Construction , also called building construction , the techniques and industry involved in the assembly and erection of structures, primarily those used to provide shelter. Construction is an ancient human activity. It began with the purely functional need for a controlled environment to moderate the effects of climate. Constructed shelters were one means by which human beings were able to adapt themselves to a wide variety of climates and become a global species. Human shelters were at first very simple and perhaps lasted only a few days or months.
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Reinforced concrete RC also called reinforced cement concrete or RCC is a composite material in which concrete 's relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength or ductility.
The reinforcement is usually, though not necessarily, steel reinforcing bars rebar and is usually embedded passively in the concrete before the concrete sets. Modern reinforced concrete can contain varied reinforcing materials made of steel, polymers or alternate composite material in conjunction with rebar or not.
Reinforced concrete may also be permanently stressed concrete in compression, reinforcement in tension , so as to improve the behaviour of the final structure under working loads. In the United States, the most common methods of doing this are known as pre-tensioning and post-tensioning. For a strong, ductile and durable construction the reinforcement needs to have the following properties at least:.
Wilkinson reinforced the concrete roof and floors in the two-storey house he was constructing. His positioning of the reinforcement demonstrated that, unlike his predecessors, he had knowledge of tensile stresses. Joseph Monier was a French gardener of the nineteenth century, a pioneer in the development of structural, prefabricated and reinforced concrete when dissatisfied with existing materials available for making durable flowerpots.
In , Monier was granted another patent for a more advanced technique of reinforcing concrete columns and girders with iron rods placed in a grid pattern. Though Monier undoubtedly knew reinforcing concrete would improve its inner cohesion, it is less known if he even knew how much reinforcing actually improved concrete's tensile strength.
Before the use of concrete construction, though dating back to the Roman Empire, and having been reintroduced in the early s, was not yet a proven scientific technology. His work played a major role in the evolution of concrete construction as a proven and studied science. Without Hyatt's work, more dangerous trial and error methods would have largely been depended on for the advancement in the technology. Ernest L. Ransome was an English-born engineer and early innovator of the reinforced concrete techniques in the end of the 19th century.
With the knowledge of reinforced concrete developed during the previous 50 years, Ransome innovated nearly all styles and techniques of the previous known inventors of reinforced concrete. Ransome's key innovation was to twist the reinforcing steel bar improving bonding with the concrete. The home was designed to be fireproof for his wife.
Wayss was a German civil engineer and a pioneer of the iron and steel concrete construction. Up until the s, Wayss and his firm greatly contributed to the advancement of Monier's system of reinforcing and established it as a well-developed scientific technology.
In April , Julia Morgan , an American architect and engineer who pioneered the aesthetic use of reinforced concrete, completed her first reinforced concrete structure, the foot bell tower at Mills College , El Campanil,  which is located across the bay from San Francisco. Two years later, El Campanil survived the San Francisco earthquake without any damage,  which helped build her reputation and launch her prolific career. One of the first skyscrapers made with reinforced concrete was the story Ingalls Building in Cincinnati, constructed in On April 18, a magnitude 7.
The strong ground shaking and subsequent fire destroyed much of the city and killed thousands. The use of reinforced concrete after the earthquake was highly promoted within the U.
In , a partial collapse of the Bixby Hotel in Long Beach killed 10 workers during construction when shoring was removed prematurely. This event spurred a scrutiny of concrete erection practices and building inspections. The structure was constructed of reinforced concrete frames with hollow clay tile ribbed flooring and hollow clay tile infill walls.
Many different types of structures and components of structures can be built using reinforced concrete including slabs , walls , beams , columns , foundations , frames and more. Reinforced concrete can be classified as precast or cast-in-place concrete. Designing and implementing the most efficient floor system is key to creating optimal building structures. Small changes in the design of a floor system can have significant impact on material costs, construction schedule, ultimate strength, operating costs, occupancy levels and end use of a building.
