C-G1G1 Composite ordinary moment frames (C-OMF)

G1.2 Basis of Design

Composite ordinary moment frames (C-OMF) represent a type of composite moment frame that is designed and detailed following the Specification and ACI 318 (ACI, 2019), excluding Chapter 18. ASCE/SEI 7 (ASCE, 2022) limits C-OMF to seismic design categories A and B. This is in contrast to steel ordinary moment frames (OMF), which are permitted in higher seismic design categories. The design requirements for C-OMF recognize this difference and provide minimum ductility in the members and connections. The $R$ and $C_{d}$ values for C-OMF are chosen accordingly.