I felt it!

[Titleistguy]

Not too many EQs on this side of the globe but we get them occasionally. 

(Detroit) 

View attachment 18455

 

[Reverse Polish]

Every once in a while, the earth jiggles a bit just to remind you to check your LFRS design.  In 2019, there were four noticeable events off the coast of Lake County, Ohio.  For one of them, a relative whopper at Magnitude 4.0, I was home sick and felt the house oscillating while lying in bed.  Not the most pleasant experience of my life, but it could have been worse.

If we don't cut this thread short, the Lake Erie basin will end up in Seismic Design Category D in ASCE 7-22.

 

[leggo PE]

Haha re: SDC D for Lake Erie basin!

I pretty much only ever design in SDC D or E. Occasionally, we get a SDC F, but in that case the geotech will definitely recommend ground improvement to bring it up a category; i.e. from F to E, or sometimes from E to D also.

 

[Reverse Polish]

I pretty much only ever design in SDC D or E. Occasionally, we get a SDC F, but in that case the geotech will definitely recommend ground improvement to bring it up a category; i.e. from F to E, or sometimes from E to D also.

That's interesting to know.  Apparently, the cost of ground improvement is less than the cost of additional seismic detailing? 

In the eastern part of the country, we have the opposite problem--many engineers are surprised to find their project is in SDC C or D, and they may or may not be familiar with the Code requirements (It's an even bigger problem if your fee was accepted before you determine SDC).  Nearly the entire state of Tennessee (and areas in adjoining states) is in SDC D (assuming Site Class D) and there's also a high seismic pocket around Charleston, South Carolina.  Heck, when I was taking the SE exam, I overheard engineers complain, "Why do we need to know high seismic design in Illinois?"  *headdesk*

 

[DoctorWho-PE]

That's interesting to know.  Apparently, the cost of ground improvement is less than the cost of additional seismic detailing? 

In the eastern part of the country, we have the opposite problem--many engineers are surprised to find their project is in SDC C or D, and they may or may not be familiar with the Code requirements (It's an even bigger problem if your fee was accepted before you determine SDC).  

And oftentimes it is.  Although, I think sometimes we will put a qualifier that indicates that if SDC is greater than B, additional design fees would apply. I have done one SDC C building.

 

[User1]

That's interesting to know.  Apparently, the cost of ground improvement is less than the cost of additional seismic detailing? 

it can be, considering sometimes ground improvement is just mixing in some better stuff or grout or something vs drilling deep foundation elements designed for lateral resistance and uplift forces