Monday, September 9, 2019
Poetry- Hidden Social or Politicial Ideology or Agenda Essay
Poetry- Hidden Social or Politicial Ideology or Agenda - Essay Example His poems were much influenced by the African-American Jazz Music and the contents were radical. However, this was not given much attention. Because ââ¬Å"his radical poetry was neglected,â⬠a tone of frustration and the willingness to revolt are very evident in his poem, ââ¬Å"Harlemâ⬠(Dawahare 21). The series of questions would lead the readers to realize the climax. ââ¬Å"Harlemâ⬠is a poem which describes a people full of longing to be truly free from discrimination and marginalization; their ideals and dream of social equity is prevalent amidst the oppression of the white American community. The ââ¬Å"dreamâ⬠(Hughes line 1) being referred by Hughes is the yearning of the black Americans to equality; a dream stressing out that they too, are people with feelings and intellect and not mere slaves that the whites made them to be. The onset of abolitionism gave the African-Americans liberty and the government gave them rights that they were not able to exercise before such as the right to vote and the right to own a property. Despite of the government abolishing the slavery, they could not achieve fully what they really wanted. Hughes used images that appeal to the senses as if the dream he is talking about is tangible; can be seen and felt. The second ââ¬Å"big questionâ⬠mentioned in the poem: ââ¬Å"Does it dry up like a raisin in the sun?â⬠(Hughes 2) might suggest a very symbolic representation of an African American ideal. Like a grape losing its juice when exposed to the sun for a long time, a dream may lose its vitality if it is not realized in time . Putting together side by side two very unlike objects which seem to set in the opposite poles adds more effect in the delivery of the message; a very large object, powerful, and made as a god by ancient people (the sun), and an object made from a preserved fruit, almost unnoticeable (the raisin). Next symbolism that can be
Sunday, September 8, 2019
Why was the civil war significant Essay Example | Topics and Well Written Essays - 1000 words
Why was the civil war significant - Essay Example Other than the cause or the objective which originally motivated the pursuit and concretization of the Civil War, one could also look into matters of consequence from which to judge the grounds it is signified by. Pondering on the significance of U.S. Civil War bears the equivalent work of recounting the occurrences which essentially depict the post-war impact and which may be put together and labelled into what has since been known in U.S. History as ââ¬ËReconstructionââ¬â¢ at the height of which could be found the tumultuous state of political affairs which not merely distinguished the philosophy of the Radical Republicans from that of the Democrats but even shaped the fate of the ââ¬Ëfreedmenââ¬â¢, in the process. During the period of Reconstruction (1865 - 1877) particularly with respect to the early years of its commencement by the persistent rule of Congress that was then chiefly composed of the Radicals, the federal government experienced yet another severe case of division between the two dominant political parties. On one hand, the Radical Republicans who had become accustomed to dealing with the issue of slavery conveyed the desire for implementing Reconstruction policies in a manner that would materialize a vision in which ââ¬Å"Equality of opportunity created a more fluid social structureâ⬠as exemplified via ââ¬Å"the model of free individuals, competing equally in the labor market and enjoying equal political rightsâ⬠(Faragher et al, 464). On the contrary, however, Pres. Andrew Johnson who belonged to the Democratic Party contested such visionary scheme by augmenting the powers of civil governments in the South as well as replacing certain military officials with a commanding staff that seemed less likely persuaded in advancing the cause of the blacks especially in matters concerning suffrage (Wheeler et al, 310). Before the Civil War broke out and by the time it took place, factions generally existed between the federal N orth and the confederate South but after the test of martial skills, bloodshed, and the taste of several deaths came another era that would eventually justify whether or not the Civil War deserved to be treated with significance. Apparently, through these factions narrowed within the political domains of the federal government, Reconstruction served as a projection of Civil War or the rebirth of a principle which resembled a test by fire designed to refine and determine whose spirits remained driven and sincere in defending the great original cause. This became evident the moment when the Moderates and the Radicals of Republicans united to form a single huge force in the House of Representatives aimed at impeaching Johnson whom they charged heavily for violating the Tenure of Office Act in spite of the truth that the presidentââ¬â¢s removal from office was due to his intense opposition toward the policies of Congressional Reconstruction which the Republicans could not afford to t ake any longer (466). Through the victory of the Radical Republicans, Reconstruction Acts triumphed over those of Restoration which Johnson attempted to promulgate during his effective term. Hence, with zeal kept on continuing to promote the core ideals of the Civil War, the Republicans managed to enable the Congressional Reconstruction to establish the Freedmenââ¬â¢s Bureau which, according to the findings of Wheeler and company, ââ¬Å"was given additional federal support to set up schools for African Americans, negotiate labor contracts, and with the military, help monitor electionsââ¬
Saturday, September 7, 2019
Political Socialization and Ideology Essay Example | Topics and Well Written Essays - 1250 words
Political Socialization and Ideology - Essay Example Blue: The Political Typology) TYPOLOGY AND DEMOGRAPHICS: Yes, my demographics match those with the typical person in my quiz. The majority of the traits that are present in a main street republican that is I am very critical and observant about how the government functions in American society. I believe in religion and the values that come along with it therefore I completely oppose marriages of the same sex and abortions. I do not find charm in greed and hence business does not enamor me much. I support all the efforts made by the government in order to protect this environment. And finally I have faith in labor as hard work always pays off irrespective of how crucial the circumstances might be. The only point that I disagree over is when it comes to my typology is that I support social welfare programs to an extent. There are many Americans who are in need of support by the government to make both ends meet, therefore such programs should regulate.Lastly I do support immigrants as through their efforts there have been positive benefits to our current economy. The main street republican group thus closely matches my typology. ANALYSIS OF MY SURVEY RESULTS Like I mentioned previously that my results are quite agreeable with only a few reservations that I have regarding them. My result stated that I am a main street republican which is the best group they could put me too. Since I support the Republican government and I totally side them with most of the characteristics they believe I possess. A "Main Street Republicansà differ from Staunch Conservatives in the degree of their conservatism and in their skepticism about business. They are socially and fiscally... The subject of political sociology and ideology is quite important as it helps individuals to understand the depth of politics and their stance over it. Politics is an integral component of every person's life as it directly or indirectly affects an individual in various manners. By studying political sociology one can easily affiliate himself to the prevailing system and do his best in order to change the system if required. As a main street republican I believe that the present system is the best way to sustain as it allows the direct involvement of public in the state affairs making it an issue of the entire nation. Certain amendments and strict laws and regulations need to be made in order to overcome prevailing social evils in the society. Thus "Greatness is rare and great men are few; but republican government puts power in the hands of many rather than few."
