What is the primary goal of base isolation in earthquake-resistant design?
- ATo increase the building’s natural frequency
- BTo decrease the transmission of ground motion to the buildingCorrect
- CTo make foundation more sensitive to seismic waves
- DTo improve the energy efficiency of the building
Solution
Concept
Base isolation in earthquake-resistant design
Formula
NONE
Step-by-step solution
1. Base isolation reduces the seismic forces transmitted to the superstructure during earthquake motion. Answer: B
Explanation
Base isolation decouples the superstructure from the foundation by inserting flexible isolators at the base. This significantly increases the fundamental vibration period of the structure, thereby reducing the seismic forces and ground accelerations transmitted into the building. Therefore, option B correctly identifies the primary objective of base isolation.
Why the other options are wrong
A) Base isolation decreases the building's natural frequency to move it away from dominant earthquake frequencies. C) Base isolation aims to decouple the foundation from ground vibration rather than making it more sensitive.
Shortcut
Base isolation decouples the structure from the ground to decrease transmitted motion.
Common mistake
Assuming base isolation increases the building's natural frequency and selecting option A.
Correct answer: B) To decrease the transmission of ground motion to the building