Bracing system is one such structural system that forms associate integral a part of the frame. Such a structure has to be analyzed before effective arrangement of bracing. ETABS computer code is employed to get the planning of frames and bracing systems with the smallest amount weight and applicable steel section choice for beams, columns and bracing members from the quality set of steel sections. A 3 dimensional structure is enamored four horizontal bays of dimension four meters, and twenty stories is enamored structure height of 3m. The beams and columns are designed to resist dead and loading solely. Wind load and Earthquake masses are taken by bracing. The bracings are provided solely on the peripheral columns. Most of the four bracings are employed in a structure for economic functions. Bracing may be a extremely economical and economical methodology to laterally stiffen the frame structures against wind masses. A braced bent consists of usual columns and girders whose primary purpose is to support the gravity loading, and diagonal bracing members that are connected so that all the members form a vertical cantilever truss to resist the horizontal forces. Bracing is economical as a result of the diagonals add axial stress and thus necessitate minimum member sizes in providing the stiffness and strength against horizontal shear. There are 2 varieties of bracing systems 1) homo centric Bracing System and 2) Eccentric Bracing System. The steel braces are typically placed in vertically aligned spans. This method permits to getting an excellent increase of stiffness with a marginal intercalary weight. 1) homo -centric bracings increase the lateral stiffness of the frame therefore will increase the natural frequency and conjointly typically decreases the lateral structure drift. However, increase within the stiffness could attract a bigger inertia force because of earthquake. Further, whereas the bracings decrease the bending moments and shear forces in columns and that they increase the axial compression within the columns to that they’re connected. 2) Eccentric Bracings cut back the lateral stiffness of the system and improve the energy dissipation capability. The lateral stiffness of the system depends upon the flexural stiffness property of the beams and columns, therefore reducing the lateral stiffness of the frame. The vertical part of the bracing forces because of earthquake causes lateral focused load on the beams at the purpose of association of the eccentric bracing, as a result of lateral loading on a building is reversible, braces are going to be subjected successively to each tension and compression, consequently, they’re typically designed for the additional rigorous case of compression. For this reason, bracing systems with shorter braces, for instance K bracing, could also be most popular to the total diagonal varieties. As associate exception to planning braces for compression, the braces within the double diagonal is meant to hold in tension the total shear in panel. a big advantage of the absolutely triangulated bracing varieties is that the girders moments and shears are freelance of the lateral loading on the structural designing course in kerala. Consequently, the ground framing, that during this case, is meant for gravity loading solely, will be repetitive throughout the peak of the structure with obvious economy within the style and construction. The role of internet members in resisting shear will be incontestable by following the trail of the horizontal shear down the braced bent. The conception of mistreatment steel bracing is one in every of the advantageous ideas which might be accustomed to strengthen or retrofit the present structures. The lateral structure displacements of the building are greatly reduced by the utilization of single diagonal bracings organized as diamond form in third and fourth bay compared to homo- centric (X) bracing and eccentric (V) bracing system.
Manganese is a major alloying element, has complex interactions with carbon and is used to control inclusions. Manganese is beneficial to surface quality in all carbon ranges with the exception of rimmed steels and is particularly beneficial in high-sulfur steels. Manganese provides lesser strength and hardness in comparison to carbon. The increase depends on the carbon content – higher-carbon steels being affected more by manganese. Higher-manganese steels decrease ductility and weldability (but to a lesser extent than carbon). Manganese also increases the rate of carbon penetration during carburizing.
