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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 23 Abstracts search results
Document:
SP157-19
Date:
October 1, 1995
Author(s):
P. Gergley
Publication:
Symposium Papers
Volume:
157
Abstract:
Earthquake-resistant design of reinforced concrete structures has special problems in moderate seismic zones if the possibility of a very large rare earthquake exists. This is the situation in central and eastern North America. The questions and difficulties associated with introducing a seismic design code for the first time are discussed. The seismic risk to a populated region is not reduced much for many years after the code takes effect; only the rehabilitation of existing structures will reduce the risk significantly in a meaningful time frame. The overall behavior of buildings, especially of existing older reinforced concrete buildings, is often nearly elasto-plastic in nature because a mechanism forms soon after the formation of the first hinge and there is little or no overstrength. This may not be an optimum design in most cases. The response of reinforced concrete buildings to moderate ground motions designed only for gravity loads is better than expected, with moderate drifts and no premature brittle failures in most building types. That is not the case for the rare catastrophic earthquake.
DOI:
10.14359/1010
SP157-10
A. J. O'Leary
Describes design and construction aspects of precast concrete moment resisting frames for the lateral load resistance of multistory buildings. Discussion will concentrate on the particular aspects of the framing system of a 13-story building constructed in Wellington, New Zealand. The building is octagonal in plan with a perimeter lateral load-resisting frame consisting of two-story high precast reinforced concrete elements. Each element includes a column plus two levels of beam stubs. In-situ concrete midspan beam splices and grouted steel sleeve column reinforcing bar splices form the joints between individual units. The paper also briefly presents other similar precast systems used for multistory buildings. A review of laboratory testing recently completed is given which confirms the good structural performance of the framing systems described.
10.14359/1016
SP157-05
O. Joh, Y. Goto, and T. Shibata
Based on the authors' previous tests, failure modes of beam bar anchorage with 90-degree bend used in reinforced concrete beam-column joints were classified into three types: a side split failure, a local compression failure, and a raking-out failure. To clarify the raking-out failure, the least understood of the modes, column type specimens with beam bars with 90-degree bend in the beam-column joints were tested under pullout loading at the bars. The specimen variables were development length, column depth, lateral reinforcement ratio, spacing between beam bars, and concrete compressive strength. From the test results, influence factors on the raking-out failure mode were discussed and an equation evaluating anchorage strength proposed.
10.14359/981
SP157-07
R. C. Fenwick and B. J. Davidson
To survive a major earthquake, current practice requires seismic resistant frames to be designed to be ductile. To achieve the required level of ductility in multistory frames, the majority of the potential plastic hinge zones are located in the beams. The inelastic rotation, which may develop in these zones, arises predominately from the tensile yielding of the reinforcement. The associated compressive strains are small and, as a consequence, elongation occurs. Test results show that elongation on the order of two to four percent of the member depth develop in plastic hinge zones of beams subjected to cyclic loading before strength degradation occurs. The factors influencing elongation are reviewed in this paper. The results of a time history analysis, in which elongation effects are modeled, shows that this action, which is neglected in current design practice, has important implications for the detailing of columns and the design of supports for precast components and external cladding.
10.14359/982
SP157-11
M. J. N. Priestley
Current practice in seismic analysis and design is examined in this paper, with particular reference to reinforced concrete structures. The attitude of the paper is deliberately iconoclastic, tilting at targets it is hoped will not be seen as windmills. It is suggested that current emphasis on strength-based design and ductility leads in directions that are not always rational. A pure displacement-based design approach is advanced as a viable alternative. Improvements resulting from increased sophistication of analyses are seen to be largely illusory. Energy absorption is shown to be a mixed blessing. Finally, accepted practices for flexural design, shear design, and development of reinforcement and the philosophic basis of capacity design are questioned.
10.14359/983
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