Sampoong Department Store collapse

Infobox News event


caption=
date=Thursday, June 29, 1995
time=5:52 PM KST
place=Seoul, South Korea
casualties1=501 dead
casualties2=937 injuredThe Sampoong Department Store (삼풍백화점; 三豊百貨店) collapse 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 – 501 people died and 937 sustained injuries. It was a direct result of the deliberate use of substandard construction materials, remarkably poor engineering practises, and governmental corruption.Fact|date=October 2007

Building overview

The Sampoong Group began construction of the Sampoong Department Store in 1987 over a tract of land previously used as a landfill. Originally designed as an office building with four floors, Lee Joon, the future chairman of the building, redesigned the building as a large department store later on during its construction. This involved cutting away a number of support columns in order to permit the installation of escalators. When the initial contractors refused to carry out these changes, Lee fired them and hired his own building company to construct the building.

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 in service. The store consisted of a north wing and south wing, connected by an atrium.

Later on, a fifth floor was added to the four-floor building, which was first planned to be a skating rink; the skating rink was added due to regulations that stopped the whole building from being used as a department store. Lee changed the original plan for the fifth floor to include eight restaurants. When a construction company tasked to complete the extension advised that the structure would not support another floor, they were fired, before another company finished the job. The restaurant floor also had a heated concrete base with hot water pipes going through it, as patrons sit on the ground of traditional Korean restaurants, which added a large extra load as a result of increasing the thickness of the concrete slab. In addition, the building's air conditioning unit was now installed on the roof, creating a load of four times the design limit.

Collapse

In April, 1995, cracks began to appear in the ceiling of the south wing's fifth floor. During this period, the only response carried out by Lee and his management involved moving merchandise and stores from the top floor to the basement. The store management failed to shut the building down or issue formal evacuation orders, as the number of customers in the building was unusually high, and the store was not intending to lose potential revenue for that day. However, the executives themselves had left the premises as a precaution.

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. Civil engineering experts were also invited to inspect the structure, with a cursory check revealing that the building was at risk of collapse; The National Geographic documentary series "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, vibrations from air conditioning were radiating through the cracks in the concrete columns and the floor opened up.

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

At about 5:00 p.m. Korea Standard Time (UTC+9:00), the fourth floor ceiling began to sink, resulting in store workers blocking customer access to the fourth floor. According to "Seconds From Disaster", the store was packed with shoppers 52 minutes before the collapse, but the owner did not close the store or carry out repairs at the time. When the building started to produce cracking sounds at about 5:50 p.m., workers began to sound alarm bells and evacuate customers.

Around 6:05 p.m., the roof gave way, and the air conditioning unit crashed through into the already-overloaded fifth floor ("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). 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, all of the building's columns gave way, trapping more than 1,500 people and killing 500.

The disaster resulted in about ₩270 billion (approximately US$216 million) worth of property damage.

Aftermath

Rescue and Recovery

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 would come down, and many of the rescuers were at risk. Massive protests, especially from friends and relatives of those still missing somewhere underneath the rubble, 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" and not "rescue". This conflicts with other peoples' experience in different countries, which is that humans can survive much longer than it is commonly thought. Despite the sweltering heat, those who were not rescued in the immediate few days were able to avoid dehydration by drinking rainwater. This was demonstrated when the last survivor, 19-year-old Park Seung Hyun (박승현; 朴勝賢), was pulled from the wreckage 16 days after the collapse with a few scratches.

Investigation

Shortly after the collapse, leaking gas was suspect as probable cause, because earlier in the year, two gas explosions occurred elsewhere in the city. 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, widespread fear circulated, believing the collapse was the result of a terrorist attack, including North Korea as prime suspect, perhaps similar to the Oklahoma City bombing in the US. However, the fact the building collapsed downward instead of spreading horizontally, ruled out the second possibility.Fact|Wouldn't explosives make the building fall almost straight down, too? The energy to throw off the equilibrium required to remain standing is far less than required to send all the building materials laterally. What source says the downward collapse was conclusive evidence?|date=September 2008

Initially, it was 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 the building was constructed with a substandard concrete mix of cement and sea water and poorly reinforced concrete on the ceilings and walls.

Further investigation revealed the building was built using 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 have to be reinforced in order to carry the load; even then, if the columns are too narrow, they can punch through the slab. However, plans of the building showed the concrete columns were only 60cm in diameter, below the required 80cm. Worse still, the number of steel reinforcing bars embedded into the concrete was 8, half the required 16, giving the building only half its needed strength. Steel reinforcement which strengthen the concrete floor, were also unsatisfactory in that they were placed at 10cm from the top instead of 5cm, decreasing the structure's strength by about another 20%.

The final change bringing the building down was, ironically, 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 columns were no longer adequate to support the weight of the concrete slab, eventually puncturing the ceiling.

These factors, along with the aforementioned addition of a fifth floor, including restaurants and restaurant equipment, collectively contributed to the building's eventual failure. Although the original building design would have been more than twice as strong as needed to remain erect, the flawed structure managed to stand for five years. Later, investigators found the direct cause of the collapse, known as the "trigger" or tipping point; they discovered it in the building's history.

It was revealed the building's three roof-top air conditioning units were moved in 1993 due to noise complaints from neighbours on the east side of the building. The building's managers admitted they were moved, noticing cracks on the roof, 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. Another issue attributed to the air conditioning units came from survivor accounts of the building vibrating. Over the course of two years, each time the air conditioners were switched on, vibrations radiated through the cracks, reaching the supporting columns, widening the cracks. On the day of the tragedy, although the units were shut off, it was too late; The structure suffered irreversible damage, and column "5e" gave way.

Trial

Lee was charged for negligence and received a prison sentence of ten and a half years. His son, Lee Han-Sang, the store's president, faced seven years for the same charge. [cite news| url=http://edition.cnn.com/WORLD/9512/skorea_store/sentencing/index.html| title=Korean store owner, son sentenced for role in collapse| date=December 27, 1995| publisher=CNN.com| accessdate=2006-06-01] City officials dispatched to oversee the construction of the building were also found to have been bribed into concealing the illegal changes and poor construction of the building. As a result, the participating officials, including a former chief administrator of the Seocho-gu district, were also jailed for their part. Other parties sentenced included a number of Sampoong Department Store executives and the building company responsible for completing the building.

General reaction and nationwide building review

The disaster 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.

In popular culture

*The Sampoong Department Store collapse was depicted in the 2006 film, "Traces of Love".
*It was also portrayed in a "Blueprint for Disaster" episode , as well as a Seconds from Disaster Episode.

References

* "Seconds From Disaster": "Superstore Collapse" (September 20, 2006; Season 3, Episode 11).

See also

*Seongsu Bridge

External links

* [http://web.archive.org/web/20070314002032/http://times.hankooki.com/lpage/opinion/200410/kt2004101418510554130.htm The Korea Times: The Dawn of Modern Korea - Collapse of Sampoong Department Store]
* [http://www.nema.go.kr/eng/m4_samp.jsp A National Emergency Management Agency (NEMA) article on the Sampoong Disaster]
* [http://esl.fis.edu/students/projects/disaster/sampoong.htm Sampoong Department Store Collapse, a student project from the Frankfurt International School]
* [http://jmrescue.com/index7.htm Photographs of rescue operations at the collapsed Sampoong Department Store]