Dear colleagues,
I would appreciate your clarification regarding the interpretation of ASCE 7-16 for buildings assigned to Seismic Design Category (SDC) A.
Clause 11.7 states that structures assigned to SDC A are required to comply "only" to Section 1.4.
I would like to confirm the intended scope of this provision.
Specifically, does this mean that a building classified as SDC A is exempt from the requirements of Chapter 12, including (but not limited to):
Story drift checks
P-Delta effects
Vertical and horizontal irregularity checks
Diaphragm design requirements
Other seismic analysis and detailing requirements contained in Chapter 12
Or are there specific provisions within Chapter 12 that are still applicable to SDC A structures despite the wording of Section 11.7?
I also have a broader question regarding the philosophy behind these requirements.
If Chapter 12 is not applicable to SDC A structures, it appears that all SDC A buildings are treated similarly regardless of their size or height.
For example:
A building with a floor area of approximately 200 m² would be treated the same as a building with a floor area of 10,000 m².
Likewise, a 5-story building would be treated the same as a 50-story building with respect to seismic drift checks and related serviceability requirements.
In this case, the effect of the lateral force (Fx= 1% total Dead Load) wouldn't be same at all.
Could you please explain the rationale behind this approach? Is the underlying assumption that the seismic hazard associated with SDC A is sufficiently low that these checks are not considered necessary, regardless of building size or height?
If not, when can I tell that I should apply chapter 12 requirements and check drift?
Thank you for your time and clarification. I would appreciate any references to the relevant commentary or official interpretations, if available.
Kind regards,
Abdelaziz A. Khedr, EIT, FE, GM-ICE, PMP, PMI-RMP
#ASCE7-16