Comm. C12.] PART II – COMPOSITE SPECIAL CONCENTRICALLY BRACED FRAMES
C10.
6.1–279
COMPOSITE INTERMEDIATE MOMENT FRAMES (C-IMF) The basic construction and connections for C-IMF are similar to C-SMF except that many of the seismic detailing requirements have been relaxed. C-IMF are limited for use in seismic design category C and below, and provisions for C-IMF are comparable to those required for reinforced concrete IMF and between those for steel IMF and OMF. The R and Cd values for C-IMF are equal to those for reinforced concrete IMF and between those for steel IMF and OMF.
C11.
COMPOSITE ORDINARY MOMENT FRAMES (C-OMF) C-OMF represent a type of composite moment frame that is designed and detailed following the Specification and ACI 318 (ACI, 2002b), excluding Chapter 21. C-OMF are limited to seismic design categories A and B, and the design provisions are comparable to those for reinforced concrete and steel frames that are designed without any special seismic detailing. The R and Cd values for COMF are chosen accordingly.
C12.
COMPOSITE SPECIAL CONCENTRICALLY BRACED FRAMES (C-CBF) C-CBF is one of the two types of composite braced frames that is specially detailed for seismic design categories C and above; the other is C-EBF. While experience using C-CBF is limited in high seismic regions, the design provisions for C-CBF are intended to result in behavior comparable to steel SCBF, wherein the braces often are the elements most susceptible to inelastic deformations (see Part I Commentary Section C13). The R and Cd values and usage limitations for C-CBF are similar to those for steel SCBF.
Fig. C-II-9.3. Concrete-filled tube column-to-steel beam moment connection.
Seismic Provisions for Structural Steel Buildings, March 9, 2005, incl. Supplement No. 1 AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
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