In looking at the member properties for angles and MC Channels there appears to be some discrepancies. For example if I look at a MC4x13.8 channel Ix is shown as 0.373. I believe Ix refers to the torsional property of J as defined in the AISC steel books which is 0.373 for this size channel. When I look at the section property as calculated by STAAD if gives a calculated value of J = 0.354. Is Ix as shown in the STAAD pro section tables not the same value "J" as defined in the AISC steel books?
In addition for angles when I look at for example an L4x4x1/2" single angle STAAD is calculating the Iyy at 8.828 in^4. Assuming this corresponds to a Ixx in the AISC steel book the corresponding value is actually 5.52 in^4 for a L4x4x1/2" single angle. I also checked for L4x4x3/8 and noted a similar discrepancy. How is STAAD calculating the angle section properties and do they align with with the AISC values. If the STAAD section properties for angles are not aligning with the tabulated AISC values then this is a major concern.