Evolution of Skyscrapers Essay Example for Free

Evolution of Skyscrapers Essay 1.Historical Development In High-Rise Buildings Ancient Skyscrapers The Great Ziggurat of Babylon Perhaps the most impressive structure in the ancient Middle East, the Great Ziggurat of Babylon was built over a span of several decades in the Sixth Century BC. Its seven stories, built upon a square foundation, stretched 300 feet into the sky. Some think it was the inspiration for the infamous Tower of Babel in the Book of Genesis. In this illustration, King Nebuchadnezzar, who ruled Babylon from 604 to 561 BC, is seen overlooking his capital The towers of Bologna The towers of and were built in Europe, or together until Bologna are slender, as much as 60 meters (150 feet) tall, by the rich for defense and as status symbols. No other site perhaps the world, had so many tall structures crowded the coming of skyscrapers in the late 19th century. Fig. 1 The great Ziggurat of Babylon As many as 180 towers, of many different heights, are thought to have been built in Bologna during the 1100s and slightly later; now there are barely 20. The two most prominent (seen here) are the symbols of the city and have long been known together as the Two Towers. Fig. 2 The towers of Bologna The First Safety Elevators In this period illustration, shoppers ride the elevator in the new Lord Taylors department store on Broadway in New York City sometime during the 1870s. Around the same time, the first-ever elevator in an office building was also installed in New York. It was designed by Elisha Otis, whose company became synonymous with the new contraption. Elevators revolutionized office buildings, literally turning them upside down. Prior to their invention, the lower floors of a structure were the most valuable rental property because of the difficulty and inconvenience of climbing the stairs. But the elevator made it possible for elite tenants to enjoy the view from the upper floors and allow buildings to rise higher and higher. Fig. 3 The first Safety Elevators Great Chicago Fire In this illustration, Chicago residents flee the terror of the Chicago fire which devastated their city over a three-day period in October 1871. The fire caused nearly $200 million in damage, killed some 300 people and left another 100,000 homeless. Despite this toll, the destruction cleared the way for Chicago to build scores of modern steel-framed office towers and to become one of Americas most architecturally striking cities. Fig. 4 Great Chicago Fire The First skyscraper Chicagos 10-story Home Insurance Building, built in 1884 and designed by William Jenney, was arguably the first true modern office tower. It was the first building to use structural steel at least partially in its frame, and was the first tall building to be fireproofed both inside and outside. It was torn down in 1931 but its legacy lives on in thousands of steel-framed and fireproofed buildings around the world. Fig. 5 Home Insurance Building The Tribune Tower Pedestrians walk past the ornate entrance and lower floors of Tribune Tower, home of the Chicago Tribune newspaper, which was built in 1925. The 36-story Gothic Revival structure was designed by John Mead Howells and Raymond Hood, who won a contest held by the newspaper company to create the most beautiful and distinctive office building in the world. Fig. 6 The Tribune Tower The Chrysler Building With its majestic spire, New York Citys Chrysler Building is perhaps the most famous Art Deco structure in the world. Built in 1930, the 77-storey structure was briefly the tallest building in the world. The sculptures at the top and around the edges are actually inspired by Chrysler hubcaps and hood ornaments. The buildings tapering profile is perhaps the best example of form follows zoning by taking New York Citys setback requirements from 1916 zoning laws requiring new structures to leave more open space around them and turning them into an stunning archetype Fig. 7 The Chrysler Building The Empire State Building survives a hit This photo shows the spot where a B-25 bomber struck the Empire State Building in July 1945. The aircraft was ferrying servicemen from Massachusetts to New Yorks La Guardia Airport when pilot William Smith veered disastrously off course in heavy fog. Fourteen people including Smith were killed when the bomber hit the skyscraper. The buildings 79th floor caught fire, and New York City firefighters bravely rushed up into the building to rescue occupants and put out the blaze. The buildings structure and fireproofing both proved strong enough that the New York landmark reopened the following week. Fig. 8 The Empire State Building World Trade Centre The famous twin towers of the World Trade Center were built by the Port Authority in