1、本科毕业设计外文翻译题目高层建筑结构的发展专 业 班 级 土木 姓 名 学 号 指导教师及职称 Development of Structural Forms For Tall BuildingsThe first steps towards the modern multistory building appear to have been taken in the Bronge Age, with the appearance of the emergence of proper cities. Even today there appears to be an instrinc rela
2、tionship between the tall building, and the city. Multistory buildings were considered a characteristic of ancient Rome, and four and five-story wooden tenement buildings were common. Those built after the great fire of Nero used the new burnt brick and concrete materials in the form of arch and bar
3、rel vault structures, which replaced the earlier post and lintel construction.Throughout the following centuries, the two basic materials used in building construction were timber and masonry, although the former lacked the strength required for buildings of more than about 16m in height, and always
4、 presented a fire hazard. The latter had the advantages of high compressive strength and fire resistance, but suffered from its high weight, which tended to overload the lower supports. The limits of this form of construction became apparent in 1891 in the 16-story Monadnock Building in Chicago whic
5、h required the lower walls to be over 2m thick, and was the last tall building in the city for which load-bearing masonry walls were employed. The socio-econormic problems which followed the industrialization of the 19th century, allied to the insatiable demand for space in the US cities, gave a big
6、 impetus to tall building construction. However, the growth could not have been sustained without two major technical innovations during the middle of that century, namely, the development of new higher strength and structurally more efficient materials, wrought iron and subsequently steel, and the
7、introduction of the elevator to facilitate vertical transportation. The new material allowed the development of lightweight framed or skeletal structures, permitting greater heights and more and larger openings in the building. The forerunner of the steel frame which appeared in Chicago around 1890
8、may well have been a seven-story iron-framed Manchester cotton mill, built in 1801,in which the contemporary I-beam shape appears to have been used for the first time. The Crystal Palace, built for the London International Exhibition of 1851, used a completely autonomous iron frame, with columns of
9、cast iron and beams of cast or wrought iron. One of the notable features of this design was the large-scale approach towards mass-production techniques to facilitate fabrication and erection.Although the first elevator appeared in 1851, in a New York hotel, its potential in high-rise building was ap
10、parently not realized until its incorporation in the Equitable Life Insurance Company Building in New York in 1870. For the first time, this made the upper stories as attractive a renting proposition as the lower ones, and in so doing made the taller-than-average structure financially viable.Improve
11、d steel design methods and construction techniques allowed steel-framed structure to grow steadily upwards, although progress slowed down during the period of the First World War. In 1909, the 50-story Metropolitan Tower Building. This golden age of American skyscraper construction culminated in 193
12、1 in its crowning glory, the Empire State Building. Its 102 stories rose to a height of 381m which has now increased to 449m with the addition of a TV aerial. The building used 57000t (US) of structural steel, nearly 53500m of concrete, and was designed and built in the record time of 17 months.Alth
13、ough reinforced concrete construction began to be adopted seriously around the turn of the century, it dose not appear to have been used properly for multistory buildings until after the end of the First World War. The inherent advantages of the composite material were not at that time fully appreci
14、ated, and the early systems were developed purely as imitations of steel structures. An early landmark was the 16-story Ingalls Building in Cincinnatti, Ohio, (1903), which was not superseded until 1915 when the 19-story Medical Arts Building in Dallas was hailed as the words tallest reinforced conc
15、rete building. Thereafter, progress was slow and intermittent, and when the Empire State Building was completed, the Exchange Building in Seattle had attained a height of only 23 stories.The economic depression of the 1930s put an end to the great skyscraper era, and it was not until some years afte
16、r the end of the Second World War that the construction of high-rise building recommend, bringing with it new structural and architectural solution. However, modern developments have produced new structural layouts, improved material qualities, and better design and construction techniques rather th
17、an significant increases in height.Design philosophies altered during the period of recession and war. The earlier tall buildings were characterized by having heavy structural elements and being very stiff due to the high in-plane rigidities of the interior partitions and faade cladding with low are
18、as of fenestrastion. However, modern office blocks tend to be characterized by light demountable partitions to aloe planning flexibility of occupancy, exterior glass curtain walls, and lighter sections as a result of high-strength concrete and steel material, whilst non-load-bearing infills have giv
19、e way to load-bearing walls which simultaneously divide and enclose space. As a result, much of the hidden reserve of the earlier buildings has disappeared, and the basic structure must now provide both the required strength and stiffness against vertical and lateral loads. Consequently, the last th
20、ere decades have seen major changes in structural framing systems for tall building.The building frame was traditionally designed to resist the gravitational loads which are always present and form the reason for its very existence. These loads derive from the self-weight of the vertical and horizon
21、tal structural components, including the cladding, and the superimposed floor loadings. There will give rise to necessary minimum cross-sectional areas, based on allowable stress levels, for the vertical column and wall elements, in the design.In the past three decades, therefore, designers have sou
22、ght to evolve structural systems which will reduce as far as possible the cost and weight of materials, while simultaneously fulfilling the primary building function. A suitable arrangement of the vertical column and wall elements, allied to the horizontal floor system, is required which will provid
23、e an economic method of resisting lateral forces and minimizing the additional height premium.Although the provision of load paths for gravitational forces is limited, there is considerable scope for organizing the structural system to resist lateral forces as efficiently as possible. This may be ac
24、hieved by the judicious disposition of the vertical elements and their interconnection by horizontal structural components in order to resist moment by axial forces rather than bending moments in these vertical elements.In general, different structural systems have evolved for residential and office
25、 buildings have been constructed in which the two categories have been mixed, in a deliberate attempt to revitalize moribund city center areas.The basic functional requirement of a residential building is the provision of discrete dwelling units for groups of individuals. These have common requireme
