Tension on the net section in bolted connections

I am verifying calculation sheets for design of bolted storage tanks according to AWWA and similar standards.

In the formula for tensile stress on the net section ft=0.6Fy(1.0-0.9r+3rd/s)<=0.6Fy, r and s are defined as:
r = force transmitted by the bolt or bolts at the section considered, divided by the tensile force in the member at that section.
s = spacing of bolts perpendicular to line of stress in inches

Can anyone help me with the interpretation of r and s, because I don't know how to calculate it for different bolt layouts. The different layouts are:
A | B | C
* | * | *
* | * * | * *
* | * | *
| | *
* | * | *
* | * * | * *
* | * | *
| | *
* | * | *
* | * * | * *
* | * | *
| | *


For the above layouts, what are r and s ?

I hope my question is clear, thanks in advance for the help!