This section provides the user control of parameters to be used during analysis according to the Direct Analysis Method of AISC 360-05. Note that if AISC 360-05 (ASD or LRFD) is chosen in Steel > Standard Provisions module, the parameters in this section should be set accordingly. If the user does not select the " Use Reduced Stiffness " option, the choices set in this section are not applied. Otherwise, they are considered in the analysis. Thus, it is responsibility of the user to select the Use Reduced Stiffness option according to their choice of design code in the Steel > Standard Provisions module.

If Use Reduced Stiffness is selected, you are given the option to either set τ_b to 1 or to some specific value (see Appendix 7 of AISC 360-05 for further information on τ_b). The flexural stiffness of all frame members is then modified according to Eq (A-7-2) and the axial stiffness is modified according to Eq. (A-7-3) in AISC 360-05, Appendix 7. Also note that the modification in only applied to steel members.

After the design has been performed the user should run the AISC 360 Direct Analysis Validation report to verify the validity of all selections.