the 1960s as part of an effort to revitalize lower Manhattan. The structure was derided by critics as boring. One wag likened it to a giant pair of filing cabinets, but in time it became a popular New York landmark. The original WTC was the first to use sky lobbies where people would change from express to local elevators, a setup inspired by the New York subway system. It also had wide-open, column-free spaces that were ideal for Fig. 9 The World Trade Centre the cubicles then becoming popular in office design. The towers were destroyed in the 2001 terrorist attack that killed more than 2,700 people Sears Tower When the Sears Tower, later renamed the Willis Tower, opened in 1973, the 108-story structure became the tallest building in the world and held that title until Malaysias Petronas Towers claimed the distinction in 1998. This skyscraper was able to achieve that height through a spectacular engineering innovation that introduced the bundled tube structure the Sears Tower is really nine square towers bundled together. It was the start of a revolution in structural design that permitted higher and thinner towers than had ever been built before Fig. 10 The Sears Tower The Citicorp Building Skirts Disaster The 59-story Citigroup Center building, completed in 1977, had to undergo a costly strength upgrade the following year after it was discovered that the structure was dangerously vulnerable to strong diagonal winds hitting the buildings corners. This weakness was a consequence of the placement of the main support columns at the centre of the sides rather than on the corners because the building had to float over a church that owned the property. This bold design did win praise for the architect but he subsequently had to suffer the consequences largely in secret lest panic break out of experimenting with untested structural elements. If strong dangerous winds had actually toppled the Citicorp building, it is estimated that it might have taken 16 blocks of Manhattan with it. Fig. 11 The Citicorp Building The Petronas Tower Tourists have their picture taken outside the soaring spires of the Petronas Towers in Kuala Lumpur, Malaysia. The 88-story towers, which were completed in the mid-to-late 1990s, were for several years the worlds tallest buildings. The project was the harbinger of a global shift in skyscraper building in which Middle Eastern and Asian countries have been racing to erect the tallest and most majestic towers Fig. 12 The Petronas Tower The Gherkin, London One of the more unusual sights in the London skyline is 20 St. Mary Axe, a 41-story office tower opened in 2004, which is nicknamed The Gherkin because of its resemblance to a pickle. Though odd-looking, the structure is a prototype for a new generation of innovative, super energy-efficient buildings. Vertical gaps in the building create a natural ventilation system that allows warm air to rise out of the structure. These openings also allow the interior offices to use more Fig. 13 The 20 St. Mary Axe natural light to greatly reducing electrical consumption The Marina Bay Sands Singapores Marina Bay Sands, a casino and resort complex which opened in 2011, cost an astonishing $8 billion to build. Architect Moshie Safdies unorthodox design, with its trio of 55-story towers, reportedly was inspired by card decks on gaming tables. The three towers are connected by a giant terrace that supports the worlds longest elevated swimming pool. The steel for the pool weighs 191,416 kilos (422,000 pounds) and the water it can hold weighs an additional 1,424,098 kilos (3,139,600 pounds). The towers are constructed to allow movement in the wind up to 50 centimetres and longer-term settling in the soil. Fig. 14 The Marina Bay Sands Burj Khalifa Dubais 160-storey Burj Khalifa, which opened in 2010, is by far the worlds tallest building. Its startling, rocket ship-like appearance, seen in this photo, seems intended to get attention more than anything else. As architectural critic Paul Goldberger has written, You dont build this kind of skyscraper to house people you do it to make sure the world knows who you are. The tall, tapering design is reminiscent of skyscrapers like the Chrysler Fig. 15 The Burj Khalifa and Empire State buildings although you could put the two New York skyscrapers one on top of the other and they still would not be as tall. The New World Trade Centre One World Trade Center (also known as Tower One) rises over lower Manhattan on the site of where the twin towers destroyed in 2001. When completed in 2013, it will have a spire thats precisely 1,776 feet tall (541 meters), making it the third tallest building in the world and the highest in the Western Hemisphere. The new WTCs base is enclosed in thick concrete, steel panels and blast-resistant