June 29, 1995, the A building of Sanfeng Department Store with pink marble exterior collapsed within 20 seconds, the golden area of Seoul, South Korea, a landmark building in Seoul. The collapse of the building
smashed more than 1,500 people in the mall under the ruins, causing a total of 502 deaths and 937 injuries.
is the worst casualty accident in peacetime on South Korean history. It is also one of the most tragic building collapse accidents in the world, second only to the 911 terrorist attacks in the United States and the 2013 building collapse accident in Bangladesh in India.
Figure 1 Sanfeng Department Store Building A collapsed
Sanfeng Department Store store was one of the latest trendy and luxurious department stores in South Korea at that time.
is connected by two lateral buildings A and B with huge chrome-inlaid glass in the atrium. has nine floors, four floors underground and five floors above the ground.
collapsed Building A 5th floor are 8 high-end restaurants, and the department store area is located on the 1st to 4th floors.
The first floor underground is a supermarket, a bookstore and an ordinary hotel. In addition, the second floor, 3rd floor and 4th floor are all connected to Building B. It is a parking lot warehouse, employee restaurant, computer room, etc.
AB Building takes the lobby as the dividing point.
Figure 2 Building distribution
At that time, the economic boom in South Korea was at the time of South Korea's economy. In 1995, South Korea's GDP growth rate reached 9%.
People have money in their pockets and have a lot of desire to consume, so the business of Sanfeng Department Store is particularly good. HTML receives an average of about 40,000 customers on the 1st day, with an average daily turnover of more than 500,000 US dollars, and there are 1,000 employees in the mall.
There is a folk saying that children can see things that adults cannot see. This accident starts with a mother and a child.
The strange prediction of the child, natural disasters or man-made disasters
Time came on June 29, 1995, a mother took her daughter to shop in the mall, but the child cried and insisted on going home. She couldn't coax her no matter how she coaxed her. There was no way, so she had to take the child away.
When she got home and turned on the TV, she saw the news that the department store of Sanfeng collapsed was playing on the TV.
Figure 3 The department store opens to work
This mother was in a cold sweat and asked the child: "Why are you in a hurry to come back when you were in the mall?" The child replied: "Many people there had a black rope tied around their necks. There was an uncle wearing black clothes holding the rope. It was so terrible!"
But in fact, the collapse of Sanfeng Department Store has nothing to do with supernaturalism, it was completely a man-made disaster.
As early as April 1995, cracks began to appear on the ceiling of Sanfeng Department Store's 5th floor.
But Li Yongzhou ignored it because Sanfeng Department Store had just passed the government's regular security inspection.
There are three large air conditioners on the roof of Sanfeng Department Store, weighing 29 tons, and the total weight when filled with water is as high as 87 tons.
Figure 4 Before and after the large air cooler moves,
These three air coolers are very noisy when they run. Two years ago, due to complaints from nearby residents, they moved the air cooler from the back of the building to the front.
This movement process should have used a crane, but in order to save trouble, they directly dragged the air conditioner with pulleys, and during the dragging process, the floor slab on the top floor was crushed, so there were many cracks on the roof.
But since the security inspection has been passed, Li Yongzhou believes that those cracks are no big deal and irrelevant.
html At 10 a.m. on June 29, the owner of Chunyuan Restaurant, located on the fifth floor of Building A of the mall, suddenly found a huge fist-sized crack around a pillar in the restaurant, and the floor was obviously sunken, so he notified Li Yongzhou.
Figure 5 Several floors where cracks occurred
The column number is 5E, which is the main load-bearing column of the shopping mall.
After Li Yongzhou went over and saw it, the restaurant was temporarily closed and a construction warning sign was hung. He was afraid of affecting the reputation of the mall and asked all insiders not to tell them.
But the danger will not exist because of concealment.
At 12:30 noon, customers on the fourth floor of the mall began to hear strange sounds, and the first floor underground began to feel the building shaking.
After Li Yongzhou checked, he thought it was a vibration caused by the air conditioner and turned off the air conditioner.
At 2 pm, Li Yongzhou reported to the mall owner Li Li about the cracks in the restaurant.
Figure 6 Table tilted due to the sunken and tilted foundation
Li Li immediately convened the shopping mall management in Building A to discuss how to repair it, and asked Li Hezhu, the structural engineer who designed and built the department store, to check the situation of the building.
After the inspection, Li Hezhu reported that the mall must be closed immediately because the entire building may collapse at any time.
But Li Li rejected the proposal because the shopping mall had a lot of traffic that day and he did not want to delay business. However, due to Li Hezhu's warning, the senior management left Building A and moved to Building B to continue the meeting, and did not notify the lower-level employees.
