Date of Award

1992

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

V. K. A. Gopu

Abstract

This study deals with the three dimensional analysis of reinforced concrete structural members under multiaxial loading conditions. An incremental formulation in conjunction with the finite element method is used to simulate the behavior of reinforced concrete material. A hypoelastic model capable of simulating response of plain concrete under nonproportional loading conditions is employed. A five parameter strength envelope is used to predict the failure of concrete in multiaxial stress states. A smeared crack model capable of handling multiple non-orthogonal cracks is used to represent the post cracking behavior of concrete. Objectivity in the results of analysis utilizing the smeared cracking approach is achieved by employing a consistent characteristic length in three dimensional applications. The reinforcement in concrete is simulated using the embedded representation which allowed the bars to be modeled at their exact locations. Slip between concrete and steel is modeled by incorporating an additional degree of freedom, associated with the slip, at the intersection of the rebar with concrete finite element. Ability of the embedded steel segments to simulate the confinement effect on concrete is verified by analyzing an axially loaded reinforced concrete column. A general mesh mapping procedure that significantly reduces the amount of work involved to prepare the data for finite element models, is proposed and implemented for three dimensional applications. This procedure eliminates the limitations on the choice of the grid for the concrete finite element mesh and simplifies the use of embedded representation in three dimensional applications. The proposed models are implemented in a special purpose finite element program. The capabilities of the models are explored by simulating a number of experimental test specimens. These examples include, a notched beam, a beam under torsion, a beam without stirrups, a beam-column, and a beam-column-slab connection. The results of analysis indicate that the effect of concrete cracking and yielding of steel on the behavior of concrete are simulated well. Also, the predicted cracking pattern and failure loads are found to be in good agreement with those obtained from experimental procedures.

Pages

185

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