glass, making it one of the toughest skyscrapers ever built, but security concerns have caused the buildings cost to soar, reaching the vicinity of $4 billion. Fig. 16The New World Trade Centre Fig. 17 Height Comparison of Noticeable Tall Buildings 2. Classification of Tall Building Structure System In 1969 Fazlur Khan classified structural systems for tall buildings relating to their heights with considerations for efficiency in the form of â€Å"Heights for Structural Systems† diagrams Fig. 18 Classification of Tall Building Structure System by Fazlur Khan. Left : steel; Right: Concrete He developed these schemes for both steel and concrete. Khan argued that the rigid frame that had dominated tall building design and construction so long was not the only system fitting for tall buildings. Because of a better understanding of the mechanics of material and member behavior, he reasoned that the structure could be treated in a holistic manner, that is, the building could be analyzed in three dimensions, supported by computer simulations, rather than as a series of planar systems in each principal direction. Feasible structural systems, according to him, are rigid frames, shear walls, interactive frame-shear wall combinations, belt trusses, and the various other tubular systems. Structural systems of tall buildings can be divided into two broad categories: interior structures and exterior structures. This classification is based on the distribution of the components of the primary lateral load-resisting system over the building. A system is categorized as an interior structure when the major part of the lateral load resisting system is located within the interior of the building. Likewise, if the major part of the lateral load-resisting system is located at the building perimeter, a system is categorized as an exterior structure. It should be noted, however, that any interior structure is likely to have some minor components of the lateral load-resisting system at the building perimeter, and any exterior structure may have some minor components within the interior of the building. This classification of structural systems is presented more as a guideline and should be treated as such. It is imperative that each system has a wide range of height applications depending upon other design and service criteria related to building shape, aspect ratio, architectural functions, load cond itions, building stability and site constraints. For each condition, however, there is always an optimum structural system, although it may not necessarily match one of those in the system’s tables due to the predominant influence of other factors on the building form. The height limits shown are therefore presumptive based on experience and the authors’ prediction within an acceptable range of aspect ratios of the buildings, say about 6 to 8. On occasions, an exterior structure may be combined with an interior one, such as when a tubular frame is also braced or provided with core-supported outriggers and belt trusses, to enhance the building’s stiffness 2.1 Interior Structures The two basic types of lateral load-resisting systems in the category of interior structures are the moment-resisting frames and shear trusses/shear walls. These systems are usually arranged as planar assemblies in two principal orthogonal directions and may be employed together as a combined system in which they interact. Another very important system in this category is the core-supported outrigger structure, which is very widely used for super tall buildings at this writing. The moment-resisting frame (MRF) consists of horizontal (girder) and vertical (column) members rigidly connected together in a planar grid form. Such frames resist load primarily through the flexural stiffness of the members (Kowalczyk, Sinn, Kilmister, 1995). The size of the columns is mainly controlled by the gravity loads that accumulate towards the base of the building giving rise to progressively larger column sizes towards the base from the roof. The size of the girders, on the other hand, is controlled by stiffness of the frame in order to ensure acceptable lateral sway of the building. Although gravity load is more or less the same in all typical floors of a tall building, the girder sizes need to be increased to increase the frame stiffness. Likewise, columns already sized for gravity loads need to be slightly increased to increase the frame stiffness as well. MRFs can be located in or around the core, on the exterior, and throughout the interior of the building along grid lines. Table 1 Interior Structures Braced frames are laterally supported by vertical steel trusses, also called shear trusses, which resist lateral loads primarily through axial stiffness of the members. These act