Earthquake engineering structures - AbsoluteAstronomy.com

Earthquake-resistant structures are designed and constructed to withstand various types of hazardous earthquake

Earthquake

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

exposures at the sites of their particular location.

Earthquake engineering

Earthquake engineering

Earthquake engineering is the scientific field concerned with protecting society, the natural and the man-made environment from earthquakes by limiting the seismic risk to socio-economically acceptable levels...

is treating its subject structure

Structure

Structure is a fundamental, tangible or intangible notion referring to the recognition, observation, nature, and permanence of patterns and relationships of entities. This notion may itself be an object, such as a built structure, or an attribute, such as the structure of society...

s like defensive fortifications in military engineering but for the warfare on earthquakes. Both earthquake and military general design principles are similar: be ready to slow down or mitigate the advance of a possible attacker.

According to building code

Building code

A building code, or building control, is a set of rules that specify the minimum acceptable level of safety for constructed objects such as buildings and nonbuilding structures. The main purpose of building codes are to protect public health, safety and general welfare as they relate to the...

s, earthquake-resistant structures are meant to withstand the largest earthquake of a certain probability that is likely to occur at their location. This means the loss of life should be minimized by preventing collapse of the buildings for rare earthquakes while the loss of functionality should be limited for more frequent ones.

Ancient architects believed that devastating earthquakes were a result of wrath of gods and therefore, could not be resisted by humans. Still, they could build their landmark structures to last, often by making them excessively stiff

Stiffness

Stiffness is the resistance of an elastic body to deformation by an applied force along a given degree of freedom when a set of loading points and boundary conditions are prescribed on the elastic body.-Calculations:...

and strong

Strength of materials

In materials science, the strength of a material is its ability to withstand an applied stress without failure. The applied stress may be tensile, compressive, or shear. Strength of materials is a subject which deals with loads, deformations and the forces acting on a material. A load applied to a...

, like the El Castillo pyramid at Chichen Itza

El Castillo, Chichen Itza

;El Castillo , also known as the Temple of Kukulkan, is a Mesoamerican step-pyramid that dominates the center of the Chichen Itza archaeological site in the Mexican state of Yucatán...

Currently, there are several design philosophies in earthquake engineering, making use of experimental results, computer simulations and observations from past earthquakes to offer the required performance for the seismic threat at the site of interest. These range from appropriately sizing the structure to be strong

Strength of materials

and ductile

Ductility

In materials science, ductility is a solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire. Malleability, a similar property, is a material's ability to deform under compressive stress; this is often characterized...

enough to survive the shaking with an acceptable damage, to equipping it with base isolation

Base isolation

Base isolation, also known as seismic base isolation or base isolation system, is one of the most popular means of protecting a structure against earthquake forces...

or using structural vibration control

Vibration control

In earthquake engineering, vibration control is a set of technical means aimed to mitigate seismic impacts in building and non-building structures.All seismic vibration control devices may be classified as passive, active or hybrid where:...

technologies to minimize any forces and deformations. While the former is the method typically applied in most earthquake-resistant structures, important facilities, landmarks and cultural heritage buildings use the more advanced (and expensive) techniques of isolation or control to survive strong shaking with minimal damage. Examples of such applications are the Cathedral of Our Lady of the Angels

Cathedral of Our Lady of the Angels

The Cathedral of Our Lady of the Angels, also called "COLA" and the Los Angeles Cathedral, is a cathedral of the Roman Catholic Church in Los Angeles, California, United States...

and the Acropolis Museum

Acropolis Museum

The Old Acropolis Museum was an archaeological museum located in Athens, Greece on the archeological site of Acropolis. It is built in a niche at the eastern edge of the rock and most of it lies beneath the level of the hilltop, making it largely invisible. It was considered one of the major...

Trends and projects

Some of the new state-of-the-art trends and/or projects in the field of earthquake engineering structures are presented below.

Proofed low cost earthquake building material

A leading German composite construction company developed a proofed earthquake-safe supported core material RexWall - based on internal beam/frame constructions. The same principle allows construction of hurricane-safe houses.

Earthquake shelter

One Japanese construction company has developed a six-foot cubical shelter, presented as an alternative to earthquake-proofing an entire building.

Concurrent shake-table testing

Concurrent shake-table testing of two or more building models is a vivid, persuasive and effective way to validate earthquake engineering

Earthquake engineering

solutions experimentally.

Thus, two wooden houses built before adoption of the 1981 Japanese Building Code were moved to E-Defense http://www.allamericanpatriots.com/node/12697 for testing (see both pictures aside). The left house was reinforced to enhance its seismic resistance, while the other one was not. These two models were set on E-Defense platform and tested simultaneously http://www.youtube.com/watch?v=kc652Zp5qWk&feature=PlayList&p=F297EF2ADDEAD86C&index=182.

Combined vibration control solution

Albert C. Martin, Sr.

Albert Carey Martin was an American architect and engineer.He founded the architectural firm of Albert C...

Architects of Los Angeles, the Municipal Services Building at 633 East Broadway, Glendale

Glendale, California

Glendale is a city in Los Angeles County, California, United States. As of the 2010 Census, the city population is 191,719, down from 194,973 at the 2000 census. making it the third largest city in Los Angeles County and the 22nd largest city in the state of California...

was completed in 1966 http://www.ci.glendale.ca.us/planning/MSB%20EIR/AppendixB.pdf. Prominently sited at the corner of East Broadway and Glendale Avenue, this civic building serves as a heraldic element of Glendale’s civic center.