Friday, September 6, 2019
Sara Lee Case Study Essay Example for Free
Sara Lee Case Study Essay Sara Lee managements should continue focusing on the food -based industries and trying to link those industries as much as possible. One of their main strengths is brand recognition. People can expect to get premium quality products when they purchase anything from the Sara Lee product line. Sara Lee is struggling in the bakery industries, both North American and International with the exception of fresh breads, a narrowing of product lines may help make this brand more profitable. They are doing a great job in the International Beverage market, with the number one selling item being coffee. The global retail coffee market was expected to grow from $51 billion in 2009 to $62 billion in 2013. With this being said this market is a cash cow and Sara Lee management should focus on Coffee and tea in the International Beverage business and they can also create new products to expand the product line. Since they are already the number one seller in single-serving coffeemakers, a good idea would be for them to make single-serve pods that are compatible with any single-serve coffeemaker. With a current market share of 40 percent, this will only help increase their overall market share. Since Sara Lee is divesting many of their of their product lines and expect to contain growth in operating expenses through reducing inventory, focusing on promising markets and emphasis on efficiency, they will have more money to use in other places like advertisement. They should do more with putting their name out there. Creating a marketing campaign to bring back name recognition that has been overshadowed by competitors will help product sales. They can bring back their slogan ââ¬Å"Nobody does it like Sara Lee.â⬠Focusing on profitable products and expanding product line will help the Company have significant gains in shareholder value and improve the companyââ¬â¢s performance.
History of African American Music Essay Example for Free
History of African American Music Essay The history of African American music has been characterized by a mixture among various forms of music. Country blues, urban blues, New Orleans Jazz, Bebop, big-band jazz, and rhythm and blues, have all influenced each other profoundly. These influences flowed back and forth among the various forms. But, black gospel music had only a very limited effect on popular styles, until a few church-trained artists, such as Sam Cooke and Ray Charles, began to incorporate gospel styling into their popular work. The result is usually described as soul music, a mix of blues, rhythm and blues, and gospel voices. But, if Ray Charles was one of the originators of soul music, Aretha Franklin reshaped it, by bringing even more of her gospel background to bear on secular love songs (Wade and Picardie 27). By combining popular elements with her stunning voice, her great musicianship, and the feeling for a song that she learned in church, Aretha became one of the greatest soul singers to ever live. Aretha Franklin is a well-known pop, RB, and gospel singer. She has been nicknamed ââ¬Å"The Queen of Soulâ⬠and is an internationally known artist and a symbol of pride in the African American community. Her popularity soared in 1967 when she released an album containing songs ââ¬Å"I Never Loved a Manâ⬠, ââ¬Å"Respectâ⬠, and ââ¬Å"Baby I Love You. â⬠Throughout her career she has achieved fifteen Grammy Awards, Lifetime Achievement Award, National Academy of Recording Arts and Sciences Legend Awards, and many Grammy Hall of Fame Awards. In 1987 she became the first woman inducted into the Rock Roll Hall of Fame. Time magazine chose her as one of the most influential artists and entertainers of the 20th century. She sang at Dr. Martin Luther Kingââ¬â¢s funeral and at former President Bill Clintonââ¬â¢s inaugural party. Although she has all these accomplishments and awards there are other reasons that have driven Franklin to fame and landed her on the front cover of Time magazine on June 28, 1968. The reasons I believe allowed Aretha Franklin to become so successful are the following: Her familyââ¬â¢s involvement with religion, the inspiring people that surrounded her, and the pain she suffered. It is clear that because her familyââ¬â¢s involvement with religion would be one reason why Aretha Franklin became as famous as a Gospel singer. Some people would say that her love for religion is unbelievable, but after researching her childhood it is very believable. Her father, Reverend Clarence LaVaugh Franklin lived in Shelby Mississippi and preached while living the life of a sharecropper. As soon as he had enough money, he would move to Memphis, Tennessee to become a pastor of two churches. After a couple of years he attended LeMoyne College, and he studied Education and English Literature. With his education he was able to bring a more liberal view to his preachingââ¬â¢s. Then he moved the family to Buffalo, New York. When he had the resources, he moved the family again to Detroit, Michigan were he settled and became a pastor of a churched called New Bethel Baptist Church. He quickly became one of the most famous pastors in the city of Detroit. Aretha was two years old when they made their final move, she would grow up here and grab the emotion of Church and incorporate it into her music. Aretha Franklinââ¬â¢s mom, Barbara V. Skaggers, served as choir director and pianist. Aretha describes her mom as ââ¬Å"a Superb singer, her voice was clear and distinctiveâ⬠. (Franklin and Ritz, 6) Her parents taught her how to sing with great pride. This was a big issue because the late ââ¬Ë50s, early ââ¬Ë60s was a time of turmoil for African Americans. Her father especially tried to instill pride into her. He was a Civil Rights activist and he was a close colleague with Dr. Martin Luther King. With her parents keeping her involved in Church she was bound to become one of the worldââ¬â¢s greatest singers. At around age 12, the father recognized Arethaââ¬â¢s talent as a singer. So he took her on the road with his traveling gospel show. This was important because it shows the kind of support Aretha received from her family. It was said, ââ¬Å"She was a spellbinding performer at the age of fourteen. â⬠(Franklin, 3) So her family really supported and inspired her to become a gospel singer. What also made her a great artist was that she had inspiring people all around her. Aretha grew up in Detroit which at the time was a rousing city or a city of hope for the African Americans running away from the brutality of the South. Though Detroit still had its problems such as race riots, many famous musicians grew up there. Also since New Bethel Baptist Church was so prominent, many musicians and political leaders used Reverend Franklinââ¬â¢s pulpit as a platform to sing or speak to the Blackââ¬â¢s of Detroit. Aretha was introduced to classical music by Smokey