In the largest department store in Seoul, South Korea, more than 1,000 people shopping suddenly heard a loud noise on the roof, and the entire building collapsed, 502 people died directly and nearly a thousand injured.

In the largest department store in Seoul, South Korea, more than 1,000 people shopping suddenly heard a loud noise on the roof, and the entire building collapsed, 502 people died directly and nearly a thousand injured. Before the accident, the mall manager had seen the floor crack.

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At 7 a.m. on June 27, 1995, tens of millions of Seoul citizens were rushing to their jobs and starting their busy day. The 19-year-old Park Seung Hyun is one of them. She works as a salesperson in Sanfeng Department Store. Sanfeng Department Store is one of the largest shopping malls in South Korea. There are more than 1,000 salesmen here, and more than 40,000 customers they receive every day and more than 4 million US dollars in a week. This is an astronomical figure in the eyes of ordinary people in the 1990s. The main building of Sanfeng Department Store was built in 1989 and has a total of nine floors, including four floors underground and five floors above the ground. At 8:05, the mall manager just arrived at the office and saw the note left by the night guards on his desk yesterday. In the early morning, the guards heard a strange sound on the rooftop and needed maintenance personnel to check it out. The manager attached great importance to the situation reported by the guards, so he went straight to the roof to check the situation. After a closer look, there was nothing unusual except one crack. This crack has existed on the roof for two years and is not a big deal. So the manager came down from the roof. When I passed by the fifth floor, I was stopped by someone. There are eight restaurants on the fifth floor of the mall. There are cracks around the pillars near one of the restaurants, and the floor has obviously been sunken. The restaurant manager happened to see the manager and reacted to him. Seeing this, the manager immediately closed the restaurant and hung a construction warning. To avoid panic, the manager conveyed an order to the mall employees, prohibiting the spread of news that there were cracks in the mall.

A moment later, it was almost noon, and the customer who was shopping on the fourth floor heard a sound from the rooftop, and the matter was reported to the manager again. The manager went to the roof to observe again, but still found no specific reason. He believed that the vibration of the central air conditioner caused a sound, so he turned off the air conditioner. In the afternoon, he reported the abnormal noise to the mall owner and told the boss that there was a crack on the fifth floor, which had expanded by ten centimeters from the morning to now. Also present were the designers of the mall. After analyzing the manager's report, the designer told the boss that the department store should be closed immediately for investigation and repair. But the boss was very angry when he heard this proposal, because it was about to be the prime time for shopping at night. How could he close the mall now? Wouldn't he have to make a lot of money? He directly rejected the proposal of closure and said that he would see what to do if he saw the subsequent development.

At 5:40 pm, another loud bang came from the rooftop and the ceiling began to shake. At this time, Park Seung-hyun, who was working on the first floor and more than 1,000 people in the mall did not know that death was getting closer and closer to them. 5:52 A loud bang came from the roof again, and the ceiling broke out. The salesperson and customers were panicked and ran towards the escape exit, but the building did not support them to run out of the door. In less than 20 seconds, Sanfeng Department Store was reduced to ruins. After the dust disappeared, the building disappeared, leaving only a piece of tiles and ruins, with nearly 1,500 people buried under the rubble. The media first rushed to the scene to conduct a live broadcast report that South Korea had never had such a heavy casualties in peacetime. Then more than 1,000 search and rescue personnel and volunteers arrived one after another to start the rescue work. In the ruins, they found one survivor after another and the bodies of the victims. The next day, they confirmed the identities of the 44 victims. By the fourth day, the number of victims increased to 107. Time passed day by day, and the bodies were dug out one by one. The hope of finding the survivors next was slim, because it would be a blessing to survive for three days in the weather of more than 30 degrees. The families of the missing person who had not been found were extremely sad when they heard the news.

On the second day of the accident, the South Korean government set up an investigation team to study the specific causes of the accident. When investigators arrived at the scene of the accident, they never expected such a disaster.After learning that the building was completed only six years ago, they focused on external factors, one of which is the gas explosion, as there have been two gas explosions in Seoul in the past eight months. The most recent one happened at a subway station, where the explosion killed more than 100 people and injured hundreds. The situation at the scene at that time was so similar to the accident. Could it be that this disaster was also caused by the gas explosion? However, investigators found that one very obvious feature of the gas explosion was the fire. However, there was no flame at the collapse site of Sanfeng Department Store, which allowed them to rule out the possibility of gas explosion. Then another bolder idea appeared in investigators' minds, which was the collapse caused by the bomb explosion of the terrorist attack. Because two months ago, a terrorist attack occurred in the United States on the other side of the earth. A federal government building was blown into ruins by three-ton chemicals, directly killing more than 100 U.S. government personnel. However, one unique phenomenon in that explosion is the wreckage belt. The shock wave generated by the bomb explosion will throw the debris of the building hundreds of meters away, forming a wreckage belt. However, at the site of Sanfeng Department Store, investigators found that this was not the case. The ruins of the building did not scatter outwards, but collapsed inwards, which allowed them to directly rule out the possibility of bomb explosion. After removing these two options, they could only turn the cause to the collapse caused by the problems of the building itself, but the building was only six years old and should not be a problem of the essence of the building. However, other possibilities have been ruled out, so they had to start in this regard and find out the truth as soon as possible.

