Civil Engineering Disasters-Sampoong Department Store collapse

On June 29, 1995 a mall in Seoul, South Korea collapsed with an estimated 1,5000 people inside. In less than 20 seconds, a section of the five-story building came crashing down into the basement, killing over 500 people.  The collapse of the building, which was constructed using steel-reinforced concrete pillars, was blamed on faulty construction. 

The building had a number of structural modifications during its lifetime which contributed to the collapse. It was originally designed as an office building with four floors, and constructed in 1987. When it was later converted to a department store, support columns were cut away to accommodate escalators. The owner, Lee Joon, carried out these modifications over the objections of the original contractors, whom he fired and replaced.
A fifth floor was eventually added to house a restaurant. It involved installation of a heavy concrete slab. A heavy air conditioning unit was added to the building's roof, exceeding the design loads by a factor of four. Haphazard relocation of the air conditioning unit damaged the roof structure.
Prior to its collpase, the building showed cracking due to the overloading produced by the faultily-engineered fifth floor and air-conditioning unit placement.
In 1995, the store was very successful, with about 40,000 customers passing through its doors every day. On June 27, a gas leak was reported, but Joon refused to shut down the store. Two days later, the fifth-floor ceiling showed signs of imminent collapse. However, the only preventive measure taken was to move expensive merchandise out of the way. Some executives were also allowed to leave early.
At about 6 p.m., hundreds of people were eating dinner in the food area of the store’s basement level when the entire structure collapsed on top of them. The fifth-floor ceiling fell in and caused all the floors underneath it to buckle as well. Fires broke out throughout the structure, some fueled by gasoline from the cars parked in the store’s garage. The fires were not put out for several days.
Rescue efforts continued for weeks and, amazingly, one survivor was pulled out 16 days after the collapse. Most people were not so lucky–more than 500 died and another 900 suffered severe injuries. Twenty-five people were put on trial for charges relating to the disaster. Lee Joon was convicted of criminal negligence and received a seven-and-a-half-year prison sentence.

What happened: A 9-story department store building in Seoul completely collapsed in just 20 seconds. Five hundred and one people died, 6 were never found and 937 were injured.
-Why it happened: The building was initially designed as a commercial complex but was changed into a department store without approvals. Restaurants and heavy air-conditioning units were added near the top of the building, increasing the weight load. Cracks in the building began to appear months before the collapse. Renovations to the parking lot in the basement were also blamed for instability. Despite clear signs of major structural faults, an evacuation order wasn’t given until 15 minutes before the building collapsed at 6.05 pm on June 29, 1995.
-Aftermath: The chairman of the department store was sentenced to 7 and a half years in jail in 1996. The court also fined or sentenced to prison terms 12 city officials found to have received bribes in exchange for allowing illegal design changes and slipshod construction of the shopping mall.