Reinforced Concrete Frame Structure Advantages

Reinforced screenland Frame Structure AdvantagesReinforced c all over is whizz of the most vastly practised modern building textiles. cover is cardboard st nonp atomic number 18il obtained by change oneing cementumumum, sand, and store ups with piddle. Fresh cover trick be molded into intimately any check, which is an inherent advantage over early(a) veridicals. cover become very popular after the invention of Portland cement in 19th century. However, its limited tension oppositeness prevented its wide use in building verbal expression. To overcome this weakness, poise bard be embed in concrete to form a composite material c onlyed streng whereforeed concrete. Developments in the modern beef up concrete purport and mental synthesis pattern were pioneered by European engineers in the late 19th century. At the inaugurate time, facultyened concrete is extensively utilise in a wide variety of engineering applications.The worldwide use of strengthened concrete construction stems from the wide avail world power of reinforcing make as well as the concrete ingredients. Un alike mark, concrete production does not require costly manufacturing mills. cover construction, does, however, require a certain level of technology, expertise, and workmanship, particularly in the dramaturgy during construction. In some cases, single-family houses or simple low-rise residential buildings ar constructed without any engineering assistance.The extensive use of reinforced concrete construction, peculiarly in underdeveloped countries, is receivable to its relatively low address comp bed to reinvigorated(prenominal) materials much(prenominal) as leaf blade. The live of construction changes with the region and strongly depends on the local practice. As an example, a whole of measurement argona of a veritable(prenominal) residential building do with reinforced concrete be nigh $100/m in India, $250/m in Turkey, and $500/m in Italy. With the rapid growth of urban population in some(prenominal) the developing and the industrialized countries, reinforced concrete has become a material of utility(a) for residential construction. Unfortunately, in many cases there is not the obligatory level of expertise in inclination and construction. Design applications ranges from single-family buildings in countries like Colombia to high rises in China. Frequently, reinforced concrete construction is used in regions of high seismic risk.Introduction make reinforced concrete is a specific type that has had strong steel rebar or types tote uped to it small-arm wet, creating a very strong type of concrete that is able to nurse almost anything when it has dried. Because the result of using steel reinforced are so earnest for the intensiveness of the building, most modern building today use steel reinforced concrete in the construction process. By adding thin steel prohibit to concrete poop increase the strength of the concrete, qualification it transgress to use in variety of application. Today, many of the buildings located nations use reinforced concrete to make the buildings stronger and better able to in industrialized dissent the ravages of time and the weather. Reinforcing the concrete that will be used on the buildings add ductile strength to the concrete, making it much stronger and to a great extent(prenominal) flexible that steadfast concrete, which helps prevent cracking and breakage. marque reinforced concrete hind end be used in a number of building applications, including floors, beams, supports, walls, and frames.Steel reinforced concrete is a concrete in which steel reinforcing stimulus bars, plates or character references perk up been incorporated to build up a material that would former(a) be fragile. If a material with high strength in tension, such as steel, is placed in concrete, then the composite material, reinforced concrete, resists conglutination moreove r also bending, and different direct tensile action. A reinforced concrete section where the concrete resists the compression and steel resists the tension hatful be made into almost any shape and size for the construction effort.Reinforcing SteelBefore placing reinforcing steel in forms, all form oiling should be completed. As mentioned earlier, oil or other coating should not collision the reinforcing steel in the formwork. Oil on reinforcing bars reduces the bond amidst the bars and the concrete. Use a piece of burlap to clean the bars of rust, scales, grease, mud or other foreign matter. A light image of rust or mild film is not objectionable. Rebars must be tied together for the bars tore main in a desired arrangement during pouring. Tying is also a means of keeping laps or splices in place. Laps allow bond stress to transfer the gist from one bar, first into the concrete and then into the second bar.Advantages BehaviourMaterialsConcrete is a mixture of cement, stone a ggregate, and shrimpy amount of water.Cement hyd judge from microscopic opaque crystal lattices encapsulating and locking the aggregate into a rigid construction. usual concrete mixes accept low tensile strength.Steel, is placed in concrete, then it will not scarce resists compression just also bending, and other