Robinsonââ¬â¢s sister Sylvia Burston. She listened to well known local DJââ¬â¢s like Ruth Brown and Senator Brystal Brown. When Aretha was younger, she would ride her bike to the local park, and on her way home she would stop by a night club where you could here B. B. King perform. She says, ââ¬Å"You could hear the soft sound of his guitar all the way to the sidewalk (Franklin and Ritz, 22). National and local political leaders would give there speeches. Speakers such as Dr. Adam Clayton Powell, Sr. , Dr. Martin Luther King, and Reverend Jesse Jackson would speak powerfully to the church. Aretha was directly influenced by Miriam Anderson, Sammy Davis, and Roy Wilkins. Detroit was overflowing with talent and speakers which I believe also contributed to Arethaââ¬â¢s success. Pain was probably what really drove Aretha Franklinââ¬â¢s success. As stated before, Franklinââ¬â¢s family was highly religious and was continually involved in the Church. But that doesnââ¬â¢t mean that she hadnââ¬â¢t been through a tremendous amount of pain. Early in life her mother and father got a divorce. The father was better suitable to raise Aretha and her four Siblings. The mother moved to Buffalo, New York and tried to make regular visits to see her children. She was supported her children in the best way she could, but when Aretha needed her, she still was not reachable. Matters became worst a few years later when Arethaââ¬â¢s mom dies of a stroke. Aretha described her mom by saying ââ¬Å"she was the absolute ladyâ⬠(Smith, 3). At age 15 she had her first child and two years later another would come. But Aretha still wanted to go out and be with friends, so her grandmother usually babysat for her periodically. In a time when Black Activism, Feminism, and Sexual Liberation were high, she needed to provide for herself. So when Aretha was old enough and was ready to start performing, she hired a man named Ted White to be her manager. He later became her husband. In the future she would divorce him for a famous actor which would end in divorce, too. Even though in 1968 to 1969, Franklinââ¬â¢s career was rising rapidly. She was still described by her Producer Jerry Wexler as ââ¬Å"a person whose depressions runs deeper than the seaâ⬠(Ritchie Unterberger, 3). Then one of Franklinââ¬â¢s highest admirers, gospel giant Mahalia Jackson died. Right after her death a extremely emotional gospel album was released my Aretha ââ¬Å"Amazing Graceâ⬠This record was considered to be one of the most emotional records of its time. Much of the pain that Aretha suffered was not really publicized, but still it had to be one of the reasons for her to have such a powerful voice. Aretha Franklin was a successful artist and still inspires musicians today. Her voice is still described as incredible. She has all the awards that she needs to show her talent. Works cited Franklin, Aretha, and David Ritz. Aretha: From These Roots. New York: Villard, 1999. Print. Carroll, Jillian. Aretha Franklin. Chicago: Raintree, 2004. Print.
History of African American Music Essay Example for Free
History of African American Music Essay The history of African American music has been characterized by a mixture among various forms of music. Country blues, urban blues, New Orleans Jazz, Bebop, big-band jazz, and rhythm and blues, have all influenced each other profoundly. These influences flowed back and forth among the various forms. But, black gospel music had only a very limited effect on popular styles, until a few church-trained artists, such as Sam Cooke and Ray Charles, began to incorporate gospel styling into their popular work. The result is usually described as soul music, a mix of blues, rhythm and blues, and gospel voices. But, if Ray Charles was one of the originators of soul music, Aretha Franklin reshaped it, by bringing even more of her gospel background to bear on secular love songs (Wade and Picardie 27). By combining popular elements with her stunning voice, her great musicianship, and the feeling for a song that she learned in church, Aretha became one of the greatest soul singers to ever live. Aretha Franklin is a well-known pop, RB, and gospel singer. She has been nicknamed ââ¬Å"The Queen of Soulâ⬠and is an internationally known artist and a symbol of pride in the African American community. Her popularity soared in 1967 when she released an album containing songs ââ¬Å"I Never Loved a Manâ⬠, ââ¬Å"Respectâ⬠, and ââ¬Å"Baby I Love You. â⬠Throughout her career she has achieved fifteen Grammy Awards, Lifetime Achievement Award, National Academy of Recording Arts and Sciences Legend Awards, and many Grammy Hall of Fame Awards. In 1987 she became the first woman inducted into the Rock Roll Hall of Fame. Time magazine chose her as one of the most influential artists and entertainers of the 20th century. She sang at Dr. Martin Luther Kingââ¬â¢s funeral and at former President Bill Clintonââ¬â¢s inaugural party. Although she has all these accomplishments and awards there are other reasons that have driven Franklin to fame and landed her on the front cover of Time magazine on June 28, 1968. The reasons I believe allowed Aretha Franklin to become so successful are the following: Her familyââ¬â¢s involvement with religion, the inspiring people that surrounded her, and the pain she suffered. It is clear that because her familyââ¬â¢s involvement with religion would be one reason why Aretha Franklin became as famous as a Gospel singer. Some people would say that her love for religion is unbelievable, but after researching her childhood it is very believable. Her father, Reverend Clarence LaVaugh Franklin lived in Shelby Mississippi and preached while living the life of a sharecropper. As soon as he had enough money, he would move to Memphis, Tennessee to become a pastor of two churches. After a couple of years he attended LeMoyne College, and he studied Education and English Literature. With his education he was able to bring a more liberal view to his preachingââ¬â¢s. Then he moved the family to Buffalo, New York. When he had the resources, he moved the family again to Detroit, Michigan were he settled and became a pastor of a churched called New Bethel Baptist Church. He quickly became one of the most famous pastors in the city of Detroit. Aretha was two years old when they made their final move, she would grow up here and grab the emotion of Church and incorporate it into her music. Aretha Franklinââ¬â¢s mom, Barbara V. Skaggers, served as choir director and pianist. Aretha describes her mom as ââ¬Å"a Superb singer, her voice was clear and distinctiveâ⬠. (Franklin and Ritz, 6) Her parents taught her how to sing with great pride. This was a big issue because the late ââ¬Ë50s, early ââ¬Ë60s was a time of turmoil for African Americans. Her father especially tried to instill pride into her. He was a Civil Rights activist and he was a close colleague with Dr. Martin Luther King. With her parents keeping her