requirements for a geo report seismic c=

huangyhg

requirements for a geo report seismic c+
also, posted question in geotech area, but not sure which area it better applies, geo or structural.
according to 1802.2.6 & 7 of the ibc, it is required to have a geotech report for seismic categories c and above.  is there something that is acceptable for a geotech report not be performed if a more stringent analysis is used?  i was informed there was such an entry, but i am unable to find it.
fyi, this is more of an office discussion instead of me trying to design without a geotech report.
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if the soils are unknown, use d unless the building official states it is less.  it is in there somwhere.
section 1615.1.1 in the second paragraph it says use site class d unless the building official determines that e or f soil is likely present, provided soil properties are unknown.
-mike
sorry, maybe i did not state the question clear.  the above posts are refer to the site class (which it is acceptable to use d), but i am referring to the seismic design catagory c and above as stated in 1802.2.6 & 7.
djyork,
what do you mean by "a more stringent analysis is used"fff">?  do you mean a more stringent geotechnical analysis, or a more stringent structural analysis?
well, it seems a little difficult to put into words, but i'll try.
if you have a seismic design category less than c (for seismic purposes) the ibc does not require a geotech report per 1802 (my understanding).  so if you have a seismic design category in c or above are there values, assumptions, or provisions that the code allows if you still do not have a geotech report.
it is somewhat ambiguous question, since the design values do not have a great deal to do with the seismic design category.
it a short version is there any way to design a foundation/building without a geotech report (by code) if the design category is above c.
again, this is a long story how this question came about in our office, but i want to reiterate that we are not trying to design without a soils report.
i guess i'd question your statement that with category c you have to do a "geotech report".  
what the text of ibc 2000 says is, "where a structure....category c in accordance with section 1616, an investigation shall be conducted, and shall include an evaluation of the following potential hazards resulting from earthquake motions:  slope instability, liquefaction, and surface rupture due to faulting or lateral spreading."fff">.
those are three distinct items that simply need to be "evaluated" by the geotech, and, i presume, reported back to the design team to consider.  its not saying here that a full geotech report is required.  that's taken care of in 1802.1.