Roark Formula - Need Explanation on Usage

Dear All,
Help me on this or find and expert to assist me in design rectangular tank?

1. I have design Rectangular Tank with stiffener using Roark formula. The problem is, I realised that there is another calc for Rectangular Tank in ASME and Design of Welded Strcuture by W. Blodgett. I found that also ref. calc by Kanti K.Mahajan "Design of Process Equipment". Which one is more reliable especially in selecting stiffener on the side of the tank?. The design by Blodgett assumed beam theory in calculating plate thickness, so we can find plate "Z" value and max. moment to find the allowable bending stress , whereas Roark Formula assume a homogeneous plate.

I list down below references of my calc which will assist in finding the answer to my question?


2. The ratio a/b as per Roark Formula is a-longest length of the wall and b-the less one. I READ also this Theory of Stress and Strain by Timoshenko that say differently. I used a as the longest one for my calc as per Roark. But if a/b is less than one, the value beta, alpha is out of range from Table 11.4 Case 1a . How I want to estimate the beta and alpha values? ... Can I interpolate using other values...? I got confused also that the a/b ratio is different between Roark Table and Table in Eugene,R Meysey book.... . will anyone explain that to me why?.

I will fwd later my calc if anyone can help me the solution to my query here.

DETAILED OF MY REF CALCULATION

for the Plate under investigation....
As per Table 11.4 Case No.1a Chapter 10 of Roark's
"Rectangular plate, all edges simply supported, with uniform loads over entire plate."

for the Stiffener under investigation...
Bending Moment
As per Table 8.1 Case 2e of Roark's (Uniform load on entire span)-FOR HORIZONTAL STIFFENER
As per Table 8.1 Case 2d of Roark's (Uniformly increasing load)-FOR VERTICAL STIFFENER


Thanks for helping me,

regards,

CR4 Admin - email address removed

From the Site FAQ: Do not post phone numbers or email addresses. The CR4 Admin will delete all phone numbers posted in threads or comments, and we strongly urge you not to put up email addresses.