involved in Church she was bound to become one of the worldââ¬â¢s greatest singers. At around age 12, the father recognized Arethaââ¬â¢s talent as a singer. So he took her on the road with his traveling gospel show. This was important because it shows the kind of support Aretha received from her family. It was said, ââ¬Å"She was a spellbinding performer at the age of fourteen. â⬠(Franklin, 3) So her family really supported and inspired her to become a gospel singer. What also made her a great artist was that she had inspiring people all around her. Aretha grew up in Detroit which at the time was a rousing city or a city of hope for the African Americans running away from the brutality of the South. Though Detroit still had its problems such as race riots, many famous musicians grew up there. Also since New Bethel Baptist Church was so prominent, many musicians and political leaders used Reverend Franklinââ¬â¢s pulpit as a platform to sing or speak to the Blackââ¬â¢s of Detroit. Aretha was introduced to classical music by Smokey Robinsonââ¬â¢s sister Sylvia Burston. She listened to well known local DJââ¬â¢s like Ruth Brown and Senator Brystal Brown. When Aretha was younger, she would ride her bike to the local park, and on her way home she would stop by a night club where you could here B. B. King perform. She says, ââ¬Å"You could hear the soft sound of his guitar all the way to the sidewalk (Franklin and Ritz, 22). National and local political leaders would give there speeches. Speakers such as Dr. Adam Clayton Powell, Sr. , Dr. Martin Luther King, and Reverend Jesse Jackson would speak powerfully to the church. Aretha was directly influenced by Miriam Anderson, Sammy Davis, and Roy Wilkins. Detroit was overflowing with talent and speakers which I believe also contributed to Arethaââ¬â¢s success. Pain was probably what really drove Aretha Franklinââ¬â¢s success. As stated before, Franklinââ¬â¢s family was highly religious and was continually involved in the Church. But that doesnââ¬â¢t mean that she hadnââ¬â¢t been through a tremendous amount of pain. Early in life her mother and father got a divorce. The father was better suitable to raise Aretha and her four Siblings. The mother moved to Buffalo, New York and tried to make regular visits to see her children. She was supported her children in the best way she could, but when Aretha needed her, she still was not reachable. Matters became worst a few years later when Arethaââ¬â¢s mom dies of a stroke. Aretha described her mom by saying ââ¬Å"she was the absolute ladyâ⬠(Smith, 3). At age 15 she had her first child and two years later another would come. But Aretha still wanted to go out and be with friends, so her grandmother usually babysat for her periodically. In a time when Black Activism, Feminism, and Sexual Liberation were high, she needed to provide for herself. So when Aretha was old enough and was ready to start performing, she hired a man named Ted White to be her manager. He later became her husband. In the future she would divorce him for a famous actor which would end in divorce, too. Even though in 1968 to 1969, Franklinââ¬â¢s career was rising rapidly. She was still described by her Producer Jerry Wexler as ââ¬Å"a person whose depressions runs deeper than the seaâ⬠(Ritchie Unterberger, 3). Then one of Franklinââ¬â¢s highest admirers, gospel giant Mahalia Jackson died. Right after her death a extremely emotional gospel album was released my Aretha ââ¬Å"Amazing Graceâ⬠This record was considered to be one of the most emotional records of its time. Much of the pain that Aretha suffered was not really publicized, but still it had to be one of the reasons for her to have such a powerful voice. Aretha Franklin was a successful artist and still inspires musicians today. Her voice is still described as incredible. She has all the awards that she needs to show her talent. Works cited Franklin, Aretha, and David Ritz. Aretha: From These Roots. New York: Villard, 1999. Print. Carroll, Jillian. Aretha Franklin. Chicago: Raintree, 2004. Print.
Thursday, September 5, 2019
Earthquake Simulation for Buildings
Earthquake Simulation for Buildings Abstract Earthquake is an independent natural phenomenon of vibration of the ground which can become dangerous mainly when it is considered in relation with structures. Earthquakes can be very weak, without even realizing them but (they) can also be strong enough to result serious damages to buildings which can lead to injures or even loss of human lives. In order to avoid any structural damage the legislation sets conditions on the building design. For that purpose, Eurocode 8 is established in European countries and sets up all the appropriate criteria and measures for the design of buildings for earthquake resistance (Eurocode 8 is established in Europe and suggests 4 different methods of analysis.) In this project the response of eight buildings is examined (investigated) under seismic excitation. Firstly, is examined the case of four buildings (1 storey, 2 storey, 3 storey and 4 storey) where all the storeys are facsimile (replica). Afterwards, is examined the case of four buildings (aga in 1-4 storeys) where while the storeys of each building are increased, the mass, the stiffness and the height of each floor are decreased. Both the lateral method of analysis and the modal response spectrum analysis are used as recommended by EC8 to calculate the inter-storey drifts, the total shear forces and the overturning moments at the base of each building. The results are plotted and compared so that useful outcomes can be obtained. 1. Introduction One of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible aftereffects especially when they are associated with structures. An earthquake is a sudden movement of the Earth, caused by the abrupt release of strain that has accumulated over a long time. Earthquake intensity and magnitude are the most common used parameters in order to understand and compare different earthquake events.