Which statement is true? A. Impact load equals the sum of the load actually caused and the load had it been a dead load. B. Impact load equals the difference between these two.
Try it first: pick an option, then read the explanation.
Correct answer: B. Only B
Asked in SSC JE 29/01/2018 (Morning)
Detailed Explanation
A moving or falling load produces a larger effect than the same load at rest. The extra part is called the impact load (or dynamic increment).
Why “Only B” Is Correct
Impact load = load effect actually produced − load effect if the same load were static (dead). It is the difference, so only statement B is true. In design it is usually added as an impact factor times the live load.
Why the Other Options Are Wrong
- A. Only A: The sum would count the static load twice.
- C. Both A and B: A is false.
- D. Neither A nor B: B is true.
Key Point
Impact load = dynamic effect − static effect.
Key Concepts for Students
- Impact factor for crane girders and bridges is given in codes (IS 875, IRC 6).
- Suddenly applied load: dynamic effect = 2 × static, impact = 1 × static.
- Falling weights can multiply stress many times.
Practice more: this is question 21 in Stress and Strain MCQs – Part 2. Try the whole set and check every answer instantly.