Posts Tagged earthquake engineering
Earthquake Resistant Structures | Engineering Tips
Posted by Architect in Earthquake Engineering on June 15, 2010
Earthquakes are a major geological phenomena. Man has been terrified of this phenomena for ages, as little has been known about the causes of earthquakes, but it leaves behind a trail of destruction. There are hundreds of small earthquakes around the world everyday. Some of them are so minor that humans cannot feel them, but seismographs and other sensitive machines can record them. Earthquakes occur when tectonic plates move and rub against each other. Sometimes, due to this movement, they snap and rebound to their original position. This might cause a large earthquakes as the tectonic plates try to settle down. This is known as the Elastic Rebound Theory.
Haiti Earthquake 2010
Every year, earthquakes take the lives of thousands of people , and destroy property worth billions. The 2010 Haiti Earthquake killed over 1,50,000 people and destroyed entire cities and villages. Designing Earthquake Resistant Structures is indispensable. It is imperative that structures are designed to resist earthquake forces, in order to reduce the loss of life. The science of Earthquake Engineering and Structural Design has improved tremendously, and thus, today, we can design safe structures which can safely withstand earthquakes of reasonable magnitude.
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Effect of Earthquakes on Structures
Posted by Architect in Earthquake Engineering on June 15, 2010
Violent Ground Motion During Earthquakes
The seismic waves travel for great distances before finally losing most of their energy. At some time after their generation, these seismic waves will reach the earth’s surface, and set it in motion, which we surprisingly refer to as earthquake ground motion. When this earthquake ground motion occurs beneath a building and when it is strong enough, it sets the building in motion, starting with the buildings foundation, and transfers the motion throughout the rest of building in a very complex way. These motions in turn induce forces which can produce damage.
Haiti Earthquake Damage 2010
Real earthquake ground motion at a particular building site is vastly more complicated than the simple wave form. Here it’s useful to compare the surface of ground under an earthquake to the surface of a small body of water, like a pond. You can set the surface of a pond in motion – by throwing stones into it. The first few stones create a series of circular waves, which soon being to collide with one another. After a while, the collisions, which we term interference patterns, are being to predominate over the pattern of circular waves. Soon the entire surface of water is covered by ripples, and you can no longer make out the original wave forms. During an earthquake, the ground vibrates in a similar manner, as waves of different frequencies and amplitude interact with one another.
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Building Planning | Earthquake Resistant Buildings
Posted by Architect in Earthquake Engineering on June 15, 2010
The behavior of building during earthquakes depends critically on its overall shape, size and geometry. Hence, at planning stage itself, architects and structural engineers must work together to ensure that the unfavorable features are avoided and a good building configuration is chosen. If both shape and structural system work together to make the structure a marvel.
“If we have a poor configuration to start with, all the engineer can do is to provide a band-aid – improve a basically poor solution as best as he can. Conversely, if we start-off with a good configuration and reasonable framing system, even a poor engineer cannot harm its ultimate performance too much”.
Size of Buildings
Size of Buildings
Building Construction Materials for Earthquake Resistance
Posted by Architect in Earthquake Engineering on June 15, 2010
In India, most non-urban buildings are made in masonry. In the plains, masonry is generally made of burnt clay bricks and cement mortar. However in hilly areas, stone masonry with mud mortar is more prevalent. But now a day we are very familiar with R.C.C. buildings, and a variety of new composite constructions materials.
Brittle and Ductile Building Materials
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Concept of Earthquake Resistant Engineering
Posted by Architect in Earthquake Engineering on June 15, 2010
If two bars of same length and same cross-sectional area – one made of ductile material and another of a brittle material. And a pull is applied on both bars until they break, then we notice that the ductile bar elongates by a large amount before it breaks, while the brittle bar breaks suddenly on reaching its maximum strength at a relative small elongation. Amongst the materials used in building construction, steel is ductile, while masonry and concrete are brittle.
Comparison of Brittle and Ductile Building materials
The correct building components need to be made ductile. The failure of columns can affect the stability of building, but failure of a beam causes localized effect. Therefore, it is better to make beams to be ductile weak links then columns. This method of designing RC buildings is called the strong-column weak-beam design method. Special design provisions from IS: 13920-1993 for RC structures ensures that adequate ductility is provided in the members where damage is expected.
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