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64-649: The Salzhaus was originally built around 1600. It had a rich carved façade on the gable side, making it not only the most important artisan-produced civil building in the city, but also one of the greatest achievements of the Renaissance in the German-speaking world . This building was largely destroyed in World War Two by aerial bombing in March 1944 . The base of the old building was preserved, but

128-525: A Georgian building, but the appearance is only skin deep and some of the interior rooms still have Jacobean plasterwork ceilings. This new construction has happened also in other places: in Santiago de Compostela the three-metre-deep Casa do Cabido was built to match the architectural order of the square, and the main Churrigueresque façade of the Santiago de Compostela Cathedral , facing

192-453: 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 might have been depended on for the advancement in the technology. Joseph Monier , a 19th-century French gardener, was a pioneer in the development of structural, prefabricated and reinforced concrete, having been dissatisfied with the existing materials available for making durable flowerpots. He

256-419: A reduction in its durability. Corrosion and freeze/thaw cycles may damage poorly designed or constructed reinforced concrete. 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,

320-426: A well-chosen concrete mix will provide additional protection for many applications. Uncoated, low carbon/chromium rebar looks similar to standard carbon steel rebar due to its lack of a coating; its highly corrosion-resistant features are inherent in the steel microstructure. 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

384-658: Is a mixture of coarse (stone or brick chips) and fine (generally sand and/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 shape. The aggregates used for making concrete should be free from harmful substances like organic impurities, silt, clay, lignite, etc. Typical concrete mixes have high resistance to compressive stresses (about 4,000 psi (28 MPa)); however, any appreciable tension ( e.g., due to bending ) will break

448-528: Is coating them with zinc phosphate . Zinc phosphate slowly reacts with calcium cations and the hydroxyl anions present in the cement pore water and forms a stable hydroxyapatite layer. 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

512-504: Is located across the bay from San Francisco . Two years later, El Campanil survived the 1906 San Francisco earthquake without any damage, which helped build her reputation and launch her prolific career. The 1906 earthquake also changed the public's initial resistance to reinforced concrete as a building material, which had been criticized for its perceived dullness. In 1908, the San Francisco Board of Supervisors changed

576-541: 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

640-428: 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 the section in which besides the tensile reinforcement the concrete element is also reinforced near the compressive face to help the concrete resist compression and take stresses. The latter reinforcement is called compression steel. When

704-430: 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

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768-579: 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-318, CEB, Eurocode 2 or the like. WSD, USD or LRFD methods are used in design of RC structural members. 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

832-446: 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. The reasons that the two different material components concrete and steel can work together are as follows: (1) Reinforcement can be well bonded to

896-487: Is typically reached within minutes of the start of a fire. Fire stops for such building joints can be qualified, too. Putting fire sprinkler systems on each floor has a profoundly positive effect on the fire safety of buildings with curtain walls. The extended use of new materials, like polymers , resulted in an increase of high-rise building façade fires over the past few years, since they are more flammable than traditional materials. Some building codes also limit

960-404: Is usually, though not necessarily, steel reinforcing bars (known as rebar ) and is usually embedded passively in the concrete before the concrete sets. However, post-tensioning is also employed as a technique to reinforce the concrete. In terms of volume used annually, it is one of the most common engineering materials. In corrosion engineering terms, when designed correctly, the alkalinity of

1024-522: The Plaza del Obradoiro , is actually encasing and concealing the older Portico of Glory . In modern high-rise building, the exterior walls are often suspended from the concrete floor slabs. Examples include curtain walls and precast concrete walls. The façade can at times be required to have a fire-resistance rating , for instance, if two buildings are very close together, to lower the likelihood of fire spreading from one building to another. In general,

1088-468: The tensile strength of concrete was improved by the reinforcing. Before the 1870s, the use of concrete construction, though dating back to the Roman Empire , and having been reintroduced in the early 19th century, was not yet a proven scientific technology. Ernest L. Ransome , an English-born engineer, was an early innovator of reinforced concrete techniques at the end of the 19th century. Using

1152-719: The 1890s, Wayss and his firm greatly contributed to the advancement of Monier's system of reinforcing, established it as a well-developed scientific technology. One of the first skyscrapers made with reinforced concrete was the 16-story Ingalls Building in Cincinnati, constructed in 1904. The first reinforced concrete building in Southern California was the Laughlin Annex in downtown Los Angeles , constructed in 1905. In 1906, 16 building permits were reportedly issued for reinforced concrete buildings in

