74-668: The Coolidge Dam is a reinforced concrete multiple dome and buttress dam 31 miles (50 km) southeast of Globe, Arizona on the Gila River . Built between 1924 and 1928, the Coolidge Dam was part of the San Carlos Irrigation Project. Coolidge Dam was named after the 30th US president, Calvin Coolidge and was dedicated by President Coolidge on March 4, 1930. The design and construction engineer
148-573: A crest length of 580 feet (180 m). Two uncontrolled ogee crest spillways are concrete-lined and located on each abutment . Construction of the dam incurred opposition from the Apache tribe, who feared a violation of their treaty rights, according to an author writing for the Federal Writers' Project : A compromise was finally made with the Indians, and the tribal burial grounds and
222-539: A factory for zero-emissions heavy trucks , with a production capacity of 2,500 trucks per year. According to the United States Census Bureau , the city has a total area of 5.0 square miles (13 km ), all of it land. It contains no mountains and is almost entirely flat, lying in a fertile valley located just south of the Gila River. The Sacaton Mountains are visible to the west, and
296-452: A female householder with no husband present, and 25.0% were non-families. 20.8% of all households were made up of individuals, and 9.9% had someone living alone who was 65 years of age or older. The average household size was 3.00 and the average family size was 3.44. In the city, the population was spread out, with 32.9% under age 18, 10.4% aged 18–24, 24.4% aged 25–44, 18.9% aged 45–64, and 13.4% who were aged 65 years or older. The median age
370-465: 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
444-583: A hydroelectric plant. A diesel electric generating plant also run by the Project was built simultaneously and located on withdrawn land near the town of Coolidge. The latter facility provided power for irrigation wells, local towns, rural users, and mining operations. The diesel generators no longer function, therefore electricity is delivered to SCIP by the Western Area Power Administration. However, flood damage in 1983 rendered
518-453: 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
592-419: 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,
666-425: A significant flood or an earthquake occur. Earlier floods that had resulted in water topping the dam had eroded the abutments, and the buttresses were judged to be unstable. Work started in 1991 and included an access road to the downstream side of the dam. The work concluded in 1995. The final cost was estimated at $ US46.5 million. ($ 84.9 million in 2023 dollars) In January 1993, heavy rainfall (up to three times
740-426: 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
814-752: Is a city in Pinal County , Arizona , United States. According to the 2020 census , the city's population is 13,218. Coolidge is home of the Casa Grande Ruins National Monument . The monument was the first historic site to receive protected status by the United States Government in 1892. Coolidge is also home to both Central Arizona College and the Central Arizona Valley Institute of Technology . The area containing what
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#1732771957697888-658: 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
962-528: 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
1036-414: Is infrequent, occurring 2–3 days per month usually following the passage of a cold front . The record low temperature for the city is 8 °F (−13 °C). Summers are long and very hot, with temperatures of 100 °F (38 °C) to 110 °F (43 °C) almost daily from the end of May until September, with temperatures above 115 °F (46 °C) not uncommon. The record high temperature for
1110-520: Is just 11 miles (18 km) south of town. Coolidge features a hot desert climate ( Köppen climate classification BWh), typical of the Sonoran Desert . Winters are characterized by abundant sunshine and are typically brief and mild, consisting of daytime highs in the 65 °F (18 °C) to 75 °F (24 °C) range. Lows are usually between 35 °F (2 °C) and 45 °F (7 °C), though several freezes occur annually. Rain
1184-504: 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
1258-618: Is now the City of Coolidge was occupied by the Hohokam , an indigenous ancient Sonoran Desert people who built a massive compound consisting many of caliche structures and remained in the area for over 1,000 years. The only remaining and preserved structure from this compound is the Casa Grande Ruins National Monument. The modern history of the city is centered around agriculture, particularly cotton. Coolidge
1332-541: 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
1406-428: 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
1480-430: 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
1554-463: Is one of the largest lakes in Arizona. The San Carlos Apache Tribe Recreation & Wildlife Dept. stocks several species of fish using various methods to create a good fishing environment. Several species are self-sustaining: Other fish are stocked from cold-water fisheries including brown trout and rainbow trout . Jet-skiing, water skiing and boating are allowed. Individuals who are not members of
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#17327719576971628-447: Is recommended for cyclists traveling east from the dam to Rte 70. 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 is usually, though not necessarily, steel reinforcing bars (known as rebar ) and
1702-579: 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
1776-446: 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
