How did they decide the rotational factor, rp=0.4 in BS 7448-1 and rp=0.2 in ASTM E1290-08?

Reverse calculation shows for SEN(B) specimens, BS 7448-1 uses rp=0.4 and ASTM E1290-08 uses rp=0.2. I have not found any reference citing these values. I've been told that BS 7448-1 opted rp=0.4...

03 September 2014 1,299 6 View