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RE: Factor of Safety against Uplift

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John MacClean wrote: 
 
> I'm glad that Daryl mentioned limit states design for overturning which
IMHO
> is far superior to the allowable stress method at least for overturning
> (otherwise it's mostly a pain). 

Why do you consider limit states design superior to allowable stress design
for overturning? Personally, I have never heard of using limit states load
factors in stability calculations (overturning, uplift, sliding, etc). In
Chapter 18 of IBC 2000, it states to use allowable stress design load
combinations with formulas in that Chapter and in Section 1610.2 it
recommends a factor of safety of 1.5 against overturning, sliding, and water
uplift of retaining walls. Presumably this safety factor is for service
loads as it would be excessive to apply it to factored loads. (This section
should be clarified that it applies to service loads, and it also should not
apply to seismic design conditions.) IMHO limit states should only be
applied to "strength" design (material stresses) and not to "stability"
design. 

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