Sampoong Department Store collapse

Sampoong Department Store collapse
Time 5:52 p.m. KST
Date June 29, 1995 (1995-06-29)
Location Seoul, South Korea
Cause Structural Overload, Punching Shear
Deaths 502
Non-fatal injuries 937
Suspect(s) Lee Joon, Lee Han-Sang
Charges Negligence, Bribery
Verdict Guilty
Convictions Manslaughter

The Sampoong Department Store collapse (Korean: 삼풍백화점 붕괴 사고) was a structural failure that occurred on June 29, 1995, in the Seocho-gu district of Seoul, South Korea. The collapse is the largest peacetime disaster in South Korean history as 502 people died and 937 were injured. It was the deadliest modern building collapse until the September 11 attacks in New York City, and the deadliest non-terror-related building collapse until the 2013 Savar building collapse near Dhaka, Bangladesh.[1]

Background

In the events leading up to the 1988 Summer Olympics, there was a large development boom in the Seoul area. Because of bans against international construction contractors signing contracts for projects in Seoul, most buildings were being erected by South Korean companies, who typically built the structures quickly because of the large amount of projects assigned to them.[2][3]

The Sampoong Group began construction of the Sampoong Department Store in 1987 over a tract of land previously used as a landfill. The building's plans originally called for a residential apartment with four floors, and the apartments were to be built by Woosung Construction.[2][3] Instead, the blueprints were changed to that of a large department store during the building's construction by the future chairman of the building, Lee Joon. This involved cutting away a number of support columns in order to install escalators.[4][5][2][3] When Woosung refused to carry out these changes, Lee ignored their warnings and fired them, and instead using his own building company to complete construction.[5][2][3] The building was completed in late 1989, and the Sampoong Department Store opened to the public on July 7, 1990, attracting an estimated 40,000 people per day during the building's five years of existence. The store consisted of north and south wings, connected by an atrium.[5]

The completed building was a flat-slab structure, without crossbeams or a steel skeleton, which effectively meant that there was no way to transfer the load across the floors. The floor columns were 24 inches (61 cm) thick, instead of the minimum of 31 inches (79 cm) that was required for the building to stand safely. In addition, each column was 36 feet (11 m) apart to maximize retail space, a decision that also meant that there was more load on each column than there would have been if the columns were closer together.[2]

A fifth floor was originally planned to house a skating rink; it was added later to comply with zoning regulations that prevented the entire building from being used as a department store.[5][3] However, Lee changed the plan for the fifth floor to include eight restaurants instead.[2][3] When a construction company tasked to complete the extension advised that the structure would not support another floor, they were fired, and another company was hired to complete the project instead. The restaurant floor had a heated concrete base referred to as ondol, which has hot water pipes going through it; the presence of the 4-foot-thick (1.2 m) ondol greatly increased the weight and thickness of the slab.[2][3] As a result of the fifth floor's presence, the columns held up four times the maximum weight that they were supposed to support.[2]

In addition, the building's air conditioning unit was also installed on the roof, creating a 45-tonne (50-ton) load that was four times the design limit. In 1993, the air conditioning units were dragged across the delicate roof, which is where the cracking started.[5] The units were moved over the column 5E from which the most visible cracks in the floor of the fifth level were seen before the collapse. The cracks in the columns were worsened because the columns supporting the fifth floor were mismatched with the ones supporting the floors below it.[2][3]

Collapse

View of the Sampoong building shortly after the collapse. With the exception of the end tower, the entire south wing has fallen down upon itself. A rescue helicopter is seen flying above

In April 1995, cracks began to appear in the ceiling of the south wing's fifth floor. During this period, the only response by Lee and his management staff involved moving merchandise and stores from the top floor to the basement.

On the morning of June 29, the number of cracks in the area increased dramatically, prompting managers to close the top floor and shut the air conditioning off. The store management failed to shut the building down or issue formal evacuation orders,[2][3] as the number of customers in the building was unusually high, and they did not want to lose the day's revenue. However, the executives themselves left the premises as a precaution.

Civil engineering experts were invited to inspect the structure, with a cursory check revealing that the building was at risk of collapse; the National Geographic Channel documentary programme Seconds From Disaster indicates that the facility's manager was examining the slab in one of the restaurants on the fifth floor, eight hours before the collapse, when, unknowingly, vibration from air conditioning was radiating through the cracks in the concrete columns and the floor opened up.

Five hours before the collapse, the first of several loud bangs was heard emanating from the top floors, as the vibration of the air conditioning caused the cracks in the slabs to widen further. Amid customer reports of vibration, the air conditioning was turned off, but the cracks in the floors had already grown to 10 cm wide.