There are many kinds of problems in the essence of architecture, and they choose to use exclusion to investigate. First, we first check whether the concrete used for building meets the standards, because a bridge near Seoul collapsed a month ago, causing 32 deaths. The reason for the identification at that time was that the concrete did not meet the standards. Investigators put the concrete samples from Sanfeng Department Store into hydraulic press for testing, but the results showed that the quality of the concrete was completely fine. After eliminating the reasons for concrete, they turned their attention to the design defects of the building. After obtaining the architectural drawings of the mall, they indeed found problems. The structural process of Sanfeng Shopping Mall is a beamless floor slab structure. This is a commonly used construction method for multi-story buildings. Concrete pillars are used to support the weight of each floor. In order to increase the strength of profit , multiple steel bars will be added to each column to strengthen it, and steel bars will also be added to the floor slab. From the perspective of the entire design structure, there is no problem at all. However, after the investigation team recalculated the column size required by the building, a trace of abnormality was found. According to calculations, the columns in the building should be 80 cm thick, but the diameter of the columns on the design drawing has been reduced to 60 cm. Could it be that the design drawing is wrong? The investigation team went to the site to measure the size of the columns in the wreckage. The thing they were most worried about was that the size of the columns was built at 60 cm.

In addition to the reduction in the column diameter, they also discovered another even more shocking flaw. There should have been 16 steel bars in one column, but only eight steel bars were placed during construction, which directly reduced the number by half. However, based on the calculation results, the investigation team showed that even if it was reduced by half, it would not cause such a large-scale collapse. Because there will be safety errors in general architectural design. The architectural drawing standards of Sanfeng Shopping Mall exceed two and a half times the safety index. Even if the building materials are reduced by half, there will be no problem with the load bearing of the entire building. There must be problems in other places. After a deeper exploration, the investigation team found that the original original design of Sanfeng Department Store was only four floors above the ground, but when the construction was halfway through, the owner of Sanfeng Department Store planned to add another floor.However, the contractor refused the request for safety reasons, so the contractor was replaced by the owner of Sanfeng Department Store, which made another construction company raise one floor. The fifth floor was originally intended to be covered with an ice rink, but later the boss changed his mind and decided to open eight restaurants on the fifth floor. It sounds like there is no difference, but in fact it increases the risk factor, because traditional Korean restaurants sit on the floor, and heating is mostly needed to install, while heating requires thickening the floor, which directly increases the weight of the floor on the fifth floor, so that the pressure on the columns is under further increase. However, even if one layer of weight is added, Sanfang Department Store should not collapse suddenly, as there will be signs before it collapses.

After asking the surviving manager of Sanfeng Department Store, they learned that the three large air conditioners on the roof had been moved two years ago. The normal movement process should be to lift the equipment with a crane and transfer it to another location. However, at that time, the staff of Sanfeng Department Store directly used a drag device to pull the equipment to the other side of the roof. Each equipment weighed as much as 15 tons. During the dragging process, it passed through the position of the column, causing the column to be under excessive pressure and cracked. Moreover, in the next two years, each time the air conditioner was turned on, there would be a vibration. This long-term resonance spread through the floor on the roof and spread to the cracked column, so that the cracks seen in the morning were created on the fifth floor. On the morning of the day of the incident, the opening of the air conditioner external unit became the last straw that broke the camel's back. The collapse began to spread rapidly to the entire building from this pillar, causing the overall collapse.

Investigation team finally understood the specific cause of the disaster and submitted the final accident report to the government. The owner of Sanfeng Department Store was immediately arrested and sentenced to ten and a half years in prison for . His son was also imprisoned for seven years for embezzlement and manslaughter. More than 20 senior executives of the entire Fengfang Group were arrested, mostly due to corruption and fraud. The relevant departments finally calculated that the accident caused 502 deaths and nearly 1,000 injuries, which is one of the worst accidents in South Korea in recent decades. After that, the South Korean government conducted a nationwide thorough investigation. To their surprise, one in every seven tall buildings needs to be rebuilt, four-fifths of buildings need to be renovated, and only 2% of the buildings in South Korea are considered safe. In this society where money is paramount and materialistic, I hope that capitalists can take care of themselves, not be too greedy, and not be careless about human life in order to blindly pursue interests. While pursuing modernization, we should also pay attention to life safety.