1850-480: 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 the concrete protects the steel rebar from corrosion . Reinforcing schemes are generally designed to resist tensile stresses in particular regions of
1924-454: Is when the area's status as the hub of the Arizona cotton industry was solidified and led to the incorporation of Coolidge as a city in 1945. Up until the 1950s, the city's economy was completely dependent on mining and cotton. It has since diversified to include manufacturing, regional trade , and services for agricultural producers and farm families. In 2019, Nikola Motor Company purchased 389 acres (157 ha) in Coolidge and operates
1998-465: 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 the first iron reinforced concrete structure,
2072-468: 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
2146-719: 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
2220-646: 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
2294-539: The Cotton Express, which provides local bus service. The City of Coolidge also operates Central Arizona Regional Transit (CART), which provides transportation between Florence , Coolidge, Central Arizona College and Casa Grande . The town was home to a station for Amtrak ; it closed in June 1996. The Coolidge Municipal Airport , which has two asphalt runways , is located 5 miles (8.0 km) southeast of
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2368-607: 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
2442-489: The Gila and San Carlos rivers) during January 1993 peaked between 3,000 to 3,500 cubic metres per second (110,000 to 120,000 cu ft/s). The flow from Coolidge Dam reached 927 cubic metres per second (32,700 cu ft/s), about seven times the expected maximum release rate of 133 cubic metres per second (4,700 cu ft/s), and was the highest release rate for the dam since its construction. Discharge at Winkleman
2516-624: The Picacho Mountains are visible to the southeast. Arizona State Route 87 and Arizona State Route 287 pass through the town, providing connections to the Phoenix metropolitan area , Casa Grande , and Eloy . Interstate 10 is located approximately 10 miles (16 km) to the west. Coolidge is 56 miles (90 km) southeast of Phoenix , 69 miles (111 km) northwest of Tucson , 21 miles (34 km) northeast of Casa Grande and 11 miles southwest of Florence . Picacho Reservoir
2590-487: The San Carlos Apache tribe who wish to use the lake must contact the tribal office for a permit since the lake is on tribal land. Bicyclists can ride the access road to the dam face and back. The route is scenic and little-traveled, and rises a total of about 700 feet along the 13 mile route. The elevation at the dam is about the same as the starting point, so the trip is not strictly a climb, but peaks about
2664-695: 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
2738-461: 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
2812-543: 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
2886-537: The city is 123 °F (51 °C). Summertime lows are usually above 70 °F (21 °C), with occasional periods of lows above 80 °F (27 °C). Coolidge is affected by the North American Monsoon , which brings brief heavy downpours and gusty winds in the second half of summer. Severe events can sometimes cause haboobs and flash flooding . As of the census of 2000, there were 7,786 people, 2,585 households, and 1,938 families residing in
2960-756: 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
3034-598: The city. The population density was 1,549.1 inhabitants per square mile (598.1/km ). There were 3,212 housing units at an average density of 639.1 per square mile (246.8/km ). The racial makeup of the city was 57.9% White , 8.3% Black or African American , 5.6% Native American , 0.7% Asian , 0.1% Pacific Islander , 23.6% from other races , and 3.8% from two or more races. 39.2% of the population were Hispanic or Latino of any race. There were 2,585 households, out of which 38.5% had children under age 18 living with them, 48.8% were married couples living together, 19.3% had
Coolidge Dam - Misplaced Pages Continue
3108-422: 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
3182-541: 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
3256-412: 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
3330-423: 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 the behavior of the final structure under working loads. In
3404-416: 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
3478-445: 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. Carbonation, or neutralisation, is a chemical reaction between carbon dioxide in the air and calcium hydroxide and hydrated calcium silicate in the concrete. Coolidge, Arizona Coolidge
3552-403: 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
3626-568: The dam in 1930, the dam had not begun to fill. Humorist Will Rogers looked at the grass in the lake bed, and said, "If this were my lake, I'd mow it." Coolidge Dam was constructed between 1924 and 1928 by the Bureau of Indian Affairs (BIA), which also owns and operates it, at a cost of US$ 10 million. The overall structure used 200,000 cubic yards (150,000 m) of concrete and consists of three domes, which are supported by buttresses on 100-foot (30 m) centers. It rises 249 feet (76 m), with
3700-403: 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,
3774-568: 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