Without reinforcement, constructing modern structures with concrete material would not be possible. Concrete is a mixture of coarse stone or brick chips and fine generally sand or crushed stone aggregates with a paste of binder material usually Portland cement and water.
When cement is mixed with a small amount of water, it hydrates to form microscopic opaque crystal lattices encapsulating and locking the aggregate into a rigid structure.
The aggregates used for making concrete should be free from harmful substances like organic impurities, silt, clay, lignite etc. For this reason, typical non-reinforced concrete must be well supported to prevent the development of tension. If a material with high strength in tension, such as steel , is placed in concrete, then the composite material, reinforced concrete, resists not only compression but also bending and other direct tensile actions.
A composite section where the concrete resists compression and reinforcement " rebar " resists tension can be made into almost any shape and size for the construction industry. Carbonation of concrete along with chloride ingress are amongst the chief reasons for the failure of reinforcement bars in concrete. Reinforcing bars are normally round in cross-section and vary in diameter. Distribution of concrete in spite of reinforcement strength characteristics along the cross-section of vertical reinforced concrete elements is inhomogeneous.
The reinforcement in a RC structure, such as a steel bar, has to undergo the same strain or deformation as the surrounding concrete in order to prevent discontinuity, slip or separation of the two materials under load.
Maintaining composite action requires transfer of load between the concrete and steel. The direct stress is transferred from the concrete to the bar interface so as to change the tensile stress in the reinforcing bar along its length.
This load transfer is achieved by means of bond anchorage and is idealized as a continuous stress field that develops in the vicinity of the steel-concrete interface. Because the actual bond stress varies along the length of a bar anchored in a zone of tension, current international codes of specifications use the concept of development length rather than bond stress.
The main requirement for safety against bond failure is to provide a sufficient extension of the length of the bar beyond the point where the steel is required to develop its yield stress and this length must be at least equal to its development length. However, if the actual available length is inadequate for full development, special anchorages must be provided, such as cogs or hooks or mechanical end plates. The same concept applies to lap splice length mentioned in the codes where splices overlapping provided between two adjacent bars in order to maintain the required continuity of stress in the splice zone.
Good design and a well-chosen concrete mix will provide additional protection for many applications. It can be identified by the unique ASTM specified mill marking on its smooth, dark charcoal finish. Epoxy coated rebar can easily be identified by the light green colour of its epoxy coating.
Hot dip galvanized rebar may be bright or dull grey depending on length of exposure, and stainless rebar exhibits a typical white metallic sheen that is readily distinguishable from carbon steel reinforcing bar. Another, cheaper way of protecting rebars is coating them with zinc phosphate. Penetrating sealants typically must be applied some time after curing. Sealants include paint, plastic foams, films and aluminum foil , felts or fabric mats sealed with tar, and layers of bentonite clay, sometimes used to seal roadbeds.
Corrosion inhibitors , such as calcium nitrite [Ca NO 2 2 ], can also be added to the water mix before pouring concrete. This causes the passivation of steel at the anodic oxidation sites. Nitrite is a much more active corrosion inhibitor than nitrate , which is a less powerful oxidizer of the divalent iron.
A beam bends under bending moment , resulting in a small curvature. At the outer face tensile face of the curvature the concrete experiences tensile stress, while at the inner face compressive face it experiences compressive stress.
A singly reinforced beam is one in which the concrete element is only reinforced near the tensile face and the reinforcement, called tension steel, is designed to resist the tension. A doubly reinforced beam is one in which besides the tensile reinforcement the concrete element is also reinforced near the compressive face to help the concrete resist compression. The latter reinforcement is called compression steel.
When the compression zone of a concrete is inadequate to resist the compressive moment positive moment , extra reinforcement has to be provided if the architect limits the dimensions of the section. An under-reinforced beam is one in which the tension capacity of the tensile reinforcement is smaller than the combined compression capacity of the concrete and the compression steel under-reinforced at tensile face.
When the reinforced concrete element is subject to increasing bending moment, the tension steel yields while the concrete does not reach its ultimate failure condition. As the tension steel yields and stretches, an "under-reinforced" concrete also yields in a ductile manner, exhibiting a large deformation and warning before its ultimate failure. In this case the yield stress of the steel governs the design. An over-reinforced beam is one in which the tension capacity of the tension steel is greater than the combined compression capacity of the concrete and the compression steel over-reinforced at tensile face.
So the "over-reinforced concrete" beam fails by crushing of the compressive-zone concrete and before the tension zone steel yields, which does not provide any warning before failure as the failure is instantaneous. A balanced-reinforced beam is one in which both the compressive and tensile zones reach yielding at the same imposed load on the beam, and the concrete will crush and the tensile steel will yield at the same time.
This design criterion is however as risky as over-reinforced concrete, because failure is sudden as the concrete crushes at the same time of the tensile steel yields, which gives a very little warning of distress in tension failure. Steel-reinforced concrete moment-carrying elements should normally be designed to be under-reinforced so that users of the structure will receive warning of impending collapse.
The design strength or nominal strength is the strength of a material, including a material-safety factor. The value of the safety factor generally ranges from 0. The ultimate limit state is the theoretical failure point with a certain probability.
It is stated under factored loads and factored resistances. Reinforced concrete structures are normally designed according to rules and regulations or recommendation of a code such as ACI, CEB, Eurocode 2 or the like. Analysis and design of RC members can be carried out by using linear or non-linear approaches. When applying safety factors, building codes normally propose linear approaches, but for some cases non-linear approaches.
To see the examples of a non-linear numerical simulation and calculation visit the references:  . Prestressing concrete is a technique that greatly increases the load-bearing strength of concrete beams. The reinforcing steel in the bottom part of the beam, which will be subjected to tensile forces when in service, is placed in tension before the concrete is poured around it.
Once the concrete has hardened, the tension on the reinforcing steel is released, placing a built-in compressive force on the concrete. When loads are applied, the reinforcing steel takes on more stress and the compressive force in the concrete is reduced, but does not become a tensile force.
Since the concrete is always under compression, it is less subject to cracking and failure. Reinforced concrete can fail due to inadequate strength, leading to mechanical failure, or due to a reduction in its durability. When rebar corrodes, the oxidation products rust expand and tends to flake, cracking the concrete and unbonding the rebar from the concrete. Typical mechanisms leading to durability problems are discussed below.
Cracking of the concrete section is nearly impossible to prevent; however, the size and location of cracks can be limited and controlled by appropriate reinforcement, control joints, curing methodology and concrete mix design.
Cracking can allow moisture to penetrate and corrode the reinforcement. 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 under excess loading, or due to internal effects such as early thermal shrinkage while it cures.
Ultimate failure leading to collapse can be caused by crushing the concrete, which occurs when compressive stresses exceed its strength, by yielding or failure of the rebar when bending or shear stresses exceed the strength of the reinforcement, or by bond failure between the concrete and the rebar.
Flexible pipe must deflect to reach its maximum installed performance. Since rods are helically wrapped under tension , the structural integrity of these pipes is greatly enhanced because of the interlocking of steel elements of the pipe. This standard describes the manufacture of circumferentially reinforced concrete pressure pipe, without a steel cylinder and not prestressed, in sizes from 12 in. If you are using for loops, you are most likely coding R as if it was C or Java or something else.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. TABLE 7. While advances in extraction technology are capable of easing our dependence on foreign sources of raw materials, improved technology in other stages of the materials cycle could enhance the effectiveness of materials utilization and hence relieve pressure on new supply.
Offshore vessels are ships that specifically serve operational purposes such as oil exploration and construction work at the high seas. There are a variety of offshore vessels, which not only help in exploration and drilling of oil but also for providing necessary supplies to the excavation and construction units located at the high seas. As mentioned, above, the denotation of offshore vessels is a collective reference and as such includes a wide array of vessels employed in the high seas sector. They can be mainly classified into the following main groups:.