In October 2004 Architectural Resources Group (ARG) was contracted by Nabih Youssef

Nabih Youssef

Nabih Youssef, S.E., F.A.S.C.E is an Egyptian-American structural engineer, most recognized for his work in earthquake engineering.-Education & Working Life:...

& Associates, Structural Engineers, to provide services regarding a historic resource assessment of the building due to a proposed seismic retrofit.

In 2008, the Municipal Services Building of the City of Glendale, California was seismically retrofitted using an innovative combined vibration control solution: the existing elevated building foundation of the building was put on high damping rubber bearings.

Steel plate shear walls system

A steel plate shear wall

Steel plate shear wall

A steel plate shear wall consists of steel infill plates bounded by a column-beam system.- Overview :They constitute an SPSW. Its behavior is analogous to a vertical plate girder cantilevered from its base. Similar to plate girders, the SPW system optimizes component performance by taking...

(SPSW) consists of steel infill plates bounded by a column-beam system. When such infill plates occupy each level within a framed bay of a structure, they constitute a SPSW system.

SPSW behavior is analogous to a vertical plate girder

Girder

A girder is a support beam used in construction. Girders often have an I-beam cross section for strength, but may also have a box shape, Z shape or other forms. Girder is the term used to denote the main horizontal support of a structure which supports smaller beams...

cantilevered from its base. Similar to plate girders, the SPSW system optimizes component performance by taking advantage of the post-buckling

Buckling

In science, buckling is a mathematical instability, leading to a failure mode.Theoretically, buckling is caused by a bifurcation in the solution to the equations of static equilibrium...

behavior of the steel infill panels.

The Ritz-Carlton/JW Marriott hotel building, a part of the LA Live development in Los Angeles, California

Los Angeles, California

Los Angeles , with a population at the 2010 United States Census of 3,792,621, is the most populous city in California, USA and the second most populous in the United States, after New York City. It has an area of , and is located in Southern California...

, is the first building in Los Angeles that uses an advanced steel plate shear wall system to resist the lateral loads of strong earthquakes and winds.

Kashiwazaki-Kariwa Nuclear Power Plant is partially upgraded

The Kashiwazaki-Kariwa Nuclear Power Plant

Kashiwazaki-Kariwa Nuclear Power Plant

The is a large, modern nuclear power plant on a 4.2-square-kilometer site including land in the towns of Kashiwazaki and Kariwa in Niigata Prefecture, Japan on the coast of the Sea of Japan, from where it gets cooling water...

, the largest nuclear generating station in the world by net electrical power rating, happened to be near the epicenter of the strongest M_w

Moment magnitude scale

The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

6.6 July 2007 Chūetsu offshore earthquake

2007 Chuetsu offshore earthquake

The Chūetsu Offshore Earthquake was a powerful magnitude 6.6 earthquake that occurred 10:13 a.m. local time on July 16, 2007, in the northwest Niigata region of Japan. The earthquake shook Niigata and neighbouring prefectures...

. This initiated an extended shutdown for structural inspection which indicated that a greater earthquake-proofing was needed before operation could be resumed.

On May 9, 2009, one unit (Unit 7) was restarted, after the seismic upgrades

Seismic retrofit

Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent experiences with large earthquakes near urban centers,...

. The test run had to continue for 50 days. The plant had been completely shut down for almost 22 months following the earthquake.

Seismic Test of Seven-Story Building

A destructive earthquake struck a lone, wooden condominium in Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

http://news.rpi.edu/update.do. The experiment was webcast live on July 14, 2009 to yield insight on how to make wooden structures stronger and better able to withstand major earthquakes http://www.nsf.gov/news/newsmedia/neeswood.

The Miki

Miki, Hyogo

is a city located in Hyōgo, Japan.As of April 30, 2011, the city has an estimated population of 82,162, with a household number of 32,143 and a population density of 465.30 persons per km²...

shake at the Hyogo Earthquake Engineering Research Center is the capstone experiment of the four-year NEESWood project, which receives its primary support from the U.S. National Science Foundation

National Science Foundation

The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...

Network for Earthquake Engineering Simulation (NEES) Program.

“NEESWood aims to develop a new seismic design philosophy that will provide the necessary mechanisms to safely increase the height of wood-frame structures in active seismic zones of the United States, as well as mitigate earthquake damage to low-rise wood-frame structures,” said Rosowsky, Department of Civil Engineering at Texas A&M University

Texas A&M University

Texas A&M University is a coeducational public research university located in College Station, Texas . It is the flagship institution of the Texas A&M University System. The sixth-largest university in the United States, A&M's enrollment for Fall 2011 was over 50,000 for the first time in school...

. This philosophy is based on the application of seismic damping systems for wooden buildings. The systems, which can be installed inside the walls of most wooden buildings, include strong metal frame, bracing

Timber framing

Timber framing , or half-timbering, also called in North America "post-and-beam" construction, is the method of creating structures using heavy squared off and carefully fitted and joined timbers with joints secured by large wooden pegs . It is commonplace in large barns...

and damper

Tuned mass damper

A tuned mass damper, also known as an active mass damper or harmonic absorber, is a device mounted in structures to reduce the amplitude of mechanical vibrations. Their application can prevent discomfort, damage, or outright structural failure...

s filled with viscous fluid.