Note from the publisher: Now in its sixth edition, this bestselling reference focuses on the basic materials and methods used in building construction. Emphasizing common construction systems such as light wood frame, masonry bearing wall, steel frame, and reinforced concrete construction, the new edition includes new information on building materials properties; the latest on "pre-engineered" building components and sustainability issues; and reflects the latest building codes and standards. It also features an expanded series of case studies along with more axonometric detail drawings and revised photographs for a thoroughly illustrated approach. Edward Allen, FAIA, has taught for forty years as a faculty member at Yale University and the Massachusetts Institute of Technology, and has frequently taught as a guest lecturer at other institutions throughout the United States. He has designed more than fifty constructed buildings and is the bestselling coauthor of The Architect's Studio Companion, Architectural Detailing, Form and Forces , and Fundamentals of Residential Construction , all published by Wiley. Joseph Iano is an author, illustrator, and practicing architect who has taught design and technology in schools of architecture throughout the United States, and has also worked in the construction trades.
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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.
The great fires of the s in Chicago, New York, and elsewhere spurred a technology race to develop the best fireproof floor system. The years between the s and s represented a golden age of new technology in structural systems. Cast iron, wrought iron, structural steel and reinforced concrete framing systems, terra cotta arch construction, cinder concrete slabs, and many proprietary systems were introduced during this period. Of these varied archaic systems, cinder concrete slab construction became one of the most dominant structural slab systems used from the s to the s.
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:.
Crimped wire mesh is usually used for reinforcement of ferroconcrete items or brickwork; it is used also as fencing, frames for greenhouse, cages for birds or animals etc. This kind of wire mesh is made of carbon iron wire, galvanized steel wire or stainless steel wire. Crimped wire mesh is woven after wire being crimped. Wire diameters are 3; 4; 5; 6,5 mm. Conveyer mesh belts are used in conveyer lines for drying of various materials and food products.SEE VIDEO BY TOPIC: Australia Reinforcing Wire Mesh, Reo Mesh, Steel Reinforcing Mesh, Concrete Reinforcing Mesh
This invention relates to a barge on which reinforced concrete goods, such as Hume pipes and concrete piles, are manufactured. It has been customary that, when given reinforced concrete products are in demand at a place distant, for example across the sea, from a cement- and reinforcement-producing district, either precast products are sent by sea to the site where they are desired, or a factory is temporarily built at or near that site to meet the local demand. However, the marine transportation of the precast goods requires much freight and can cause damage when the destination is very far from the place of origin. The temporary construction of a factory at the place of consumption is not economically justified unless the demand is sufficiently large. The construction work in a remote area can take more time than expected and cause a delay in the delivery of the products. In addition, an unduly large proportion of the equipment can be damaged, worn out, or otherwise lost during the course of dismantling after the local demand has been satisfied. Another possible method is to manufacture the reinforced concrete products off the coast of the consuming district, by a so-called floating plant. Such a plant, if built to be a reproduction in layout of a land plant of the same scale, would require a formidably large plane area; the vessel would have too large a breadth for towing or handling otherwise.
Ну а вы для начала должны определить, что хотите видеть и. На стене гостиной Паккеттов появилось превосходное цветное изображение симпатичного мальчишки, заполнявшего все чрево матери. Макс и Эпонина радовались почти целый час, когда выяснилось, что у них будет мальчик. Время шло, и Николь удалось определить то, что она хотела, а качество картинок быстро улучшалось.
Разве может существо, обладающее хотя бы крупицей разума, оправдать накопление небольшим числом особ огромных материальных ценностей, когда у остальных нет еды, одежды и прочих самых необходимых вещей. В подвале Арчи держался не столь уклончиво и ненавязчиво, как бывало иногда в Изумрудном городе.
Сама понимаешь. Однако я недооценивала Макса. Он действительно необычный человек. Под этой грубой внешностью. Эпонина умолкла. Николь широко улыбалась. - Едва ли Макс способен одурачить кого-нибудь. по крайней мере тех, кто знает. Грубиян и ругатель - просто маска, зачем-то придуманная (быть может, для самозащиты) на той же ферме в Арканзасе.
Обе женщины помолчали несколько секунд.
Я провожу. Симона проводила мать по длинному коридору к дверце из имитированной - Итак, с вами здесь живут шестеро детей, - проговорила Николь, - в том числе трое, которых ты выносила и родила. - Да, это. У нас с Майклом было двое мальчиков и двое девочек, рожденных "естественным методом", как ты говоришь. Старший, Даррен, умер, когда ему было семь. долгая история, и, если у нас будет время, я расскажу тебе ее завтра.
Все остальные дети выросли из эмбрионов в их лаборатории. Они добрались до дверей в туалетную. - А ты знаешь, сколько твоих детей вырастили Орел и его коллеги. - спросила Николь.
На какое-то время она успокоилась, хотя шум над головой становился сильнее. Но когда над входом в ее укрытие принялись двигать огромные мешки с цыплячьим кормом, страх вернулся. "Вот оно, - сказала себе Николь. - Сейчас меня вновь арестуют". Николь подумала, не убьют ли ее полицейские сразу как только обнаружат. Услыхав громкий металлический стук у входа в ее подземелье, она не смогла усидеть на месте. Приподнявшись, Николь ощутила, как в груди два раза болезненно кольнуло, ей стало трудно дышать.
Воскликнула Николь. - Я так рада. - Она встала и обняла - И ты _веришь_ в .
Став на четвереньки, они направились по грунтовому ходу сперва параллельно полу, но через несколько метров он круто повернул. Было очень тесно.
Ричард улыбнулся. - О'кей. Какого же рода эмоции ты выражаешь.
Открылась дверь, из коридора вошел октопаук, торопливо заговоривший с Синим Доктором с помощью весьма узких цветовых полос. Николь разобрала только слова "разрешение" и "сегодня днем". Когда гость удалился, Синий Доктор сказала Николь, что ее ждет сюрприз. - Сегодня одна из наших цариц будет класть яйца.