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Re: asd vs lrfd

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>Are you considering both load cases per ACI 318 Section 9.2.2 (i.e. a
>reduced 
>dead load with wind or earthquake)?  I am surprised that uplift
>disappears if 
>both load cases are considered. 

This has occured to me so often with eccentrically loaded footings
under just DL and LL loads and with retaining walls, all not subject
to wind or earthquake loads, that I now expect this to happen.  My
*solution* to the problem has been to hold the point of zero soil
pressure as determined from service loads and apply the load factors
to the soil pressures from DL and LL at the point of maximum combined
service load pressure. 

The only additional thing that I can say is, check it out the next
time that you have an eccentrically loaded footing that has partial
uplift under dead and live service loads.  Of course, if you use a
computer program, you can't *see* what is happening and the computer
program is incapable of thinking about what is happening.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona