Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: higher loads or better details.

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Moni Serhal wrote: 
 
>If you compare the Rw factor for RC frame structures with shear walls, 
it dropped from 8 in the UBC 91 to 5.5 in the UBC 97, a 45% increase in 
base shear load ! This illustrates how much uncertainties there still 
are in computing the lateral loads.< 
 
Actually the base shear load per the above changed very little - UBC 97 
provides factored loads whereas UBC provides allowable stress loads.  UBC 97 
loads may be reduced by a factor of 1.4 for comparison with UBC 91.  Thus 
(8/5.5)/1.4=1.04 for only a 4 percent increase.  Where I have found 
significant base shear differences, it has been due to changes in soil 
parameters to determine soil type.  
 
I certainly agree that connections and continuous load paths are the most 
critical aspects for adequate seismic resistance, although magnitude of 
seismic forces cannot be ignored.