At about 5:00 p.m. Korea Standard Time (UTC+9:00), the fifth floor ceiling began to sink, resulting in store workers blocking customer access to the fifth floor. According to Seconds From Disaster, the store was packed with shoppers 57 minutes before the collapse, but Lee did not close the store or carry out repairs during that time. When the building started to produce cracking sounds at about 5:52 p.m., workers began to sound alarms and evacuate the building, but by then it was too late.

Around 5:52 p.m., the roof finally gave way, and the air conditioning units crashed through into the already-overloaded fifth floor.[6] The main columns, weakened to allow the insertion of the escalators, collapsed in turn, and the building's south wing pancaked into the basement. Within 20 seconds of the disaster, all of the building's columns in the south wing gave way, trapping more than 1,500 people and killing 502. The disaster resulted in about ₩270 billion (approximately US$216 million) worth of property damage.

Aftermath

Rescue and recovery

Rescue crews at the site of the collapse

Rescue crews were on the scene within minutes of the disaster, with cranes and other heavy equipment being brought in the next day. However, authorities announced that they would call off the rescue, due to the danger that the unstable remains of the store could come down, and many of the rescuers would be at risk. Massive protests, especially from friends and relatives of those still missing, compelled officials to continue looking for survivors, with the remains of the store being steadied by guide cables. After nearly a week, the focus was on removing the debris, though construction crews were careful to check for victims.

Two days after the collapse, some officials said that anybody who was still in the building must have already died; therefore, further efforts would be made only towards "recovery", not "rescue". This conflicts with the fact that people can survive much longer.[7] Despite the sweltering heat, those who were not rescued in the first few days were able to avoid dehydration by drinking rainwater. The last to be rescued, 19-year-old Park Seung-hyun (박승현; 朴昇賢), was pulled from the wreckage 17 days after the collapse with a few scratches. She said that she heard the sounds of other survivors drowning in the fire department's deflation water.

Investigation

The investigation committee and effort was headed by Professor Lan Chung of Dankook University's engineering school. Shortly after the collapse, leaking gas was suspected as the probable cause because two gas explosions had occurred elsewhere in the city that year. However, fires amid the rubble were from burning automotive gasoline coming from crushed cars parked in the underground garage, whereas a gas explosion would have been a massive inferno. In addition, it was widely feared that there had been a terrorist attack, with North Korea as the prime suspect. However, the fact the building collapsed downward with little debris thrown outward ruled out a significant explosion according to U.S. and South Korean experts.

Once the investigation focused on structural failure, it was initially believed the building's poorly-laid foundation, and the fact it was built on unstable ground, led to the failure. Investigation of the rubble revealed that a substandard concrete mix of cement and sea water and poorly reinforced concrete was used for the ceilings and walls.

Further investigation revealed the building was built with incorrect application of a technique called "flat slab construction". Reinforced concrete buildings are often built using columns and beams, with the floor slab supported over the full length of the beams. "Flat slab construction" does not use beams, but supports the floor slab directly on the columns. The area of floor around the columns must be reinforced in order to carry the load; even then, if the columns are too narrow, they can punch through the slab. However, examination of the building showed the concrete columns installed were only 60 cm in diameter, below the required 80 cm shown in the plans. Worse still, the number of steel reinforcing bars embedded into the concrete was 8, not the required 16, giving the building only half its needed strength. Steel reinforcements intended to strengthen the concrete floor were placed 10 cm from the top instead of 5 cm, decreasing the structure's strength by about another 20%.

Ironically, one of the changes that contributed to the collapse was the installation of a safety feature. Fire shields were installed around all escalators to prevent the spread of fire from floor to floor, but in order to install them, the builders cut into the support columns, reducing their diameter further. The reduced diameter concentrated the burden on a smaller area of supported slab, leading to an eventual puncturing of the slab. These factors, along with the addition of a fifth floor including restaurants and heavy restaurant equipment, collectively contributed to the building's eventual failure. However, the original building design would have been more than twice as strong as needed to remain erect, and the flawed structure managed to stand for almost five years.

