If you use a value of 2 for the TRACK parameter, you will get an expanded output that shows that for all the members with the RD16 section, the KL/r value is greater than a 1000.
In the AISC ASD code, the limits for KL/r are 200 in compression and 300 in tension. So, ordinarily, everyone of those members (with the RD16 section) ought to be reported as having failed the KL/r condition. But in STAAD, this test is performed only if the magnitude of axial load in the member from all the load cases considered for the design is greater than a certain tolerance, which is 0.2 pounds. In your model, those members whose axial force is smaller than this tolerance pass the code check because the interaction ratio from all other conditions is less than 1.0. Members such as 352, 354, 355, 377, etc. fall in this category.
If you do not want the KL/r check to per performed, set the MAIN parameter to 1.0.
In the AISC ASD code, the limits for KL/r are 200 in compression and 300 in tension. So, ordinarily, everyone of those members (with the RD16 section) ought to be reported as having failed the KL/r condition. But in STAAD, this test is performed only if the magnitude of axial load in the member from all the load cases considered for the design is greater than a certain tolerance, which is 0.2 pounds. In your model, those members whose axial force is smaller than this tolerance pass the code check because the interaction ratio from all other conditions is less than 1.0. Members such as 352, 354, 355, 377, etc. fall in this category.
If you do not want the KL/r check to per performed, set the MAIN parameter to 1.0.