Answer:
The RF‑STEEL AISC module does not optimize cross-sections for the Serviceability Limit State design. Optimization is only calculated for the Ultimate Limit State design.
Users must manually adjust the cross-section in RFEM or within the add-on module and can export the cross-section back into RFEM. In either scenario, the model must be rerun in order to calculate the correct internal forces with adjusted member size.
