Thesis
Hybrid multi-tube concrete columns incorporating advanced composite materials
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2022
DOI:
https://doi.org/10.25918/thesis.291
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Abstract
A new form of hybrid structural column that can enhance the compressive strength and ultimate strain of concrete is the fibre-reinforced polymer (FRP)-confined multi-tube concrete column (MTCC). MTCCs comprise of an outer FRP tube, multiple internal metallic tubes, and a concrete infill. This column form offers many benefits over existing column forms, such as strength and ductility enhancements, improved corrosion resistance, constructability, and cost-effectiveness. This PhD thesis aims to expand the understanding of the confinement mechanism of MTCCs by investigating the influence that key column parameters have on their axial compressive behaviour. Both experimental and theoretical investigations were undertaken to achieve this objective.
The experimental component of this thesis consists of three test programmes. The first experimental programme consisted of monotonic axial compression tests on FRP-confined concrete to gain an improved understanding of the confinement mechanism of normal- and high-strength concrete confined with different FRP jackets. The second experimental programme consisted of monotonic axial compression tests on MTCCs to investigate the influence of several key parameters on their compressive response. The test results show that MTCCs effectively confine the concrete by delaying buckling of the internal tubes, resulting in significant strength and ductility enhancements. The third experimental programme consisted of cyclic axial compression tests on MTCCs. The experimental results show that MTCCs have a large deformation capacity under cyclic axial compression, and the envelope curve resembles the corresponding MTCC subjected to monotonic compression.
The theoretical component of this thesis involves the development of models of varying levels of complexity. Firstly, a unified dilation equation was developed for normal- and high-strength concrete confined with FRP composites with rupture strains of up to 9%. This equation can be used in conjunction with existing analysis-oriented stress-strain models for confined concrete. A three-dimensional finite element (FE) model was then developed to understand the complex confinement mechanism of MTCCs with different column parameters and was verified against the experimental results. Using this FE model, a parametric study was undertaken to produce a comprehensive database of stress-strain responses of concrete in MTCCs. This database was then used to develop an analytical stress-strain model for concrete in MTCCs. An existing cyclic stress-strain model developed for FRP-confined concrete columns was used to predict the unloading/reloading curves of concrete in the experimentally tested MTCCs. The existing cyclic model was modified to include the analytical model developed for MTCCs to predict the full cyclic response of the concrete in MTCCs.
Details
- Title
- Hybrid multi-tube concrete columns incorporating advanced composite materials
- Creators
- Nicholas Sirach
- Contributors
- Scott Thomas Smith (Supervisor) - Southern Cross UniversityAhmed Mostafa Thabet (Supervisor) - Southern Cross UniversityTao Yu (Supervisor) - Hong Kong Polytechnic University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xxxi, 276 pages
- Identifiers
- 991013135413802368
- Copyright
- © N Sirach 2022
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis