Doctor of Philosophy
School of Civil, Mining and Environmental Engineering
Wang, Weiqiang, Structural behaviour of FRP tube reinforced concrete (FTRC) columns, Doctor of Philosophy thesis, School of Civil, Mining and Environmental Engineering, University of Wollongong, 2016. https://ro.uow.edu.au/theses/4784
FRP tube reinforced concrete (FTRC) column is a novel hybrid concrete column proposed in this thesis. In the FTRC column, FRP tube is placed into the concrete to act as internal reinforcement of the column. Two types of FTRC columns have been investigated. Type I FTRC column is reinforced with perforated FRP tube. Type II FTRC column is reinforced with intact FRP tube, and polymer grid is embedded into the concrete cover to prevent the premature spalling of concrete cover. Both types of FTRC columns are expected to achieve excellent durability under harsh environments as well as superior performance under different loading conditions. This thesis presents experimental and theoretical investigations on the structural behaviour of the proposed FRTC column.
The first part of the research program is concerned with the behaviour of Type I FTRC column under axial compression. Different FRP tube configurations (intact tube, axially perforated tube and diagonally perforated tube) have been chosen to provide internal reinforcement of FTRC columns. The experimental results show that Type I FTRC column can obtain a considerable amount of strength and ductility under axial compression. Axially perforated tube performed better than diagonally perforated tube in improving the strength and ductility of Type I FTRC columns. Numerical simulations have also been carried out to assess the influence of tube perforations on the performance of Type I FTRC columns. In addition, the axial compressive behaviour of perforated FRP tube has been investigated. Different parameters that influence the performance of perforated FRP tube under axial compression have been investigated. Design-oriented equations have been proposed to predict the performance of perforated FRP tube under axial compression.
The second part of the research program is concerned with the behaviour of Type II FTRC column under axial compression. In addition to Type II FTRC columns, FRP confined concrete columns have also been tested for comparison. The experimental results indicate that, if properly designed, Type II FTRC columns can perform better than FRP confined concrete columns in terms of strength and ductility. Based on the test results, an analytical model has been developed. The analytical model has been verified by the test results. The model has been subsequently adopted to investigate the influences of various parameters on the axial compressive behaviour of Type II FTRC column. In addition, the behaviour of concrete confined solely by polymer grid under axial compression has been studied. Based on the test results in this study as well as previous studies, an analytical model has been developed for the axial compressive behaviour of polymer grid confined concrete with strain-softening response.
The last part of the research program is focused on the behaviour of both types of FTRC specimens under different loading conditions. Four groups of 16 specimens have been tested under concentric, 25 mm eccentric, 50 mm eccentric, and four-point loadings. All specimens were 240 mm in diameter and 800 mm in height. In addition to FTRC specimens, specimens reinforced with longitudinal steel bars and steel helices have also been tested for comparison. Results from the experimental investigations show that FRP tubes significantly increase the load carrying capacity and ductility of FTRC specimens. Type II FTRC specimens performed better than Type I FTRC specimens as well as specimens reinforced with longitudinal steel bars and helices in terms of strength and ductility. In addition, an analytical procedure has been developed for the performance of FTRC specimens under different loading conditions. The results of the developed analytical procedure have been found to be in good agreements with the experimental results.