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Re: Lateral Load--Is it THE Design?

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I work in the bridge design business, and seismic loads tend to dominate
the foundation and abutment designs, even here in New York.  It is somewhat
silly that I have to spend 8 months on a non-linear site specific time
history analysis for an earthquake on Long Island that is probably never
going to happen, but it does have certain advantages. The main advantage is
that it gives you a reason to be conservative, and therefore the ability to
sleep better at night with less worry of the thing falling down. One
difference between bridges and houses though, is that generally our clients
tend to push us towards more conservative analysis for lateral loads,
whereas in residential you seem to go the other way.

Michael Ludvik, PE

             "Bill Polhemus"                                               
             >                                                          To 
             09/16/2004 09:43                                           cc 
                                       Lateral Load--Is it THE Design?     
             Please respond to                                             


Is it just me, or is everyone here pretty much resigned to the fact that
lateral loads dicate maybe 80% of our efforts?

Of course I know those of you on the Left Coast who do commercial &
facilities design know this because of seismic, but even those doing
residential there admit that wind loads tend to govern their designs, and
they still spend the greater portion of their efforts in this.

This comes to mind because in talking with typical clients, they just don’t
seem to “get it.” They say “why are these roof purlins so big? There’s not
that much load on them!” and I have to tell them about design for wind.
They say “but it doesn’t get that windy here!”

Now, how silly a comment is that? Ask the folks in Gulf Shores, AL, just
how “windy” it got last night! When I say to them that we have to design
for hurricanes, they act like I’m just being outrageously conservative.

I have begun telling them that lateral loads account for the majority of
building structural failures (I’m flying by the seat of my pants here; I
have no way of knowing if this but every time I see photos of devastation
it’s hurricane or earthquake).

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