Acceptance Criteria for Moment Frames Based on Structural Testing and Commentary (ACI 374.1-05)

Description

For seismic design, ACI 318-11 specifies in Section21.1.1.8 that “a reinforced concrete structural system not satis-fying the requirements of this chapter (Chapter 21) shall be permitted if it is demonstrated by experimental evidence and analysis that the proposed system has strength and toughness equal to or exceeding those provided by a comparable mono-lithic reinforced concrete structure that satisfies the require-ments of this chapter.” This Standard defines the minimum experimental evidence that shall be provided in order to vali-date the use, in regions of high seismic risk or for structures assigned to satisfy high seismic performance or design categories, of a weak beam/strong column moment frame not satisfying the requirements of Chapter 21 of ACI 318-11.

Consistent with the ACI 318-11 requirement for analysis,this Standard specifies that, before the testing mandated by theStandard, a design procedure shall have been developed for prototype frames having the generic form for which accep-tance is sought and that design procedure shall be used to proportion the test modules. Further, the Standard assumesthat the prototype frames have forms that are essentiallyregular, having no significant physical discontinuities in planor in vertical configuration or in their lateral-force-resistingsystems, and that the frames satisfy some, but not all, of therequirements of Chapter 21.

Such frames might, forexample, involve use of precast elements, precastprestressed elements, post-tensioned reinforcement, orcombinations of those elements and reinforcement. Prescrip-tive requirements for moment frames constructed with suchelements are not included in ACI 318-11. Such frames mightalso, for example, use alternate methods, other than thosespecified in Chapter 21, for force transfer through beam-column joints.