Seismic Cat A Exception

[CTSeng]

Just want to make sure I'm reading this right.

ASCE7-05 Section 11.4.1 allows use of Design Category A for locations where S1 and Ss are less than 0.04 and 0.15 respectively regardless of the site classification.

Others have questioned the use of this exception for site classes other than B since that is what the spectral response accelerations figures are based on.

Any thoughts are appreciated.

 

[msucog]

so pretty much florida? maybe so. maybe other things are driving the design much more.

i'd have to see the specific wording since i don't remember off the top of my head.

 

[Metlpro]

I always take advantage of this exception for such low seismic regions. It does not matter what the site class is for the project when the response spectral accelerations are so low.

 

[msucog]

checked it today...it does look like it's giving the okay for very low seismic areas like florida as long as you follow the other guidelines described later in that section for SDC A. essentially, wind is a much bigger force to deal with living in places like florida and things like liquefaction are addressed as geotechnical issues. more or less, if there's no seismic forces acting on the structure, then it should have a pretty good SDC...at least that's my interpretation.