The effects of manganese can be summarized as.1. Lowers the temperature at which austenite begins to decompose 2. Extends the metastable austenitic region and delays the commencement of all the austenite decomposition reactions 3. Favors the formation of lower bainite and suppresses the upper bainite reaction on isothermal transformation 4. Is the most effective alloying addition for lowering the martensite-start (MS) temperature 5.Favors the formation of e-martensite 6.Has little effect on the strength of martensite and on the volume change from austenite to martensite 7. Has little or no solution-hardening effect in austenite and between 30–40 MN/m2 per wt. % in ferrite (by lowering the stacking-fault energy of austenite, manganese increases the work-hardening rate) 8. By lowering the MS temperature, manganese prevents the deleterious effects of auto tempering 9. Lowers the transformation temperature, causing substantial grain refinement 10. In general, lowers the tough-to-brittle impact transition temperature (due to its grain-refinement action) 11. Increases the propensity for weld cracking due to the effect on hardenability. The severity of its influence depends to a great extent on the type of steel and the welding techniques. 12. Does not increase the susceptibility of the steel to delayed fracture due to hydrogen absorption 13. Improves the fatigue limit 14. Reduces the number of cycles to failure under high strain conditions 15. Forms five carbides (Mn23C5, Mn15C4, Mn3C, Mn5C2 and Mn7C3), the dominant one being Mn3C, which forms a continuous range of solid solutions with Fe3C, thus reducing the solubility of carbon in a-iron 16. Prevents the formation of an embrittling grain-boundary cementite. 17. Suppresses the yield extension in deep-drawing steels by virtue of its grain-refinement effect 18. Suppresses strain aging 19. In combination with nitrogen, has a solid-solution hardening effect and improves high-temperature properties 20. Extends the range of use of low-carbon steels 21. Has a strong influence on the pearlite morphology of high-carbon steels 22. Extends the range of use of high-carbon steels through its grain-refining and pearlite-refining actions 23. Raises strength values in bainitic steels by reducing grain size and increasing dispersion hardening 24. Allows bainitic steels to be produced by air hardening 25. Increases hardenability 26. Slows down the temper reactions in martensite 27. Assists interphase precipitation 28. Improves austemper and martemper properties 29. Increases temper embrittlement unless the carbon content is very low and trace element impurities are minimal 30. In spring steels, promotes ductility and fracture toughness without undue loss in tensile strength 31. Removes the risk of hot shortness and hot cracking when the ratio of manganese to sulfur is greater than 20:1 by forming a higher melting-point eutectic with sulfur than iron sulphide 32. Has a major influence on the anisotropy of toughness in wrought steels due to the ability to deform manganese sulfides during hot working 33. Forms three manganese sulfide morphologies (Type I, II and III) dependent upon the state of oxidation of the steel 34. Enhances free-cutting steels 35. Increases the stability of austenite 36. Has similar atomic size as iron 37. Lowers the stacking-fault energy of austenite (in contrast to alloying element additions such as chromium or nickel) 38. Allows lower solution temperatures for precipitation-hardening treatments in highly alloyed austenite due to increased carbon solubility 39. Forms s intermetallic compounds suitable for precipitation-hardened austenitic steel detailing course in kochi 40. Plays a major role in controlling the precipitation process that occurs during isothermal transformation to austenite 41. Increases the rate of carbon penetration during carburizing 42. Contributes, in combination with nitrogen, to the performance of work hard enable austenitic stainless steels 43. Improves hot corrosion resistance in sulfurous atmospheres 44. Enhances wear-resistance in carbon-containing austenitic steels where the manganese content is between 12-14% 45. Improves response of low-alloy steels to thermomechanical treatments 46. Strengthens certain steels by producing an austenitic structure using manganese-containing compounds 47. Enhances the performance of TRIP steels 48. Promotes Ferro-elastic behavior in appropriate steels 49. Less tendency to segregate within the ingot 50. In general, improves surface quality.
Structural steel is a material used for steel construction, that is created with a selected form following sure standards of chemical composition and strength. They are even outlined as hot rolled merchandise, with a cross section of special type like angles, channels and beams/joints. Steel has been thoroughly employed in numerous constructions everywhere in the planet attributable to its numerous specific characteristics that are significantly ideally fitted to construction. Steel is sturdy and may be shaped to provide the required form to provide associate degree final look to the structure that has been made Steel Beams is taken into account to be a structural component that chiefly carries load in flexure that means bending. Typically beams carry vertical gravitation, however are capable of carrying horizontal hundreds usually within the case of associate degree earthquake. The mechanism of carrying load in a very beam is incredibly distinctive, like; the load carried by a beam is transferred to walls, columns or girders that successively transfer the force to the adjacent structural compression members. The joints rest on the beam in lightweight frame constructions. The beams are acknowledged by their profile meaning:
• The length of the beam
• the form of the cross section
• the fabric used the foremost
.Such beams are unremarkable employed in the development of bridges and steel frame buildings. The foremost un-remarkably found varieties of steel beams are varied and are as follows • Wide projection beams • power unit form beams. Typical characteristics of beams are: Beams expertise tensile, sheer and compressive stresses internally. Usually underneath gravity, there’s a small reduction within the original length of the beam. This ends up in a smaller radius arc enclosure at the highest of the beam therefore showing compression. Whereas identical beam at all-time low is slightly stretched envelopment a bigger radius arc thanks to tension. The length of the beam midway and at the bends is that the same because it isn’t underneath tension or compression and is outlined because the neutral axis. The beam is totally exposed to shear stress higher than the support. There are some concrete beams that are fully underneath compression, these beams are known as pre-stressed concrete beams and are inbuilt such a way to provide a compression over the expected tension underneath loading conditions. The pre-stressed concrete steel beams have the producing method like, initial the high strength structural steel designing course in kerala tendons are stretched so the beam is forged over them. Then because the concrete begins to cure, the tendons are free therefore the beam is instantly underneath eccentric axial hundreds. An indoor moment is formed due to the eccentric axial load that successively increases the instant carrying capability of the beam. Such beams are usually employed in road and bridges. Materials employed in today’s trendy construction are the beams that are usually created of materials like: Steel, Wood, concrete. There are different types of beams: Simply supported beam,Cantilever beam,continuous beam,fixed beam and overhanging beam.
Simply supported beams
Simply supported beams are the most simple type of beams and have two supports at either end i.e.,pinned and roller. This considered to be a common type of beam and can be solved by using equilibrium equations.
Cantilever Beams use a fixed support that provides support from one end. This support provides moment resistance that is required for the beam to remain static. Pinned or roller support cannot provide the restraint that the beam would need. An example of a cantilever beam, is a shop awning – in which the beam is bolted directly into the wall.
Continuous beams are defined as multi-spanned beams having multiple supports across the length of the beam. A single beam that is supported by a number of columns along its length is a very good example of a continuous beam. It is considered to be an indeterminate beam – as there are more unknowns than equilibrium equations available.
Overhanging beams consists of two supports, but when compared to the simply supported beams, one of the supports is not at the end of the member. An example of this is of a balcony which is being extended from a frame structure. The frame provides two supports, but no support exists at the end of the member – allowing it to ‘overhang’ .