Investigators finally pinpointed the direct cause of the collapse, known as the "trigger" or tipping point, in the building's history. It was revealed that two years before the collapse, the building's three rooftop air-conditioning units had been moved due to noise complaints from neighbours on the east side of the building. The building's managers admitted noticing cracks on the roof during the move, but instead of lifting them with a crane, the units were put on rollers and dragged across the roof, further destabilizing the surface due to each unit's immense weight. Cracks formed in the roof slabs and the main support columns were forced downward; column 5E took a direct hit, forming cracks in the position connected to the fifth-floor restaurants. According to survivor accounts, each time the air conditioners were switched on the vibrations radiated through the cracks, reaching the supporting columns and widening the cracks, over the course of two years. On the day of the tragedy, although the units were shut off, it was too late; the structure had suffered irreversible damage, and the fifth floor slab around column 5E finally gave way.

Trial

Lee Joon was charged with criminal negligence and received a prison sentence of ten and a half years.[8] However, Lee's sentence was reduced to seven years on appeal in April 1996. Lee died of health complications on October 4, 2003, a few days after being discharged. His death was due to heart failure related to high blood pressure and diabetes.

His son, Lee Han-Sang, the store's president, who is now working for religious causes in Mongolia, received seven years for accidental homicide and corruption.[8] City officials Lee Chung-Woo and Hwang Chol-Min, in charge of overseeing the construction of the building, were also found to have been bribed into concealing the illegal changes and poor construction. As a result, the participating officials, including a former chief administrator of the Seocho-gu district, were also jailed. Other parties sentenced included a number of Sampoong Department Store executives and the company responsible for completing the building.

The settlement involved 3,293 cases, totaling ₩375.8 billion (about $350 million USD). The former chaebol Lee family was stripped of all of their possessions and assets to cover the costs, and as a result, the Sampoong Group was disbanded.

General reaction and nationwide building review

The initial reaction was enormous public outrage that led to months of demonstration on the streets. The disaster later led to skepticism and fears regarding safety standards on other engineering projects undertaken as South Korea experienced an economic boom during the 1980s and 1990s, and resulted in a review of South Korean safety regulations; the incident also revealed the level of corruption among city officials, who were willing to accept payoffs with little regard for public safety.

Notable survivors

The site today

The remains of the building were demolished shortly after the disaster, and the site remained vacant until 2000. The former location of the department store is now home to a luxury apartment complex called Acrovista Apartments, whose construction began in 2001 (but not without complaints from some of the victims' families) and was completed in 2004.[12]

Memorials

The Yangjae Citizen's Forest has a sculpture made in memory of the collapse.

Media

See also

References

  1. ↑ "Bangladesh building collapse death toll passes 700". BBC News. 7 May 2013. Retrieved 7 May 2013.
  2. 1 2 3 4 5 6 7 8 9 10 "Sampoong Department Store". Failures. 1990-07-07. Retrieved 2016-02-09.
  3. 1 2 3 4 5 6 7 8 9 Wearne, P. (2000). Collapse: When Buildings Fall Down. TV Books. ISBN 978-1-57500-144-9. Retrieved 2016-02-09.
  4. ↑ "China's weapons of mass construction". The News From Wabu-eup. July 2, 2009. Retrieved 29 March 2012.
  5. 1 2 3 4 5 Marshall, Colin (2015-05-27). "Learning from Seoul's Sampoong Department Store disaster – a history of cities in 50 buildings, day 44". the Guardian. Retrieved 2016-02-09.
  6. ↑ Seconds From Disaster indicates that the fifth floor slab and roof were the first to collapse, causing the air conditioning units to fall through the structure
  7. ↑ HowStuffWorks.com mentions cases of people surviving weeks without food and says that "a Japanese hiker [in 2006] survived for 24 days...without food and water".
  8. 1 2 "Korean store owner, son sentenced for role in collapse". CNN. 27 December 1995. Retrieved 9 January 2012.
  9. ↑ Seo Dong-shin, "Biennale Director Sacked for Academic Forgery", The Korea TimesJuly 12, 2007. Retrieved on March 31, 2008.
  10. ↑ Ilbo, Dong-A (June 25, 2005). "삼풍백화점 참사 10년...당시 생존자 최명석씨 (Sampoong Department Store disaster, 10 years later - survivors)". Naver (in Korean). Retrieved 25 December 2011.
  11. ↑ News, Yeonhap (October 13, 2010). "역대 국내 대형 매몰사고와 구조사례는 (Rescue cases in Korea for burying accident)". Naver (in Korean). Retrieved 13 October 2010.
  12. ↑ Emporis GmbH. "Daesang Acrovista". emporis.com.
  13. ↑ Seconds from Disaster. Season 3, Episode 5.
  14. ↑ "[REVIEW] SBS series "Giant"". hancinema.net. Retrieved 9 December 2010.
  15. ↑ "Answer Me 1994 (Drama - 2013)". Retrieved 30 November 2013.

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