26、nts of living, sleeping, cooking and toilet areas, which must be separated by partitions which offer fire and acoustic insulation between dwelling.Framed structures may be usefully employed for residential buildings, since the presence of permanent partitions allows the column layout to the correspo
27、nd to the architectural plan. However, these depend on the rigidity of the joints for their resistance to lateral forces, and tend to become uneconomic at heights above 20-25 stories, depending on the overall dimensions, when wind forces begin to control the design, and it becomes increasingly diffi
28、cult to meet stiffness requirements. Since their introduction in the late 1940s, shear walls, acting either independence or in the form of core assemblies, have been used extensively as additional stiffening elements for traditional frame structures.In order to provide adequate fire and acoustic ins
29、ulation between dwellings, infill panels of brickwork or blockwork are introduced into the frames. Although techniques exist for assessing the influence of these infill panels on the strength and stiffness of the frame, they are generally assumed to be non-load-bearing, in view of the designers fear
30、 that they may be either removed or perforated for a change of function at some future date, as well as the difficulty of achieving a tight fit between an infill panel and the surrounding frame. Consequently, later trends were to utilize the walls which are required for space division in a structura
31、l context, and omit the relatively heavy infills which could not be employed in a load resisting capacity. This has led to the development of the shear wall building, in which structural walls are used to divide and enclose space, while simultaneously resisting both vertical and horizontal loads. Th
32、ese walls are generally of precast large panel or reinforced concrete in-situ construction, but concrete blockwork and brickwork have also been employed, allied to precast floor slab construction. Since the functional plan requires a large number of division walls between dwellings, it is frequently
33、 found that the minimum thickness required for fire and acoustic insulation will be adequate for structural requirements also.Functional requirements for this form of building have given rise to the slab block of cross-wall construction, in which horizontal movement of occupants is achieved by long
34、corridors running along the length of the building, with apartments positioned on either side, or to point blocks in which apartments are grouped around the area of vertical transportation, lifts and stairwells. In each case, the basic structure consists of orthogonal systems of shear walls, connect
35、ed by floor slabs and perhaps lintel beams spanning across door, window or corridor openings, to form a stiff structure. Structural cores, which consist of assemblies of walls along their vertical edges to form open or partially closed box sections enclosing lift shafts and stair wells act as additi
36、onal strong points in such buildings, and can play a major role in resisting lateral forces.In a design, the shear walls must be sufficiently stiff to meet the imposed deflection criterion, and in addition, should be so arranged that tensile stresses caused by wind forces are less than the compressi
37、ve stresses produced by the weight of the building. A careful arrangement of walls can improve structural efficiency which consists of a series of cross-walls and two flank walls running across the width of the building. As a reasonable approximation, each wall will carry the vertical loads associat
38、ed with the surrounding tributary area shown hatched in the figure, so that the compressive stresses in the cross walls will be roughly twice those in the flank walls, if they are of the same thickness, However, if all walls deflect equally under the action of the wind forces, as a result of the hig
39、h in-plane rigidity of the floor slabs, the bending moment and associated stresses in each wall will be proportional respectively to its moment of inertia and section modulus. Consequently, the maximum tensile stresses in the flank walls will be roughly four times those in the cross-walls. The flank
40、 walls may then be subjected to unacceptable tensile stresses. A more efficient structure could be achieved by splitting each flank wall into two units, perhaps by forming an architectural feature by having them out of alignment. The flank walls would then be subjected to roughly the same wind momen
41、ts as the cross-walls, and the tensile wind stresses reduced by a factor of more than four.Shear wall structures are well suited for resisting seismic loadings, and have performed well in recent disasters. They tend to become economical as soon as lateral forces affect the design and proportioning o
42、f flat plate or framed systems. However, they do possess the disadvantage of an inherent lack of flexibility for future modifications, while discontinuities are frequently required at the critical ground level area to provide a different architectural function on the ground floor, and special detail
43、ing becomes necessary. A relative recent innovation which is particularly suitable for residential blocks is the staggered wall-beam system. The structure consists of a series of parallel bents, each comprising columns with perforated story-height walls between them, in alternate bays. Each wall pan
44、el acts in conjunction with, and supports, the slab above and below to form a composite I-beam. By this device, large clear areas are created on each floor, yet the floor slabs span only half the distance between adjacent wall beams, from the bottom of one to the top of the next. The wind shears are
45、 transmitted through the floor slabs from the wall beams on one story to shoes on the next. Similar systems are possible with staggered trusses rather than stagtered walls.The essential functional requirement of an office building is the provision of areas unobstructed as possible by walls or column
46、s to allow each occupant to design the partitioning and space enclosure most suitable for his particular business organization. The partition layout will generally alter when tenants change, and this necessitates flexibility in the distribution of the various services to any particular floor. As a r
47、esult, services tend to be carried vertically within one or more service cores, and a distribution network run beneath the structural floor slab to the entire floor area.By judicious planning of the column layout to maximize the open floor areas, shear wall-frame interactive structures may also be e
48、mployed for office blocks, although the presence of the columns may make it difficult to achieve the desired planning flexibility.Possibly the simplest method of creating open floor areas is to use a central concrete shear core, which carries all essential services and which is designed to resist al
49、l lateral forces. The floor system spans between the central core and the exterior faade columns, and a large unobstructed floor area is created between the two vertical components. The exterior columns can be designed to be effectively pin-connected at each floor level, so that they transmit vertical forces only, in conjunction with the interior core. These exterior columns are frequently precast to form a sculptured faade. Another possibility is to provide a core at each end, especially if th
