For an 18-meter-tall URM building, what is the approximate collapse zone distance?

For an 18-meter-tall URM building, what is the approximate collapse zone distance?

• A. 36 meters
• B. 54 meters
• C. 72 meters
• D. 90 meters

Answer: (B)

Unreinforced masonry (URM) buildings are especially prone to heavy, rapid collapse with debris spreading far from the base. To stay safe on the fireground, the collapse zone is typically set at about three times the building height for URM structures. For an 18-meter-tall URM building, that means a collapse zone of 3 × 18 = 54 meters. This distance best accounts for the potential reach of debris during failure, which is why 54 meters is the appropriate choice. The other distances correspond to smaller multiples and would not provide the same level of safety for URM collapse scenarios.

Unreinforced masonry (URM) buildings are especially prone to heavy, rapid collapse with debris spreading far from the base. To stay safe on the fireground, the collapse zone is typically set at about three times the building height for URM structures. For an 18-meter-tall URM building, that means a collapse zone of 3 × 18 = 54 meters. This distance best accounts for the potential reach of debris during failure, which is why 54 meters is the appropriate choice. The other distances correspond to smaller multiples and would not provide the same level of safety for URM collapse scenarios.