related strictly to the materials of construction, the most commonly used structural systems used in high-rise buildings can be categorized as follows: 1. Moment-resisting frames. 2. Braced frames, including eccentrically braced f
4、rames. 3. Shear walls, including steel plate shear walls. 4. Tube-in-tube structures. 5. Tube-in-tube structures. 6. Core-interactive structures. 7. Cellular or bundled-tube systems. Particularly with the recent trend toward more complex forms, but in response also to the need for increased stiffnes
5、s to resist the forces from wind and earthquake, most high-rise buildings have structural systems built up of combinations of frames, braced bents, shear walls, and related systems. Further, for the taller buildings, the majorities are composed of interactive elements in three-dimensional arrays. Th
6、e method of combining these elements is the very essence of the design process for high-rise buildings. These combinations need evolve in response to environmental, functional, and cost considerations so as to provide efficient structures that provoke the architectural development to new heights. Th
7、is is not to say that imaginative structural design can create great architecture. To the contrary, many examples of fine architecture have been created with only moderate support from the structural engineer, while only fine structure, not great architecture, can be developed without the genius and
8、 the leadership of a talented architect. In any event, the best of both is needed to formulate a truly extraordinary design of a high-rise building. While comprehensive discussions of these seven systems are generally available in the literature, further discussion is warranted here .The essence of
9、the design process is distributed throughout the discussion. Moment-Resisting Frames Perhaps the most commonly used system in low-to medium-rise buildings, the moment-resisting frame, is characterized by linear horizontal and vertical members connected essentially rigidly at their joints. Such frame
10、s are used as a stand-alone system or in combination with other systems so as to provide the needed resistance to horizontal loads. In the taller of high-rise buildings, the system is likely to be found inappropriate for a stand-alone system, this because of the difficulty in mobilizing sufficient s
11、tiffness under lateral forces. Analysis can be accomplished by STRESS, STRUDL, or a host of other appropriate computer programs; analysis by the so-called portal method of the cantilever method has no place in todays technology. Because of the intrinsic flexibility of the column/girder intersection,
12、 and because preliminary designs should aim to highlight weaknesses of systems, it is not unusual to use center-to-center dimensions for the frame in the preliminary analysis. Of course, in the latter phases of design, a realistic appraisal in-joint deformation is essential. Braced Frames The braced
13、 frame, intrinsically stiffer than the moment resisting frame, finds also greater application to higher-rise buildings. The system is characterized by linear horizontal, vertical, and diagonal members, connected simply or rigidly at their joints. It is used commonly in conjunction with other systems
14、 for taller buildings and as a stand-alone system in low-to medium-rise buildings. While the use of structural steel in braced frames is common, concrete frames are more likely to be of the larger-scale variety. Of special interest in areas of high seismicity is the use of the eccentric braced frame
15、. Again, analysis can be by STRESS, STRUDL, or any one of a series of two or three dimensional analysis computer programs. And again, center-to-center dimensions are used commonly in the preliminary analysis. Shear walls The shear wall is yet another step forward along a progression of ever-stiffer
16、structural systems. The system is characterized by relatively thin, generally (but not always) concrete elements that provide both structural strength and separation between building functions. In high-rise buildings, shear wall systems tend to have a relatively high aspect ratio, that is, their hei
17、ght tends to be large compared to their width. Lacking tension in the foundation system, any structural element is limited in its ability to resist overturning moment by the width of the system and by the gravity load supported by the element. Limited to a narrow overturning, One obvious use of the
18、system, which does have the needed width, is in the exterior walls of building, where the requirement for windows is kept small. Structural steel shear walls, generally stiffened against buckling by a concrete overlay, have found application where shear loads are high. The system, intrinsically more
19、 economical than steel bracing, is particularly effective in carrying shear loads down through the taller floors in the areas immediately above grade. The sys tem has the further advantage of having high ductility a feature of particular importance in areas of high seismicity. The analysis of shear wall systems is made complex because of the inevitable presence of large openings through these walls. Preliminary analysis can be by truss-analogy, by the finite element method, or by making use of a proprietary computer program designed to consider the interaction, or coupling, of shear walls.