System-based design of planar steel frames, II: Reliability results and design recommendations

• System resistance factors were developed for a series of planar low- to mid-rise braced and rigid frames.
• Various load combinations and failure modes were considered in developing the system resistance factors.
• Different target reliability levels were considered.
• Recommendations are made for the appropriate target reliabilities and system resistance factors for system design.

This is the second of two papers that describe a study conducted to develop system resistance factors for Direct Design Method (DDM) of steel frames by advanced analysis in accordance with Appendix 1 of the AISC Specification and similar design requirements. A companion paper [1] presents a framework for determining system resistance factors accounting for inherent uncertainties in the ultimate strength of a frame. In this paper, system resistance factors are developed for low- to mid-rise braced and moment resisting frames with regular and irregular configurations for various loading conditions and different target reliability levels. Recommendations are made for the appropriate target reliabilities and associated system resistance factors for use in designing steel frames at the system level by advanced analysis.