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#17327719576973848-399: The force of the water and failed. The water flow was concentrated through the release gates, as opposed to letting the water overtop the dam, which would have created a different scour rate. The force of the Gila River undermined and ultimately caused the failure of the north and south abutments of the bridge crossing at Attaway Road, upstream from Coolidge. The flow into San Carlos Lake (from
3922-468: The hydroelectric station inoperable and restoration plans have been deemed infeasible. The electric plant at the dam was completed and began generating electricity in 1935, and the diesel plant was completed in December of that year and produced electricity the following year. In 1988, the Bureau of Reclamation completed a study that concluded that the dam needed modifications to prevent a failure should
3996-660: 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
4070-824: 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
4144-438: 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
4218-404: The middle of the distance and then descends again to about 2,600 ft. When they reach the dam, cyclists can either return to the starting point along the two-lane paved road, or they can continue eastward along the rougher part of the road until it rejoins U.S. Route 70 . Before traveling on the reservation, non-tribe members must obtain a permit. A mountain bike or other rugged type bicycle
4292-656: 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
4366-460: The normal amount) in Arizona filled San Carlos Lake, and the operators were forced to release excess water. The ground was saturated, and the continuing rainfall ran off into the streams and rivers. In addition, the weather pattern for the year caused higher than normal temperatures in areas that would typically remain under snow. These areas received rain instead of snow, and the rivers began to run earlier and with far more volume than normal. Rivers in
4440-577: The old camp from which Geronimo started his bloody raids now lie deep under the waters of the reservoir . It was proposed to disinter the bodies but the Apache vehemently objected to what they considered desecration of the dead, so a concrete slab was laid over the principal burial ground at a cost of $ 11,000. As part of the San Carlos Indian Irrigation Project (SCIIP), Coolidge Dam formerly generated electricity from
4514-448: 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
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#17327719576974588-509: The poverty line, including 30.9% of those under age 18 and 20.5% of those age 65 or over. In 2010, Coolidge had a population of 11,825. The racial and ethnic composition of the population was 43.6% non-Hispanic white, 7.3% non-Hispanic black, 0.5% Hispanic blacks, 3.8% non-Hispanic Native American, 1.9% Hispanic or Latino Native American, 1.0% Asian, 0.1% Pacific Islander, 0.1% non-Hispanic from some other race, 5.0% from two or more races and 42.0% Hispanic or Latino. The City of Coolidge operates
4662-433: 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
4736-581: 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
4810-484: The southern part of Arizona at that time contained anywhere from three to nearly six times their normal amount of water. To complicate matters, the snowpack was already 150% the normal amount. Dam operators for Coolidge Dam released water in record levels because storage capacity had been reached. As a result of the heavy water releases, several El Paso Natural Gas pipelines, which crossed the Gila River near Coolidge , Winkelman , and Kelvin were "scoured" or uncovered by
4884-474: 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
4958-454: 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
5032-403: 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
5106-406: Was 31 years. For every 100 females, there were 93.2 males. For every 100 females age 18 and over, there were 88.1 males. The median income for a household in the city was $ 29,049, and the median income for a family was $ 33,536. Males had a median income of $ 29,159 versus $ 21,472 for females. The per capita income for the city was $ 13,663. About 20.9% of families and 24.7% of the population were below
5180-565: Was Herman Neuffer, who oversaw much of the construction undertaken by the Bureau of Indian Affairs (BIA) during the 1920s in Arizona and New Mexico. Coolidge Dam impounds San Carlos Lake on the San Carlos Apache Indian Reservation . The project irrigates 100,000 acres (40,000 ha). Since the water is impounded so it can be released when farmers need it, San Carlos Lake is often at a low level except in wet periods. When former President Coolidge dedicated
5254-500: Was founded in 1925 when R.J. Jones laid out an 80 acres (32 ha) site during the construction of the Coolidge Dam on the nearby Gila River , which was completed in 1930. Both the dam and the townsite were named for Calvin Coolidge , the 30th President of the United States. The dam made the sandy soil native to the area into very rich farmland , and soon vast expanses of desert were plowed and acres of cotton were planted. This
5328-404: 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
5402-413: Was recorded at 1,050 cubic metres per second (37,000 cu ft/s) on January 20, 1993. Winkleman Flats, a small area near Winkleman, was flooded as well. However, despite earlier concerns about the dam's safety, it survived the flood even though retrofit work was in process at the time. San Carlos Lake is stocked periodically, and when the winter has experienced average or above average precipitation,
5476-422: 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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