Which of the following best describes an impact load?

• A. A constant wind load over several hours
• B. A slow settling load from soil
• C. Loads delivered to a building in a short period of time
• D. A load from furniture movement

Answer: (C)

An impact load is a force applied to a structure very quickly, creating a high peak load over a short duration. The description of loads delivered to a building in a short period of time best captures that rapid, transient nature. By contrast, a constant wind load over hours is a long-duration, static load; a slow settling load from soil is gradual and quasi-static; and a load from furniture movement is a small, routine dynamic event that doesn’t constitute an impact in structural design terms.