Why did the Sampoong Department Store Collapse? | Disaster Autopsy | National Geographic UK

Summary

The transcript discusses the structural design of a building's top floor, which was initially intended to be lightly loaded for a roller rink. However, after the approval, the floor was repurposed as a restaurant, significantly increasing the load from 1 ton per square meter to 1.5 tons. This change was not followed by recalculating the load-bearing requirements. Additionally, the original design was altered by reducing the diameter and reinforcement of columns, making the structure weaker. These alterations could have serious consequences for the building's safety and stability.

Takeaways

• 😀 The new top floor of the building was intended to be lightly loaded to reduce the load on the floors beneath.
• 😀 The original design for the fifth floor featured a roller rink, which is a mostly open space with minimal weight from people skating.
• 😀 The design changed after approval, and the fifth floor was repurposed as a restaurant, significantly altering the load requirements.
• 😀 A restaurant requires much heavier equipment, tables, chairs, and people compared to a roller rink, leading to a significant increase in structural load.
• 😀 The original load calculation for the roller rink was 1 ton per square meter, but when the floor was changed to a restaurant, the load increased to 1.5 tons per square meter.
• 😀 Despite the change in use and the increased load, the structural calculations were not revised to reflect this increase.
• 😀 Photographic evidence suggests that the additional floor was inherently weaker than the floors below it.
• 😀 One major design change was the reduction in column sizes for the fourth and fifth floors, deviating from the original 80 cm diameter to 60 cm.
• 😀 The reduction in column diameter and rebar count (from 16 to 8 rebars) weakened the structure, making it less capable of supporting the increased load.
• 😀 The alteration in column size and reinforcement steel was a significant divergence from the approved design, with consequences for structural integrity.

Q & A

What was the original intended purpose for the top floor of the building?

The original design for the top floor intended it to be a roller rink, which is a mostly open space with the weight of people skating on it.

How did the use of the top floor change after approval?

After approval, the use of the top floor changed from a roller rink to a restaurant floor.

What is the primary difference between the load requirements for a roller rink and a restaurant?

A roller rink requires about 1 ton per square meter, while a restaurant requires about 1.5 tons per square meter, which is a significant increase in load.

Did the building undergo recalculation for structural load after the change in use?

No, the structural load calculations were not recalculated after the change from a roller rink to a restaurant.

What evidence suggests that the new top floor was weaker than the floors below it?

Photographic evidence from the site reveals clues that the new top floor was weaker than the floors below, indicating potential structural issues.

What was the original design for the columns on the fourth and fifth floors?

The original design for the columns on the fourth and fifth floors was to have columns with a diameter of 80 cm and 16 rebars for reinforcement.

What changes were made to the column design when the building was finished?

The columns on the fourth and fifth floors were reduced from 80 cm to 60 cm in diameter, and the amount of reinforcing steel was cut in half.

What consequences does reducing the size of the columns have on the building?

Reducing the size of the columns makes the structure weaker, which could lead to potential safety issues.

What is rebar, and why is it important in the construction of columns?

Rebar is steel reinforcement embedded in concrete columns, and it is essential for providing tensile strength, which helps the structure withstand loads and stresses.

Why was the change from a roller rink to a restaurant a significant issue for the building's structural integrity?

The change from a roller rink to a restaurant significantly increased the load on the building without recalculating the structural load, leading to potential safety risks due to under-designed columns.