( ÃŽâ⬠° are the most common parameters used to appreciate and compare.) In recent years have been giving increasing attention to the design of buildings for earthquake resistance. Specific (particular) legislation is (have been) established to make structures able to resist at any seismic excitation. In Europe, Eurocode 8 explains how to make buildings able to resist to earthquakes, and recommends the use of linear and non-linear methods for the seismic design of the buildings Simple structures can be modelled either as equivalent single degree of freedom systems (SDOF) or as a combination of SDOF systems. In this project 8 different buildings with a variation either on the number of storeys or on their characteristics are simulated as a combination of SDOF systems for which the mode shapes and their corresponding eigenfrequencies and periods are calculated. Afterwards the fundamental frequency is obtained for each case and the elastic design is used in order to obtain the base shear forces and the overturning moments. (INELASTIC DESIGN AND LATERAL FORCE METHOD) 2. Literature review 2.1 Introduction to earthquake engineering Definition and earthquake derivation or generation or creation or production or formation or genesis The lithosphere is the solid part of Earth which includes or consists of the crust and the uppermost mantle. The sudden movement of the earths lithosphere is called earthquake (technical name seism). Fractures in Earths crust where sections of rock have slipped past each other are called Faults. Most earthquakes occur along Faults. Generally, earthquakes are caused by the sudden release of built-up stress within rocks along geologic faults or by the movement of magma in volcanic areas. The theory of plate tectonics provides geology with a comprehensive theory that explains how the Earth works. The theory states that Earths outermost layer, the lithosphere, is broken into 7 large, rigid pieces called plates: the African, North American, South American, Australian- Indian, Eurasian, Antarctic, and Pacific plates. Several subcontinental plates also exist, including the Caribbean, Arabian, Nazca, Philippines and Cocos plates. Boundaries of tectonic plates are found at the edge of the lithospheric plates and can be of various forms, depending on the nature of relative movements. By their distinct motions, three main types can be characterized. The three types are: subduction zones (or trenches), spreading ridges (or spreading rifts) and transform faults.. convergent, divergent and conservative. At subduction zone boundaries, plates move towards each other and the one plate subducts underneath the other (ÃŽà ® à ¼Ãâ¬Ã ¿Ã à Ã
½ à ½Ã ± Ãâ¬Ãâ°: one plate is overriding another, thereby forcing the other into the mantle beneath it.) The opposite form of movement takes place at spreading ridge boundaries. At these boundaries, two plates move away from one another. As the two move apart, molten rock is allowed to rise from the mantle to the surface and cool down to form part of the plates. This, in turn, causes the growth of oceanic crust on either side of the vents. As the plates continue to move, and more crust is formed, the ocean basin expands and a ridge system is created. Divergent boundaries are responsible in part for driving the motion of the plates. At transform fault boundaries, plate material is neither created nor destroyed at these boundaries, but rather plates slide past each other. Transform faults are mainly associated with spreading ridges, as they are usually formed by surface movement due to perpendicular spreading ridges on either side. Earthquake Location When an earthquake occurs, one of the first questions is where was it?. An earthquakes location may tell us what fault it was on and where the possible damage most likely occurred. The hypocentre of an earthquake is its location in three dimensions: latitude, longitude, and depth. The hypocentre (literally meaning: below the center from the Greek Ãâ¦Ãâ¬Ã Ã
âà ºÃ µÃ ½Ãâà à ¿Ã ½), or focus of the earthquake, refers to the point at which the rupture initiates and the first seismic wave is released. As an earthquake is triggered, the fault is associated with a large area of fault plane. The point directly above the focus, on the earths surface where the origin of an earthquake above ground. The epicentre is the place on the surface of the earth under which an earthquake rupture originates, often given in degrees of latitude (north-south) and longitude (east-west). The epicentre is vertically above the hypocentre. The distance between the two points is the focal depth. The location of any station or observation can be described relative to the origin of the earthquake in terms of the epicentral or hypocentral distances. Propagation of seismic waves Seismic waves are the energy generated by a sudden breaking of rock within the earth or an artificial explosion that travels through the earth and is recorded on seismographs. There are several different kinds of seismic waves, and they all move in different ways. The two most important types of seismic waves are body waves and surface waves. Body waves travel deep within the earth and surface waves travel near the surface of the earth. Body waves: There are two types of body waves: P-waves (also pressure waves) and S-waves (also shear waves). P-waves travel through the Earth as longitudinal waves whose compressions and rarefactions resemble those of a sound wave. The name P-wave comes from the fact that this is the fastest kind of seismic wave and, consequently, it is the first or ââ¬ËPrimary wave to be detected at a seismograph. Speed depends on the kind of rock and its depth; usually they travel at speeds between 1.5 and 8 kilometers per second in the Earths crust. P waves are also known as compressional waves, because of the pushing and pulling they do. P waves shake the ground in the direction they are propagating, while S waves shake perpendicularly or transverse to the direction of propagation. The P-wave can move through solids, liquids or gases. Sometimes animals can hear the P-waves of an earthquake S-waves travel more slowly, usually at 60% to 70% of the speed of P waves. The name S-wave comes from the fact that these slower waves arrive Secondary after the P wave at any observation point. S-waves are transverse waves or shear waves, so that particles move in a direction perpendicular to that of wave propagation. Depending in whether this direction is along a vertical or horizontal plane, S-waves are subcategorized into SV and SH-waves, respectively. Because liquids and gases have no resistance to shear and cannot sustain a shear wave, S-waves travel only through solids materials. The Earths outer core is believed to be liquid because S-waves disappear at the mantle-core boundary, while P-waves do not. (3: http://www.globalchange.umich.edu/globalchange1/current/lectures/nat_hazards/nat_hazards.html) Surface waves: The surface waves expand, as the name indicates, near the earths surface. The amplitudes of surface waves approximately decrease exponentially with depth. Motion in surface waves is usually larger than in body waves therefore surface waves tend to cause more damage. They are the slowest and by far the most destructive of seismic waves, especially at distances far from the epicenter. Surface waves are divided into Rayleigh waves and Love waves. Rayleigh waves, also known as ground roll, are the result of an incident P and SV plane waves interacting at the free surface and traveling parallel to that surface. Rayleigh waves (or R-waves) took their name from (named for) John Strutt, Lord Rayleigh who first described them in 1885 (ÃŽà ® who mathematically predicted the existence of this kind of wave in 1885) and they are an important kind of surface wave. Most of the shaking felt from an earthquake is due to the R-wave, which