Hi Dave,

Thanks once more for your helpful information but I'm quite lost...

As you you have explained, is defensible the second ecuation but...is intention of ASME code to analyze in the same ecuation such different concepts as thermal stresses and seismic displacements? ASME code specifies different allowable stress for thermal and occasional loads so, is it neccessary to "mix" them? That is what it seem to be stated according to interpretation 20.45 of the code, dated october 2005.

Could it be more "logical" to isolate the seismic problem, taking into accout both inertia and seismic displacement in the same ecuation, as it happens in the third ecuation?
On the other hand I understand that this ecuation does not "belong" to B31.3 code.

You also have talk about B31E code, where both seismic inertia and relative anchor motion are considered for longitudinal stress. I'm sorry but my company has not buyed yet this code, I'm trying to convince them. In the meanwhile please let me ask you:
Does this means that for the computed stress for seismic, which is compared with 1,33Sh, should we consider both seismic inertia and relative anchor motion effects?

I apologize for asking so much, I'm only trying to clarify the most accurate way to study stresses due to seismic anchor displacement in compliance with ASME code.

Many thanks in advance.