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Steel Structure

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Sahil dhawan gcad/09/222 B.arch <id>

~STEEL~

The history of steel-making in India can be traced back to 400 BC when the Greek emperors used to
recruit Indian archers for their army who used arrows tipped with steel. Many more evidences are there of Indians’ perfect knowledge of steel-making long before the advent of Christ. Archaeological finds in Mesopotamia and Egypt testify to the fact that use of iron and steel was known to mankind for more

than six thousand years and that some of the best products were made in India. Among the widelyknown relics is the Iron Pillar near Qutab Minar in Delhi. The pillar, built between 350 and 380 AD, did not rust so far -----an engineering marvel that baffles the scientists even today. Yet another engineering feat is the famous Sun Temple at Konark in Orissa, built around 1200 AD, where steel structurals were used for the first time in the world. These were the halcyon days when India flourished in all directions and when its prosperity was a matter of envy for the foreigners. But as ill luck would have it, India’s prosperity gave way to poverty after the advent of the foreign rule. India’s indigenous industry languished because of a deliberate policy of the colonial rulers to make the country only a supplier of raw materials. Steel Role plays a vital role in the development of any modern economy. The per capita consumption of steel is generally accepted as a yardstick to measure the level of socio-economic development and living standards of the people. As such, no developing country can afford to ignore the steel industry.

Beginnings
The first notable attempt to revive steel industry in India was made in 1874 when the Bengal Iron Works (BIW) came into being at Kulti, near Asansol in West Bengal. However, forty-four years before that, in 1830 to be precise, a foreigner, named Joshua Marshall Heath, had set up a small plant at Porto Novo on Madras Coast. Heath produced in his plant pig iron at the rate of forty tonnes a week. His method of iron-making needed approximately four tonnes of charcoal to produce one tonne of low quality pig iron which proved to be too expensive for Heath to carry on in the face of stiff competition from the British steel industry. The BIW made considerable improvement in the process of iron and steel making. It used coke as the fuel instead of charcoal. But the plant fell sick as the source of funds dried up. It was taken over by the Bengal Government and was rechristened as Barakar Iron Works. In 1889 the Bengal Iron and Steel Company acquired the plant and by the turn of the century the Kulti plant became a success story. It produced 40,000 tonnes of pig iron in 1900 and continued to produce the metal until it was taken over by Indian Iron and Steel Company (IISCO) in 1936. For modern India’s iron and steel industry August 27, 1907 was a red-letter day when the Tata Iron and Steel Company (TISCO) was formed as a Swadeshi venture to produce 120,000 tonnes of pig iron. The TISCO plant at Sakchi (renamed Jamshedpur) in Bihar, started pig iron production in December 1908 and rolled out its first steel the following year. TISCO had expanded its production capacity to one million tonnes ingot by the time the country achieved freedom. The Tatas, as Gandhiji said, represented the "spirit of adventure" and Jamsetji Tata, in the words of Jawaharlal Nehru," laid the foundation of heavy industries in India". The British rulers disfavoured this and other attempts to start indigenous industry. It was chiefly with the help of American experts that the Tatas started their industry. Its childhood was precarious but the war of 1914-18 gave it a fillip. Again it languished and was in danger of passing into the hands of British debenture holders. But nationalist pressure saved it. In 1918, soon after the war, Indian Iron and Steel Company (IISCO) was formed. The then Mysore government also decided to start an iron works at Bhadravati. While IISCO started producing pig iron at Burnpur in 1922, the Mysore Iron and Steel Works took about 18 years to start its plant. Meanwhile, the Bengal Iron Works

