69-544: Grafton Bridge is a road bridge spanning Grafton Gully in Auckland , New Zealand. Built of reinforced concrete in 1910, it connects the Auckland CBD and Karangahape Road with Grafton . It spans about 97.6 metres (320 feet), rises 25.6 metres (84 feet) above the abutments to a height of around 43 metres (141 feet) over the gully . When the bridge was constructed, it contained the largest reinforced concrete arch in
138-605: A feature of the bridge. These repairs cost £21,800. After this point a weight limit was imposed on traffic using the bridge; even during the Second World War the large trucks used by the US Forces stationed in the camp located in the Domain were not allowed to drive over Grafton Bridge. Further reinforcing was carried out in 1957. The bridge was closed for reinforcement works between late 2008 and October 2009 as part of
207-453: 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
276-540: A quiet re-installation in 2002). There have been no suicides from the bridge since then until 2015, and the feature has been called an example of best practice of preventing such acts. The bridge in 2007 carried around 13,000 vehicles per day. Starting in 2009, Auckland City planned to use the bridge as a major part of the Central Connector project, connecting downtown Auckland and the commercial centre of Newmarket with improved bus services. This resulted in
345-419: 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,
414-725: 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 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
483-426: 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
552-415: 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 is usually embedded passively in the concrete before the concrete sets. However, post-tensioning is also employed as
621-658: 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
690-528: 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
759-478: Is crossed by Grafton Bridge near its south end. Symonds Street Cemetery lies on its western slope. The gully is of the few areas in central Auckland that has not been claimed by buildings or for recreation (mostly due to the steepness of its sides), though prior to the construction of the motorway part of the gully was occupied by the Blandford Park sports facility until the mid-1960s. Large parts of
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#1732776649085828-504: 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
897-541: 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
966-428: 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
1035-430: 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
1104-515: Is open to all traffic. [REDACTED] Media related to Grafton Bridge at Wikimedia Commons Grafton Gully Grafton Gully is a deep (about 50 m) and very wide (about 100 m) gully running northwards towards the sea through the volcanic hills of the Auckland volcanic field in New Zealand. It divides the CBD from the suburbs of Grafton and Parnell in the east. The Grafton Gully
1173-579: 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
1242-446: 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
1311-547: The Auckland City Hospital needed to take a longer route. The bridge carries one traffic lane in each direction and a footpath on each side. It underwent reinforcing repairs in 1938 when cracks were discovered in the Vierendeel frames of the approach areas of the bridge. The remedy was to erect two steel trusses on the deck to support the damaged area. The octagonal openings were filled in and are no longer
1380-485: The Central Connector , a 3 km bus priority route connecting the Auckland CBD to Newmarket and other destinations. It received a $ 7 million carbon fibre strengthening upgrade to bring it up to current earthquake standards and to enable it to serve as a dedicated route for large numbers of buses. It can now accommodate up to 1200 bus trips a day. The bridge now has a load-carrying capacity of 40 tonnes, instead of
1449-590: The Symonds Street Cemetery , a historic Auckland cemetery containing the graves of many important early settlers, including the first Governor William Hobson . When the current bridge was constructed the cemetery had been in existence for 70 years, and the bridge was inserted in such a way as to require the moving of only eight graves. Built of reinforced concrete by the Ferro-Concrete Company of Australasia Ltd , at opening it
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#17327766490851518-468: 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
1587-719: 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
1656-595: The CBD and Newmarket , and is closed to private vehicles except taxis during the day. Prior to the current structure, two previous bridges spanned the Grafton gully. The first, built in 1884, was a cable-stay pedestrian bridge from the bottom of St Martins Lane to Bridge Street in Grafton (the current bridge connects Karangahape Road and Grafton Road). Designed by the City Engineer Edward Anderson,
1725-697: 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
1794-607: 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
1863-529: The Ferro-Concrete Company of Australasia. The city's engineer, W. E. Bush, who supervised the project, recommended the more expensive option, as maintenance costs would be significantly less than the steel option. The ferro-concrete design of the bridge was championed by the mayor Arthur Myers , who advocated for it to be twice as wide as built. Even in its narrower form it was to cost £31,918, resulting in it being called "Myers' Folly" by many at
1932-673: The Howard Taft Memorial Bridge in Washington DC Taft Bridge which took ten years to construct 1897-1907 (as opposed to the two years for Grafton Bridge). In order to dispel doubts about the strength of the still relatively untested type of construction, at the opening in April 1910 two steam rollers were driven across it. This lack of trust also led to a stipulation in the original construction contract that no progress payments should be made, causing
2001-695: 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
2070-461: 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
2139-479: 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
Grafton Bridge - Misplaced Pages Continue
2208-440: The bridge becoming a 7am to 7pm bus lane with other traffic banned, prioritizing up to 1,500 daily bus trips and up to 65,000 passengers. For this project, somewhat controversial due to the interruption of the direct car connection to Grafton , the bridge was tested and in 2008–2009, strengthened. The modification design was undertaken by Beca, Carter, Hollings & Ferner . The modifications, which for structural reasons closed
2277-441: The bridge opened in April 1910. Construction was difficult due to the steep Grafton gully, covered in native bush. During the project, the Ferro-Concrete Company declared bankruptcy, likely due to the terms of the contract for the bridge which stipulated that no progress payments could be made to the company until the concrete arches were completed and tested. Work was finished by Auckland City council labour. The bridge crosses part of
