Abstract
The compressive response of hollow section, centrifugal concrete-filled GFRP tube (HS-CFGT) members is examined experimentally and reported analytically in this paper. A total of 17 specimens separated into two groups were tested; the specimens in each group were of four different lengths and included thirteen straight columns and four tapered columns. The details of the test rigs, procedures as well as key test observations composed of ultimate-moment capacities, load-displacement curves, and failure modes were truthfully reported. The test results were analyzed to evaluate the influence of initial eccentricity on the structural performance. Therefore, the aim of this paper is: (1) to propose a proper coefficient, φe, reflecting the effect of initial eccentricity based on the Chinese design code; and (2) to determine a new confinement coefficient, kcc = 1.10, for centrifugal concrete confined by GFRP tubes. Comparisons of the present design codes and specifications of confined concrete members with test results on 17 full-scale tube columns are also presented. Accordingly, new design equations, whose predictions generally agree well with the test results, are recommended to estimate the compressive capacity of the proposed HS-CFGT columns.
Highlights
Hollow section concrete columns have been used for off-shore structural columns, bridge piers, and electric poles due to their enhanced service performance, higher bending stiffness, and higher strength–weight ratios than solid section concrete columns [1,2,3,4,5,6,7,8]
The axial displacement δ of testing columns was measured by two 50 mm range linear variable differential transformers (LVDTs) arranged at the upper end of the testing machine and in the same position near the platen
Applicability of current design rules for hollow section concrete-filled GFRP tube (HS-CFGT) columns were evaluated against the test results
Summary
Hollow section concrete columns have been used for off-shore structural columns, bridge piers, and electric poles due to their enhanced service performance, higher bending stiffness, and higher strength–weight ratios than solid section concrete columns [1,2,3,4,5,6,7,8]. Thin-walled concrete-filled steel tubes have been proposed and investigated [9,10]. With declining urban land resources, electric poles possessing an insulation property are needed, which means that the steel elements such as steel tubes and reinforcing bars should be avoided. A novel type of electric pole, namely the hollow section concrete-filled GFRP tube (HS-CFGT), formed by concrete centrifugation in a GFRP tube, is proposed in this study. There is no previous steel corrosion problems owing to the absence of reinforcing bars embedded in the concrete; (3) HSCFGT is lightweight and is easy to transport, especially suitable for post-disaster reconstruction; (4) Since there is no steel reinforcement, the HS-CFGT is insulated, which avoids the problems of pollution flashover, lightning flashover, and wind flashover on overhead lines.
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