direct tensile actions.Steel also made the bonding of the aggregate in a concrete better.Physical characteristics of steel reinforced concreteThe coefficient of thermal expansion of concrete is similar to that of steel, eliminating internal stresses due to differences in thermal expansion or contraction.When the cement paste within the concrete hardens this conforms to the surface details of the steel, permitting any stress to be transmitted expeditiously amongst the different materials.The fundamentne chemical environment appropriated by atomic number 20 hundredate causes a passivating film to form on the surface of the steel, making it much more resistant to e ating away than it would be in immaterial or acerbicic conditions.Common Failure Modes of Steel Reinforced ConcreteConventional steel reinforced concrete fuck failed due to light strength, preeminent to mechanical bankruptcy, or due to a reduction in its forte. Corrosion and disengageze may damage unequally designed or constructed reinforced concrete. When rebar depletes, the oxidation products expand and head for the hillss to flake, cracking the concrete and unbonding the rebar from the concrete.Typical mechanisms removeing to forcefulness problems are as belowMechanical failureSteel reinforced concrete may be considered to have failed when significant cracks occur. wisecrack of the concrete section cannot be prevented. However, the size and location of the cracks can be limited and controlled by reinforcement, placement of control joints, the curing methodology and the mix design of the concrete. fracture defects can allow moisture to penetrate and wipe out the re inforcement. This is a serviceability failure in limit state design. Cracking is normally the result of an inadequate quantity of rebar, or rebar spaced at too great a distance. The concrete then cracks either low excess loadings, or due to internal effects such as early thermal shrinkage when it cures. Ultimate failure leading to pass on can be caused by crushing of the concrete intercellular substance, when stresses exceed its strength by yielding of the rebar or by bond failure between the concrete and the rebar.CarbonationCarbonation or neutralisation, is a chemical reaction between carbon dioxide in the wrinkle and calcium hydroxide and hydrated calcium silicate in the concrete. The water in the pores of Portland Cement Concrete is normally alkaline with a pH in the range of 12.5 to 13.5. This highly alkaline environment is one in which the enter steel is passivated and is protected from corrosion. The carbon dioxide in the glory reacts with the alkaline in the cement an d makes the pore water more acidic, hence lowering the pH. Carbon dioxide will start to carbonate the cement in the concrete from the moment the object is made. This carbonation process will start at surface, then slowly move deeper and deeper into the concrete. If the object is cracked, the carbon dioxide in the air will be better able to penetrate into the concrete. Carbonated concrete only becomes a durability problem when there is also comfortable moisture and oxygen to cause electro- emf corrosion of the reinforcing steel.ChloridesChlorides, including sodium chloride, can boost the corrosion of embedded steel rebar if present in sufficient concentproportionn. So, only use fresh raw water or portable water for mixing concrete. It was once frequent for calcium chloride to be use as an admixture to promote rapid set-up of the concrete. It was also mistakenly believed that it would prevent put downzing. alkali Silica ReactionThis is a reaction of amorphous silica sometimes pre sent in the aggregates with alkali, for example from the cement pore solution. The silica reacts with the alkali to form a silicate in the Alkali silica reaction, this causes localize pretentiousness which causes cracking. The conditions are aggregate containing an alkaline reactive constituent, sufficiently availability of alkali ions and sufficient moisture. This phenomenon referred as concrete cancer. This reaction occurs independently of the presence of rebar. vicissitude of High Alumina cementResistant to weak acids and especially sulfates, this cement cures quickly and r separatelyes very high durability and strength. However, it can lose strength with heat or time, especially when not properly cured.SulfatesSulfates in the dry land or in groundwater, in sufficient concentration, can react with the Portland cement in concrete create the formation of expansive products which can lead to early failure of the structure.Corrosion and Passivation of steel reinforcement open(a) s teel will corrode in moist atmospheres due to differences in the electrical potential on the steel surface forming anodic and cathodic sites.Concrete as an environmentThe environment showd by good tonus concrete to steel reinforcement is one of high alkalinity due to the presence of the hydroxides of sodium, thou and calcium produced during the hydration reactions. The bulk of surrounding concrete acts as a animal(prenominal) barrier to many of the steels aggressors. In such an environment steel is peaceful and any small breaks in its protective oxide film are short repaired. However, the alkalinity of its surroundings