On 29th of June, 1995, the Sampoong Department
Store in Seoul, South Korea, completely collapsed. The collapse is the
deadliest modern building collapse until the attacks in New York city and is the
deadliest non-deliberate building that collapsed until Savar building collapsed
in 2013. The tragedy occurred due to multiple errors made by the designers and
contractors who built the store and the negligence of the store owner.
The structure was built on top of a landfill, it was
originally designed for an office building but midway through construction the
chairman wanted to make it into a department store. Many engineers that were
working on the project warned the owner Joon that the changes were dangerous
but he fired them.
In the disaster occurred, they were 1500 people that were
trapped in which over 500 died and 937 received non-fatal injuries. The rescue
crews did not start to search until the next day and the search was called off
because of unstable remains and rescuers would be at risk. In figure 1 it
illustrates the department facilities for each story.
The construction of the Sampoong started in 1987, it was
originally designed to be an office but the future chairman of the building
Joon Lee midway through the construction, wanted it to be a department store. The process involved cutting the numbers of
support columns to be able to install the escalators. The contractors refused
to carry these changes as they were not safe, Lee Joon the future chairman
ignored their concerns and hired another building company for the construction.
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. (Almarwae Mohammed 2017).
Lee Joon ignored the safety procedures and risked the
life of all those people involved in the incident even after knowing the possible
consequences. In April 1995, cracks began
to appear in the ceiling of the south wing’s fifth floor. 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 as the number of customers in the
building was unusually high, and it did not want to lose the day’s revenue.
However, the executives themselves left the premises, as a precaution. (Guo, H.and others
Civil engineering experts were asked to
inspect the structure but they only carried a cursory check in which they
stated that the building was at risk of collapse. Around five hours before the
collapsed occurred, several loud bangs were heard from the top floors, as the
vibration of the air conditioning caused the cracks in the slabs to widen
further. After the cracks already grown 10cm wide, it was realised that the
collapsed was unavoidable and an emergency meeting was held. In the meeting.
The directors suggested that all costumers should be evacuated. However, Joon
Lee refused over the fear of losing revenues. Joon Lee did leave the building
himself as he was aware of the dangers but did not evacuate the customers.
On the 29th of June, the north
wing of the Sampoong store collapsed, the disaster killed over 500 people. The large
number of fatalities was due in part to a distinct lack of concern by the
building owners/ occupiers in failing to take note of signs of serious
structural distress before the collapse and evacuating the occupants. The
five-storey building was a flat plate structure with elevator shafts and
services located in rigid shear wall structures between the two wings and at
the building extremities. (N.J Gardner and others 2002). From
the point of the critical failure, it only took around 20 seconds for the entire
south wing of the structure to collapse. In figure 2 it illustrates the
Sampoong Department store after collapsed. In addition, it is estimated that
the property damage was around $216 million.
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. As a
result of the fifth floor’s presence, the columns held up four times the
maximum weight that they were supposed to support. 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. (Guo, H.and
others 2010). In
1993, the air conditioning units were moved over the column 5E, where the most
visible cracks were, the purpose of the air conditioning was to cover the
cracks, the cracks worsened due to the columns supporting the fifth floor.
According to the
witnesses, the collapse started from the fifth floor. The committee that was in
charge of the inquiry concluded that the collapse started at column 5E on the
fifth floor. The reasons for the collapse were noted as design errors,
construction faults, poor construction quality control, reduction in the
cross-section of the columns support in the fifth floor. In figure 3 it
illustrates how column 5E was damaged and in figure 4 it illustrates vibrations
for AC units.
At around 5.00 p.m. of the local
time, the fifth-floor ceiling began to sink, the store workers blocked the
access to the fifth floor. Before the incident, the store was packed with
hundreds of customers, however, Joon Lee did not feel the need to close the
store or carry out any repair 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 it was too late. Around 5:52 p.m., the roof gave way, and the
air conditioning units crashed through into the already-overloaded fifth floor.
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, killing 502 people and trapping more than 1,500 inside. (Almarwae Mohammed
It is evident that the
whole tragedy could had been avoided if they evacuated the customers on time
but Joon Lee did not consider such approach necessary. Joon Lee was aware that
the collision was unavoidable therefore, it was very selfish to not do anything
about it and put the life of so many people at risk.
After the disaster, Lan
Chung, a professor of civil engineering and Professor Oan Chul Choi, head of
department of Architecture, started investigating the reason why the structure
collapsed. The first
thing they noticed in their investigation was that the structure of the store
was a flat-slab structure as illustrated in figure 5, there are no cross beams or steel framework; without cross
beams, there is a form of load transmission missing, which means the framework must be constructed perfectly. Secondly,
they began to look at the site on which the building was constructed and the
materials used. Research revealed that
even though the superstructure was built on a landfill, the foundations and
basement rested on rock and survived the collapse well. (Chris McLean and
others 2010). The investigation revealed that cutting holes in every slab
weakened the structural integrity of each slab. The columns were supposed to be
around 31-35 inches thick but were less than 24 inches thick. In addition, the
distance between each column was around 36 feet which was very dangerous.