2346-538: The bridge to all but cyclist and pedestrian traffic starting October 2008, were to ensure that the weight limit could be raised from 13 tons to 40 tons, allowing heavier buses to cross. The works also ensured that the bridge would be able to withstand a 1000-year earthquake. The bridge had been found to be in good shape, despite around 2,800 primarily minor faults being found during the upgrade, and only two pieces of reinforcing steel had to be replaced. Costs were originally expected to be around $ 7.3 million for new anchors at
2415-543: 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
2484-756: 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
2553-422: 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
2622-541: 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
2691-412: 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
2760-416: 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
2829-475: The construction company to go into bankruptcy , with the bridge having to be completed by the city. This also added to the final costs, which were around £33,000. The bridge had very low maintenance costs, until 1936 when cracks in the structure worsened and a large concrete chunk near the Grafton side of the structure fell off. After repairs were made, the bridge was opened for exclusively car and pedestrian traffic; meaning that any trucks or fire engines accessing
Grafton Bridge - Misplaced Pages Continue
2898-403: 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
2967-403: 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,
3036-402: The first bridge proved to be comparatively unstable, at least towards the end of its life when it would appear that maintenance was not kept up. By the time it was approaching 20 years old, police were stationed at each end after rugby matches to ensure rowdy crowds did not cause it to wobble alarmingly by jumping or stamping on it. In 1904, a report showed it was not only beyond repair but that it
3105-568: 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
3174-511: 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
3243-552: The full intended level of bus services did not immediately use the bridge, as the Central Connector project was not finished. Compliance with the bus lane regulations was low initially, and after issuing warnings only for an initial period Auckland City Council began issuing infringement notices, ticketing 831 offenders during the first five days. The bridge is open to buses and emergency services from 7am to 7pm Monday to Friday, closed to other traffic. At other times it
3312-400: The gully are still mostly covered with bush, though the bottom of the gully carries multiple motorway lanes of State Highways 16 into the city further north (such as to Ports of Auckland ). SH16 (Stanley Street) carried an average of 34,000 vehicles per day in 2003. The Grafton Gully motorway project included two stages (with a third planned for when future traffic reaches trigger levels) and
3381-660: 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
3450-824: 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
3519-438: 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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#17327766490853588-656: 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
3657-448: 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
3726-427: The previous 13 tonnes. In October 2009 the bridge was reopened by Mayor John Banks . The footpaths are covered with curved transparent screens installed in 2002, to prevent people from falling or jumping off and providing weather cover (the bridge had suicide prevention barriers from as early as 1936, replaced with mesh screens in 1957 that were removed in 1997. After the removal, suicides increased fivefold, leading to
3795-433: 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
3864-581: 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
3933-474: 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
4002-454: 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
4071-426: The time, but was also seen to symbolise a commitment to a 'Greater Auckland', indicating leadership in technology development. Many people maintained that the city would never get big enough to warrant the cost of so large a piece of engineering. Conversely Myers predicted that the population of Auckland would double in the next two decades, and he was proved correct. Construction work was undertaken over two years, and
4140-401: The two main piers, carbon fibre wrapping around various steelwork and improvements to footpaths. The strengthening process involved the use of epoxy resin injections in cracked areas concrete beams and columns, the first time this technique had been used on a major structure in New Zealand. In October 2009, the bridge was reopened ahead of schedule, the works having cost $ 6.9 million. However,
4209-403: 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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#17327766490854278-574: The world. The bridge is listed by Heritage New Zealand and on the IPENZ Engineering Heritage Register. In a 2006 poll of 600 alumni of the University of Auckland School of Engineering, the bridge was third in the list of New Zealand engineering achievements, after Manapouri Power Station and Black Magic . Since 2009 the bridge has formed a core part of the Central Connector public transport route between
4347-495: Was built for NZ$ 68 million during 2001-2003. In 2014 the Grafton Gully Cycleway was opened through the gully to Beach Road with links to the University of Auckland campus areas in the eastern Auckland CBD . 36°51′31″S 174°46′00″E / 36.858712°S 174.766678°E / -36.858712; 174.766678 Reinforced concrete Reinforced concrete , also called ferroconcrete ,
4416-400: Was claimed to have been the biggest-span concrete arch bridge in the world. It utilises large 'false piers' on each side of the central arch, which give the appearance of strength in the classical masonry style, but are not required to be anywhere as massive, since the arch itself carries the full load via the thin vertical members. It resembles closely similar bridges of the period, specifically
4485-580: Was conflict over whether any new bridge should be another pedestrian bridge or one that would take vehicle traffic as well. Eventually the decision to build a road bridge was taken. In 1907 the Auckland City Council received two tenders for the bridge: a cheaper steel structure proposed by the American Bridge Company , and a more expensive ferro-concrete option designed by engineers R. F. Moore and Karl Rosegger Agster for
4554-647: Was formerly home to the Waipārūrū Stream, known to early European settlers as the Graveyard Spring. One of early Governors of New Zealand was Robert FitzRoy , whose grandfather was the third Duke of Grafton. The suburb that developed next to the Government Domain and Hospital was called Grafton . Eventually the adjoining gully became known as Grafton Gully although many people continued to call it Cemetery Gully for some years. Grafton Gully
4623-404: 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
4692-509: Was lucky it hadn't collapsed. It was immediately closed and supplemented by a temporary bridge of quite simple design at the bottom of the gully. The old disused bridge stood until 1906. Discussions within Council over the design of a new permanent bridge dragged on for years, requiring a rebuild of the temporary bridge and the construction of long flights of wooden steps from St Martins Lane and Bridge Street to make pedestrian access easier. There
4761-422: 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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