API RP2A 21st edition is an old, superseded code. API RP2A 21st edition is NOT accepted by our Clients as a steel design code check for tubular members. API RP2A 22nd edition is accepted by our Clients. It would be straight forward for STAAD to update. From reviewing the editions, same adopted formula in both editions for member design. However, some changes in the joint design between the two editions.
Thank you for posting this idea. We are constantly reviewing the status of design codes and modules that represent published requirements and this code is part of that review process.