as vertical cantilever trusses where the columns act as chord members and the concentric K, V, or X braces act as web members. Such systems are called concentric braced frames (CBF). Eccentric braced frames (EBF) have, on the other hand, braces which are connected to the floor girders that form horizontal elements of the truss, with axial offsets to introduce flexure and shear into the frame (Popov, 1982). This lowers stiffness-to-weight ratio but increases ductility and therefore EBFs are used for seismic zones where ductility is an essential requirement of structural design. EBFs can also be used to accommodate wide doors and other openings, and have on occasions been used for non-seismic zones (Corrin Swensson, 1992). Braced frames are generally located in the service and elevator core areas of tall buildings. The frame diagonals are enclosed within the walls. Reinforced concrete planar solid or coupled shear walls have been one of the most popular systems used for high-rise construction to resist lateral forces caused by wind and earthquakes. They are treated as vertical cantilevers fixed at the base. When two or more shear walls in the same plane are interconnected by beams or slabs, as is the case with shear walls with door or window openings, the total stiffness of the system exceeds the sum of the individual wall stiffnesses. This is so because the connecting beam forces the walls to act as a single unit by restraining their individual cantilever actions. These are known as coupled shear walls. Shear walls used in tall office buildings are generally located around service and elevator cores, and stairwells. In fact, in many tall buildings, the vertical solid core walls that enclose the building services can be used to stabilize and stiffen the building against lateral loads. Many possibilities exist with single or multiple cores in a tall building with regard to their location, shape, number, and arrangement. The core walls are essentially shear walls that can be analyzed as planar elements in each principal direction or as three-dimensional elements using computer programs.

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â€Å"Either with your shield, or on it.† These were the words said by Spartan women as their men left for war. The meaning is clear: either return with your shield, alive and victorious, or return as a corpse. There are no other options. This mentality of â€Å"Spartans never retreat, Spartans never surrender,† and a lifetime of physical training produced in ancient Sparta an elite caste of warriors who dominated classical Greece for centuries. The Spartans were greatly respected during their day, causing one exiled King to say â€Å"the Lacedaemonians, when they fight singly, are as good as any in the world.† Time has done nothing to soften the praise felt for the Spartan warrior. Innumerable video games, films, and novels have represented Spartans as invincible warriors, the valiant Spartan phalanx standing strong against a horde of unending barbarians. Invariably, the Spartans have been represented as speaking of ‘freedom’ and ‘reason,’ versus the forces of tyranny and barbarism. While most wars the Spartans fought were against other Greeks, as the fractious Greek city-states were wont to do, invariably the popular culture accounts of the 20th and 21st century depict them as being pitted against the largest contemporary empire, the Persians, who, in an incredibly short period, were able to create the largest land empire the world had yet seen. The Persians surpassed the Greeks in many ways, and yet there are no Hollywood blockbusters about Cyrus conquering Babylon, or video games of Persian military feats. Modern popular culture has raised the Spartan to the highest pedestal of adoration, producing pulp of every kind to feed his flame. The Persians, meanwhile, have been brought low and demonized, even neglected. The questi... ...aging.† This logic struck Cyrus so much that he acted on the advice of Croesus and reclaimed the booty. Here Cyrus is portrayed as a rational, just ruler, who treats conquered subjects with restraint. This is in contrast to the loser in the struggle, Croesus, who, although Herodotus represents as wise and strong, is much too hasty. When he received the prophecy from the Oracle at Delphi of â€Å"If you attack, you will destroy a great empire,† in response to his question of whether he should bring the fight to the Achaemenids, he rushed across the river to attack Cyrus’s position, eager to destroy a great empire. Of course, the ambiguity of the oracle was his undoing, as it was his own Lydian empire that he destroyed. In this episode, Herodotus is not afraid to admit the faults of his Ionian Greek brethren, or to ascribe positive attributes to the Greek’s enemy.