1216-697: The City of Los Angeles, including the Temple Auditorium and 8-story Hayward Hotel. In 1906, a partial collapse of the Bixby Hotel in Long Beach killed 10 workers during construction when shoring was removed prematurely. That 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. That practice

1280-607: The English counties of Norfolk and Suffolk. In 1877, Thaddeus Hyatt , published a report entitled An Account of Some Experiments with Portland-Cement-Concrete Combined with Iron as a Building Material, with Reference to Economy of Metal in Construction and for Security against Fire in the Making of Roofs, Floors, and Walking Surfaces , in which he reported his experiments on the behaviour of reinforced concrete. His work played

1344-749: The French façade , which in turn comes from the Italian facciata , from faccia meaning 'face', ultimately from post-classical Latin facia . The earliest usage recorded by the Oxford English Dictionary is 1656. It was quite common in the Georgian period for existing houses in English towns to be given a fashionable new façade. For example, in the city of Bath , The Bunch of Grapes in Westgate Street appears to be

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1408-535: The Salzhaus in various documents in the 14th century, which derived from the salt trade taking place there. It is likely that until the early 17th century there were two independent, very narrow half-timbered buildings on the plot, commonly known as the Salzhaus. This is shown both by pictures of the Römerberg from various older coronation records. On May 1, 1843, the city acquired the house and integrated it with

1472-467: The Salzhaus was built on a massive ground floor made of local red sandstone. As the only part of the building that has been preserved almost holistically to this day, the mastery of the Frankfurt stone masonry is still evident today. The half-timbered part of the building rose above the stone ground floor into two upper and upper cantilever levels, cantilevering north and east. From the ground floor to

1536-665: The Salzhaus was considered one of the most beautiful buildings in Central Europe. In terms of quality, the Kammerzell House in Strasbourg is comparable, since it was similarly redesigned in 1589, but in contrast it survived not only the Franco-Prussian war , but also both world wars without damage. The first mention of the building goes back to a document dated May 5, 1324. It was being referred to as

1600-695: 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. In wet and cold climates, reinforced concrete for roads, bridges, parking structures and other structures that may be exposed to deicing salt may benefit from use of corrosion-resistant reinforcement such as uncoated, low carbon/chromium (micro composite), epoxy-coated, hot dip galvanized or stainless steel rebar. Good design and

1664-461: 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

1728-544: The ashes. Today the city's Salzhaus serves as an administration building with an information centre for tourists on the ground floor. In the 1980s, there were efforts by citizens to rebuild the Salzhaus true to the original. This didnt happen due to a lack of money. An exhibition of the fragments in the Historisches Museum Frankfurt in December 2004 also showed that not as much building substance

1792-479: The behavior 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: François Coignet used iron-reinforced concrete as a technique for constructing building structures. In 1853, Coignet built

1856-543: The chief reasons for the failure of reinforcement bars in concrete. The relative cross-sectional area of steel required for typical reinforced concrete is usually quite small and varies from 1% for most beams and slabs to 6% for some columns. Reinforcing bars are normally round in cross-section and vary in diameter. Reinforced concrete structures sometimes have provisions such as ventilated hollow cores to control their moisture & humidity. Distribution of concrete (in spite of reinforcement) strength characteristics along

1920-756: The city's building codes to allow wider use of reinforced concrete. In 1906, the National Association of Cement Users (NACU) published Standard No. 1 and, in 1910, the Standard Building Regulations for the Use of Reinforced Concrete . Many different types of structures and components of structures can be built using reinforced concrete elements including slabs , walls , beams , columns , foundations , frames and more. Reinforced concrete can be classified as precast or cast-in-place concrete . Designing and implementing

1984-422: 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

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2048-521: The concrete protects the steel rebar from corrosion . Reinforcing schemes are generally designed to resist tensile stresses in particular regions of the concrete that might cause unacceptable cracking and/or structural failure. 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

2112-541: The concrete resists compression and reinforcement " rebar " resists tension can be made into almost any shape and size for the construction industry. Three physical characteristics give reinforced concrete its special properties: As a rule of thumb, only to give an idea on orders of magnitude, steel is protected at pH above ~11 but starts to corrode below ~10 depending on steel characteristics and local physico-chemical conditions when concrete becomes carbonated. Carbonation of concrete along with chloride ingress are amongst

