Fire impact on the structural safety of modular buildings



This research looks at how modular buildings (buildings made from factory-built “boxes” that are put together on-site) behave in a fire.

Scientists wanted to see:
  • How long these buildings can survive in a fire,
  • What parts of the building fail first,
  • And what happens when fire spreads from one room to another.
They tested this using computer models and math simulations instead of burning a real full-size building (which would be way too expensive).

Key things they found

1. The strong columns help a lot 

The buildings use special columns called CFST columns (concrete-filled steel tubes).
  • The steel tube on the outside heats up,
  • But the concrete inside slows down the heat and keeps it strong.
  • This makes the building more fire-resistant than normal steel columns.
2. Where the fire starts matters
  • Corner fires are more dangerous because there are fewer other parts of the building to help carry the load.
  • Lower floor fires are also worse because those floors are holding up all the weight above them.
3. If fire spreads between rooms (multi-compartment fire)

Things get scary fast.
  • More columns and beams heat up,
  • The “backup paths” for carrying weight shrink,
  • So the building is much more likely to fail.
4. If fire spreads upward (vertical fire)

When flames move from the ceiling of one room into the floor beams of the room above:
  • Beams lose strength quickly,
  • Columns start swaying sideways,
  • The connectors between modules get overloaded,
  • And the whole system can fail much earlier.
5. Not every part of the building is equally stressed
  • Central areas (surrounded by other rooms) can survive longer, because they have more “help” from neighbors.
  • Edge and corner areas are weaker because they don’t have as many backup connections.
Why this matters

1. Modular buildings are becoming more popular because they’re cheap, fast to build, and eco-friendly.

2. But for tall modular buildings, fire safety is a big concern.

3. This study shows that we can design them to survive fires pretty well, but engineers need to:
  • Pay extra attention to lower floors, corners, and connectors.
  • Think about fire spreading, not just a single room burning.
  • Use full-building analysis (not just testing one piece) to understand real fire performance.

In short: Modular buildings with CFST columns are generally safe in fires, but if flames spread across multiple rooms or floors, or if a fire starts low or in a corner, the risk of collapse goes way up.

Structural performance of modular buildings subjected to fire 2025 https://doi.org/10.1016/j.engstruct.2025.121404


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