can be much larger than the other waves. In Rayleigh waves the particles of soil move vertically in circular or elliptical paths, just like a wave rolls across a lake or an ocean. As Rayleigh wave particle motion is only found in the vertical plane, this means that they most commonly found on the vertical component of seismograms. The Rayleigh equation is: Love waves (also named Q waves) are surface seismic waves that cause horizontal shifting of the earth during an earthquake. They move the ground from side to side in a horizontal plane but at right angles to the direction of propagation. Love waves took their name from A.E.H. Love, a British mathematician who worked out the mathematical model for this kind of wave in 1911. Love waves are the result from the interaction with SH-waves. They travel with a slower velocity than P- or S- waves, but faster than Rayleigh waves, their speed relate to the frequency of oscillation. Earthquake size: Earthquake measurement is not a simple problem and it is hampered by many factors. The size of an earthquake can be quantified in various ways. The intensity and the magnitude of an earthquake are terms that were developed in an attempt to evaluate the earthquake phenomenon and they are the most commonly used terms to express the severity of an earthquake. Earthquake intensity: Intensity is based on the observed effects of ground shaking on people, buildings, and natural features. It varies from place to place within the disturbed region depending on the location of the observer with respect to the earthquake epicenter. Earthquake magnitude: The magnitude is the most often cited measure of an earthquakes size. The most common method of describing the size of an earthquake is the Richter magnitude scale, ML. This scale is based on the observation that, if the logarithm of the maximum displacement amplitudes which were recorded by seismographs located at various distances from the epicenter are put on the same diagram and this is repeated for several earthquakes with the same epicentre, the resulting curves are parallel to each other. This means that if one of these earthquakes is taken as the basis, the coordinate difference between that earthquake and every other earthquake, measures the magnitude of the earthquake at the epicentre. Richter defined as zero magnitude earthquake one which is recorded with 1à ¼m amplitude at a distance of 100 km. Therefore, the local magnitude ML of an earthquake is based on the maximum trace amplitude A and can be estimated from the relation: ML= log A log A (3) Where A is the amplitude of the zero magnitude earthquake (ML=0). The Richter magnitude scale can only be used when seismographs are within 600 km of the earthquake. For greater distances, other magnitude scales have been defined. The most current scale is the moment magnitude scale MW, which can be used for a wide range of magnitudes and distances. Two main categories of instruments are used for the quantitative evaluation (estimation, assessment) of the earthquake phenomenon: the seismographs which record the displacement of the ground as a function of time, and the accelerographs (or accelerometers) which record the acceleration of the ground as a function of time, producing accelerograms. X the accelerogram of the 1940 El Centro earthquake. For every earthquake accelerogram, elastic or linear acceleration response spectrum diagrams can be calculated. (obtained, estimated) The response spectrum of an earthquake is a diagram of the peak values of any of the response parameters (displacement, acceleration or velocity) as a function of the natural vibration period T of the SDOF system, subjected to the same seismic input. All these parameters can be plotted together in one diagram which is called the tripartite plot (also known as four coordinate paper). 2.2 Earthquake and Structures simulation 2.2.1 Equation of motion of SDOF system Introduction Vibration is the periodic motion or the oscillation of an elastic body or a medium, whose state of equilibrium has been disturbed. Ãâ" à ¼Ãâ¬Ã ¿Ã Ãâ° Ã ½Ã ± Ãâ¬Ãâ°: whose position of equilibrium has been displaced. There are two types of vibrations, free vibration and forced vibration. Vibration can be classified as either free or forced. A structure is said to be in a state of free vibration when it is disturbed from its static equilibrium by given a small displacement or deformation and then released and allowed to vibrate without any external dynamic excitation. Number of Degrees of Freedom (DOF) is the number of the displacements that are needed to define the displaced position of the masses relative to their original position. Simple structures can be idealised as a system with a lumped mass m supported by a massless structure with stiffness k. It is assumed that the energy is dissipated through a viscous damper with damping coefficient c. Only one displacement variable is required in order to specify the position of the mass in this system, so it is called Singe Degree of Freedom (SDOF) system. Undamped Free Vibration of SDOF systems Furthermore, if there is no damping or resistance in the system, there will be no reduction to the amplitude of the oscillation and theoretically the system will vibrate forever. Such a system is called undamped and is represented in the below: By taking into consideration the inertia force fin and the elastic spring force fs the equation of the motion is given by: fin + fs = 0 ââ â m+ ku = 0 Considering the initial conditions u(0) and (0), where u(0) is the displacement and (0) is the velocity at the time zero, the equation (4) has the general solution: u(t) = u(0) cosÃâ°nt + sinÃâ°nt where Ãâ°n is the natural frequency of the system and is given by, Ãâ°n = (6) The natural period and the natural frequency can be defined by the above equations: Tn = (7) fn = (8) Viscously damped Free Vibration of SDOF systems The equation of motion of such a system can be developed from its free body diagram below: Considering the inertia force fin, the elastic spring force fs and the damping force fD, the equation of the motion is given by: m+ c+ ku = 0 (9) Dividing by m the above equation gives: + 2à ¾Ãâ°n+ Ãâ°2u = 0 (10) where à ¾ is the critical damping and is given by: à ¾ = (11) and Cc is the critical damping ratio given by: Cc = 2mÃâ°n * If à ¾ > 1 or c > Cc the system is overdamped. It returns to its equilibrium position without oscillating. * If à ¾ = 1 or c = Cc the system is critically damped. It returns to its equilibrium position without oscillating, but at a slower rate. * If à ¾ Taking into account that all the structures can be considered as underdamped systems, as typically their damping ratio à ¾ is less than 0.10 the equation (9) for the initial conditions u (0) and (0) gives the solution below: U (t) = eâ⬠¦Ã¢â¬ ¦Ã¢â¬ ¦Ã¢â¬ ¦Ã¢â¬ ¦[u(0)cosÃâ°n+[â⬠¦.