2176-412: The concrete roof and floors in the two-story house he was constructing. His positioning of the reinforcement demonstrated that, unlike his predecessors, he had knowledge of tensile stresses. Between 1869 and 1870, Henry Eton would design, and Messrs W & T Phillips of London construct the wrought iron reinforced Homersfield Bridge bridge, with a 50' (15.25 meter) span, over the river Waveney, between

2240-416: The concrete, thus they can jointly resist external loads and deform. (2) The thermal expansion coefficients of concrete and steel are so close ( 1.0 × 10 to 1.5 × 10 for concrete and 1.2 × 10 for steel) that the thermal stress-induced damage to the bond between the two components can be prevented. (3) Concrete can protect the embedded steel from corrosion and high-temperature induced softening. Because

2304-403: 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

2368-467: The debris in the old town. By 1950 the rubble and ruins had been completely removed. In that time the decision had been made for a modern reconstruction based on the ideas of urban planning at the time. The “New Salzhaus” was completed in 1952. There was a serious discussion about the pros and cons of a possible reconstruction of the Salzhaus. However, there was an architectural community and also large parts of politics, which were opposed to "historicism of

2432-513: The eastern city centre. The Salzhaus remained undamaged again, although the Paulskirche on the opposite side of the street was hit and burned out completely. On March 22, the heaviest air raid hit the old town . More than seven thousand buildings were destroyed or badly damaged. The Salzhaus was also hit by incendiary bombs and burned down. The entire interior was lost, only parts of the stone basement remained. In 1946, work began on clearing

2496-403: 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,

2560-401: The façade of a building is often the most important aspect from a design standpoint, as it sets the tone for the rest of the building. From the engineering perspective, the façade is also of great importance due to its impact on energy efficiency . For historical façades, many local zoning regulations or other laws greatly restrict or even forbid their alteration. The word is a loanword from

2624-472: The façade systems that are suspended or attached to the precast concrete slabs will be made from aluminum (powder coated or anodized) or stainless steel . In recent years more lavish materials such as titanium have sometimes been used, but due to their cost and susceptibility to panel edge staining these have not been popular. Whether rated or not, fire protection is always a design consideration. The melting point of aluminum, 660 °C (1,220 °F),

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2688-568: The first concrete buildings constructed in the United States was a private home designed by William Ward , completed in 1876. The home was particularly designed to be fireproof. G. A. Wayss was a German civil engineer and a pioneer of the iron and steel concrete construction. In 1879, Wayss bought the German rights to Monier's patents and, in 1884, his firm, Wayss & Freytag , made the first commercial use of reinforced concrete. Up until

2752-511: The first iron reinforced concrete structure, a four-story house at 72 rue Charles Michels in the suburbs of Paris. Coignet's descriptions of reinforcing concrete suggests that he did not do it for means of adding strength to the concrete but for keeping walls in monolithic construction from overturning. The, 1872–1873, Pippen building in Brooklyn stands as a testament to his technique. In 1854, English builder William B. Wilkinson reinforced

2816-479: The floors above it were rebuilt in 1951/52 in a simple post-war architectural form. The reconstruction of the historic facade is still under discussion; it was considered in the 1980s along with a row of houses on the other side of the square (the Ostzeile) but was not carried out. Since then, the organisation Friends of Frankfurt have continued this discussion. Like most of the buildings in Frankfurt's old town,

2880-467: The front if necessary for a scene . Within theme parks, they are usually decoration for the interior ride or attraction, which is based on a simple building design. Reinforced concrete Reinforced concrete , also called ferroconcrete , is a composite material in which concrete 's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement

2944-427: The gable, the building was 22 metres high, and at the widest point only 10 metres across. The fact that the roof structure alone made up almost half of the total height of the building emphasised the late Gothic proportions, despite the rich Renaissance decorations. Probably shortly after 1595 the house was completely redesigned in the style of the late Renaissance, or probably even completely rebuilt. From then on,

3008-484: The historic parts removed. This included all removable relief panels from the Salzhaus - only the carvings worked into the supporting beams of the actual half-timbered house remain on site. On October 5, 1943, the first heavy bomb attack hit the city centre. Incendiary bombs devastated the interior of the Roman and the civil hall. The neighbouring salt house was initially spared. On March 18, 1944, about 750 aircraft attacked

3072-555: The house adjoining it to create a building complex around the Römerberg square. In the years 1887 to 1888, urgently needed renovation work took place. City officials moved into the house in 1890. In the Second World War it became apparent from July 1942 at the latest that Frankfurt would also be the target of heavy bombing . A large part of the historically significant buildings in the old town of Frankfurt were then documented and immovable art monuments were walled in or had

