| Popis: |
The research reported in this thesis was carried out in two phases to investigate the behaviour of reactive powder concrete (RPC) columns. In the first phase of this study, six steel fibre reinforced RPC columns of 150 mm square cross section were tested to failure under various loading eccentricities. The RPC mix contained 2 percent (by volume) of straight steel fibres with a concrete strength of about 150 MPa. The columns contained either 4 or 7 percent of longitudinal reinforcement but no tie reinforcement in the test region. All the columns failed in a controlled manner and no buckling of the longitudinal steel or cover spalling was observed, even well beyond the peak load. The tests revealed that stirrups can be significantly reduced for steel fibre reinforced RPC columns, which could lead to an increase in the speed of construction with an associated potential reduction in construction costs. In the second phase, 17 RPC columns were tested with 16 confined using carbon fibre reinforced polymer (CFRP). The concrete mix contained either no fibres or 2 percent (by volume) of straight steel fibres with concrete strength of approximately 160 MPa. The columns contained no conventional steel reinforcement. For the concentrically loaded specimens, failure occurred at or close to the peak loading and the CFRP increased the strength by 19 percent compared with the unconfined specimen. The tests showed that the formulae developed to predict the peak strength of concentrically loaded FRP confined conventional strength concrete columns, in general, overestimate the load carrying capacity of FRP confined RPC specimens. The CFRP was shown to be effective in controlling the failure for the eccentrically loaded specimens. There was no evidence, however, that the use of CFRP in the hoop direction significantly increased the strength of the columns. Three dimensional nonlinear FE analyses of the test specimens were undertaken using the program DIANA. The FE analyses showed a reasonable comparison with the experimental results for the specimens tested under eccentric loading. |