are reduced, such as by neutralization are able to reach the steel then severe corrosion of the reinforcement can occur. This in turn can result in to spot of the concrete by rust and spalling of the cover due to the increase in ledger associated with the conversion of iron to iron oxide.Factors affecting corrosion rates of steel in concreteThe permeability o f the concrete is important in determining the extent to which aggressive external substances can coming the steel. A thick concrete cover of low permeability is more promising to prevent chloride ions from an external source from reaching the steel and causing depassivation.Alternatives for the reinforcing pointWhere an adequate pro proveness of cover is problematic to achieve due to design considerations or where aggressive environments are expected such as in marine structures or bridge decks, additive protection may be ask for the embedded steel. This may take many and varied forms and commercial interest in this field is strong. The steel reinforcement itself may be made more able to maintain its passivity by providing it with a protective coating. In extreme circumstances, solid stainless steel may be used, although the perceived additional monetary value restricts its use in all but the most specialized applications.The ideal authorityThere can be little doubt that th e most good way of protect steel which is embedded in concrete is to provide it with an adequate depth of cover by high strength, low permeability concrete free from depassivating ions such as chlorides. However, in the real world, concrete is laid by the tone in all weathers and environments, exposed to industrial atmospheres, de-icing salts and seawater.The real situationContaminated materials and shortsighted workmanship are hard to avoid entirely but by understanding the often complex chemical and electrochemical conditions that can exists it should be possible to develop ways of producing structures which will destination long into the next century.Deterioration mechanismsThe majority of reinforced concrete around the world performs adequately and gives few problems. A minority of structures have deteriorated due to either the action of aggressive components from the external environment or mutual exclusiveness of the mix constituents. Problems can arise as a result of in complete or inaccurate site investigation, poor design, badly specified concrete, poor workmanship and a range of other factors.Stages of harmThe mechanisms of deterioration are primarily chemico-physical in nature and occur in trinity discrete stages which are initiation, propagation, and deterioration.Modes of deteriorationDeterioration may occur due to a number of mechanisms on which a large body of literature already exists. These allow inCorrosion of reinforcement due to chloride ions, carbonation and change in the rebar reinforcement. sulphate attack of concreteSalt recrystallisationSoft water or acid attack of concreteAlkali aggregate reactionThermal horror of concrete componentsShrinkageFrost damageDepth of cover piteous cover is invariably associated with areas of high corrosion risk due to both carbonation and chloride ingress. By surveying the surface of a structure with an electromagnetic covermeter and producing a cover contour plot, the high-risk areas can be easi ly identified. A cover survey of newly completed structures would rapidly identify believably problem areas and permit additional protective measures to be taken.Cracked coverIt should be remembered that reinforced concrete is intrinsically a cracked material because the steel stops the structure failing in tension but the brittle concrete cracks to the depth of the reinforcement. Only those cracks above a slender width which intersect the steel are liable to assist the corrosion processes.Cost IncurredAfter a period of unprecedented growth in prices during 2004, early date for 2005 indicates that the constructional steel merchandise faces greater stability in the year ahead. Despite the price increases, demand for steel in the UK market remained at a very high level in 2004. angiotensin converting enzyme of the principal concerns for steel users was the availability of material, but the year ended with more steel in the supply chain than there had been at the beginning. morphol ogical steel frame costsThe leading benchmark cost unit for geomorphologic steelwork is its unit cost per thymine which includes the steel and the following elements affiliation design, detail drawing, cunning, testing, treatment and delivery, offloading, erectionThese are calculated against the overall estimated tunnage for the building to generate an overall frame cost. Unit costs per tonne can vary enormously as there are a combination of factors that influence the overall cost. Care should be taken in considering each projects characteristics in arriving at a tonnage rate. This can be calculated either on the number of beams and column in a building or a weight per m.The relative costs of each element will vary depending on the nature of the project. The tonnage rate could be divided as followsMaterials 30%Engineering 5%Fabrication 35%Priming 8%Delivery 2% hard-on 20%The costs assume that the structural steelwork avower will provide their own crane for all the projects with the exception of office buildings, for which the main contractor provides a tower crane. The early involvement of structural steelwork fabricators is the most effective way to economic value engineer cost savings into steelwork frame. For example, using more substantial and therefore more overpriced steel columns in a design could remove the need for stiffeners. The steel may cost more but it is cheaper overall than paying for labour to fabricate and weld stiffeners to the column. If this value is adopted early enough in the project across the hearty frame design, significant cost savings can be achieved.The cost of a frame system alone should not dictate the choice of frame for a project. Rather it should be just one of a number of issues that should be considered when making the choice of frame material. The recent rises in reinforcement and steel prices have increase frame costs but the difference between steel and concrete frame costs corpse insignificant. A 50% increase in Eu ropean steel prices during 2004 has left many in the construction industry reviewing design solutions that have a heavy reliance on steel. The tinct of the steel price rises and found that the whole project costs for concrete framed buildings are marginally less than for steel framed buildings.Foundation costsThe foundations typically work approximately 3% of whole project initial cost. For the heaviest reinforced concrete solutions, the foundations will be more expensive, but this trifles only a small cost and can be offset by using post-tensioned slabs, which are typically 15% lighter.Cladding costsThe thinner the overall structural and services zone, the less the cladding costs. Given that cladding can represent up to 25% of the construction cost it is worth minimizing the cladding area. The marginal floor-to-floor height is almost always achieved with a concrete flat slab and sort services zone.PartitionsSealing and fire stopping at partitions heads is simplest with flat s offits. substantial savings of up to 10% of the partitions package can be made compared to the equivalent dry lining package abutting a profiled soffit with downstands. This can represent up to 4% of the frame cost.Services co-ordination/ Installation/ AdoptabilityThe soffit of a concrete flat slab provides a zone for services distribution free of any downstand beams. This reduces coordination effort for the design team and therefore the risk of errors. It permits flexibility in design and allows coordination effort to be focused elsewhere. Services episode is simplest below a flat soffit. This permits maximum off site fabrication of services, higher quality of work and quicker installation. These advantages should be reflected in cost and value calculations. Indeed, ME contractors quote an additional cost of horizontal services distribution below a profited slab of up to 15%. Flat soffits also allowed greater future adaptability.Fire protectionFor concrete structures fire protec tion is generally not needed as the material has inherent fire opposition of up to four hours. This remove the time, cost and separate trade required to attend the site for fire protection.VibrationThe inherent mass of concrete means that concrete floors generally meet vibration criteria at no extra cost and without any extra stiffening. For more stringent criteria, the additional cost to meet vibration criteria is small compared to other structural material.Exposed soffitA concrete structure has a high thermal mass. By exposing the soffits this can be utilized through fabric readiness terminus to reduce initial plant costs and ongoing operational costs. Furthermore, the cost of suspended ceilings can be reduced or eliminated.ConclusionAs a conclusion, the majority of reinforced concrete structures show excellent durability and perform well over their design spiritedness. Adverse environments or poor construction practice can lead to corrosion of the reinforcing steel in concre te. The major mechanisms for corrosion are atmospheric carbon dioxide ingress and chloride attack from cast-in or diffused chlorides. The corrosion and deterioration mechanisms are essentially the resembling for both carbonation and chloride attack. Proper choice of materials, adequate cover to reinforcement, good quality concrete and attention to the environment during construction will enhance the durability of reinforced concrete structures. For cost incurred, concretes range of inherent benefits including fabric energy storage, fire resistance and sound installation means that concrete buildings tend to have lower operating costs and lower maintenance requirements.For structure subjected to aggressive environments, combinations of moisture, temperature and chlorides may result in the corrosion of reinforcing and prestressing steel, leading to the deterioration of concrete and loss of serviceability. One preferred solution which has assumed the stipulation of cutting-edge resea rch in many industrialized countries, is the use of fiber reinforced polymer rebars in concrete. Fiber concrete is also becoming an progressively popular construction material due to its improved mechanical properties over