went into liquidation and merged with IISCO. The Steel Corporation of Bengal (SCOB) formed in 1937, started making steel in its Asansol plant. Later in 1953, SCOB merged with IISCO. Prime Minister Nehru firmly believed that "no country can be politically and economically independent unless it is highly industrialized and has developed its resources to the utmost". Nehru’s ideas about India’s development were broadly incorporated in free India’s first Industrial Policy Resolution adopted by the Constituent Assembly in 1948. The resolution officially accepted the principle of mixed economy. Industries were divided into four categories. In the first category were strategic industries which were made the monopoly of the Government. In the second category were six industries which included, among others, coal, iron and steel. It was decided that new units would be started exclusively by the government in the public sector without disturbing the existing ones in the private sector. Eighteen industries, including heavy castings and forings of iron and steel, Ferro alloys and tool steel were covered by the third category and the rest of the industries by the fourth. In sum, the government committed itself to the development of basic steel industry while the private sector was to benefit through the establishment of downstream units which would use pig iron, billets, blooms and flat products to be made by the public sector steel plants. In keeping with the spirit of the resolution the Government decided to start a chain of steel plants all over the country in the public sector. The first such plant was set up at Rourkela in Orissa. The second came up at Bhilai in Madhya Pradesh. It was followed by a third at Durgapur in West Bengal. Each of these three plants had an initial production capacity of one million tonne ingot. Durgapur was followed by a steel plant at Bokaro in Bihar. The onward march of Indian steel did not stop at Bokaro. The fifth public sector steel plant was set up at Visakhapatnam in Andhra Pradesh. As a matter of fact, the country was dotted with steel and steel-related plants in public and private sectors, like Alloy Steel Plant, Salem Steel Plant, Kalinga Iron Works, Malavika Steel Ltd., Jindal Vijaynagar Steel Ltd., to name only a few. About the same time TISCO launched its two-million-tonne expansion programme. The Government’s Industrial Policy had undergone changes ____ once in 1956 and then in 1991. The resolution modified in 1956 brought changes in the category pattern and listed more industries for the public sector than did the earlier one, though it was not harsher towards the private enterprise. In the new industrial policy announced in 1991 iron and steel industry, among others, was included in the list of industries reserved for the public sector and exempted from the provision of compulsory licensing. With effect from May 24, 1992 iron and steel industry was included in the list of ‘high priority’ industry for automatic approval for foreign equity up to 51% (now 74%). Export-import regime for iron and steel has also undergone major liberalisation. The freight equalisation scheme was withdrawn removing freight disadvantage to States located near steel plants. The new policy has already borne fruit. The finished steel production in India has gone up from mere 1.1 million tonnes in 1951 to 23.37 million tonnes in 1997-98 despite overall economic slow-down in the country. It has been estimated that the demand for finished steel in 2001-02 would touch 38.68 million tonnes and the projected availability of 38.01 tonnes is almost adequate to meet the domestic demand along

with export of six million tonnes. Similarly, by 2006-07, the final year of the tenth plan, the demand for finished steel would be around 48.80 million tonnes, providing adequate surplus for meeting the projected export potential of nine million tonnes. However, there is hardly any scope for complacence over the fact that India continues to be the 10th largest steel producer in the world. In 1997 India’s per capita steel consumption was only 22 kg which was much below the world average of about 126 kgs. Even if the domestic demand grows up from 34.5 million tonnes to 100 million tonnes in 2025 the industry is unlikely to catch up with the production in the developed countries. The redeeming feature is the cost competitiveness of Indian steel in the global market. According to World Steel Dynamics, the total cost of steel production in the USA is $510 per metric tonne while in Japan it is $550, in Germany $557, in Canada $493 and in India it is $497. This is because of high material cost due to high excise and import duties. Reduction of cost on these accounts will make Indian steel more competitive in the world market. Indian steel can reasonably expect a good market in the neighboring countries now that the Asian economy is looking up. In conclusion, it can be said with a certain measure of confidence that India’s iron and steel industry which had a glorious past and has an uncertain present may now look forward to a bright future.

Definition

Steel is the common name for a large family of iron alloys which are easily malleable after the molten stage. Steels are commonly made from iron ore, coal, and limestone. When these raw materials are put into the blast furnace, the result is a "pig iron" which has a composition of iron, carbon, manganese, sulfur, phosphorus, and silicon. As pig iron is hard and brittle, steelmakers must refine the material by purifying it and then adding other elements to strengthen the material. The steel is next deoxidized by a carbon and oxygen reaction. A strongly deoxidized steel is called "killed", and a lesser degrees of deoxodized steels are called "semi killed", "capped", and "rimmed". Steels can either be cast directly to shape, or into ingots which are reheated and hot worked into a wrought shape by forging, extrusion, rolling, or other processes. Wrought steels are the most common engineering material used, and come in a variety of forms with different finishes and properties. Standard Steels

According to the chemical compositions, standard steels can be classified into three major

groups: carbon Steels

steels, alloy steels, and stainless steels:
Compositions Alloying elements do not exceed these limits: 1% carbon, 0.6% copper, 1.65% manganese, 0.4% phosphorus, 0.6% silicon, and 0.05% sulfur. Steels that exceed the element limits for carbon steels. Also includes steels that contain elements not found in carbon steels such as nickel, chromium (up to 3.99%), cobalt, etc. Contains at least 10% chromium, with or without other elements. Based on the structures, stainless steels can be grouped into three grades: Austenitic: Typically contains 18% chromium and 8% nickel and is widely known as 18-8. Nonmagnetic in annealed condition, this grade can only be hardened by cold working.