Erection of Steel
Erection of steel structures is that the method by that the fictitious structural members are assembled along to create the structure. The erection is generally distributed by the erection contractor. The erection method needs right smart coming up with in terms of fabric delivery, material handling, member assembly and member affiliation. Correctly coming up with of fabric delivery would minimize storage demand and extra handling from the positioning storage, significantly significant things. Erection of steel work might be created safe and correct if temporary support, false work, staging etc. are erected. Before erection the fictitious materials ought to be verified at web site with relation to mark numbers, key arrange and shipping list. The structural parts received for erection ought to be stacked in such some way that erection sequence isn’t affected because of improper storing. Care conjointly ought to be taken in order that steel structural designing parts shouldn’t are available in contact with earth or accumulated water. Stacking of the structures ought to be exhausted such some way that, erection marks and mark numbers on the parts square measure visible simply and handling don’t become tough. a spread of ways may be utilized for the erection of a structure. Normally, the choice of the strategy is influenced by the sort of the structure, web site conditions, equipment, quality of ball-hawking labour, etc. obtainable to the erector. However, notwithstanding the strategy adopted the most aim throughout erection is that the safety and preservation of the soundness of the structure the least bit times. Most structures that collapse do thus throughout erection and these failures square measure fairly often because of an absence of understanding on someone’s a part of what another has assumed regarding the erection procedure. Before the commencement of the erection, all the erection instrumentality tools, shackles, ropes etc. ought to be tested for his or her load carrying capability. Such tests if required could conjointly be recurrent at intermediate stages also. Throughout the complete erection, the steel work ought to be firmly fast or otherwise mounted and braced to require care of the stresses from erection instrumentality or the hundreds carried throughout erection. additionally to the current, adequate provisions to resist lateral forces and wind masses throughout erection ought to even be created consistent with native conditions. Unremarkable bracing are engineered into every type of structures to grant them a capability to face up to horizontal forces made by wind, temperature and also the movements of crane and different plant in and on the building. Bracing may be permanent or temporary. Temporary bracing needed at some stages of the work should have properly designed connections and will be specifically cited within the erection technique statement. the choice on sequence of erection like that member ought to be erected 1st for providing initial stability to the structure or whether or not temporary bracing ought to be used for this purpose ought to be taken at AN early stage of designing of the erection method. Any miss-alignment at initial stage can impair the performance, of the structure once completed. Early or unauthorized removal of temporary bracing could be a common reason for collapse in an exceedingly part completed frame. once having thought-about the requirement for putting in temporary bracing and also the ought to delays fixing permanent bracing, thought ought to run to the general economy of holding the temporary bracing and maybe deed out the permanent bracing . It is a pricey and doubtless dangerous business to travel into a structure entirely so as to require out temporary members, or to insert parts that had to be unnoticed quickly.
Structural steels are sometimes made by rolling steel solid from the steel making method when reheating it to a temperature higher than 850°C. Rolling consists of passing the steel through a series of rolls that kind the solid steel into the form and thickness needed. A big selection of shapes and sizes are presently rolled or out there. The properties of steel for the most part result from the influence of micro structure and grain size the different factors like non-metallic inclusions are vital. The grain size is powerfully influenced by the cooling rate, to a lesser extent by different aspects of warmth treatment and by the presence of little quantities of components like atomic number 41, metallic element and atomic number 13. Thus, the assembly of steel and steel product involves heat and therefore the effects of heating and cooling throughout. The chemical composition of steel is essentially determined once the steel is liquid except for a given chemical content the structure is essentially determined by the speed at that it’s cooled and should be altered by ulterior reheating and cooling below controlled conditions. Carbon steels are for the most part composed of iron with up to one.7% carbon, however the addition of comparatively little quantities of different components greatly influences its behavior and properties. For structural functions it’s fascinating that steel be ductile and weldable, and consequently most structural carbon steels are low-carbon steel with carbon within the vary zero.15 to 0.29% and should embody little quantities of metal, element and copper. the right production of steel structures may be a complicated method involving creating the steel, process it into helpful product, fabricating these product into helpful assemblies or structures by cutting, drilling and fitting, and erection and grouping these parts, assemblies, and structures into buildings or bridges. it’s vital to investigate processes as a result of they’ll have a significant result on the investigated environmental impact of a steel structure, however they ordinarily don’t specify or would like details of exactly however the steel is made, rolled or fashioned. Presently, attachment is maybe the foremost vital method employed in the fabrication and