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|Other Titles:||Aluminium İn Architecture|
Proje ve Yapım Yönetimi
Project and Construction Management
|Publisher:||Fen Bilimleri Enstitüsü|
Institute of Science and Technology
|Abstract:||Yeryüzünde en çok kullanılan metal olan alüminyum; boksit maden filizinden, Bayer ve Hall-Herault metodları ile iki aşamada elde edilmektedir. Başlıca Özellikleri; hafiflik, korozyon direnci ve yumuşak oluşudur. Mimari uygulamalar için ekstrüzyon, döküm, levha veya tel olarak üretilmekte olup, bu ürünlerin eldesinde saf alüminyum değil, mekanik ve fiziksel özellikleri değişik metallerle iyileştirilmiş alüminyum alaşımlar kullanılmaktadır. Mimariye ilk girişi heykel ve dekoratif amaçlarla olmuştur. Gelişen teknoloji ile birlikte fonksiyonel amaçla kullanımı ön plana çıkmıştır. Yapıda en önemli uygulama alanları: kapı, pencere doğramaları; tavan, duvar çatı kaplamaları; giydirme cepheler olmakla birlikte strüktürel eleman, merdiven korkulukları ve çeşitli bitiş elemanlarından, iskele, kalıp ve yalıtım elemanlarına kadar çok geniş bir uygulama alanına sahiptir. Birleştirmelerde; civatalama, perçin, kaynak, lehim, özel vidalar perçinler, metal sıkıştırma, mekanik, ektrüzyon veya yapıştırma gibi geleneksel veya geliştirilmiş yöntemler kullanılmaktadır. Atmosfer, iklim koşulları, galvanik etki veya detay hataları gibi nedenlerle malzemenin bozulmasını önlemek veya dekoratif etki nedeniyle, mekanik, kimyasal, elektrokimyasal veya organik, seramik türü işlemler uygulanmaktadır. 1955 yılında 3,5 milyon ton olan dünya üretim kapasitesinin 1992'de 373 milyon tona ulaşması ve yatırımların hız kazanması talebin artacağının göstergesidir. 1990'da Avrupa'da kişi başına 183 kg., A.B.D.'de 28,9 kg., Japonya'da 30,9 kg. olan alüminyum tüketimi ülkemizde 2 kg.'dır. Sonuç olarak ülkemiz de madenlerimizin kullanımında etkili önlemler alınması, teknik, ekonomik ve siyasal açıdan ilgili politikaların oluşturulması kısa vadede çözümlenmesi gereken bir problemdir.|
Several metals have a history of architectural application extending över thousands of years and the large scale use of metals on building industry has a long tradition. Today the demand of technology have resulted in the development and production of many metals and alloys with an extensive range of well-defined properties. After the last war the building industury was faced with the gigantic task of rebuilding Europe.Because of the urgent demands it was not suprising that the industry tura to prefabrication to new building materials and to new methods to achieve the high rate of building required. The discovery and use in building of a new metal may be said to have marked milestones in the development of civilization. Although aluminium is the most abundant metalle element in the earth's crust (%8), it isn't found in a metalic state and so it remained undiscovered through the centuries, until the collateral development of electrolytic and chemical processes of the nineteenth century opened up a new world of metallurgy. The process which is in two stages now used for extracting aluminium from its öre bauxite requires tremendous amounts of electricity-about 10 kilovvatt hours for each found (0.454 g.) of metal. The first stage, the Bayer process, fields almost püre alumina (A12Û3) from bauxite öre, the second stage the Hall-Herault process, reducess the oxide to metalic aluminum more than 99% püre. in architectural work ali fabricated forms of aluminium used that is rod, bar, extrusion, casting, sheet strip, ete. However these products are not fabricated from aluminium in the purest obtainable form. The mechanical strength and other properties of the metal may be improved by the addition of öne ör more a number of elements, under closely controlled conditions. 50 standart aluminium alloys are avaible and many others can be produced for specifıc purposes. Its characteristics are sufficiently different from other metals to require different and special methods of design even though suffıcient similarities exist to permit the designer to draw, to extent, on experiences gained from designs in other ferrous and non-ferrous metals. -xvi- Only the full recognition of the principles can lead to the succesful exploitaion of the inherent economical and tecnological advantages of the material. Püre aluminium (99.996 percent püre) is the most corrosion resistant form of aluminium but it is extremely soft and weak. Alloys of aluminum with chromium, manganese, silicon are stili highly resistant to corrosion. Alloys containing appreciable amounts of copper are more susceptible to corrosion. The addition of zinc improves the machining qualities, nickel increases its hardnees and manganese aluminium alloys are even more resistant than püre aluminum to salt water and some alkaline solutions. Aluminium alloys are divided into two majör groupings, wrought alloys and foundry alloys depending on manufacturing processes each group is further subdivided into heat-treatable and non-heatreatable depending on if ör not the alloys can be further strengthened by heat treatment. Casting alloys are those in which the metal is cast in its final form vvrought alloys are those in which the cast metal is worked mechanically by process such as rolling exruding ör drawing. When plate, sheet, bars ör rods are to be produced rolling process is used. Products of sheet mili are classified according to their thickness. For producing structural and architectural shapes may be solid ör hollow, extrusion process by a hydrolic extrusion press is used. in general, sheet is the most economical form of aluminium f ör construction use. However extrusions are more widely used, because of the variety of shapes that are not possible in roll ör brake forming. Aluminium castings offer a wide range in both configuration and texture. But the patterns are expensive and thickness requirements are greater than the other methods. Structural shapes are used as structural members in the same