New Developments in Steel - Report Example

Steel and its Developments By Lecturer’s and For years, the use of steel in railway construction and renovation projects has been agitated all over the world due to its strength. Currently, there is the use of special steel in the construction of bridges such as girder bridges, arch bridges, slab culverts, pipe culverts and other types with different percentages of steel being used. Bridges made of steel have proofed to stay for a very long period (SHEN & CHAN, 2005). However, these are being renovated by the use of new special steel due to their aging, increased loading standards for axle load, increased longitudinal load, rebuilding meter gauge bridges, replacement of early steel grinders, corrosion problem in areas around the coast. In this paper, I will examine the advantages of steel in bridge construction, the need for special steel in the railways, properties of HPS and recent development in HPS. Indian railways are the case study for this report. Introduction There are different types of bridges which total 120,000 bridges in the Indian Railways comprised of about two bridges in each kilometre per route. This can be broken down into 20% of the girder bridges, 19% of the arch bridges, 23% slab culverts, 19% pipe culverts, and other types account for about 19% (SHEN & CHAN, 2005). It is worth noting that about half of the build Indian railways have been there for about 100 years. Despite the fact that about a thousand bridges are renovated and/or rebuilt yearly, the build-up is so large. Such old railways face a lot of challenges that include growing old and weariness, intensified loading calibre for the axle cargo, intensified longitudinal cargo, reassembling metre scale bridges for extensive scale work, renewal of the initial steel girders, and corrosion drawbacks near the coast areas (SHEN & CHAN, 2005). High numbers of girder bridges made up of steel are characterised by heterogeneous composition since early steel requires frequent attention for their upkeep. The early steel girder bridges are those bridges that were constructed before 1905. In those moments, there were high percentages of phosphorous and steel than the present day ones. High contents of sulphur and phosphorous cause brittle failures steel structures. The government has taken steps to replace such bridges (LULA, 1985). There has been high improvement in steel making technologies all over the world for the last few years in terms of metallurgical progresses and rolling and heat treatment process growths. However, different countries have not changed their specifications for steel that is supposed to be used in such activities as building the railways or bridges. Therefore, the aim of this report is to examine the use of special steel in construction process such as railways, for instance, the Indian Railway. Advantages of use of Special Steel in the Bridge Construction Steel is a very versatile material that comprises a lot of advantages as compared to other materials also used in construction. The Mega Bridge, which is associated with the Railways, is a good example of a steel superstructure making use of special steel. For decades, the railway has depicted a lot of confidence in steel in relation to PSC. The reason behind this is that in case of steel, the bridge rehabilitation process is easy and it comprises minimum delays, inspection are easier as it gives a chance for deformations to be achieved and easily assessed besides the fundamental fact that railway (LULA, 1985) engineers feel an ease in the development and maintaining steel bridges. Therefore, the steel bridge has high strength to weight ratio, which is an advantage that it reduces substructure costs, which is specifically beneficial in poor ground situation. Minimum self weight is the other vital factor in handling the bridge components in such areas as North-East and Jammu and Kashmir. Additionally, this helps very shallow construction intensity for girders (National Structural Steel Conference, 1984). Moreover, this low self weight helps to minimize a lot of work on the foundation while constructing rails near the existing rails. Second is that it is a high quality material readily available in all parts of the world in different qualified grades, shapes and sizes. The tests carried out by the steel millers have given the engineers’ assurance that it is favourable for use in projects. The quality does not only involve its development, but also cutting, drilling, welding and fit-up. Due to its favourable weight, it enables it to be used in different areas, even those that are prone to earthquakes. The next advantage is its aesthetic. This involves its ability to be turned into different and broad architectural possibilities. In this regard, steel can be made to seem as if it is heavy or light or structured into different shapes or forms. Forth is that bridges made of steel are readily repairable in case of derailment, terrorism damage or natural causes such as earthquakes. In this consideration, steel can be easily replaced without much delay. Next is its versatility (SHEN & CHAN, 2005). This enables the steel to be used in very many different construction methods and sequences giving the engineers wide flexibility in regard to the erection sequence and programs. When the steel grinders are erected, they give a chance for the following operations. Last