Audience expectations Essay

In this essay I will discuss how Arthur Miller set out the first scene of the play, ‘The Crucible’ to prepare the audience for what the play is about, and how well he did this. I will look at the dramatic devices, language etc.  The play ‘The Crucible’ has strong links with the USA in the 1950’s when communism was a problem. The name of the play creates parallels between Salem 1692 and the USA 1950s. A definition of crucible can be, â€Å"used to extract impurities† this is related Salem 1692 because the judges and townsfolk were trying to purify the village from witches whilst Joseph McCarthy was trying to purify the USA of communists. People’s views and opinions have not changed since the 1600s and people believe only one way is right, communists and witches are both evil and therefore should be rid of, this is what miller is trying to portray about the world. No-one gets a chance to prove themselves or prove they are good and mean no harm. If you are a witch or a communist you are evil and it’s not acceptable therefore the only thing to do it get rid of them. This is shown in the play by the fact that lots of people in the village are being accused of witchery, and you die whether you have an excuse or proof that your not a witch, if you admit it you are saved but have to promise you want to come back to the lord but if you are truly faithful to the lord such as goody Proctor, you will not falsely admit to being a witch and therefore will be killed. Miller uses dramatic devices in the play ‘The Crucible’, one of these devices is dramatic irony. This is when the audience knows something about a certain character but the other characters don’t. They are like secrets no one knows apart from the characters involved. This creates tension as it seems as I everyone is hiding something. Miller uses this technique when the audience knows that Proctor and Abigail had an affair but the other characters are not aware. The audience then gets frustrated because it seems so obvious to them and they want to tell the characters what’s going on. He also uses this when the characters don’t know that Abigail is lying and the accusations are not real. The audience think it is so simple to realise what is going on because they know there is no such thing a witches. And the audience knows that dramatic irony is a clear device used throughout the play. Exits and entrances are also used in the crucible; this is so the characters can have their private conversations like Abigail and Proctor. This creates confusion between the characters as they all have secrets, this then creates panic of others finding out and this panic can grow like Abigail’s panic grew for her being found out to be untruthful. This panic grew and grew until she was confessing random names/accusations. â€Å"I saw goody Sibber with the devil!†, â€Å"I saw Goody Hawkins with the devil!†, â€Å"I saw Goody Bibber with the devil!†, â€Å"I saw Goody Booth with the devil† † The audience however would know that Abigail and her friends are making it up because there is no such thing as witches. Another technique is the use of offstage action these are events that are not shown but they are mentioned. This is like the affair between Proctor and Abigail, this happens before the play begins. Also the audience doesn’t see the dancing in the forest they only hear about it, they don’t see it. This is the driving force behind the story; the audience are intrigued by what is going on.  At the beginning of the play there is an overture, Miller begins the play by describing the setting and the scenery in detail, this is so the audience can see what it is like and will help them understand what is going on in the play. â€Å"A narrow window on the left† the detail is important in linking the beginning with the rest of the play, as later on in the play, Betty uses the window, previously described to attempt to jump out of, screaming â€Å"mama†, and this shows hysteria in the play, it is obvious to the audience that introducing themes of witchcraft will cause hysteria. â€Å"Uncle, themes of witchcraft are all about†, all the rumours of witchcraft could have calmed down if Abigail hadn’t said Betty had fainted, which is a blatant lie because she didn’t know Ruth had apparently ‘fainted’ as well. â€Å"We did dance uncle†, a bad mistake by Abigail, letting Parris know he was right he was right and therefore giving him more to suspect about witchcraft, â€Å"and when you leapt out of the bush so suddenly, Betty was frightened and then she fainted†.

What Is a Nonoxidizing Acid

A nonoxidizing acid is an acid that cannot act as an oxidizing agent. While many acids are good oxidizers, they dont all technically oxidize in any given reaction. Nonoxidizing Acid Examples Hydrochloric acid, hydroiodic acid, hydrobromic acid, hydrofluoric acid, phosphoric acid are all nonoxidizing acids. Example Use The element beryllium dissolves in a nonoxidizing acid, such as hydrochloric or dilute sulfuric acid, but not in water or nitric acid.