Nikhil,

FirstI would like to recommend that for the stress summation and the allowables please go through the paper titled "Criteria of the ASME Boiler and Pressure
Vessel Code for Design by Analysis in Sections III and VIII Division 2"Published by ASME in 1969.

Also the same thing ( minus the rationale for doing so) can be found in ASME SEC VIII Div 2 appendix 4.

There is nothing known as two times max. shear stress intensity. Shear intensity itself is defined as two times max. shear stress ( which is equal to the algebraic difference betweeen the max. and min. principal stresses).

Both WRC 107 and 297 tells you how to arrive at the membrane and bending stresses at the four locations based on the typical loadings as well as how to compute the shear stresses based on non dimensional graphs.

Next you compute the stress intensities by dividing every category ( general primary membrane, local primary membrane,primary bending ,secondary etc. as each one has different summation rules and allowables ) into normal and shear stress .

Allowable for bending is more in comparison to membrane as a result of limit analysis ( elastic-perfectly plastic i.e. with no strain hardening.)

All summations and allowbles will be as per DIV 2 requirements. There is no room for self imposed allowables.

Hope this answers your question.

A.BHATTACHARYA

STRESS ANALYST

BECHTEL CORPORATION