度。这些筒体不是同样的功能，也就是说，有些筒体是结构的，而有些筒体是用来支撑的。
在考虑这种筒体时，清楚的认识和区别变形的剪切和弯曲分量是很重要的，这源于对梁的对比分析。在结构筒中，剪切构件的偏角和柱、纵梁（例如：结构筒中的网等）的弯曲有关，同时，弯曲构件的偏角取决于柱子的轴心压缩和延伸（例如：结构筒的边缘等）。在支撑筒中，剪切构件的偏角和对角线的轴心变形有关，而弯曲构件的偏角则与柱子的轴心压缩和延伸有关。
根据梁的对比分析，如果平面保持原形（例如：厚楼板），那么外层筒中柱的轴心压力就会与中心筒柱的轴心压力相差甚远，而且稳定的大于中心筒。但是在筒中筒结构的设计中，当发展到极限时，内部轴心压力会很高的，甚至远远大于外部的柱子。这种反常的现象是由于两种体系中的剪切构件的刚度不同。这很容易去理解，内筒可以看成是一个支撑（或者说是剪切刚性的）筒，而外筒可以看成是一个结构（或者说是剪切弹性的）筒。
核心交互式结构：
核心交互式结构属于两个筒与某些形式的三维空间框架相配合的筒中筒特殊情况。事实上，这种体系常用于那种外筒剪切刚度为零的结构。位于Pittsburgh的美国钢铁大楼证实了这种体系是能很好的工作的。在核心交互式结构中，内筒是一个支撑结构，外筒没有任何剪切刚度，而且两种结构体系能通过一个空间结构或“帽”式结构共同起作用。需要指出的是，如果把外部的柱子看成是一种从“帽”到基础的直线体系，这将是不合适的；根据支撑核心的弹性曲线，这些柱子只发挥了刚度的15%。同样需要指出的是，内柱中与侧向力有关的轴向力沿筒高度由拉力变为压力，同时变化点位于
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筒高度的约5/8处。当然，外柱也传递相同的轴向力，这种轴向力低于作用在整个柱子高度的侧向荷载，因为这个体系的剪切刚度接近于零。
把内外筒相连接的空间结构、悬臂梁或桁架经常遵照一些规范来布置。美国电话电报总局就是一个布置交互式构件的生动例子。
1．结构体系长59.7米，宽28.6米，高183.3米。
2．布置了两个筒，每个筒的尺寸是9.4米×12.2米，在长方向上有27.4米的间隔。
3. 在短方向上内筒被支撑起来，但是在长方向上没有剪切刚度。 4. 环绕着建筑物布置了一个外筒。
5. 外筒是一个瞬时抵抗结构，但是在每个长方向的中心15.2米都没有剪切刚度。 6. 在建筑的顶部布置了一个空间桁架构成的“帽式”结构。 7. 在建筑的底部布置了一个相似的空间桁架结构。
8. 由于外筒的剪切刚度在建筑的底部接近零，整个建筑基本上由两个钢板筒来支
持。
框格体系或束筒体系结构：
位于美国芝加哥的西尔斯大厦是箱式结构的经典之作，它由九个相互独立的筒组成的一个集中筒。由于西尔斯大厦包括九个几乎垂直的筒，而且筒在平面上无须相似，基本的结构体系在不规则形状的建筑中得到特别的应用。一些单个的筒高于建筑一点或很多是很常见的。事实上，这种体系的重要特征就在于它既有坚固的一面，也有脆弱的一面。
这种体系的脆弱，特别是在结构筒中，与柱子的压缩变形有很大的关系，柱子的
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压缩变形有下式计算：
△=ΣfL/E
对于那些层高为3.66米左右和平均压力为138MPa的建筑，在荷载作用下每层柱子的压缩变形为15（12）/29000或1.9毫米。在第50层柱子会压缩94毫米，小于它未受压的长度。这些柱子在50层的时候和100层的时候的变形是不一样的，位于这两种体系之间接近于边缘的那些柱需要使这种不均匀的变形得以调解。
主要的结构工作都集中在布置中。在Melbourne的Rialto项目中，结构工程师发现至少有一幢建筑，很有必要垂直预压低高度的柱子，以便使柱不均匀的变形差得以调解，调解的方法近似于后拉伸法，即较短的柱转移重量到较高的邻柱上。
附件2：外文原文（复印件）
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 the universal traits of simplicity of thought and clarity of expression.
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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 become 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 frames. 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 stiffness 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.
The 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. This is not to say that imaginative structural design can create great architecture. To the contrary, many examples of fine architecture have been created with
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only moderate support from the structural engineer, while only fine structure, not great architecture, can be developed without the genius and 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 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 frames 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 stiffness 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 today’s technology.
Because of the intrinsic flexibility of the column/girder intersection, 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.
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土木工程外文文献翻译
