【導讀】確實，較好的高層建筑普遍具有構思簡單、表現(xiàn)明晰的特點。這并不意味著沒有進行宏觀構思的余地。今天的技術中已經變得平常了。1．抗彎矩框架。2．支撐框架，包括偏心支撐框架。3．剪力墻，包括鋼板剪力墻。5．筒中筒結構。6．核心交互結構。7．框格體系或束筒體系。而且，就較高的建筑物而言，大多數(shù)都是由交互式構件組成三維陳列。進一步討論，設計方法的本質貫穿于整個討論。系結合起來使用，以便提供所需要水平荷載抵抗力。發(fā)現(xiàn)該本系不宜作為獨立體系，這是因為在側向力的作用下難以調動足夠的剛度。尤其引人關注的是，在強震區(qū)使用偏心支撐框架。的寬度和構件承受的重力荷載的限制。方式加以擴大，以便提從所需的抗傾覆能力。出了很多的技術，用以減小剪力滯后的影響，這其中最有名的是桁架的應用。配置第二層柱的目的是增強抗顛覆能力和增大側移。于對梁的對比分析。的偏角則與柱子的軸心壓縮和延伸有關。

　　

【正文】 ery well. Here, the inner tube is a braced frame, the outer tube has no shear stiffness, and the two systems are coupled if they were considered as systems passing in a straight line from the “hat” structure. Note that the exterior columns would be improperly modeled if they were considered as systems passing in a straight line from the “hat” to the foundations。 these columns are perhaps 15% stiffer as they follow the elastic curve of the braced core. Note also that the axial forces associated with the lateral forces in the inner columns change from tension to pression over the height of the tube, with the inflection point at about 5/8 of the height of the tube. The outer columns, of course, carry the same axial force under lateral load for the full height of the columns because the columns because the shear stiffness of the system is close to zero. The space structures of outrigger girders or trusses, that connect the inner tube to the outer tube, are located often at several levels in the building. The ATamp。T headquarters is an example of an astonishing array of interactive elements: 1. The structural system is 94 ft () wide, 196ft() long, and 601ft () high. 2. Two inner tubes are provided, each 31ft() by 40 ft (), centered 90 ft () apart in the long direction of the building. 3. The inner tubes are braced in the short direction, but with zero shear stiffness in the long direction. 4. A single outer tube is supplied, which encircles the building perimeter. 5. The outer tube is a momentresisting frame, but with zero shear stiffness for the center50ft () of each of the long sides. 6. A spacetruss hat structure is provided at the top of the building. 7. A similar space truss is located near the bottom of the building 8. The entire assembly is laterally supported at the base on twin steelplate tubes, because the shear stiffness of the outer tube goes to zero at the base of the building. Cellular structures A classic example of a cellular structure is the Sears Tower, Chicago, a bundled tube structure of nine separate tubes. While the Sears Tower contains nine nearly identical tubes, the basic structural system has special application for buildings of irregular shape, as the several tubes need not be similar in plan shape, It is not unmon that some of the individual tubes one of the strengths and one of the weaknesses of the system. This special weakness of this system, particularly in framed tubes, has to do with the concept of differential column shortening. The shortening of a column under load is given by the expression △=ΣfL/E For buildings of 12 ft () floortofloor distances and an average pressive stress of 15 ksi (138MPa), the shortening of a column under load is 15 (12)(12)/29,000 or () per story. At 50 stories, the column will have shortened to in. (94mm) less than its unstressed length. Where one cell of a bundled tube system is, say, 50stories high and an adjacent cell is, say, 100stories high, those columns near the boundary between .the two systems need to have this differential deflection reconciled. Major structural work has been found to be needed at such locations. In at least one building, the Rialto Project, Melbourne, the structural engineer found it necessary to vertically prestress the lower height columns so as to reconcile the differential deflections of columns in close proximity with the posttensioning of the shorter column simulating the weight to be added on to adjacent, higher columns. 指導教師意見： 指導教師簽字： 年 月 日 系 (教研室 )意見： 主任簽字： 年 月 日 注：此表單獨作為一頁。