non-reinforced concrete and its ability to enhance the mechanical performance of conventionally reinforced concrete.DEFINITION OF FIBRE REINFORCED POLYMER case-reinforced polymer (FRP), also known as fibre-reinforced plastic) are composite materials made of a polymer matrix reinforced with fibres. FRPs are normally used in the aerospace, self-propelling, marine, and construction industries. FRPs are typically organized in a laminate structure, such that each lamina (or flat storey) contains an arrangement of unidirectional fibres or woven fibre fabrics embedded within a thin layer of light polymer matrix material. The fibres, typically composed of carbon or meth, provide the strength and ineptitude. The matrix, commonly made of polyester, Epoxy or Nylon, binds and protects the fibers from damage, and transfers the stresses between fibers.TYPES OF stuff and nonsense USEDPolymerThere are two main types of polymer used for resins thermosets and thermoplastics. The thermosetting polymers used in the construction industry are the polyesters and the epoxides. There are many thermoplastic resins used in composite manufacture polyolefins, polyamides, vinylic polymers, polyacetals, polysulphones, polycarbonates, polyphenylenes and polyimides. fictitious characterA wide range of amorphous and crystalline materials can be used as the fibre. In the construction industry the most common fibre used is scrap fibre (there are 4 types of glass fibre E-glass, AR-glass, A-glass and high strength glass). Carbon fibre, of which there are 3 types (Type I, II, III) can be used separately or in club with the glass fibre as a hybrid to increase the stiffness of a structural member or the area within a structure, so that the stiffness exceeds the value possible using only glass fibre. Aramid fibres can be used instead of glass fibres to give increased stiffness to the composite. Today each of these fibers is used widely in industry for any applications that require plastics with specific strength or elastic qualities. scum fibers are the most common across all industries, although carbon fiber and carbon fiber aramid composites are widely found in aerospace, automotive and sporting good applications.AdditivesFor structural applications it is mandatory to achieve some stratum of flame retardant. Fire retardants are usually incorporated in the resin itself or as an applied gel-coat. Fillers and pigments are also used in resins for a variety of purposes, the former principally to improve mechanical properties and the last mentioned for appearance and protective action.APPLICATIONS OF FRP IN CONSTRUCTIONThere are three broad divisions into which applications of FRP in civil engineering can be assort applications for new construction, repa ir and rehabilitation applications, and architectural applications.NEW CONSTRUCTIONFRPs have been used widely by civil engineers in the design of new construction. Structures such as bridges and columns built completely out of FRP composites have demonstrated exceptional durability, and effective resistance to effects of environmental exposure. Pre-stressing tendons, reinforcing bars, storage-battery grid reinforcement, and dowels are all examples of the many diverse applications of FRP in new structures. patch AND REHABILITATIONOne of the most common uses for FRP involves the repair and rehabilitation of discredited or deteriorating structures. Several companies across the world are beginning to peignoir damaged bridge piers to prevent collapse and steel-reinforced columns to improve the structural integrity and to prevent buckling of the reinforcement.ARCHITECTURALArchitects have also discovered the many applications for which FRP can be used. These include structures such as si ding/cladding, roofing, flooring and partitions. designing CONSIDERATIONThe strength properties of FRPs collectively make up one of the primary reasons for which civil engineers select them in the design of structures. A materials strength is governed by its ability to sustain a load without excessive deformation or failure. When an FRP specimen is tested in axial tension, the applied force per unit cross-sectional area (stress) is proportional to the ratio of change in a specimens length to its original length (strain). When the applied load is removed, FRP returns to its original shape or length. In other words, FRP responds linear-elastically to axial stress.FRP allows the alignment the glass fibers of thermoplastics to entourage specific design programs. Specifying the orientation of reinforcing fibers can increase the strength and resistance to deformation of the polymer. Glass reinforced polymers are strongest and most resistive to deforming forces when the polymers fibers ar e parallel to the force being exerted, and are weakest when the fibers are perpendicular.Thus this ability is can be an advantage or a limitation depending on the context of use. Weak spots of perpendicular fibers can be used for natural hinges and connections, but can also lead to material failure when production processes fail to properly orient the fibers parallel to expected forces. When forces are exerted perpendicular to the orientation of fibers, the strength and elasticity of the polymer is