3136-660: The knowledge of reinforced concrete developed during the previous 50 years, Ransome improved nearly all the styles and techniques of the earlier inventors of reinforced concrete. Ransome's key innovation was to twist the reinforcing steel bar, thereby improving its bond with the concrete. Gaining increasing fame from his concrete constructed buildings, Ransome was able to build two of the first reinforced concrete bridges in North America. One of his bridges still stands on Shelter Island in New Yorks East End, One of

3200-824: The light green color of its epoxy coating. Hot dip galvanized rebar may be bright or dull gray depending on length of exposure, and stainless rebar exhibits a typical white metallic sheen that is readily distinguishable from carbon steel reinforcing bar. Reference ASTM standard specifications A1035/A1035M Standard Specification for Deformed and Plain Low-carbon, Chromium, Steel Bars for Concrete Reinforcement, A767 Standard Specification for Hot Dip Galvanized Reinforcing Bars, A775 Standard Specification for Epoxy Coated Steel Reinforcing Bars and A955 Standard Specification for Deformed and Plain Stainless Bars for Concrete Reinforcement. Another, cheaper way of protecting rebars

3264-438: The microscopic rigid lattice, resulting in cracking and separation of the concrete. 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

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3328-656: 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. When reinforced concrete elements are used in construction, these reinforced concrete elements exhibit basic behavior when subjected to external loads . Reinforced concrete elements may be subject to tension , compression , bending , shear , and/or torsion . Concrete

3392-448: 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

3456-600: The percentage of window area in exterior walls. When the exterior wall is not rated, the perimeter slab edge becomes a junction where rated slabs are abutting an unrated wall. For rated walls, one may also choose rated windows and fire doors , to maintain that wall's rating. On a film set and within most themed attractions, many of the buildings are only façade, which are far cheaper than actual buildings, and not subject to building codes (within film sets). In film sets, they are simply held up with supports from behind, and sometimes have boxes for actors to step in and out of from

3520-401: The previous building. The decoration of the new building, on the other hand, is unusually rich for the time it was built. Below the windows there is limestone cladding, the eastern side is occupied by a glass mosaic spanning the three full storeys by the artist Wilhelm Geißler. It is intended to symbolise the mood of development and departure after the war and shows the motif of the phoenix from

3584-433: 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

3648-420: The romantic kind" (Mayor Kurt Blaum), and still a great shortage of materials and finance. Nevertheless, the new Salzhaus belongs to the small number of buildings from the early 1950s which are to be regarded as an artistic contribution of a time that is primarily determined by material constraints. The “Salzhaus” of the post-war period is a modern reinforced concrete building on the preserved ground floor of

3712-581: 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 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

3776-474: The structure will receive warning of impending collapse. The characteristic strength is the strength of a material where less than 5% of the specimen shows lower strength. 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 0.75 to 0.85 in Permissible stress design . The ultimate limit state

3840-454: 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

3904-403: The water mix before pouring concrete. Generally, 1–2 wt. % of [Ca(NO 2 ) 2 ] with respect to cement weight is needed to prevent corrosion of the rebars. The nitrite anion is a mild oxidizer that oxidizes the soluble and mobile ferrous ions (Fe ) present at the surface of the corroding steel and causes them to precipitate as an insoluble ferric hydroxide (Fe(OH) 3 ). This causes

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3968-404: Was granted a patent for reinforcing concrete flowerpots by means of mixing a wire mesh and a mortar shell. In 1877, Monier was granted another patent for a more advanced technique of reinforcing concrete columns and girders, using iron rods placed in a grid pattern. Though Monier undoubtedly knew that reinforcing concrete would improve its inner cohesion, it is not clear whether he even knew how much

4032-637: Was lost in the Second World War as is generally assumed - around 60% of the facade is still intact in city archives. 50°06′39″N 8°40′55″E  /  50.1108°N 8.6819°E  / 50.1108; 8.6819 Facade A façade or facade ( / f ə ˈ s ɑː d / ; ) is generally the front part or exterior of a building . It is a loanword from the French façade ( pronounced [fasad] ), which means " frontage " or " face ". In architecture ,

4096-422: Was strongly questioned by experts and recommendations for "pure" concrete construction were made, using reinforced concrete for the floors and walls as well as the frames. In April 1904, Julia Morgan , an American architect and engineer, who pioneered the aesthetic use of reinforced concrete, completed her first reinforced concrete structure, El Campanil, a 72-foot (22 m) bell tower at Mills College , which

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