erection of structural steel designing course in kerala work. it’s used terribly extensively to hitch parts to form up members and to hitch members into assemblies and structures. attachment used and done well helps within the production of terribly safe and economical structures as a result of attachment consists of primarily connection steel element to steel element with steel that’s intimately united to each. Corrosion of steel takes place by a fancy chemical science reaction between the steel and atomic number 8 that’s expedited by the presence of wetness. Structural needs further protection and therefore the usual strategies are paint systems or exciting. steel is an environmentally friendly artefact which means less environmental impacts compared with the opposite trendy structural parts. The usage of steel to implement the property criteria from the extraction and mineral processing of raw materials, through the look and construction of buildings to the tip of life is extremely vital for overall property. Steel and concrete bridge structures have similar impacts on the atmosphere. Steel will totally justify its claims to be the best construction material. It’s ability implies that instead of being destroyed to form means for a replacement building with modified use, a steel-framed building will typically be reconfigured for a replacement use, and given an entire vogue by ever-changing its protection. The long span capabilities of steel construction provides clear areas that may be simply reconfigured, providing the prospect of extending a building’s helpful life. At the tip of a building’s helpful life its steel frame may be simply demolished and components of it either re-used or recycled; de-mountability may be designed into a steel building, permitting house owners to arrange for future use on another web site. Steel employed in construction won’t visit lowland as even scrap steel includes a price and could be a very important part within the method of manufacturing new steel. Steel may be recycled which means subsequent re- cyclings do nothing to cut back its qualities; it’s not simply recycled, however multicycled.
Design is that the start line in any project, the mixing between the look and construction phases can lead to bigger crew productivity as construction concerns are taken under consideration at the design stage. Designers of steel structures ought to remember not solely with style method necessities for the structures however additionally with fabrication and erection strategies to make sure that a steel Structure design course in kerala style will be safely, economically and dependably dead (fabricated, assembled and erected),these could verify whether or not a style is sensible and value economical. There are 2 separate phases of design: • Structural style • style for Erection. Fabrication is that method wont to manufacture steel structures parts which will, once assembled and joined, form a whole frame. The frame usually uses without delay out there normal sections that are purchased from the shaper or steel shareowner, along side such things as protecting coatings and bolts from alternative specialist suppliers. Fabrication involves handling of the stock members, cutting them to size, punching and drilling for connections, and getting ready the connections, in addition as search painting or finishes once needed. The principal activities at the fabrication works: Pre-assembly butt attachment Cutting and identification Drilling and edge preparation Assembly attachment Fitting of stiffeners Shear connectors Trial erection (rarely carried out) Coating application. There are several factors that has to be thought-about throughout the fabrication and have an excellent impact on up the crew productivity for the development of steel structure projects: • Accuracy • Handling and transportation • Shortage materials • broken or defective material • Delivery priority • Schedule time for fabrication. Steel shall be hold on and handled in an exceedingly manner that forestalls injury or distortion. And don’t store materials on the structure in an exceedingly manner which may cause distortion or injury to members of the structure. unreal steel shall be delivered in an exceedingly sequence which will allow economical and economical fabrication and erection and don’t adversely have an effect on productivity, wherever the delivery of materials on dates before beginning the period of erection appropriate time helps to boost the crew productivity wherever they’ll be reviewed and transferred to the erection at the appropriate time, The transfer of materials to the erection website before beginning the method of erection is one among the foremost necessary factors that have an effect on the up crew productivity. In developing the erection methodology totally different aspects of weather will have an effect on productivity, detail coming up with, and therefore the behavior of the structure. And cause hazards for health & safety. The character of the weather at the actual website throughout the amount of the year once erection is to require place must be appreciated, as will its significance for every operation. Safety within the erection steel structure has invariably been a significant issue. Where reliable records are there, steel construction is found to be one among the foremost dangerous on safety and health criteria. Though abundant improvement in steel construction safety has been achieved, the erection steel structure still continues to lag behind most alternative activities with relevance safety. The principal safety objectives once building steelwork are: • Safe access and dealing positions; • Safe lifting and inserting of steel components; • Stability and structural adequacy of the part-erected structure. Quality concerns would like special care. Particularly once the assembly (construction/installation) isn’t in situ, value of remedial works could go extraordinarily high if attention isn’t paid to quality assurance. Within the trendy construction market, quality may be a major performer in construction organization.
