building implosion

File:Radio Network House implosion.ogv, in the Christchurch Central City]]

{{Blockquote|The term "implosion" was coined by my grandmother back in, I guess, the '60s. It's a more descriptive way to explain what we do than "explosion". There are a series of small explosions, but the building itself isn't erupting outward. It's actually being pulled in on top of itself. What we're really doing is removing specific support columns within the structure and then cajoling the building in one direction or another, or straight down.|Stacy Loizeaux|NOVA, December 1996{{Cite web|title=NOVA Online/Kaboom!/Loizeaux Interview|url=https://www.pbs.org/wgbh/nova/kaboom/loizeaux.html|access-date=2021-03-18|website=www.pbs.org}}}}

The term building implosion can be misleading to a layperson: The technique is not a true implosion phenomenon. A true implosion usually involves a difference between internal (lower) and external (higher) pressure, or inward and outward forces, that is so large that the structure collapses inward into itself.{{Citation needed|date=July 2009}}

In contrast, building implosion techniques do not rely on the difference between internal and external pressure to collapse a structure. Instead, the goal is to induce a progressive collapse by weakening or removing critical supports; therefore, the building can no longer withstand gravity loads and will fail under its own weight.{{Citation needed|date=July 2009}}

Numerous small explosives, strategically placed within the structure, are used to catalyze the collapse. Nitroglycerin, dynamite, or other explosives are used to shatter reinforced concrete supports. Linear shaped charges are used to sever steel supports. These explosives are progressively detonated on supports throughout the structure. Then, explosives on the lower floors initiate the controlled collapse.{{Citation needed|date=July 2009}}

A simple structure like a chimney can be prepared for demolition in less than a day. Larger or more complex structures can take up to six months of preparation to remove internal walls and wrap columns with fabric and fencing before firing the explosives.{{Citation needed|date=July 2009}}

Image:Buffalo Implode2 2.jpg]]

File:Demolition of the New Haven Coliseum.gif in New Haven, Connecticut]]

As part of the demolition industry, the history of building implosion is tied to the development of explosives technology.{{Citation needed|date=July 2009}}

One of the earliest documented attempts at building implosion was the 1773 razing of Holy Trinity Cathedral in Waterford, Ireland with {{convert|150|lb|kg st|2|abbr=on}} of gunpowder, a huge amount of explosives at the time. The use of low velocity explosive produced a deafening explosion that instantly reduced the building to rubble.{{cite news | first= Dick |last=Grogan | title = Pillars of the church may save the nave | page = 2 | work= The Irish Times|edition=City |department=Home News | date = 1997-06-11 }}

The late 19th century saw the erection of—and ultimately the need to demolish—the first skyscrapers, which had more complicated structures, allowing greater heights. This led to other considerations in the explosive demolition of buildings, such as worker and spectator safety and limiting collateral damage. Benefiting from the availability of dynamite, a high-velocity explosive based on a stabilized form of nitroglycerine, and borrowing from techniques used in rock-blasting, such as staggered detonation of several small charges, the process of building implosion gradually became more efficient.{{Citation needed|date=July 2009}}

Following World War II, European demolition experts, faced with huge reconstruction projects in dense urban areas, gathered practical knowledge and experience for bringing down large structures without harming adjacent properties.

{{cite conference | first= Brent |last=Blanchard | title = A History of Explosive Demolition in America | book-title = Proceedings of the Annual Conference on Explosives and Blasting Technique | pages = 27–44 |date=February 2002 | issn = 0732-619X | publisher = International Society of Explosives Engineers}} This led to the emergence of a demolition industry that grew and matured during the latter half of the twentieth century. At the same time, the development of more efficient high-velocity explosives, such as RDX, and non-electrical firing systems combined to make this a period of time in which the building implosion technique was extensively used.{{Citation needed|date=July 2009}}

Meanwhile, public interest in the spectacle of controlled building explosion also grew. On 30 October 1994, Philadelphia's Sears Eastern Regional Catalogue Headquarters was demolished, with onlookers numbering an estimated 50,000."Record Blast" (Associated Press story). Indiana (PA) Gazette, 31 October 1994, 3. Thomas Mazza, vice president of Mercer Wrecking, estimated the building's size as 25 million cubic feet, exceeding the size of the previous "largest implosion" record cited by Guinness, the Traymore Hotel in Atlantic City."Record Blast" (Associated Press story). Indiana (PA) Gazette, 31 October 1994, 3.

