This thesis describes a non-linear finite element model suitable
for the analysis of reinforced concrete, or steel, structures under
general three-dimensional states of loading. The 20 noded
isoparametric brick element has been used to model the concrete and
reinforcing bars are idealised as axial members embedded within the
concrete elements. The compressive behaviour of concrete is
simulated by an elasto-plastic work hardening model followed by a
perfectly plastic plateau which is terminated at the onset the
. crushing. In tension, a smeared crack model with fixed orthogonal
cracks has been used with the inclusion of models for the retained
post-cracking stress and the reduced shear modulus.
The non-linear equations of equilibrium have been solved using an
incremental-iterative technique operating under load control. The
solution algorithms used are the standard and the modified
Newton-Raphson methods. Line searches have been implemented to
accelerate convergence. The numerical integration has been generally
carried out using 15 point Gaussian type rules. Results of a study
to investigate the performance of these rules show that the 15 point
rules are accurate and computationally efficient compared with the
27(3X3X3) point Gaussian rule.
The three- dimensional finite element model has been used to
investigate the problem of elasto-plastic torsion of homogeneous
members. The accuracy of the finite element solutions obtained for
beams of different cross-sections subjected to pure and warping
torsion have been assessed by comparing them with the available exact
or approximate analytical solutions.
Because the present work is devoted towards the analysis of
reinforced concrete members which fail in shear or torsional modes,
the computer program incorporates three models to account for the
degradation in the compressive strength of concrete due to presence
of tensile straining of transverse reinforcement. The numerical
solutions obtained for reinforced concrete panels under pure shear
and beams in torsion and combined torsion and bending reveal that the
inclusion of a model for reducing the compressive strength of cracked
concrete can significantly improve the correlation of the predicted
post-cracking stiffness and the computed ultimate loads with the
experimental results.
Parametric studies to investigate the effects of some important
material and solution parameters have been carried out. It is
concluded that in the presence of a compression strength reduction
model, the tension-stiffening parameters required for reinforced
concrete members under torsion should be similar to those used for
members in which bending dominates. / The scholarship of the Ministry of Higher Education of the Republic of Iraq.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/3576 |
| Date | January 1990 |
| Creators | Shaarbaf, Ihsan Ali Saib |
| Contributors | May, I.M. |
| Publisher | University of Bradford, Department of Civil Engineering |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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