Carbon Steels

Alloy Steels

Stainless Steels

Ferritic:

Contains very little nickel and either 17% chromium or 12% chromium with other elements such as aluminum or titanium. Always magnetic, this grade can be hardened only by cold working.

Martensitic:Typically contains 12% chromium and no nickel. This grade is magnetic and can be hardened by heat treatment.

Steel as a construction material The use of steel for long-span roof structures has its roots in 19th-century bridges, train sheds, market halls, and exhibition spaces. Structures like the Crystal Palace (1851) in London and the Galerie des Machines (1889) in Paris already showed the potential of iron (or steel, in the case of the Galerie). New functions requiring long-span roofs evolved in the 20th century, including hangars for airships and aircraft as well as single-level factories oriented towards the new flexible assembly-line production techniques pioneered in the automobile industry.

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Paxton: Crystal Dutert: Galerie des Palace under . Machines construction Long-span steel trusses, originating with 19th-century bridges (Benjamin Baker's steel truss Forth Bridge in Scotland was the world's longest spanning structure at the time of its completion in 1890) were used in numerous factories and other building types to create large, column-free interior spaces. Albert Kahn's Glenn Martin Aircraft Plant (1937) in Middle River, Maryland, is of interest not only because its 300-foot (91 m) trusses created the largest flat-roof span attempted up to that time but because Mies van der Rohe used a photograph of its interior to construct his famous collaged image for a Concert Hall project, published in 1943. Additional representative examples in which steel parallel-chord, horizontal trusses are featured as important architectural elements include the New Haven Veterans Memorial Coliseum (1972) by Kevin Roche and John Dinkeloo, where exposed corrosion-resistant steel trusses carry a multilevel parking structure over the stadium below; and the McCormick Place Convention Center (1970) in Chicago by C.F. Murphy Associates, in which two perpendicular sets of parallel trusses are used. An unusual multistory application of long-span steel trusses can be seen at the Pompidou Center (1977) by Renzo Piano and Richard Rogers, where the truss span—and therefore the required depth of the structure—is reduced through the use of sophisticated cast steel "gerberettes" cantilevered inwards from water-filled tubular steel columns to support the trusses, the columns being expressed on the building's exterior along with tensioned steel rods and diagonal cross-bracing.

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A. Kahn: Glenn . Mies: Concert Hall Collage

Martin Factory sectional views

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Roche & Dinkeloo: C.F.Murphy: Piano & Rogers: Memorial Coliseum . McCormick Place . Pompidou Center Convention Center Variations on steel trussed arches and frames, providing lightweight and structurally efficient spans, can be seen in early 20th-century hangars for airships (Zeppelins) and factory buildings, especially in Germany. An early example, influenced by the three-hinged steel arch forms of 19th-century bridge and exhibition structures, is Peter Behrens's AEG Turbine Factory (1909) in Berlin, in which hinges and vertical elements comprising the repetitive steel arches are expressed on the exterior of the side facade. Norman Foster's Sainsbury Centre (1977) in Norwich, England, uses tubular steel trussed rigid portal frames, which contain the mechanical services for the building while providing a clear span for the display and academic functions within. A more complex three-hinged trussed arch appears in Nicholas Grimshaw's Waterloo International Rail Terminal (1994) in London. There, the required asymmetry results in steel tension elements of the truss— expressed as thin rods—being located first above, then below the roof structure, creating a form at once rational and counter-intuitive. A final example is the International Exhibition Center (1996) in Leipzig by Ian Ritchie, in which arched trusses with cast-steel support arms form an exoskeleton supporting the vaulted Main Hall.

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Behrens: AEG Foster: Turbine Sainsbury . Factory Center

Grimshaw: Waterloo . Terminal

Ritchie: International . Exhibition Center

Polyhedral-based structures— three-dimensional versions of simple planar trusses—were pioneered by Alexander Graham . Bell in 1907, and developed into more sophisticated space-frames by Max Mengeringhausen in Germany in the 1940s and Konrad Fuller: Geodesic Pei: Javits Wachsmann in the United States in Dome at Montreal . Convention Center the 1950s. Buckminster Fuller Expo invented the geodesic dome, based on the triangulation of a spherical surface, in the late 1940s. Steel lamella roofs, consisting of intersecting, offset systems of parallel ribs, have been used in hangars, stadiums, and other long-span applications. Later 20th-century versions of these forms include the Javits Convention Center (1986) in New York City by I.M. Pei, consisting of a steel space frame used for both walls and roofs; Fuller's geodesic dome for the USA Pavilion (1967) at the Montreal Expo; and the steel lamella Louisiana Superdome (1975) by Sverdrup and Parcel Assoc. Long-span masted tension structures, inspired by 19th-century suspension bridge and 20th-century cable-stayed designs, use steel rods in tension to support horizontal roof surfaces. The Burgo Paper Mill (1962) in Mantua, Italy, by Pier Luigi Nervi quite literally mirrors the form of conventional suspension bridges to create clear span spaces below its suspended roof. More recent masted steel structures exploit the same principles, although their forms have become less derivative of bridge design and more articulate in expressing the exposed steel connections between tension rod, horizontal beam, and vertical mast. Notable examples by Richard Rogers include the Fleetguard Distribution Center (1979) in Quimper, France; the Inmos Microprocessor Factory (1982) in South Wales; and the PA Technology Laboratories (1985) in Princeton, New Jersey. Norman Foster's Renault Distribution Center (1980) at Swindon, England, has a more complex geometry defined by perforated, tapered beams, masts, and tension rods. The Darling Harbour Exhibition Center (1988) in Sydney, Australia, by Philip Cox, Richardson and Taylor makes reference, in its masted supports and steel outriggers, to the adjacent maritime harbor and its associated nautical motifs. The suppression of tension elements and the elaboration of the mast into compressive "tree-like" structural forms—first systematically studied by Frei Otto—can be seen in several steel-framed projects by Santiago Calatrava,

including the BCE Place Gallery (1992) in Toronto and the Oriente Station (1998) in Lisbon.

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Nervi: Burgo Paper Rogers: Inmos Mill . Microprocessor Factory

Rogers: PA . Technology Lab

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Foster: Renault Cox et al.: Darling Calatrava: BCE Distribution Center . Harbour Exhibition . Place Gallery Center

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Otto: Munich Olympics

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Weidlinger: Georgia Dome

In tensioned-membrane structures, steel cables are combined with fabric membranes to create extremely light-weight, long-span . structures. Frei Otto's tent structures for the German Pavilion (1967) at the Montreal Expo and for the Munich Olympics (1972) are Rogers: Millenium Davis Brody: landmarks in the development of Dome . American Pavilion, these forms. Two late-20th-century Osaka long-span examples are the Georgia Dome (1992) in Atlanta, engineered by Weidlinger Associates and based on a patented "tensegrity" geometry defined by triangulated steel tension cables and floating steel compression struts; and the Millennium Dome (1999) by Richard Rogers in which the dome—historically a compressive structure—is transformed into a tensioned membrane by hanging the steel cable net defining its domical surface from an array of twelve inclined steel masts that penetrate the membrane. Light-weight domical surfaces can also be formed with membranes by mechanically increasing the interior air pressure, as in a balloon: an early example of such a pneumatic structure, contained by a net of steel cables, is the American Pavilion at the Osaka Expo (1970) by Davis Brody Associates. With the development of welded connections—first invented in the late 19th century, but not used in buildings until the 1920s— steel beams and frames could more readily be designed within the modernist syntax of interpenetrating line and surface, uninterrupted by gusset plates, bolts, or rivets. The buildings of Mies van der Rohe at IIT in Chicago illustrate this type of abstract welded steel expression, most dramatically in the exposed parallel portal frames of Crown Hall (1956). Later projects from the 1960s and 1970s, influenced by Mies' work, include Roche and Dinkeloo's Cummins Engine Company plant (1966) at Darlington, England; the Reliance Controls plant at Swindon, England (1966) by Team 4 (including Norman Foster and Richard Rogers); and Skidmore, Owings and Merrill's Republic Newspaper Plant (1971) at Columbus, Indiana. Functional requirements, for example the need for daylighting in the immense new factory buildings of the steel, automotive, and aircraft industries, could also be addressed using welded steel frames, angled or stepped to accommodate monitor skylights. Such bent frames can be found in Albert Kahn's Chrysler Half-Ton Truck Plant (1937) in Detroit and, more recently, in Helmut Jahn's Terminal One Complex for

United Airlines (1987) in Chicago, the latter project utilizing clusters of tubular steel columns supporting perforated steel beams that define skylit, linear public circulation spaces within the terminal. Curved, welded ribbed frames are used at an even more monumental scale in Rafael Viñoly's Tokyo International Forum (1996), defining an immense elliptical tied-arch roof supported by two centrifugally-spun steel pipe columns 400 feet (124 m) apart.

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