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RE: amusement structures

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You can not disconnect the discussion of R values from the discussion of
rho.  I would recommend that you read the 1997 NEHRP Commentary Sec. 5.2.4.
There was never an inferred redundancy in the R values for cantilevered
columns, as there was with other structural systems like special moment
resisting frames. 

Be careful on the design of the elements.  If wind is governing by a factor
of 1.5.  Seismic may still govern for certain elements.  Consider that the
omega sub 0 is 2.0 for cantilevered column structures.

Harold Sprague

> -----Original Message-----
> From:	Aaron Burkhardt [SMTP:aaron(--nospam--at)]
> Sent:	Tuesday, January 04, 2000 3:52 PM
> To:	'seaint(--nospam--at)'
> Subject:	re: amusement structures
> Thanks for the responses. I think I should have been a little clearer in 
> what I was looking for. My main concern is the UBC's stipulation that
> these 
> type of structures can be designed with a rho=1.0. I don't understand
> where 
> the redundancy in the cantilevered column system is. If it were to have to
> be designed with a rho=1.5, then seismic would govern the design in my 
> case.
> Aaron J. Burkhardt, P.E.
> KPFF Consulting Engineers
> Portland, OR