Earthquake Engineering
Earthquakes are vibrations felt at the surface of the earth which are caused by disturbances of the energy in the earth's interior. These vibrations are known as seismic waves. (Skinner Robinson McVerry 1) There are different type sof seisimc waves such as Primary (P) waves, whcih travel the fastest, Secondary (S) waves which cause the earth to vibrate vertically, Surface (L) waves. P and S waves are "affected by changes in the density and the rigidity of the materials through which they pass." (Columbia Encyclopedia) Earthquakes vary in their intensity and duration. Often times they are strong enough to cause massive destriction. Tall buildings often suffer as a result of these natural disasters. In recent years this has become a larger and larger threat with both the number of large buildings, and their number of occupants increasing. In an effort to try to minimize the damage caused by earthquakes many some engineers focus primarily on designing and constructing earthquake resistant buildings. Earthquake engineers have gathered much of their information from analyzing past earthquakes, and learning which buildings can and can't withstand the tremors. The goals of these engineers is to design buildings that can withstand moderate earthquakes and obtain minimal damage, and that the buildings will not collapse lowering the probability of human deaths.
Authorities have attempted to implement codes or regulations, but that has proved to be very difficult tasks becasue there are many variables that effect the dynamic response of buildings. One way to try to avoid disaster is to evaluate seismic risk is to look at a buildings hazards, exposure, vulnerability, and location. Hazards are, for example, landslides ad soil type. Exposure is a building's occupancy and function. Vulnerability is the expected performance of a building's system, and location is how often earthquakes occur in the area. (Lagorio)
Some other things that have become evident are that geometric simplicity and symmetry are key to constructing an earthquake resistant building. Simplicity often leads to symmetry, and in turn symmetry tends to decrease the likelihood of a concentration of mass. This idea of lighter buildings being safer can be explained mathematically using the formula F=MA. To understand how this formula works it is pertinent to recognize that earthquakes alone do not cause damage because all they provide is an acceleration.
Earthquakes, by Webster’s dictionary definition, are, “a shaking or trembling of the earth that is volcanic or tectonic in origin.” World Book Encyclopedia reports scientists believe that more than 8,000 earthquakes occur each day without causing damage. A little more than 1,000 each year are strong enough to be felt. Earthquakes occur in the general sense, anywhere on land. Other earthquakes go by different names, such as volcanic eruptions and tsunamis, large tidal wave storms that occur underwater, primarily in the Pacific Ocean.
Earthquakes play a major role into understanding the composition and materials that exist within the Earth (Merali and Skinner, 2009, p.252). Earthquakes are the main source of insight into the inner workings of the earth, due to the nature of the seismic waves they produce. P and S waves are reflected and refracted at different boundaries within the earth, and this enables seismologists to make inferences about the internal composition and structural of planet Earth. (Merali and Skinner, 2009, p.252).
The enormous responsibility that an engineer has when designing a project is often overlooked. His or her job is not only to create a design that will work under ideal conditions, but that will meet the regulations of environmental and building codes and will also survive the unpredictable forces of nature that structures are sometimes subjected to. An article in the Seattle Daily Journal of Commerce, "Structures are Held up by Both Skill and Luck,"1 describes many risks involved in the designing process and the failures that can occur when small details are overlooked. In light of a recent surge of failures in the Northwest, the article says:
Massive Mega-Quakes happen at regular intervals in the Pacific Northwest. There have been mega-quakes in the beginning of time. In Japan, a mega-quake send a 600-foot wave of water.
Skyscrapers are amazing! Architectural defeats. Wonders of the world. How are they able to withstand even the strongest of winds and earthquakes?
Earthquakes are best described as a shaking or vibration of the ground caused by breaking of rock. Sometimes they are very strong and other times you would hardly notice them. This shaking occurs when stress that builds up in the crust is suddenly released as the crust breaks free and/or slides against the other pieces of crust. Earthquakes may also be thought of as the breaking of a popsicle stick by applying pressure to both ends at the same time. Should you try this experiment , you will feel the pressure build up as you apply more force until the stick snaps. When the stick snaps you will feel an instant of pain at your fingers as the stress reduces and energy waves move throughout the stick. When the earth's crust is placed under similar types of stress, binding as the stress builds, it will also snap and release the energy into the surrounding rocks, 'ooch'. Thinking about earthquakes will become more clear if you try another experiment.
One of the major aftermaths of the Northridge Earthquake of January 17, 1994, was the widespread connection damage that posed a major question regarding the behavior of field-welded, field-bolted moment frame connections, also known as Pre-Northridge connections.
Problem Statement: Earthquakes are a natual part of the environment. They do,however,cause devistating effect on the environment. Since Earthquakes can not be avoided, maybe there is a way to determine when they are going to occur so precautions can be taken to get people to safety and protect as much of
On February 1, 2003, the Space Shuttle Columbia was lost due to structural failure in the left wing. On take-off, it was reported that a piece of foam insulation surrounding the shuttle fleet's 15-story external fuel tanks fell off of Columbia's tank and struck the shuttle's left wing. Extremely hot gas entered the front of Columbia's left wing just 16 seconds after the orbiter penetrated the hottest part of Earth's atmosphere on re-entry. The shuttle was equipped with hundreds of temperature sensors positioned at strategic locations. The salvaged flight recorded revealed that temperatures started to rise in the left wing leading edge a full minute before any trouble on the shuttle was noted. With a damaged left wing, Columbia started to drag left. The ships' flight control computers fought a losing battle trying to keep Columbia's nose pointed forward.
producing a earthquake safe environment. In a nuclear facility that in itself is a danger, an honest
As Bangladesh is located in a tectonically active much of the country including Chittagong, Sylhet, Dhaka, Rangpur, Bogra, Mymenshing, Comilla, Rajshahi are very much vulnerable to major earthquake disaster. Although, some awareness is raised among a limited groups, due to some recent earthquakes in the region, practically the country is far behind the minimum preparedness level to face such a disaster in any of our cities.
Firstly and most importantly, you need to understand what is an earthquake ? Here’s a brief introduction. An earthquake is the shaking of the ground, caused by shockwaves from movements and collisions of tectonic plates, mostly near fault lines, which is the edges of the plates. There are huge and minor earthquakes depending on the type and how the plates collided.
Disasters can occur as a result of one distinct natural even or a combination of events. Most damage is caused due to unpreparedness and lack of knowledge. Landslide risk reduction strategies have increased along with the increase in the occurrence of landslides. Assessment of high risk areas can provide the necessary knowledge needed to understand the risks associated with in the surrounding environment. Strategies such as planning and control, acceptance and adding warning systems are the most cost –effective ways to reduce damages caused by landslides; however engineering solutions are the most effective at reducing the probability of landslides but the downfall is the costs.
Taher, R. (2011). General recommendations for improved building practices in earthquake and hurricane prone areas. San Francisco, CA: Architecture for Humanity Retrieved from
Earthquakes belong to the class of most disastrous natural hazards. They result in unexpected and tremendous earth movements. These movements results from dissemination of an enormous amount of intense energy in form of seismic waves which are detected by use of seismograms. The impact of earthquakes leaves behind several landmarks including: destruction of property, extensive disruption of services like sewer and water lines, loss of life, and causes instability in both economic and social components of the affected nation (Webcache 2).