Figure 7 The construction site of two buildings
At 5 pm, the ceiling on the 4th floor of Building A became more and more serious, and the shopping mall managers urgently closed the entire floor.
At 5:50 pm, a loud noise came from the rooftop, the ceiling began to shake, the staff sounded the alarm and began to evacuate customers.
But it was too late.
At 6:5 pm, most of the panicked customers had not had time to leave the mall, and the 5E load-bearing column could not support it and collapsed first. The ceiling of the top floor and the air conditioner fell down and hit the floor on the fifth floor.
Figure 8 The collapsed ceiling
The floor on the fifth floor could not bear it and collapsed to the fourth floor, and then collapsed down one by one. In just 20 seconds, the department store on the 15th floor collapsed into the 4 underground floors.
The former landmark building in South Korea instantly turned into a pile of steel bars and cement ruins, stirring up smoke and dust in the sky.
People near the mall were stunned by this incident. After reacting, they rushed over and moved away the bricks and rubble with bare hands to help the injured who were more relying on the outside.
A few minutes later, ambulances, police cars and fire trucks flocked to the rescue and launched a chaotic rescue.
Figure 9 Rescue
Since the ruins are buried under the ruins, they dare not use heavy bulldozers and other operating equipment, and the rescue progress is very slow.
It was not until the evening that more than 30 large cranes and bulldozers started operating. By the morning of the next day, more than 200 survivors were rescued, more than 40 bodies were found, and the rest were missing.
The mall did not collapse as a whole at that time. Building B was hanging dangerously in place, but it could collapse at any time.
There are many people saving people on the ruins. If this wall falls, thousands of tons of steel bars and concrete will hit the rescuers.
Figure 10 Ruins
Such a situation is too dangerous. After the rescue is over the next day, the government decided to give up on continuing to search for survivors.
Relatives and friends, who were still under the ruins, took to the streets to parade in despair, begging the authorities to continue searching and rescue. The government dispatched riot police to stop them, and fierce violent clashes occurred between the two sides.
On the morning of the third day, the government announced that it would continue to rescue. The engineers tied the north wing of the building with steel ropes, and the search and rescue operation launched again.
A few hours later, they rescued a young woman from the ruins, but the woman was exhausted and bleeding profusely, and she died not long after being sent to the hospital.
Figure 11 The injured who were rescued
On the fourth day, 107 survivors were rescued under the ruins, but fewer and fewer living people were rescued after that, and most of the people who could be found were corpses.
A week later, most people are no longer right and can still find living people to return their hopes, because humans can usually only survive for 3 days in confined spaces without water.
But on the 17th day after the accident, people found a hole behind a concrete slab, and there was a girl living miraculously.
She is a salesperson in the children's clothing department, named Park Seung-hyun, 19 years old.
Figure 12 The continuous extension of the rescue process
During the long dark 377 hours, she persisted in her life by using the sprinkler truck to prevent the sewage sprayed from dust and flowing into the hole.
and it is not serious except for severe dehydration and minor abrasions.
But she is also the last living person to be rescued.
Finally, according to statistics, a total of 502 people died and 937 people were injured in . This accident occurred in a building that has only been built for 6 years. No one can accept it.
People took to the streets to demonstrate and marches, asking the government to investigate the cause of the incident and give an explanation.
Figure 13 Chairman of Sanfeng Group (first right)
South Korean government commissioned Tanguo University civil and structural engineering professor Zhong Lan to investigate the cause of the accident.
After Zhong Lan accepted the commission, he first ruled out whether it was an accident caused by the gas explosion.
After investigating the scene, he ruled out this possibility, because gas explosions usually cause fires, and there are no traces of fire in the Sanfeng Building.
Then he ruled out whether he had encountered a terrorist attack.
At that time, there were two such terrorist attacks in South Korea not long ago, which resulted in the innocent death of 136 people. This is likely another terrorist attack.
Figure 14 Changes in the position of steel bars
However, after Zhong Lan investigated, this possibility was also ruled out.
There will be unique traces of damage caused by bomb attacks, and the explosion debris will splash around, but the Sanfeng Building collapsed as a whole. After
ruled out that it might be caused by external factors, he began to investigate internal factors.
He first doubted whether the foundation of the building was not laid well.
Because the original site of Sanfeng Department Store was a landfill.
7 years ago, when building the building, in order to catch up with the construction period, Li Liu, the owner of Sanfeng Department Store, ordered the construction of the foundation to begin. He doubted whether there was a problem with the foundation strength.
