In the NCEES problem, the 'maximum allowable cyclic stress ratio' is given as 0.29. This makes it the CRR (cyclic resistance ratio - maximum allowable = resistance). That's why it goes into the numerator (ultimate) in the calculation of the FS. What's in the denominator is the actual shear stress induced by the earthquake, which corresponds to a CSR = 0.225, but it's given directly as 450 psfOK, so I'm confused. In the NCEES sample exam problem listed, the solution calculates the FS as CSR* sigma prime sub v / cohesion of soil
Thsi same problem is in the NCEES 2007 sample exam and is solved the same way. The way you are suggesting, and teh way that is listed in the goswami all in one practice exam places the CSR * sigma v term in the denominator, not the numerator like NCEES.
Which is correct?
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