Corrosion of Steel
Reinforcing steel corrosion is one of the most serious deterioration mechanisms in reinforced concrete structures and is also an important issue that needs be considered when evaluating and rehabilitating RC structures. Fortunately, there are two self-defense mechanisms that can be employed to protect reinforcing steel against corrosion ,physical protection provided by the dense and relatively impermeable structure of concrete and chemical protection provided by the high alkalinity of the pore solution. The ﬁrst mechanism involves concrete of sufﬁcient depth and good impermeable quality. The second one is a thin oxide covering that forms around reinforcing steel bars due to the high alkalinity of pore solutions, which contain high concentrations of soluble calcium, sodium and potassium oxides, in freshly mixed concrete. However, the random distribution of pore spaces suggests that aggressive substances such as chloride, carbon dioxide, oxygen, moisture, etc. may penetrate through weak points in the concrete cover trigger the corrosion of reinforcing steel bars in concrete and finally induce cracking of the concrete. The aggressiveness of the environment is a very important factor to consider when examining concrete that shows signs of possible distress Generally, corrosion attack is initiated either due to the carbonation of the concrete or due to diffusion of the chloride ions to the reinforcing steel bar surface or both. On account of different aggressive mechanisms, the corrosion due to concrete carbonation is much more uniform than that caused by chloride attack and, hence, it is much less susceptible to local attack .On the other hand, corrosion of reinforcing steel structural course in kerala and the consequent cracking of concrete due to the ingress of chloride ions to the reinforcing steel bar surface is more than that due to carbonation of concrete. Not only will corrosion affect the load-carrying capacity of the reinforcing steel bar, but it may also impair its ductility, which presents a serious problem for the safety of old and monumental constructions in seismically active areas. A lot of research has been done to the corrosion of reinforcement in RC, dealing with various issues related to the conﬁguration of corroded reinforcing steel bars, the load– displacement relationship, residual strength, ductility, etc. The effect of reinforcement corrosion on the residual strength has been of great interest. The ductility of reinforcing steel is normally represented by two parameters, the ratio between the yield and the total strengths and the elongation ratio. The elongation ratio is the average strain of a corroded steel bar in its gauge length. The elongation ratio associated with a shorter gauge length is much greater than that of a greater gauge length and the gauge length was taken as ﬁve times the initial diameter of the steel bar . The elongation ratio decreases with increased corrosion level, although the rates of decrease are different for steel bars corroded in simulated solutions and those corroded in concrete. For the steel bars corroded in simulated solutions the decrease rate is about 0.2, which represents a moderate loss of ductility as corrosion increases; for the steel bars corroded in concrete , the decrease rate is about 0.8, which represents a drastic loss in ductility as corrosion increases. The contribution of the highly localised peak strain does not provide a correspondingly large contribution to overall elongation (Cairns et al., 2005); therefore, the steel bars corroded in concrete present a lower elongation ratio than those corroded in simulated solutions for the same cross-sectional loss. The reinforcing steel bars subjected to local or pitting attack may suffer a signiﬁcant loss of ductility. As far as the fracture pattern is concerned, fracture of the reinforcing steel bar usually occurred at pitted sections and usually happened with a less ductile fracture when the notch was wide and deep.
