| Fiber-reinforced polymer(FRP)bars have many distinguished andvantages as compared to conventional steel bars,including high strength-to-weight ratio,corrosion resistance,anti-electromagnetic interference.Since current design codes have strict limitations on the post-earthquake residual displacements of the bridge columns,it will be of great importance to apply the FRP bars in reinforced concrete(RC)column members to enhance the column post-yield stiffness,thus to improve the self-centering capacities and reduce the residual displacements.Existing studies of the author's research group have demonstrated that FRP bars are quite vulnerable to crush and bukling failure when they are adopted in columns.Therefore,in order to improve the utilization efficiency of the FRP bars,the research group further proposes a novel composite bar,which is made by placing the FRP bar in the center of a metal duct and filling the duct with high-strength grout.The effectiveness of the duct confined FRP bar(DCFB)concept was successfully validated in this master degree research project.The main work contents are summarized as follows:(1)On the material level,the tensile and compressive mechanical properties of the DCFB are firstly investigated as the breakthrough point of this project;the tensile properties of the DCFB were also compared to those of the corresponding FRP bars;(2)On the member levels,five DCFB-RC columns were tested under combined constant axial load and cyclic lateral displacement,the seismic performance were investigated and compared in terms of lateral strength,stiffness degradation,hysteretic energy dissipation,and so on;(3)Based on the OpenSees platform,a refine finite element(FE)model of the DCFB-RC column was developed,which considered the strain penetration effects;comparisons between the simulation and the test results indicated the accuracy of the FE model,and the considerable influence of the strain penetration effects was also revealed. |
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