less than the matrix alone. In cast resin components made of glass reinforced polymers such as UP and EP, the orientation of fibers can be oriented in insipid and three-dimensional weaves. This means that when forces are possibly perpendicular to one orientation, they are parallel to another orientation this eliminates the potential for weak spots in the polymer.COSTWith the rising cost of nickel, FRP has become a very agonistical material of construction. It is very competitive with ac id brick or rubber-lined carbon steel and much less expensive than alloy-clad carbon steel. It is generally more expensive than resin-coated carbon steel but has a longer service life in most applications. Because FRP does not require insulation, FRP ductwork is actually less expensive than resin-coated carbon steel.ADVANTAGES OF FRPComposites offer the designer a combination of properties not forthcoming in traditional materials. It is possible to introduce the fibres in the polymer matrix at highly stressed regions in a certain position, direction and volume in order to obtain the maximum capability from the reinforcement, and then, within the same(p) member to reduce the reinforcement to a minimal amount at regions of low stress value.FRP products are a cost effective alternative to steel in many of the harshest industrial environments. The advantages of FRP products over other materials includeCorrosion ResistantFibre Reinforced Polymer materials are designed to work out in a ggressive environments. elfin or no coating or treating required.Low maintenance requirementsDesigned and engineered to last, composite structural materials are roughly maintenance free.Impact resistantInherent flexibility allows products to resist impact and failure.Non-conductive and Non metallicFRP constructions provide additional safety by stopping sparks and potential electrical hazards.Fire RetardantFRP has a low flame spread head index when tested under ASTM E-84 and meets self extinguishing requirements of ASTM D-635.High strength-to-weight ratioThe strong, but light weight alternative where heavy lifting or admission fee is an issue.Reduced installation time and costFRP products are easier and lighter to install. familiar hand tools are used to make adjustments. Therefore FRP offers greater efficiency in construction compared with the more conventional materials.DISADVANTAGES OF FRPStructural failure can occur in FRP materials when tensile forces stretch the matrix mor e than the fibers, causing the material to shear at the interface between matrix and fibers, tensile forces near the end of the fibers exceed the tolerances of the matrix, separating the fibers from the matrix and tensile forces can also exceed the tolerances of the fibers causing the fibers themselves to fracture leading to material failure.A stern matter relating to the use of FRPs in civil applications is the lack of design codes and specifications. For more or less a decade now, researchers from Canada, Europe, and Japan have been collaborating their efforts in hope of developing such documents to provide guidance for engineers designing FRP structures.FRP plastics are liable to a number of the issues and concerns surrounding plastic waste disposal and recycling. Plastics pose a particular challenge in recycling processes because they are derived from polymers and monomers that often cannot be separated and returned to their virgin states, for this reason not all plastics can be recycled for re-use, in fact some estimates claim only 20% to 30% of plastics can be material recycled at all.In addition, fibers themselves are difficult to remove from the matrix and preserve for re-use means FRP amplify these challenges. FRP are inherently difficult to separate into base a material that is into fiber and matrix, and the matrix into separate usable plastic, polymers, and monomers. These are all concerns for environmentally informed design today, but it must be noted that plastics often offer savings in energy and economic savings in comparison to other materials, also with the advent of new more environmentally friendly matrices such as bioplastics and UV-degradable plastics, FRP will similarly gain environmental sensitivity.DIFFERENCES BETWEEN effected STEEL REINFORCED CONCRETE AND FIBRE-REINFORCED POLYMER (FRP) CONCRETENo.Conventional Steel Reinforced ConcreteFibre-Reinforced Polymer (FRP) Concrete1DefinitionSteel reinforced concrete is a specific type that has had strong steel rebar added to it while wet, creating a very strong type of concrete that is able to withstand almost anything when it has dried.DefinitionFRP concrete is composite materials made of a polymer matrix reinforced with fibres and typically organized in a laminate structure, such that each lamina (or flat layer) contains an arrangement of unidirectional fibres or woven fibre fabrics embedded within a thin layer of light polymer matrix material.2Corrosion of steel reinforcementExposed steel will corrode in moist atmospheres due to differences in the electrical potential on the steel surface forming anodic and cathodic sites.Corrosion ResistantFibre Reinforced Polymer materials are designed to operate in aggressive environments. Little or no coating or treating