The collapse zone distance for unreinforced masonry wall buildings is defined as a multiple of the building height. Which of the following expresses that standard?

The collapse zone distance for unreinforced masonry wall buildings is defined as a multiple of the building height. Which of the following expresses that standard?

• A. Two times the building height
• B. Three times the building height
• C. Four times the building height
• D. Five times the building height

Answer: (B)

The key idea is safety distance from a building that could collapse. Unreinforced masonry walls are brittle and can fail suddenly, sending heavy debris outward in unpredictable patterns. Because the exact path of debris can vary with height and structure, a conservative rule is used: the collapse zone should extend a distance equal to a multiple of the building’s height. For unreinforced masonry, the standard is three times the building height. This provides a practical buffer for responders and bystanders—if the building is 20 feet tall, the collapse zone would be about 60 feet. Two times the height would usually not give enough clearance for typical wall failures, while four or five times would be more conservative than necessary for this construction type.

The key idea is safety distance from a building that could collapse. Unreinforced masonry walls are brittle and can fail suddenly, sending heavy debris outward in unpredictable patterns. Because the exact path of debris can vary with height and structure, a conservative rule is used: the collapse zone should extend a distance equal to a multiple of the building’s height. For unreinforced masonry, the standard is three times the building height. This provides a practical buffer for responders and bystanders—if the building is 20 feet tall, the collapse zone would be about 60 feet. Two times the height would usually not give enough clearance for typical wall failures, while four or five times would be more conservative than necessary for this construction type.