Lightweight concretes can either be lightweight aggregate concrete, foamed concrete or autoclaved aerated concrete AAC. Lightweight concrete blocks are often used in house construction. Lightweight aggregate concrete can be produced using a variety of lightweight aggregates. Lightweight aggregates originate from either:. The required properties of the lightweight concrete will have a bearing on the best type of lightweight aggregate to use. If little structural requirement, but high thermal insulation properties, are needed then a light, weak aggregate can be used. This will result in relatively low strength concrete. Foamed concrete is a highly workable, low-density material which can incorporate up to 75 per cent entrained air.
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Mekonnen Asmare Fentahun 1 , Prof. Need for higher fuel efficiency, weight minimization, environmental regulations and policies as well as customer demand forces the auto maker companies to focus on developing new materials and re designing of the existing one and selecting materials reasonably. All material industries plastics and polymer composites, as well as steel, aluminum, and magnesium, are operating to respond to the automotive industry changing needs. For decades, advanced plastics and polymer composites have helped the improvement of appearance, functionality, and safety of automobiles while reducing vehicle weight and delivering superior value to customers at the same time. Various materials are used to make cars. The main materials used for making cars, parts and components, along with future trends, are steel, aluminum, magnesium, copper, plastics and carbon fibers. The prime reason for using steel in the body structure is its inherent capability to absorb impact energy in a crash situation. The use of aluminum can potentially reduce the weight of the vehicle body.
How Smart, Connected Products Are Transforming Competition
Information technology is revolutionizing products. Once composed solely of mechanical and electrical parts, products have become complex systems that combine hardware, sensors, data storage, microprocessors, software, and connectivity in myriad ways. Information technology is revolutionizing products, from appliances to cars to mining equipment. Products once composed solely of mechanical and electrical parts have become complex systems combining hardware, sensors, electronics, and software that connect through the internet in myriad ways. The changing nature of products is disrupting value chains, argue Michael Porter and PTC CEO James Heppelmann, and forcing companies to rethink nearly everything they do, from how they conceive, design, and source their products; to how they manufacture, operate, and service them; to how they build and secure the necessary IT infrastructure. Smart, connected products raise a broad set of new strategic choices for companies about how value is created and captured, how to work with traditional partners and what new partnerships will be required, and how to secure competitive advantage as the new capabilities reshape industry boundaries. Smart, connected products offer exponentially expanding opportunities for new functionality, far greater reliability, much higher product utilization, and capabilities that cut across and transcend traditional product boundaries.
What are Offshore Vessels?
As an experienced consumer in the English-speaking world, you have almost certainly been the target of IMC a ctivities. Defining marketing communication is tricky because, in a real sense, everything an organization does has communication potential. The price placed on a product communicates something very specific about the product. Marketing communication refers to activities deliberately focused on promoting an offering among target audiences. The following definition helps to clarify this term:. Marketing communication includes all the messages, media, and activities used by an organization to communicate with the market and help persuade target audiences to accept its messages and take action accordingly. Integrated marketing communication is the the process of coordinating all this activity across different communication methods. Integrated marketing communication IMC makes this marketing activity more efficient and effective because it relies on multiple communication methods and customer touch points to deliver a consistent message in more ways and in more compelling ways. Different methods of marketing communication have distinct advantages and complexities, and it requires skill and experience to deploy them effectively. Not surprisingly, marketing communication methods evolve over time as new communication tools and capabilities become available to marketers and the people they target.
Reinforced Concrete Terminology
Reinforced concrete RC also called reinforced cement concrete or RCC is a composite material in which concrete 's relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel reinforcing bars rebar and is usually embedded passively in the concrete before the concrete sets.
A concrete or masonry dam, which is curved upstream so as to transmit the major part of the water load to the abutments. Double curvature arch dam. An arch dam, which is curved vertically as well as horizontally.
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A composite material also called a composition material or shortened to composite, which is the common name is a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure, differentiating composites from mixtures and solid solutions. The new material may be preferred for many reasons. Common examples include materials which are stronger, lighter, or less expensive when compared to traditional materials.