Study On Rapid Repairing Methods And Dynamic Performance Of New-type Post Earthquake Pile Columns

Earthquakes frequently occur in modern society worthwide. It is inevitable that the bridge piers are prone to damage during earthquake. Compared to the post-earthquake reconstruction, rapid repair can lead to remarkable social and economic benefits.However, it is found that pier columns with post-yielding stiffness possessed smaller residual displacement after the earthquake, making it easier to repair the pile columns. For these reasons, our researth group has developed a New Hybrid Reinforced Concrete-Filled Fiber Reinforced Polymer Tubular Bridge Piers, and prepared four specimens, as well as conducted test under quasi-static loads. On the basis of evaluating four damaged specimens, this thesis proposed an efficient rapid repairing technique for the new hybrid pile columns after reviewing current commonly-used techniques applied to repairing and strengthening post-earthquake piers. Then the foregoing damaged four specimens were repaired with the help of the above-mentioned repairing method; afterwards, the four specimens were tested by quasi-static loading and dynamic performance were measured and evaluated. Finally, a comparison was made between the experimental results and the measured values from intact columns and the numerical analyse. The main works and results are as follows:(1) On the basis of evaluating four damaged specimens, the current rapid repairing techniques are reviewed, and thus it is proposed a fast combination repairing technique where Basalt FRP (BFRP) bars were embedded in the near face of the concrete and the BFRP sheet were warpped around the damage piles. To validate its effectiveness, a numerical model was developed and analyzed the performance of the repaired pile columns. Afterwards, four specimens were repaired rapidly in terms of the proposed repair method. The study shows that the technique proposed requires little construction space and is easy to construct.(2) Four repaired specimens had been conducted experiment in quasi-static loads and dynamic performance was analyzed. Residual bearing and performance were systematically studied and assessed; furthermore, a comparison was made between the experimental results and the ones from intact columns. The results indicate that: two sharp points occurred at the decline stage of bearing capacity vs. deformation curves for the repaired columns due to the linear-elastic failure characteristics of FRP materials. Nevertheless, appropriate layers of BFRP sheets and the content of embedded FRP bars can weaken this feature; moreover, the repaired pile columns can possess the same performance as the intact piles columns in the bearing capacity and seismic indices to some extent.(3) Based on OpenSees software, the performance was simulated and analyzed for the repaired pile columns under quasi-static loads. The results show that the numerical results are in a good agreement with the experimental data. After being verified by the test results, parameter analyse were conducted by the developed numerical model. Repairing and retrofitting design suggestions were initially proposed for practical engineering application finally.