Question

During earthquake, soft storey failure in a building is due to

• A. shear failure initiated by short column effect.
• B. stress discontinuity initiated by abrupt changes of stiffness.
• C. failure of column initiated by weak column – strong beam effect.
• D. drift of building storey initiated by pounding effect.

Hint:

Ensure sufficient lateral stiffness in all storeys of a building to prevent soft storey failures during earthquakes.

Answer 1

The Correct Option is B

A soft storey failure occurs when one storey of the building has much lower stiffness compared to the other storeys. This typically happens when there are large open spaces, such as in parking floors, which do not provide sufficient lateral resistance to forces during an earthquake. This results in a stress discontinuity, where the lateral stiffness changes abruptly, causing failure at the soft storey level.
Why the other options are incorrect:
- Short column effect (A): This refers to columns that are short in height, but does not specifically explain soft storey failure.
- Weak column – strong beam effect (C): Refers to poor structural design but not directly tied to soft storey failure.
- Pounding effect (D): This occurs when adjacent buildings collide during an earthquake, not related to soft storey failure.
Thus, the correct answer is (B).