Dear Sir,
While manually calculating the Code Stress and Allowable stress for FRP piping with the guidance of formula specified in Code Stress chapter in Caesar ii Quick reference guide(C II V5.2), the manually calculated result does not match with the result /output shown by Caesar ii 5.2. Input parameters are given below
Design Code : ISO 14692
Component : Pipe
Sal(0:1) = 32300KPa, Sal(1:1) = 42500KPa, Sal(2:1) = 62100KPa, Shl(1:1) = 42500KPa, Shl(2:1) = 124300KPa, A1=1.0, A2=1.0, A3=1.0, Part factor loading f2= 0.89 – Occasional, 0.83 – Sustained including thermal, 0.67 – Sustained excluding thermal, Thermal factor K=1.0
Case i: (operating case)
At a specified node, following are the stress valve calculated by Caesar
Axial Stress: -34002.2KPa, Bending Stress: 1974.8KPa, Torsion Stress: -0.0KPa, Hoop Stress: 27668.7KPa
Code Stress: 32027.4KPa, Allowable Stress: 33475.3KPa
While calculating manually Sa(sum)=32027.4KPa, Sh(sum)=27668.7KPa. Siince Sa(sum)>Sh(sum), Sa(sum) become code stress. But manully calculating Allowable stress the value is 33449.48KPa. In this case the difference between the calculated Allowable stress and Caesar output allowable stress value seems small(25.28KPa). But in some node points where the Sa(sum) is the code stress the difference in calculated allowable stress is more the 500KPa
Case ii: (operating case – same model at different node point)
At a specified node, following are the stress valve calculated by Caesar
Axial Stress: 11172.3KPa, Bending Stress: 9717.7KPa, Torsion Stress: 0.0KPa, Hoop Stress: 58876.8KPa
Code Stress: 58876.8KPa, Allowable Stress: 103268.4KPa
While calculating manually Sa(sum)=20890KPa, Sh(sum)=58876.8KPa. Siince Sh(sum)>Sa(sum), Sh(sum) become code stress. But manully calculating Allowable stress the value is 40929.99KPa. In this case the difference between the calculated Allowable stress and Caesar output allowable stress value seems very high.
As per the formula mentioned in quick reference guide, always comparing Sa(sum) with the allowable stress value calculated based upon the condition of Sh(sum). But in my Case ii Sh(sum) becomes the code stress. There are in other cases where Sh(sum) is greater than Sa(sum), even then Sa(sum) is the governing Code Stress. Exactly in what situation Sa(sum) or Sh(sum) will become the governing Code Stress.
One line in Quick reference guide says, If Hoop stress is greater than Axial stress, then later will not be reported. What does this line states?
I had asked these doubts in my office, but dint get the answer.
Kindly correct me if my understandings are wrong.

Regards,
Kparthy