Figure 15 collapsed floor
However, after Zhong Lan checked, he found that the foundation strength was not problem.
Then he investigated whether it was a problem with building materials. But after testing the hardness of the concrete, there was no problem.
The foundation and building materials are both normal, and Zhong Lan began to suspect that it was a design problem. He transferred the building's architectural drawings, and this time he finally found the problem.
According to the original design of the drawings, this building should not have been a shopping mall, but an office building.
The original design of this building was only four floors, but when the contractor was halfway through construction, Sanfeng Group asked them to convert the office building into a shopping mall and build a floor on it.
Figure 16 Sanfeng Group logo
Contractor directly rejected this request, and President Li Yu simply fired them and asked his construction company to take over the construction.
His own construction company changed the office building into a shopping mall exactly as he wanted and built a fifth floor. This change in
has resulted in many load-bearing columns being cancelled to make room to install escalator .
. The fifth floor of the mall was originally planned to be a skating rink, but it was later changed to 8 traditional restaurants.
Figure 17 Load-bearing column cancelled
Koreans sit on the floor when eating, so floor heating must be installed under the floor of the restaurant.
Floor heating has increased the load-bearing of the fifth floor, adding a lot of pressure to the structure of the building that originally had only four floors.
In addition, when Li Liu's construction company built the building, it also changed the original designed load-bearing column with a diameter of 80 cm to 60 cm.
and the 16 steel bars inside were changed to 8, which caused the overall strength of the building to be reduced by nearly half.
But this is still not the main reason for the collapse of Sanfeng Department Store.
Figure 18 Schematic diagram of load-bearing columns in Sanfeng Department Store (b is the designed load-bearing column)
Because according to regulations, buildings must have safety reserves when constructing.
The so-called safety reserve means that the bearing capacity required by the design must be greater than the actual bearing capacity required.
Generally speaking, the bearing capacity of this safety reserve will be very high. Even if Sanfeng Group makes such a big reduction and changes, the building's strength will be greatly reduced. Without accidents, the building will not collapse.
This is also the reason why there has not been any major problems in the building since 26 years since it was built.
But Li Liu's construction company made another fatal mistake when building the building: they misplaced the steel bars in the concrete floor slab.
Figure 19 Number of steel bars
The steel bars in the floor slab should have been 5cm away from the surface, but they were placed 10cm away from the surface.
The five-centimeter error seems to be different in the eyes of laymen, but in fact is equivalent to directly weakening the thickness of the floor slab, which reduces the strength of the floor slab by 20%.
Sanfeng Department Store adopts a beamless floor structure. There is no beam under the floor slab and is directly supported by columns. This leads to the instability of a column and is easily damaged by chains.
These successive mistakes have made the overall structure of the building already very fragile, and the last straw on the camel's back is the three large air conditioners.
Figure 20 Involved in bribery
In order to save trouble, Sanfeng Group directly used pulleys to drag the air conditioner on the roof, which not only crushed the floor slab, but actually caused huge damage to the building structure.
The air conditioner passed through the column numbered 5E, crushing the connection point between it and the floor slab.
When the air conditioner is working, the vibration will cause vibration, which will make the cracks bigger and bigger. When the cracks reach a certain level, the floor slab of Chunyuan Restaurant will be separated from the load-bearing column.
After the first floor slab fell, the collapse quickly spread to the entire floor. The upper floor slab of
fell to the lower floor and caused the lower floor to collapse, and the Sanfeng Department Store was razed to the ground.
Figure 31 After the cause of the accident was announced, the Korean people demanded severe punishment for the murderer.
However, the Korean chaebol has a strong influence.
After countless Korean people conducted a marche and demonstration for several months, the government followed the public's opinion and sentenced Li Yu, the president of Sanfeng Department Store, to 10 years and 7 months in prison.
And his son Li Hanxiang was sentenced to only 7 years.
follow-up investigation found that several government officials accepted bribes during the construction of Sanfeng Department Store, and 12 officials were also sentenced to prison.
Figure 32 After the sentence of
accident, the South Korean government re-inspected all buildings in China and found that only 2% of high-rise buildings in China are safe, while the rest have problems.
inspection found that one of every seven high-rise buildings must be demolished and rebuilt, and four-fifths of the buildings need to be greatly renovated, and there are only a very small number of them that are fine.
. President Li, who is the first person in charge of this accident, only needs to think about it for more than 3,800 days for 502 people who died in the accident. On average, each person with a deceased has more than 7 days, which is terrifying to think about it carefully.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-