way that steel structural members are used. Architectural shapes are widely used f ör door and window jambs stiles, curtain wall panel frame, thresholds, threads, handrails, rails, muslins, and bars, mullions, and railings. Sheet aluminium is used f ör flashing, roofing, roof drains, chimney caps, airducts, louver blades ete. Table l Physical constants of aluminum 99-95 percent mimumum purity PROPERTIES METRIC UNITS Densityat20°C 9Percc Melting point 660 °C Boiling point 2327 °C Coefficient of Lineer Thermal Expansion 0.0000239 per °C Modulus of Hasticity 703.000 kg. per sq.cm. Hectrical Resistivity at 20 °C | 0.0000263 ohm per cm.c -xvii- In comparation with other commercial metals such as iron, copper, lead and zinc the outstanding property of aluminium is its lightness. The importance of light weight materials in building is that they reduce the dead load of structures, provide a large coverage for a given weight of sheet metal roofing and cladding and facilitate transportation handling and fabrication with corresponding reductions in labour costs. The other important usefull proferties are, versality of form, a pleasing appearence and good weathering properties. Statuary and decorative work in cast form were the first applications of aluminium. The small pyramid capping the Washington Monument (1884) and that statue of winged figure of EROS in London (1893) were early examples ot this kind use of aluminium. And important architectural application of aluminium was the window spandrels. Although used orjinally for decorative purposes there has been an increased recognition of the practical advantages of them, like simplifying building construction. The combined use of aluminium windows with spandrels, wall facings, cornices, plasters and other forms of metalwork provided considerable scope for architectural design. In the thirties, many notable buildings erected in United States extensivly used these components to get an impressive facade. By modern methods of manufacture and new qualities in glass industry provided new opportunities in design. The United Nations Secretariat Building (1949) is a striking example of aluminium and glass combination in many ways. Further developments are seen in the Alcoa Building in Pittsburg. It is the first application of on all-aluminium skin treated as completely seperate membrane which need not conform with the backing masonry. The position now, especially non-structural aluminium for a very wide range of purposes -e.g. cladding, windows partitions components and fittings- is in extensive use. Over 25 (in 1970) percent of all the aluminium produced is used in construction industry. According to European Aluminium Association's datas in 1991, 4.176.000 tons aluminium is used in general applications. The main producers of this metal are in U.SA. JEU and Canada. The types of companents used in building by functional aspects avaible in aluminium canbe summarized under these sections. 1- Doors and windows: two type of doors avaible. a) Pedestrian: Side hung, straight sliding and revolving, b) Industrial: Horizantal; Angle sliding, folding Vertical: Up and over, centre folding, roller shutter, and articulated panel or slide- over, and lifting panel. Type of windows: fixed, casements, pivots, louvers, sliding. In the information sheets functions of them are examined under consideration of some important environmental factors. 2- Roofing and siding sheets. a) Single layer flexible and corrugated sheets -xvui- b) Sandvvich panels c) Composite panels d) Condensation and vapour barriers. 3- Curtain wall's 4- Aluminium Structural Elements. Beams, Struts, Girders and Trusses 5- General Applications Rainwater goods - Rpes - Kitchen and Bathroom Equipment, and Fittings - Heating and aim conditioning - Electrical and Lighting - Mesh and wire cloth. An important detail in any architectural use of aluminium is joining- rivetmg and oxy- gas welding with a suitable flux are the older methods. There are many methods of joining conventional ör unconventional, are appliciable to aluminium and its alloys- such as bolting, brazing, soldering, using plastic adhesives ete. Aluminium is susceptible in some cases. 1- When placed in contact with dissimiliar metals such as copper, electrolitic (galvanic) corrosion occurs. 2- Especially in industrial environments the atmospheric corrosion of aluminium is greater than rural and marine environments. 3- Contact with building materials containing alkalies, acid ör cement especially when they are damp. Although aluminium has inherently good corrosion resistance, aluminium and aluminium alloy products can be given a wide range of finishes for decorative and protective purposes ör both. There are six basic kinds; Mechanical, Chemical, Electrochemical, Electroplating, Porcelain ör vitreous enamels and paints ör organic coatings. The spans and unobstructed areas required in modern buildings and structures have been increasing from year to year. At the same time buildings are grovving taller and carry heavier superimposed loads. The speedy erection, transportation, quick and easy dismantling of buildings becomes increasingmy important. The production facilities of the aluminium industry are undergoing ond increasing degree of mechanization and techniques are continually improving. it is anticipated that the demand for aluminium will continue to increase. The world production capacity was 3,5 million tons in 1955,27550 million tons in 1988, and in -xix- 1992 it was 37.302 million tons - As on immediate steep we should ensure a more efficient use of our metal supplies. Waste should be avoided by seeing that metals are specified only for those applications on both economic and technical grounds.
|Description:||Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1996|
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 1996
|Appears in Collections:||Proje ve Yapım Yönetimi Lisansüstü Programı - Yüksek Lisans|
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