+sinÃâ°Dt] (13) where Ãâ°D is the natural frequency of damped vibration and is given by: Ãâ°D = Ãâ°n (14) Hence the natural period is: TD = (15) Undamped Forced Vibration of SDOF system The equation of motion of such a system can be developed from its free body diagram below: Considering the inertia force fin, the elastic spring force fs and the external dynamic load f(t), the equation of the motion is given by: m+ ku = f(t) (16) where f(t) = f0 sinÃâ°t is the maximum value of the force with frequency Ãâ° By imposing the initial conditions u(0) and (0) the equation (16) has a general solution: u(t) = u(0)cosÃâ°nt + sinÃâ°nt + sinÃâ°t (17) Damped Forced Vibration of SDOF system The equation of motion of such a system can be developed from its free body diagram below: Considering the inertia force fin, the elastic spring force fs, the damping force fD and the external dynamic load f(t), the equation of the motion is given by: m+ c+ ku = f(t) (18) where f(t) = f0 sinÃâ°t The particular solution of equation (18) is: up = CsinÃâ°t + DcosÃâ°t (19) And the complementary solution of equation (18) is: (20) uc = e(AcosÃâ°Dt + BsinÃâ°nt) (20) 2.2.2 Equation of motion of MDOF system The equation of motion of a MDOF elastic system is expressed by: M+ C+ Ku = -MAI(t) (21) where M is the mass matrix, C is the damping matrix, K is the stiffness matrix, u is the acceleration vector, u is the velocity vector and u is the displacement vector. Finally, AI is a vector with all the elements equal to unity and ug(t) is the ground acceleration. 2.2 Earthquake and Structures simulation 2.2.1 Equation of motion of SDOF system Introduction Vibration is the periodic motion or the oscillation of an elastic body or a medium, whose state of equilibrium has been disturbed. Ãâ" à ¼Ãâ¬Ã ¿Ã Ãâ° Ã ½Ã ± Ãâ¬Ãâ°: whose position of equilibrium has been displaced. There are two types of vibrations, free vibration and forced vibration. Vibration can be classified as either free or forced. A structure is said to be in a state of free vibration when it is disturbed from its static equilibrium by given a small displacement or deformation and then released and allowed to vibrate without any external dynamic excitation. Number of Degrees of Freedom (DOF) is the number of the displacements that are needed to define the displaced position of the masses relative to their original position. Simple structures can be idealised as a system with a lumped mass m supported by a massless structure with stiffness k. It is assumed that the energy is dissipated through a viscous damper with damping coefficient c. Only one displacement variable is required in order to specify the position of the mass in this system, so it is called Singe Degree of Freedom (SDOF) system. Undamped Free Vibration of SDOF systems Furthermore, if there is no damping or resistance in the system, there will be no reduction to the amplitude of the oscillation and theoretically the system will vibrate forever. Such a system is called undamped and is represented in the below: By taking into consideration the inertia force fin and the elastic spring force fs the equation of the motion is given by: fin + fs = 0 ââ â m+ ku = 0 Considering the initial conditions u(0) and (0), where u(0) is the displacement and (0) is the velocity at the time zero, the equation (4) has the general solution: u(t) = u(0) cosÃâ°nt + sinÃâ°nt where Ãâ°n is the natural frequency of the system and is given by, Ãâ°n = (6) The natural period and the natural frequency can be defined by the above equations: Tn = (7) fn = (8) Viscously damped Free Vibration of SDOF systems The equation of motion of such a system can be developed from its free body diagram below: Considering the inertia force fin, the elastic spring force fs and the damping force fD, the equation of the motion is given by: m+ c+ ku = 0 (9) Dividing by m the above equation gives: + 2à ¾Ãâ°n+ Ãâ°2u = 0 (10) where à ¾ is the critical damping and is given by: à ¾ = (11) and Cc is the critical damping ratio given by: Cc = 2mÃâ°n * If à ¾ > 1 or c > Cc the system is overdamped. It returns to its equilibrium position without oscillating. * If à ¾ = 1 or c = Cc the system is critically damped. It returns to its equilibrium position without oscillating, but at a slower rate. * If à ¾ Taking into account that all the structures can be considered as underdamped systems, as typically their damping ratio à ¾ is less than 0.10 the equation (9) for the initial conditions u (0) and (0) gives the solution below: U (t) = eâ⬠¦Ã¢â¬ ¦Ã¢â¬ ¦Ã¢â¬ ¦Ã¢â¬ ¦[u(0)cosÃâ°n+[â⬠¦.+sinÃâ°Dt] (13) where Ãâ°D is the natural frequency of damped vibration and is given by: Ãâ°D = Ãâ°n (14) Hence the natural period is: TD = (15) Undamped Forced Vibration of SDOF system The equation of motion of such a system can be developed from its free body diagram below: Considering the inertia force fin, the elastic spring force fs and the external dynamic load f(t), the equation of the motion is given by: m+ ku = f(t) (16) where f(t) = f0 sinÃâ°t is the maximum value of the force with frequency Ãâ° By imposing the initial conditions u(0) and (0) the equation (16) has a general solution: u(t) = u(0)cosÃâ°nt + sinÃâ°nt + sinÃâ°t (17) Damped Forced Vibration of SDOF system The equation of motion of such a system can be developed from its free body diagram below: Considering the inertia force fin, the elastic spring force fs, the damping force fD and the external dynamic load f(t), the equation of the motion is given by: m+ c+ ku = f(t) (18) where f(t) = f0 sinÃâ°t The particular solution of equation (18) is: up = CsinÃâ°t + DcosÃâ°t (19) And the complementary solution of equation (18) is: uc = (AcosÃâ°Dt + BsinÃâ°nt) (20) 2.2.2 Equation of motion of MDOF system The equation of motion of a MDOF elastic system is expressed by: M+ C+ Ku = -MAI(t) (21) where M is the mass matrix, C is the damping matrix, K is the stiffness matrix, u is the acceleration vector, u is the velocity vector and u is the displacement vector. Finally, AI is a vector with all the elements equal to unity and g(t) is the ground acceleration. 