Evolution in the mastery of controlled demolition led to the world record demolition of the Seattle Kingdome on March 26, 2000.{{cite web | website= Controlled Demolition | title = Seattle Kingdome demolition | url = http://www.controlled-demolition.com/sites/default/files/kingdome.mpg | access-date = 2010-03-29 | archive-date = 2019-01-04 | archive-url = https://web.archive.org/web/20190104144346/http://www.controlled-demolition.com/sites/default/files/kingdome.mpg | url-status = dead }}

In 1997, the Royal Canberra Hospital in Canberra, Australia, was demolished. The main building did not fully disintegrate and had to be manually demolished. The explosion during the initial demolition attempt was not contained on the site and large pieces of debris were projected towards spectators {{convert|500|m|yd|2|abbr=on}} away, in a location considered safe for viewing. A twelve-year-old girl was killed instantly, and nine others were injured. Large fragments of masonry and metal were found {{convert|650|m|yd|2|abbr=on}} from the demolition site.{{cite web | last = Madden | first = Shane G. | year = 1999 | url = http://www.courts.act.gov.au/magistrates/dec/bender/Sect01.htm | archive-url = http://webarchive.loc.gov/all/20090609035707/http://www.courts.act.gov.au/magistrates/dec/bender/Sect01.htm | url-status = dead | archive-date = 2009-06-09 | title = General Chronology and Overview | work = The Bender Coronial Decision | publisher = ACT Magistrates Court and Tribunals (Coroner's Court) | access-date = 2007-03-07 }}

On October 24, 1998, the J. L. Hudson Department Store and Addition in Detroit, Michigan became the tallest, and the largest, building ever imploded.

On February 23, 2007 an unfinished Intel building known as the Intel Shell was imploded in Austin, Texas, which was halted in April 2001.{{Cite news |last=Gregor |first=Katherine |date=2007-02-23 |title=Farewell, Intel Shell |url=https://www.austinchronicle.com/news/2007-02-23/449480/ |access-date=2024-09-23 |work=Austin Chronicle |language=en-US}}

On December 13, 2009, an unfinished 31-story condominium tower, known as the Ocean Tower, was imploded in South Padre Island, Texas. Construction on the new tower had begun in 2006, but it had been sinking unevenly during construction, which halted in 2008, and could not be saved. It is believed to be one of the tallest reinforced concrete structures ever imploded.{{cite news |url=http://www.brownsvilleherald.com/articles/rubble-106263-family-span.html |title=Ocean Tower implodes into pile of rubble |archive-url=https://web.archive.org/web/20120825212321/http://www.brownsvilleherald.com/articles/rubble-106263-family-span.html |archive-date=2012-08-25 |work=The Brownsville Herald |date=December 14, 2009}}

Building implosion has been successfully used at Department of Energy sites such as the Savannah River Site (SRS) in South Carolina and the Hanford Site in Washington. The SRS 185-3K or "K" Area Cooling Tower, built in 1992 to cool the water from the K Reactor, was no longer needed when the Cold War ended and was safely demolished by explosive demolition on May 25, 2010.{{cite interview |first=Bill |last=Austin |interviewer=L. Brady |date=2012-01-31 |url=https://www.dndkm.org/DOEKMDocuments/BestPractices/21-EFCOG%20Best%20Practice%20003_185-3K%20Cooling%20Tower%20Demolition%20-%20Final.pdf |title=The Use of Explosives to Demolish the 185-3K Cooling Tower |work=D&D KM}}

The Hanford Site Buildings 337, 337B, and the 309 Exhaust Stack, built in the early 1970s and vacated in the mid-2000s due to deteriorating physical condition, were safely razed by explosive demolition on October 9, 2010.{{cite interview |date=2010-11-11 |first1=Bob |last1=Smith |first2=Daniel |last2=Beckworth |first3=Thomas |last3=Kisenwether |interviewer1=Leonel Lagos |interviewer2=Peggy Shoffner |interviewer3=Lee Brady |url=https://www.dndkm.org/DOEKMDocuments/BestPractices/18-FINAL_337%20Building%20Explosion%20Demolition_BP.pdf |title=Explosive Demolition of Buildings 337, 337B and the 309 Stack at the Hanford's 300 Area |work=D&D KM}}

File:Blasting of a chimney at the former Henninger Brewery in Frankfurt am Main, Germany.jpg|Demolition of a chimney at the former "Henninger Brewery" in Frankfurt am Main, Germany, on 2 December 2006

File:Tencza demolition.png|June 2006 demolition of the 12-story Tencza Apartment building in Arlington, Virginia. (See [https://www.youtube.com/watch?v=d-WvQbFMIWU video])

File:Tappan Zee Bridge explosive demolition 10x slow motion.webm|Tappan Zee Bridge explosive demolition in slow motion

• Controlled Demolition, Inc.
• List of tallest voluntarily demolished buildings

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• [https://www.extremeloading.com/ Demolition Simulation] Advanced structural analysis for predicting demolitions.
• [http://www.implosionworld.com/industryhistory.htm A History of Structural Demolition in America] by Brent L. Blanchard
• [http://science.howstuffworks.com/building-implosion.htm How Building Implosions Work] by Tom Harris on www.howstuffworks.com
• [https://web.archive.org/web/20070603021157/http://www.auslandsjahr.eu/2007/04/26/top-10-hochhaussprengungen/ Building Implosions] Videos
• [http://www.chksum.com/ Bank Implosion Videos and Photos] Videos

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Category:Building engineering

Category:Demolition

Category:Articles containing video clips

Category:Implosion