A critical appraisal of existing models for nonlinear finite element analysis of reinforced concrete response
Date
2012-03
Authors
De Jager, Charl
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: This study entails the appraisal of the constitutive models available for the non
linear finite element analysis of reinforced concrete, using the DIANA finite
element package and following generally accepted guidelines for non linear finite
element analyses. The constitutive models considered are plasticity and total
strain based (fixed and rotating crack) models. The appraisal consists of the
analysis of various experiments performed on reinforced concrete beams that
are governed by compressive, shear and tensile dominated failures. The
investigation is not limited to the accuracy of the results obtained using these
models but also of the consistency of the results obtained with regard to various
mesh types and sizes, as well as a study of the individual influence of several
material parameters. The intention of the study was to provide the reader with an
indication of the performance capacity (accuracy and consistency) of the
available constitutive models, where the notion of the use of the results obtained
from non linear finite element analyses for design purposes is considered.
The results obtained were varied. The models performed reasonably well in the
compressive and tension dominated studies, with the importance of accurate
material parameters being emphasized especially for the more advanced
cementitious materials investigated. The total strain rotating crack model also
showed a proclivity of simulating incorrect failure modes as well as exhibiting
reluctance towards stress redistribution. All models used for the shear dominated
study yielded mostly inaccurate and inconsistent results, but it was found that the
four node quadrilateral element with selective reduced integration performed the
best. The plasticity model did not capture shear failure well, and convergence
was often not attained. The constant shear retention factor of the total strain
fixed crack model was found to yield more detailed response curves for the
smaller mesh sizes. The results of the tension dominated beams inspired more
confidence in the models as quite accurate values were attained, especially by
the plasticity model used.
The ability of the available models to simulate realistic structural behaviour under
various failure modes is very limited, as is evident from the results obtained. The
development of a more advanced and robust model is required, which can
provide consistently accurate results and failure modes, and even ‘anticipate’
potential failure modes not considered by the user.
Description
Thesis (MScEng)--Stellenbosch University, 2012.
Keywords
Reinforced concrete, DIANA finite element package, Fixed and rotating crack models, Reinforced concrete beams, Dissertations -- Civil engineering, Theses -- Civil engineering