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Re: 3-D Loading

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I would answer that at a minimum it is specified by code.  I know for the
BOCA code for lower seismic zones it is 100% in one direction and then 100%
in other direction.  For higher seismic zones (and irregular buildings in
moderate), it is 100% in one direction plus 30% in other direction and then
100% in other direction plus 30% in perp. direction.  Take a look at the
applicable code.

Beyond code, my first boss was a firm believer in looking at lateral loads
applied at a 45 degree angle to the main face (primarily for wind).  I
believe this was a result of a lessen learn by an engineer that designed a
high rise in New York City (I believe it might have been the Citicorp
building??).  He had designed it per code...100% in one perpendicular
direction and then seperately 100% in other direction.  Either during
construction or after occupied (I can't remember), he for some reason
decided to look at it with wind at 45 degrees and ALL the lateral braces
were overstressed...to the point that there was a concern of a collapse
that could result in several blocks being destroyed...so a fix was developed.

I guess that is what I get for watching too much Discovery channel...I
actually learn interesting things.

Scott

At 02:27 PM 11/18/99 -0000, you wrote:
>Hi,
>I would like to get some input on how everybody else applies lateral
>loading; specifically seismic loading to a 3-D frame. One time to width and
>one time to length of the building in separate analysis or to the corner of
>the building or full loading to one face and a fraction of loading to the
>other face?
>Thanks,
>Joseph
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