There has been a major error discovered in the two Russian steel design modules in STAAD.Pro which are resulting in the report of unreliable results and it is recommended that users cease using the Russian steel code at this time.
The error manifests itself in designs of multiple members. The results of the second and subsequent members are being affected by the design of the preceding member. The results can either be conservative or non-conservative.
Currently there is no work around other than only to design a single member. As this is impractical to do in most projects, it is strongly recommended to avoid using the Russian steel designs.
This affects only the v8i SS5 version of STAAD.Pro. (note that previously this was thought to affect older versions too, but this has found not to be the case, V8i SS4 and earlier are found to be ok)
We apologise for the trouble and appreciate that this can be a major inconvenience. The STAAD team is working as quickly as possible to have a resolution posted. Notification will be given in the RSS feed and the Bentley Communities site when a corrected version is available for download.
Please contact Bentley technical support if additional clarification is required.