3. Description of the Method 3.1 Simplified Multi-Storey Shear Building Model It is almost impossible to predict precisely which seismic action a structure will undergo during its life time. Each structure must be designed to resist at any seismic excitation without failing. For this reason each structure is designed to meet the requirements of the design spectrum analysis based in EC8. Also some assumptions are necessary in order to achieve the best and the simplest idealization for each multi store building. Initially it is assumed that the mass of each floor is lumped at the centre of the floor and the columns are massless. The floor beams are completely rigid and incompressible; hence the floor displacement is being transferred equally to all the columns. The columns are flexible in horizontal displacement and rigid in vertical displacement, while they are provided with a fully fixed support from the floors and the ground. The building is assumed to be symmetric about both x and y directions with symmetric column arrangement. The consequence of this is tha t the centre of the mass of each floor to coincide with the centre of the stiffness of each floor. The position of this centre remains stable up the entire height of the building. Finally, it is assumed that there are no torsional effects for each of the floors. If all the above assumptions are used the building structure is idealised as a model where the displacement at each floor is described by one degree of freedom. Thus, for a jth storey building, j degrees of freedom required to express the total displacement of the building. The roof of the building has always to be considered as a floor. The mass matrix M is a symmetric diagonal nxn matrix for a n-storey building and is given below. Each diagonal value in the matrix represents the total mass of one beam and its two corresponding columns which are assumed to be lumped at each level. M = Stiffness method is used to formulate the stiffness matrix. K is the lateral stiffness of each column and is given by the relationship: K = (22) where EI is the flexural stiffness of a column. The lateral stiffness of each column is clamped at the ends and is imposed in a unit sway. The stiffness of each floor is the sum of the lateral force of all columns in the floor. The stiffness matrix is for a n-storey building is: K = In order to calculate the natural modes of the vibration, the system is assumed that vibrates freely. Thus, g(t)=0, which for systems without damping (c=0) the equation (21) specializes to: M+ Ku = 0 (23) The displacement is assumed to be harmonic in time, this is: = -Ãâ°2UeiÃâ°t (24) Hence equation (23) becomes: (K Ãâ°2M)U = 0 (25) The above equation has the trivial solution u=0. For non trivial solutions, uâⰠ0 the determinant for the left hand size must be zero. That is: |K Ãâ°2 M| = 0 (26) This condition leads to a polynomial in terms of Ãâ°2 with n roots, where n is the size of matrices and vectors as cited above. These roots are called eigenvalues. By applying the equation (6) (7), the natural frequency and the natural period of vibration for each mode shape can be determined. Each eigenvalue has a relative eigenvector which represent the natural ith mode shape. After the estimation of the eigenvector in order to compare the mode shapes, scale factors are applied to natural modes to standarise their elements associated with various degrees of freedom (X). This process is called normalization. Hence, after the estimation of the eigenvectors each mode is normalised so that the biggest value is X: eigenvector notation. unity. The eigenvectors of a symmetric matrix corresponding to distinct eigenvalues are orthogonal. This aspect is expressed by the following expression: UiTKUij = UiTMUij (27) The classical eigenvalue problem has the following form: (M-1K à » I) u = 0 (28) where à » =Ãâ°2 and I is the identity matrix. EC8 suggests that the response in two modes i and j can be assumed independent of each other when Tj âⰠ¤ 0.9 Ti where Ti and Tj are the periods of the modes i and j respectively (always Ti âⰠ¥ Tj). The calculated fundamental period can be checked by the equation that EC8 suggests: T = Ct*H3/4 where T is the fundamental period of the building, Ct is a coefficient and H is the total height of the building; this expression is valid buildings that their total height is not more than forty metres 3.2 Elastic Analysis The response method is used to estimate the maximum displacement (uj), pseudo- velocity (j) and acceleration (j) for each calculated natural frequency. It is assumed that the MDOF system oscillates in each of its modes independently and displacements, velocities and accelerations can be obtained for each mode separately considering modal responses as SDOF responses. Each maximum, displacement velocity and acceleration read from the design spectrum is multiplying by the participation factor à ±i to re-evaluate the maximum values expressed ujmax, jmax, jmax respectively. The participation factor à ±i is defined by the following equation: (28) where UijT is the transpose vector of each of the mode vectors, M is the mass matrix, AI is the unit vector and Uij is the mode shape vector. The actual maximum displacements of the jth mode are given by: u = ujmaxÃŽâ⬠¡Uj Afterwards, the root-mean-square (RMS) approximation is used in order to calculate the maximum displacement for each floor. In this approach, all the maximum values for each mode, are squared and summed and their square root is derived. If we let Dmax be the maximum displacement then: Dmax = (29) A very variable parameter to characterise the seismic behaviour of a building is the Inter-Storey Drift which can be obtained by the following equation: à ´i = Di Di-1/hi (30) where Di, Di-1, are the horizontal displacements for two contiguous floors and hi is the corresponding height of the floor. The calculated values must be lower than 4% in order to agree with the Eurocode. Afterwards the horizontal inertia forces Fjs applied at each floor are obtained by applying the following equation: Fj = MÃŽâ⬠¡UjÃŽâ⬠¡jmax (31) where M is the mass matrix, Uj is the eigenvector for each mode and jmax is the maximum acceleration. As it is suggested from the EC8, the root-mean-approximation is used again in order to obtain the total lateral forces. EC8 suggests that the combined lateral force at each floor is given by the square root of the sum of the squares of each lateral force at each floor of all the modes. If we let Ftotal,i the maximum base shear force then: Ftotal,j = [1] (32) where Fij is the lateral force at floor i of the mode j. Once the total lateral forces and the shear forces have been obtained, the maximum overturning moment is calculated. 3.3 Inelastic Analysis The inelastic response spectra are generally obtained by the scaling of the elastic design spectra via the use of response modification factors. No effect of the energy absorption was assumed in the structure for the calculated values by using the elastic design spectrum. By introducing the ductility factor this parameter is taking into consideration. Newmark has described the ductility parameter à ¼ as the ratio of maximum displacement to the displacement at yield. Apparently when yielding does not take place the concept of ductility is not relevant and à ¼ is taken equal to unity. à ¤he system is described by the damping ratio Ãâ, the natural frequency Ãâ°n, and the ductility factor à ¼. In order to calculate the new set of values of acceleration, displacement and velocity the design response spectrum has to be constructed. Newmarks procedure leads to the construction of two modified spectra. 1. For maximum acceleration: In this case the elastic design spectrum is reduced by the appropriate coefficients. The acceleration region of the graph is multiplie
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