Why may a response spectrum be adjusted for different seismic design categories?
- ATo account for variations in construction materials used in different seismic zones.
- BTo accommodate different seismic hazard levels and building importance across locations.Correct
- CTo standardize design requirements for all structures regardless of location.
- DTo consider different soil condition.
Solution
Concept
Response spectrum in seismic design categories
Formula
NONE
Step-by-step solution
1. Response spectrum values are adjusted based on seismic zone, soil condition, and importance factors. Answer: B
Explanation
Seismic design categories group structures based on expected ground motion severity at a site and the occupancy or risk category of the facility. Adjusting response spectra ensures that structures in higher hazard zones or those serving critical functions are engineered to withstand greater seismic forces. Therefore, option B correctly explains why response spectra are adjusted across design categories.
Why the other options are wrong
A) Variations in construction materials are accounted for in material design factors rather than the response spectrum. C) Standardizing design requirements across all locations ignores site-specific seismic hazard differences.
Shortcut
Response spectrum adjusts for seismic hazard level and building importance category.
Common mistake
Selecting option A or D by assuming adjustments account for construction materials or soil conditions rather than seismic hazard levels.
Correct answer: B) To accommodate different seismic hazard levels and building importance across locations.