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International Concrete Abstracts Portal

Showing 1-5 of 19 Abstracts search results

Document: 

SP205-09

Date: 

January 1, 2002

Author(s):

N. Shirai, K. Moriizumi, and K. Terasawa

Publication:

Symposium Papers

Volume:

205

Abstract:

The objective of the present study is to examine the performance of the proposed approach in simulating monotonic and cyclic behaviors of shear-dominated RC columns. The macro-element model is formulated on the basis that the total deformation of the RC column can be decomposed into flexural and shear components. The flexural behavior is simulated by the layered element model, and the shear behavior is simulated by the so-called shear element model. The shear element model is a single plane stress RC element which is developed on the basis of the smeared reinforcement and smeared rotating crack concept. Then, the total model is formulated by coupling these two models in series. Three shear-dominated RC column specimens, tested at the University of California at San Diego, are analyzed under monotonic and cyclic loading. It is shown that the proposed model can reproduce the monotonic and cyclic response behavior reasonably well.

DOI:

10.14359/11639


Document: 

SP205-07

Date: 

January 1, 2002

Author(s):

R. K. Dowell and D. R. Parker

Publication:

Symposium Papers

Volume:

205

Abstract:

Finite element analyses were conducted of as-built and seismically retrofitted RC bridge columns tested at UCSD. The as-built columns were provided with the same rectangular cross section and shear reinforcement, resulting in approximately the same shear capacity, but were designed to fail at different levels of ductility in either a brittle or flexural shear failure. This was accomplished by adjusting the shear force demand by varying the column height (or aspect ratio) and the grade of longitudinal reinforcement. In the analysis the challenge was to capture the overall force-deformation hysteretic behavior and failure mechanism, as well as the individual deformation components of flexure and shear. The analysis focuses on the shear behavior of concrete under large tensile strains and calibrates the shear stress capacity to the concrete component of the UCSD shear model, which reduces as a function of curvature ductility at the critical section. Also, the shear modulus is reduced in proportion to the ratio of cracked to gross flexural stiffness. The results show that a relatively simple design oriented shear capacity model can be used to calibrate the required shear parameters of the 3-D plasticity concrete model. In the paper, detailed finite element analyses are conducted to assess the shear force capacity and post-peak deformation response of shear dominated RC bridge columns.

DOI:

10.14359/11637


Document: 

SP205

Date: 

January 1, 2002

Author(s):

Editors: Kaspar William and Tada-aki Tanabe

Publication:

Symposium Papers

Volume:

205

Abstract:

SP-205 Nonlinear finite element analysis (NLFEA) of reinforced concrete is close to being a practical tool for everyday use by design engineers. The first in this collection of 18 papers takes a critical look at the accuracy of this analysis procedure, then identifies and discusses reasons for caution in applying nonlinear analysis methods. Subsequent papers cover topics that include: * Seismic behavior predictions of structures; * Three-dimensional cyclic analysis of compressive diagonal shear failure; * Finite element analysis of shear columns; and * Simulation strategies to predict seismic response of reinforced concrete structures. Designers and researchers who use NLFEA models and procedures for reinforced concrete must be experienced and cautious. The papers in this volume will enable the users to better understand modeling, analysis, and interpretation of results.

DOI:

10.14359/14013


Document: 

SP205-18

Date: 

January 1, 2002

Author(s):

Dilatational Response of Concrete Materials: Facts and Fiction

Publication:

Symposium Papers

Volume:

205

Abstract:

Confinement is the key to the performance of reinforced concrete structures when ductility demands are of primary interest. Hence dilatancy and restraining effects are critical for the behavior of reinforced concrete under seismic environments. In fact, restrained dilatancy is the determinant factor ensuring strength and ductility of reinforced concrete members in compression. In this paper, the issue of the dilatancy of concrete at different levels of active confinement is revisited. Experimental observations on 150x300 mm concrete cylinders, which were recently tested in a large capacity triaxial chamber, are presented. For the analysis of the dilatancy data, the elastoplastic concrete model known as the Extended Leon Model is applied. The study is focused on the volumetric behavior of concrete, which in plasticity terminlogy refers to inelastic dilatancy and the concomitant issue of normality. In particular, the test data is examined within the framework of the non-associated flow theory of plasticity. In this context, the origin of discontinuous failure mechanisms in the high confinement regime is questioned, where inelastic dilatancy together with the loss of axisymmetry are the primary reasons for localized failure in the form of discontinuous faulting.

DOI:

10.14359/11648


Document: 

SP205-12

Date: 

January 1, 2002

Author(s):

T. Tanabe and A. ltoh

Publication:

Symposium Papers

Volume:

205

Abstract:

The shear failure of a reinforced concrete beam and a column without stirrups is known to have substantial scale effect. In other words, softening characteristics of concrete play a dominant role in its pre- and post-peak behavior. The post-peak static behavior of reinforced concrete members are directly related to the dynamic post-peak behavior of reinforced concrete structures or the extent of energy absorbing capacity of a member and consequently to the safety margin to be allocated in a beam or a column in seismic design. It become more so when a structure fail in snap-back instability allowing more energy to come in a structure to be converted to dynamic energy passing the peak loading capacity. The numerical difficulty encountered to capture snap-back is itself a good challenging target. The snap-back instability is explained for the case of uniaxial tension, and the shear characteristics of reinforced concrete beams with snap-back are examined by changing the beam dimensions and the span over depth ratio.

DOI:

10.14359/11642


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