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Main article: Earthquake engineering
Chichen Itza 3

Earthquake-proof and massive pyramid El Castillo, Chichen Itza.

Earthquake engineering structures are designed and constructed to withstand various types of hazardous earthquake exposures at the sites of their particular location.

Earthquake engineering is treating its subject structures 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 codes, earthquake engineering 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 [1].

Ancient architects believed that devastating earthquakes were a result of wrath of gods and therefore, could not be resisted by humans.[citation needed] Nowadays, the people's attitude has changed dramatically though the term "earthquake engineering structure" does not necessarily mean it is an extremely strong or expensive one like the El Castillo pyramid at Chichen Itza.

File:Snapshot of base isolation effect.jpg
Currently, the most powerful and cost-effective tool of earthquake engineering is base isolation which makes use of passive structural vibration control technologies, used for example in the Cathedral of Our Lady of the Angels.

Trends and projectsEdit

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

Earthquake shelterEdit

One Japanese construction company has developed a six-foot cubical shelter, presented as an alternative to earthquake-proofing an entire building.[2]

Concurrent shake-table testingEdit

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

Thus, two wooden houses built before adoption of the 1981 Japanese Building Code were moved to E-Defense [3] 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 [4].

Combined vibration control solutionEdit

Municipal Services Building-1

Close-up of abutment of seismically retrofitted Municipal Services Building in Glendale, CA

Municipal Services Building

Seismically retrofitted Municipal Services Building in Glendale, CA

Designed by architect Merrill W. Baird of Glendale, working in collaboration with A. C. Martin Architects of Los Angeles, the Municipal Services Building at 633 East Broadway, Glendale was completed in 1966 [5]. 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 & 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 systemEdit

Pages from Kharrazi 0002

Coupled steel plate shear walls, Seattle, Copyright Mehdi Kharrazi

LA LiveTower05

The Ritz-Carlton/JW Marriott hotel building engaging the advanced steel plate shear walls system, LA

A steel plate shear wall (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 [3].

SPSW behavior is analogous to a vertical plate girder cantilevered from its base. Similar to plate girders, the SPSW system optimizes component performance by taking advantage of the post-buckling behavior of the steel infill panels.

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

File:Kashiwazaki nuclear plant.jpg
The Kashiwazaki-Kariwa Nuclear Power Plant, the largest nuclear generating station in the world by net electrical power rating, happened to be near the epicenter of the strongest Mw 6.6 July 2007 Chūetsu offshore earthquake [4]. This initiated an extended shutdown for structural inspection which indicated that a greater earthquake-proofing was needed before operation could be resumed [5].

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

File:2009-0709-earthquake.jpg
A destructive earthquake struck a lone, wooden condominium in Japan [6]. 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 [7].

The Miki 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 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. 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 and dampers filled with viscous fluid.

See alsoEdit

ReferencesEdit

  1. Seismology Committee (1999). Recommended Lateral Force Requirements and Commentary. Structural Engineers Association of California. 
  2. [1]
  3. Kharrazi, M.H.K., 2005, “Rational Method for Analysis and Design of Steel Plate Walls,” Ph.D. Dissertation, University of British Columbia, Vancouver, Canada,
  4. ""Profits shaken at Tepco"". World Nuclear News. 31 July 2007. http://www.world-nuclear-news.org/corporate/Profits_shaken_at_Tepco_310707.shtml. Retrieved 2007-08-01. 
  5. Asahi.com. Quake exposes nuke-plant danger. July 18, 2007.

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