| Author: | Liu, Kaicheng |
| Title: | Behaviour and modelling of elliptical FRP tube-confined reinforced concrete columns |
| Advisors: | Teng, Jin-guang (CEE) Yu, Tao (CEE) |
| Degree: | Ph.D. |
| Year: | 2023 |
| Subject: | Fibrous composites Reinforced concrete Columns Concrete Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Civil and Environmental Engineering |
| Pages: | xxxiii, 310 pages : color illustrations |
| Language: | English |
| Abstract: | Fibre-reinforced polymer (FRP) tube-confined reinforced concrete (RC) columns have emerged as a new form of hybrid columns, in which the outer FRP confining tube enhances both the strength and ductility of concrete. The effectiveness of FRP confinement in such hybrid columns depends highly on their cross-sectional shape: the concrete in square and rectangular columns is much less effectively confined compared with that in circular columns. While circular columns may be used to replace square columns for enhanced effectiveness of FRP confinement, the use of circular columns to replace rectangular columns is generally not desirable when the required resistances in the two orthogonal lateral directions are significantly different. In the latter case, an elliptical section, the curved counterpart of a rectangular section, may be used. This PhD thesis presents a systematic study aimed at providing insight into the structural behaviour and theoretical modelling of elliptical FRP tube-confined RC columns (EFCRCCs) under various loading scenarios. The first part of the PhD study, presented in Chapter 3, is concerned with the axial stress-strain behaviour of FRP-confined concrete in elliptical columns. Several batches of axial compression tests were conducted on elliptical FRP tube-confined concrete, with the test variables being the aspect ratio of the cross-section, the thickness and fibre orientations of the FRP tube, and the concrete strength. Based on the test results, the performance of the existing stress-strain models for FRP-confined concrete in elliptical-section columns are evaluated. Furthermore, two new stress-strain models for such concrete are proposed, which can provide more accurate predictions for the stress-strain curve than the existing models. The second part of the PhD study, presented in Chapters 4 and 5, is concerned with the static column behaviour of EFCRCCs, with focuses on the effects of load eccentricity and column slenderness. Two series of compression tests were conducted on EFCRCC specimens, providing the first insight into their structural behaviour. A theoretical model that captures the sectional behaviour through the fibre element method and the P-Δ effect using the numerical integration method of columns was developed to simulate the column behaviour of EFCRCCs and was found to provide accurate predictions of the load capacity of EFCRCCs. Furthermore, the design formulas in the relevant Chinese standard for slender FRP-confined RC columns were examined and were found to provide conservative predictions for EFCRCCs with the use of a stress-strain model for the confined concrete proposed in Chapter 3. Chapters 6 and 7 present the last part of the PhD study, which is concerned with the seismic behaviour of EFCRCCs. An experimental investigation was conducted on EFCRCC specimens subjected to combined axial compression and cyclic lateral loading. These tests were conducted to provide insights into the hysteretic behaviour of EFCRCCs and clarify the effects of the axial compression ratio, the cross-sectional aspect ratio and the direction of lateral loading. A numerical model for the hysteretic behaviour of EFCRCCs was then developed and was found to provide conservative and reasonably accurate predictions of the peak lateral load of the test specimens. |
| Rights: | All rights reserved |
| Access: | open access |
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