When designing steel members as per AISC Code, how do I specify the flexural unbraced length for the members in my model?
In STAAD the various AISC codes utilize steel design parameters UNT and UNB to specify the unsupported length used for flexural design calculations. UNT is the unbraced length for the top flange and UNB is the unbraced length for the bottom flange. The program determines which flange is in compression for each load case, and based on that uses the applicable UNT or UNB unbraced length for the purpose of computing flexural capacities.
The UNT and UNB parameters appear in the design parameters dialog box as follows:
*Please note - in the absence of the UNT and UNB parameters the program assumes their values are equal to member length.