I think Mr. Srinivasan has referred to the spreadsheets based on the well known " Kellog Method " .
Yes, this is a time tested method based on a derivation using the concept of beam on elastic foundation.

However I have found in most of the spreadsheets I have come across , an erratic way of combining stress and comparing against allowables.

In my opinion, the stress output from "Kellog Method" should be combined and checked as per recommendations of SEC VIII DIV 2 APP 4.

A.BHATTACHARYA

STRESS ANALYST

BECHTEL CORPORATION