In the context of the seismic mass participation factor, what does a higher value indicate?
- AThe structure is more flexible
- BThe structure is more rigid
- CMore mass is excited by the mode of vibrationCorrect
- DThe structure has a lower natural frequency
Solution
Concept
Seismic mass participation factor
Formula
NONE
Step-by-step solution
1. Seismic mass participation factor represents the proportion of structural mass participating in a given mode of vibration. Answer: C
Explanation
The mass participation factor quantifies how much of a structure's total mass contributes to dynamic response in a specific mode of vibration. A higher value indicates that a larger portion of the structural mass is excited and active in that particular vibrational mode during seismic motion. Therefore, option C correctly defines what a higher participation factor signifies.
Why the other options are wrong
A) Higher mass participation is not a direct measure of structural flexibility. D) Lower natural frequency depends on stiffness and mass distribution, not directly on the participation factor.
Shortcut
Higher mass participation factor means more mass is excited by that mode.
Common mistake
Associating higher mass participation with structural rigidity or flexibility and selecting option A or B.
Correct answer: C) More mass is excited by the mode of vibration