Seismic Maximum Considered Earthquake Geometric Mean PGA Maps

[RFreund]

Referring to ASCE7 seismic maps, specifically ASCE7-10 figure 22-7. Are these maps based on a 1% exceedance in 50years (5,000 yr return)? I'm trying to understand the difference between the variable "PGA" when referenced in ASCE7 vs AASHTO and I beleive the difference is the return period, but the probability is not listed on these figures. I assume they are the same as others, but I might off entirely.

ASCE7 PGA = mapped MCE (Maximum considered earthquake) peak ground acceleration (not sure what the return period is)

AASHTO PGA = Horizontal peak ground acceleration coefficient (with 7% probability of exceedance in 75 yr, 1000year return)

In general the ASCE7 PGA is higher than AASHTO which would make sense if the return period is 5,000 years.

Thanks

EIT

http://www.HowToEngineer.com

 

[straub46]

The ASCE 7-10 Commentary says Figure 22-7 uses a 2% in 50 year exceedance.

Go Bucks!

 

[Lomarandil]

(which, to save you the math, is described as a 2475yr return)

----
just call me Lo.

 

[RFreund]

Thanks for the info. I also missed it in Ch 21.5. I really air-balled this. Thanks again.

EIT

http://www.HowToEngineer.com