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International Concrete Abstracts Portal

Showing 1-5 of 20 Abstracts search results

Document: 

SP237

Date: 

October 11, 2006

Author(s):

Editors: Laura Lowes and Filip Filippou

Publication:

Symposium Papers

Volume:

237

Abstract:

SP-237CD This CD-ROM is a collection of 19 papers presented at a workshop sponsored by Joint ACI-ASCE Committee 447, Finite Element Analysis of Reinforced Concrete Structures, and JCI Committee 016SP, in Maui, Hawaii, USA, in November 2003. A broad range of topics was addressed, including the creation of new experimental data sets for use in developing, calibrating, and validating models; the development and validation of plain, reinforced, and fiber-reinforced concrete constitutive models; new approaches to simulating the response of reinforced concrete continua; new element formations to enable improved simulation of component response; and new computational techniques.

DOI:

10.14359/18184


Document: 

SP237-03

Date: 

August 1, 2006

Author(s):

K. Suzuki and A. Fujii

Publication:

Symposium Papers

Volume:

237

Abstract:

Two interior column (RC)-beam (PPC) specimens were tested. The specimens were first subjected to reversed, repeated cyclic loading to maximum rotational angles of 1/30 and 1/16, respectively. The specimens were then repaired using resin injection and mortar covering. Mechanical properties obtained following repair were almost the same as those obtained during the initial loading, probably, due to the confined concrete used in the beam ends. However, a reduction in initial stiffness of approximately 30% was observed.

DOI:

10.14359/18240


Document: 

SP237-04

Date: 

August 1, 2006

Author(s):

T. Higai, H. Nakamura, and S. Saito

Publication:

Symposium Papers

Volume:

237

Abstract:

After the Hanshin-Awaji earthquake, the volume of lateral reinforcement used in reinforced concrete structures in Japan was increased to improve seismic performance. Although a large volume of closely spaced lateral reinforcement will be effective in preventing elastic buckling of the longitudinal reinforcement, it will not prevent plastic buckling. Under severe earthquake loading, longitudinal reinforcement will be subjected to large reversed-cyclic deformation demands into the plastic regime in tension and the buckling regime in compression. The authors presented the results of low cycle fatigue testing of deformed bars and examination of failure criteria for these bars.

DOI:

10.14359/18244


Document: 

SP237-18

Date: 

August 1, 2006

Author(s):

J.G. Rots, S. Invernizzi, and B. Belletti

Publication:

Symposium Papers

Volume:

237

Abstract:

Over the past years techniques for non-linear analysis have been enhanced significantly via improved solution procedures, extended finite element techniques and increased robustness of constitutive models. Nevertheless, problems remain, especially for real world structures of softening materials like concrete. The softening gives negative stiffness and risk of bifurcations due to multiple cracks that compete to survive. Incremental-iterative techniques have difficulties in selecting and handling the local peaks and snap-backs. In this contribution, an alternative method is proposed. The softening diagram of negative slope is replaced by a saw-tooth diagram of positive slopes. The incremental-iterative Newton method is replaced by a series of linear analyses using a special scaling technique with subsequent stiffness/strength reduction per critical element. It is shown that this event-by-event strategy is robust and reliable. First, the example of a large-scale dog-bone specimen in direct tension is analyzed using an isotropic version of the saw-tooth model. The model is capable of automatically providing the snap-back response. Next, the saw-tooth model is extended to include anisotropy for fixed crack directions to accommodate both tensile cracking and compression strut action for reinforced concrete. Three different reinforced concrete structures are analyzed, a tension-pull specimen, a slender beam and a slab. In all cases, the model naturally provides the local peaks and snap-backs associated with the subsequent development of primary cracks starting from the rebar. The secant saw-tooth stiffness is always positive and the analysis always ‘converges’. Bifurcations are prevented due to the scaling technique.

DOI:

10.14359/18259


Document: 

SP237-11

Date: 

August 1, 2006

Author(s):

S. Kono, H. Bechtoula, M. Sakashita, H. Tanaka, F. Watanabe, and M.O. Eberhard

Publication:

Symposium Papers

Volume:

237

Abstract:

Damage assessment has become more important than ever since structural designers started to employ performance based design methods, which require structural and member behaviors at different limit states be predicted precisely. This study aims to clarify the confining effect of concrete of a plastic hinge zone of a reinforced concrete column confined by shear reinforcement, so that a designer can accurately predict damage when columns experience seismic loadings that includes large axial force and bilateral deformations. In an experimental program, eight half-scale columns and eight full-scale columns were tested under the reversal bilateral displacement with constant or varying axial load in order to study the effects of loading history and intensity on the confining effect. Since shear failure was inhibited by providing enough transverse reinforcement, as defined by the previous Japanese design guidelines, damage gradually progressed in a flexural mode with concrete crushing and yielding of reinforcing bars. The damage level depended on the bilateral loading paths and the axial load history. In an analytical program, a section analysis using a fiber model was employed and the effect of confinement on the behavior of core concrete was studied. The analysis predicted the observed deterioration of moment capacity and longitudinal shortening under different loading conditions and for different specimen sizes. The study is considered to increase the accuracy with which damage in reinforced concrete columns subjected to severe loading is assessed.

DOI:

10.14359/18252


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