Title:
T1.2M-03/T1.2RM-03: Special Hybrid Moment Frames Composed of Discretely Jointed Precast and Post-Tensioned Concrete Members (T1.2M-03) and Commentary (T1.2RM-03) (Metric)
Author(s):
ACI Committee 93
Publication:
Technical Documents
Volume:
Issue:
Appears on pages(s):
15
Keywords:
drift ratio; energy dissipation; hybrid construction; lateral resistance; moment frame; post-tensioning; precast concrete; prestressed concrete; seismic design; test module; toughness.
DOI:
Date:
9/1/2008
Abstract:
Note: T1.2M-03/T1.2RM-03 is only available in PDF format.
This document defines requirements that may be used to design special hybrid moment frames composed of discretely jointed precast concrete beams post-tensioned to concrete columns. Such frames are suitable for use in regions of high seismicity or for structures assigned to satisfy high seismic performance or design categories. After a major seismic event, that moment frame can be expected to exhibit minimal damage in beam-column regions and negligible permanent displacements. Such moment frames do not satisfy the prescriptive requirements of Chapter 21 of ACI 318M-99 for frames of monolithic construction. According to Section 21.2.1.5 of ACI 318M,their acceptance requires demonstration by experimental evidence and analysis that the frames have strength and toughness equal to or exceeding those provided by comparable monolithic reinforced concrete frames that satisfy the prescriptive requirements of Chapter 21. This document describes the requirements that the designer may use to demonstrate, through analysis, that such frames have strength and toughness at least equal to those of comparable monolithic frames.
Among the subjects covered in this standard are requirements for:
1. Materials, and especially the special reinforcement that is debonded in the beam adjacent to the beam-column interface;
2. The framing system, and especially the roles of the post-tensioning tendons, the special reinforcement, and the floor slab; and
3. The beams of the moment frame, and especially their required prestress force level, the contribution of the special reinforcement to their probable moment strength, and the calculation of that strength.
The commentary describes some of the issues addressed by the Innovation Task Group and Collaborators in developing the standard.
The commentary references documentary evidence, additional to the references of ACI T1.1R-01 and Chapter 21 of ACI 318RM, that supports this standard. No comparison is made, however, either within the body of this standard or in its commentary, of the performance of test modules satisfying the prescriptive requirements of ACI 318M with modules that, although not satisfying the prescriptive requirements of ACI 318M, satisfy this standard. Such comparisons, both experimental and analytical, are available in the references cited in the commentary.