Steel is known as an alloy of iron and carbon, although there are different elements found in several steels. There are different grades of steel with different properties .It has to be purified and then several elements need to be added to strengthen it. The property of steel is that some alloys are reinforced by quench hardening. The Sandwich metal is then cooled by plunging it into a liquid. These alloys will so be ductile for fabrication and far stronger as a finished product. Steels are a unit loosely sorted by carbon content into low carbon steels , medium carbon steels and high carbon steels. These numbers could seem to be tiny, however they mirror the actual fact that carbon may be a tiny, light-weight component, whereas iron is a larger, heavier atom. Among metals, steels is comparatively significant and additionally deteriorate by Steel is known as an alloy of iron and carbon, although there are different elements found in several steels. There are different grades of steel with different properties .It has to be purified and then several elements need to be added to strengthen it. The property of steel is that some alloys are reinforced by quench hardening. The Sandwich metal is then cooled by plunging it into a liquid. These alloys will so be ductile for fabrication and far stronger as a finished product. Steels are a unit loosely sorted by carbon content into low carbon steels , medium carbon steels and high carbon steels. These numbers could seem to be tiny, however they mirror the actual fact that carbon may be a tiny, light-weight component, whereas iron is a larger, heavier atom. Among metals, steels is comparatively significant and additionally deteriorate by corrosion. If steel can work, it’ll most likely be the smallest amount high-ticket metal alternative which may contain far and away the most important tonnage duty of steel created, because it includes the structural steels of bridges and buildings. These steels typically have solely tiny amounts of different alloying parts. Low carbon steels are delicate steels and these steels is also surface treated to get the most effective of each worlds – a ductile, impact-resistant interior with a tough, abrasive-resistant surface. Common surface treatments for hardness contains carburizing, nitriding, and cyaniding. Low carbon steels might also be surface treated for corrosion resistance, using processes of electric, electroplating. Medium alloy steels is quench hardened, and are used to improve hardenability. To harden steel, its temperature should be modified to avoid the formation of softer equilibrium phases, and to provide the required robust section known as primary solid solution. steel structure design course in kerala.
The temperature gradients produce stresses that, within the worst case, will crack the half. The interior might not cool quickly enough to harden. The atoms of a metal area unit positioned in symmetrical geometrical arrays are known as crystal lattices. There are the high alloy steels, with about 5%–10% by weight consisting of alloying parts apart from carbon. Although high carbon steels are utilized in the littlest amounts and are known as tool steels. These steels are used for hammers, pick-axes, and cutting tools like knives and chisels. They are used at the very best temperatures. The tool steels are usually heat treated. There are 3 stages to the quench hardening of steels: heat treat, quench, and heat up . In the Quench Hardening method – Heat Treat the steel is at a extreme temperature to dissolve the alloying parts into an even, primary solid solution beginning section. The time needed depends totally on the scale of the half. In Quench the hardening (strengthening) happens here. Fast quenches promote hardening however risk cracking. Slower quenches forestall cracking, however might not sufficiently harden. The subsequent media are ordered from severe quench (rapid) to delicate quench .In the heat up (Temper) steel is simply too brittle to be serviceable. Tempering is maintaining an intermediate temperature between the initial answer temperature and also the quench temperature. The aim of tempering is to revive impact strength to the hardened half of the steel.
Steel and Seismic Design
The different aspects of a seismic design has always been a concern when it comes to the designing of steel structure design course in kerala. A number of strategies are important to the design of structures that will behave adequately in strong earthquakes. The major aspects that are considered are continuity, adequate stiffness and strength, regularity, redundancy etc. Continuity. All of the pieces that comprise a structure must be connected to each other with sufficient strength that when the structure responds to shaking, the pieces don’t pull apart and the structure is able to respond as an integral unit. An important aspect of continuity is having a complete seismic load resisting system so that a force that is applied anywhere in the structure has a means of being transmitted through the structure and to the foundation. In addition to vertical frames, a complete seismic load resisting system must also include horizontal diaphragms to transmit inertial forces to the vertical frames. Stiffness and Strength. Structures must have sufficient stiffness so that the lateral deformations experienced during an earthquake do not result in instability and collapse. Structures must have sufficient lateral and vertical strength such that the forces induced by relatively frequent, low intensity earthquakes do not cause damage and such that rare, high-intensity earthquakes do not strain elements so far beyond their yield points that they lose strength. Regularity. A structure is said to be regular if its configuration is such that its pattern of lateral deformation during response to shaking is relatively uniform throughout its height, without bringing a lot of deformation in small areas of the structure. It is important to avoid excessive twisting of structures because it is difficult to predict the behavior of a structure that twists excessively. It also is important to avoid concentrations of deformations in structures because these concentrated deformations can become very large, leading to extreme local damage in the area of the concentration and a loss of vertical load. Redundancy is important because of the basic design strategy embodied in the building codes, which anticipates that some elements important to resisting lateral forces will be loaded beyond their elastic limits and will sustain damage. If a structure has only a few elements available to resist earthquake-induced forces, when these elements become damaged, the structure may lose its ability to resist further shaking. However, if a large number of seismic load resisting elements are present in a structure, and some become damaged, others may still be available to provide stability for the structure. Defined Yield Mechanisms. The most important strategy is to Design a predetermined yield mechanism. In this approach, which is often termed capacity design, the designer must decide which elements of the structure are going to yield under strong earthquake excitation. In order to sustain yielding without undesirable strength loss elements are detailed . At the same time, all of the other elements of the structure, such as gravity load-carrying beams, columns and their connections, are proportioned so that they are strong enough to withstand the maximum forces and deformations that can be delivered to them by an earthquake, once the intended yield mechanism has been engaged. In essence, the members that are designed to yield act as structural “fuses” and protect other elements of the structure from excessive force. This strategy ensures that critical members important to the vertical stability of the structure and its ability to carry gravity loads are not compromised.
Steel is manufactured as a product with no major trade barriers across national boundaries to be seen currently. Steel production in India has increased by a compounded annual growth rate and steel continues to have a stronghold in traditional sectors such as construction, housing and ground transportation. Special steels are increasingly used in engineering industries such as power generation, petrochemicals and fertilizers growth in India is projected to be higher than the world average, as the per capita consumption of steel in India. India occupies a central position on the global steel map. The growth of the steel industry worldwide through mergers and acquisitions has already thrown up several significant concerns. The domestic steel industry has become market oriented and integrated with the global steel industry. The private players could expand their operations and bring in new cost effective technologies to improve competitiveness not only in the domestic but also in the global market. Private sectors contribution to the total output has thus been increasing in India. Development of the private sector has caused a tremendous growth in all aspects of steel industry that is capacity, production, export and imports.
The steel industry is showing promising future growth as major players in the industry have announced their plans for significant investments in expanding their capacities. Rapid development of the steel industry with active participation of private sector and integration of India steel industry with the global steel industry has also induced the government to come up with a National Steel Policy in 2005. The pre-reform steel market in India was controlled in all relevant areas. Competition was restricted in this market that had no real role to play in the growth of the individual companies or their performance and the allocative efficiency of investible resources. The prices fixed by the government were more on political consideration and not strictly on the basis of costs of production or markets demand and supply balance. There are no facts to establish that there is formal or ‘written down’ agreements on prices among the major players. There must be difference between situations such as (i) price rise necessitated by factors external to the industry e.g. increase in capital cost, rise in border steel prices and hence erosion of profitability and (ii) expectation of demand-supply gap providing an opportunity to increase profit Intervention by the government on matters of pricing steel long products also in the recent times has also pointed to the acceptance of the government that the major steel producers have substantial value in the market and act according to the substantial net impact on the market to move the trends in the desired direction. Steel sector was the first to be liberalized and there are enough players; though the industry is concentrated in some segments. However, this in no way suggests that the sector should be subject to regulation, which also includes the government. Regulations must be restricted to market failures like natural monopolies, externalities and asymmetric information between buyers and sellers. The government’s current approach to informally control steel prices is based on the assumption that a few steel detailing course in kochi producers have sufficient command over the market and that they can be discussed to uniformly cut prices to whatever objective to fulfill.