Steel-fiber-reinforced polymer composite bar (SFCB) is a new kind of reinforcing material. It has some excellent properties such as corrosion resistance and stable post-yield stiffness. This paper focuses on the nonlinear seismic response analysis of the steel-basalt fiber composite bars concrete frame, including deducing the flexibility matrix of frame element based on the Gauss-Radau integral method, which is used for nonlinear time history response analysis of the frame structure. A RC frame and a corresponding SFCB concrete frame were designed in the district against 8 degree earthquake according to the current Code for Design of Concrete Structures. The seismic performances were compared, including rates of natural vibration period, nonlinear time history response, when and where the plastic hinge emerged. The results show that the SFCB frame has less interlayer displacement angle and maximum elasto-plastic displacement than the RC frame under the frequent and rare earthquake ground motions. Under the rare earthquake ground motion, the SFCB frame has a smaller rate of natural vibration period than the RC frame, with even slighter stiffness degradation and damage degree. Furthermore, fewer plastic hinges appear at the ends of the members in the SFCB frame and at a relatively later time, which is more likely to form the beam-hinge plastic energy dissipation mechanism. the steel-basalt fiber composite bars can make full use of the strength of materials by rational allocation of steel bar and basalt fiber, it can effectively control the plastic deformation and decrease the residual displacement of frame structure, and thus reduce the gravity second-order effect on columns and improve the seismic performance of the whole structure.
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