The Sampoong Department Store Collapse: When Greed Sliced Through Flat-Slab Concrete

From residential apartments to retail mega-complex

The building was originally commissioned as a four-story residential apartment complex by the Sampoong Group. During construction, chairman Lee Joon unilaterally decided to transform the property into a luxury department store.

When the original general contractor, Woosung Construction, warned that removing central structural columns to install escalators would compromise building stability, Lee Joon fired them on the spot and transferred construction to his own in-house construction company.

To maximize floor space, column diameters were reduced from 80 centimeters to 60 centimeters. More critically, the structural engineers omitted the drop panels and column capitals essential for flat-slab construction. Spacing between rebar steel was widened to 10 centimeters instead of the required 5 centimeters, gutting the slab's punching shear resistance.

“Flat-slab concrete without column capitals behaves like a sheet of paper pushed against the tip of a pencil.”

The 30-ton cooling towers dragged on rollers

Lee Joon added a fifth floor, initially intended for a roller-skating rink. When retail regulations intervened, he converted the fifth floor into eight traditional Korean restaurants. Traditional restaurants require hot water underfloor heating (ondol), which added massive uncalculated concrete screed dead weight across the fifth floor.

To cool the complex, three industrial air conditioning cooling towers weighing 30 tons when filled with water were hoisted onto the roof. Due to noise complaints from neighboring apartments, the cooling units had to be moved.

Renting a crane to lift the units would have cost money. Instead, management placed the 30-ton chillers on rollers and dragged them across the roof slab. This crude operation cracked the structural concrete deck and permanently fractured column 5E.

The 20-second collapse and corporate evacuation

In April 1995, cracks in the fifth-floor ceiling began widening rapidly. By June 29, vibrations from the rooftop chillers were so severe that gas was shut off, and restaurants were closed. Deep depressions were visible in the roof.

At an emergency board meeting that afternoon, structural consultants explicitly warned that the building was in imminent danger of collapse. Chairman Lee Joon refused to evacuate the complex, insisting that weekday evening sales could not be sacrificed.

At 5:52 PM, the fifth-floor roof slab finally ruptured around column 5E. In a classic progressive collapse domino effect, the entire south wing pancaked within 20 seconds, sending five floors and hundreds of shoppers into the basement.

Chairman Lee Joon and corporate executives escaped before the collapse with company cash boxes. Lee was subsequently convicted of criminal negligence and embezzlement, serving seven and a half years in prison.