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RE: Seismic Design Hypothetical

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The answer by and large is that you MUST do seismic design for most
buildings.  There are some buildings that may not require a lateral
seismic analysis per the IBC, but just about all buildings still require
some seismic "design" (might just be detailing requirements).

And I agree that by and large the lateral analysis for most buildings will
be very similar for wind and seismic...that is an "equivalent static
lateral force".  The real difference is in the detailing requirements that
must be done for seismic that usually is not done (at least not to nearly
the same level) for wind, due to the need to achieve ductility.

The point is that with the IBC, there are no "non-seismic" areas.  There
are certainly low seismic areas where the lateral load analysis (if
required for seismic) will likely be governed by wind in many cases, but
even if so, the building must STILL be detailed for the appropriate
seismic design catergory requriements.

Regards,

Scott
Adrian, MI


On Mon, 29 Aug 2005, Eli Grassley wrote:

> Gail (and some others) -
>
>
>
> How can you "not do" seismic design??  I have heard that before from others
> on this list.  Granted I do most of my work on the West coast, but there are
> pockets of seismically active areas all around the country.  I know there
> are some in WY and MT.  And especially if you are working on a critical
> facility that has an Ie = 1.5.
>
>
>
> I guess my real question is what you mean when you say, "I don't have a good
> feeling for it."  Do you mean lateral force design in general?  Because EQ
> design is really not very different than W design.the code allows you to
> treat them both as *equivalent STATIC lateral forces*.  It's pretty rare to
> do a dynamic (modal analysis or wind tunnel modeling) design.
>
>
>
> Just curious.
>
>
>
> ~~ Eli Grassley, PE
>
>
>
> -----Original Message-----
> From: gskwy(--nospam--at)aol.com [mailto:gskwy(--nospam--at)aol.com]
> Sent: Monday, August 29, 2005 9:37 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Seismic Design Hypothetical
>
>
>
> Just to make it clear, I am not looking for specific answers for a specific
> situation.  It's just kind of a general question.  It has been said (often)
> that engineers don't get any respect because nobody knows what they do.  And
> maybe nobody knows what they do because they don't seem to be able to show
> people.
>
>
>
> I don't do seismic design, so I don't have a good feeling for it.  Hence my
> question.
>
>
>
> Admittedly, the situation posed is hypothetical, but most people are faced
> with dozens of hypotethical, what-if situations each day.  And manage to
> deal with them.
>
>
>
> Say it was an "open" parking garage in DC.  Low seismic.  20 psf wind.
> Gravity load would control.  How would the same parking garage in San
> Francisco look different?
>
>
>
> Gail Kelley
>
>

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