Different Types of Moment Frames
When it comes to steel moment frames, there are three types of frames defined in the code — ordinary moment frames (OMF), intermediate moment frames (IMF) and special moment frames (SMF). They are listed in the table below along with their Response Modification Coefficient (R-value), Overstrength Factor (Ωο), and Deflection Amplification Factor (Cd) per ASCE 7.
For Steel Moment Frames
Typically OMF are used in wind regions, where a stiff, non-yielding frame is desired. SMF are typically used in seismic regions where more ductility is needed. Graphics below illustrate the difference in ductility between the three moment frame types.