but not least is that it is durable. This is evident as the current steel bridges have proven 100 years (UNITED NATIONS1979). Need for Special Steel in Indian Railways Additional to mega bridge construction projects, a new major line construction project is evident in North-East, Jammu-Kashmir. For instance, the construction of mega bridges, one in River Kosi and the other in river Brahmputra at Bogibeel. The bridges connect different parts of the country which are very vital in economic development. The reason behind this construction is to meet the long term demands of rail connection in these regions across these rivers. The major features of these mega bridges are shown in the table below (National Structural Steel Conference, 1984) Table 1 As per IS-2062:1999 currently the steel being used in the Indian railway bridge has the following chemical composition (SHEN & CHAN, 2005). The Indian railway does not use the required steel standards as stipulated by different IS certifications except only for few regions. The railway faces a lot of difficulties which they need to look into so that they develop and produce high quality steel. These include steel quality not consistent, inadequacy of plate of 63mm and more in the country, normalised steel, inadequate laser cutting forms for smooth and aesthetic, slow erection process for long spans, inadequacy of welders or riveters due to training shortages (National Structural Steel Conference, 1984) The mechanical properties required for the steel used as per IS-2062:1999 are shown in the table below (UNITED NATIONS1979). It is the appropriate time for the specification to be well defined to improve the quality of steel production and do away with inferior qualities. The inferior quality is as a result of high carbon content which has highly deteriorated its weld-ability (LULA, 1985). Such steel as those of IS 2062 have low break stiffness and that is the reason behind its fracture and cracks features. Due to the high cost of premature renewals in the rail industry, there has been a lot of concern to deal with corrosion resistance (UNITED NATIONS, 1968). Therefore, special steel is one which can be termed as high strength structural steel and high performance steel (SHEN & CHAN, 2005). Properties of High Performance Steel, HPS HPS gives a number of advantageous features for bridge construction such as the weld - ability, toughness, and ductility and corrosion resistance. In this regard, it has a minimum amount of carbon which in turn grants it good weld-ability, hence reducing pre-heating and leading to inexpensive welding techniques. In addition, it possesses high fracture toughness to reduce the possibility of brittle failure and to better the structural reliability. It also has higher atmospheric resistance to corrosion (LULA, 1985). Its weathering capability enables it add Lifecycle which in turn saves costs. The corrosion on top reduces further access of oxygen and moisture and other contaminants. This is usually denoted by letter W giving it its grade number. These grades include 50W, 70W and 100W. In terms of fracture stiffness, the greater the HPS the better. This assists in resisting cracking in the bridge structure (LULA, 1985). Recent Developments in HPS There have been continuous efforts in the advancement of the HPS grades by improving its capability. For instance, the resulting strength of HPS 70W which is the highly used HPS grade, tends to go down with plate thickness. To balance the increment, a Manganese substance can be used so that it increases. A maximum of 1.35% to 1.5% of Manganese can now be added into the HPS 70W plate to its maximum level. This alteration enables re-heat treating avoidance on the plates to achieve minimum strength requirement. In addition, research depicts a special fracture-critical application. The next grade is 100W, which is the most recent development of HPS. This increases toughness for the plate thickness, which often requires nickel content. In conclusion, it is evident that steel is a preferred construction material as compared to others due to its special features such versatility, authenticity, weld-ability, toughness, ductility and corrosion resistance. Also, there are different characteristics, both physical and chemical, and more so graded according to their level of weld-ability and toughness. Lastly is that new advancements are still being made to come up with the effective and efficient special steel (LULA, 1985). Reference List INTERNATIONAL CONFERENCE ON ADVANCES IN STEEL STRUCTURES, SHEN, Z. Y., LI, G. Q., & CHAN, S. L. (2005). Advances in steel structures proceedings of the fourth International Conference on Advances in Steel Structures, 13-15 June 2005, Shanghai, China. Amsterdam, Elsevier. LULA, R. A. (1985). New developments in stainless steel technology: conference proceedings. Metals Park, Ohio, American Society for Metals. National Structural Steel Conference. 1984. New developments in steel construction. London: British Constructional Steelwork Association.Top of Form http://www.sciencedirect.com/science/book/9780080446370. UNITED NATIONS. (1979). Iron and steel scrap: its significance and influence on further developments in the iron and steel industries. New York, United Nations. UNITED NATIONS. (1968). World trade in steel and steel demand in developing countries. New York, United Nations. Bottom of Form Read More