Application And Research Of Fiber Model In The Analysis Of FRP Strengthening Structure

In recent years, fiber reinforced composites due to its superior mechanical properties and physical properties, has been widely used in the reinforcement of member and structure, especially in the work of the restoration of earthquake structure, the restraint of FRP can not only improve the bearing capacity of the structure, but also greatly improve the energy diss ipation and ductility of structure under earthquake action. In order to study the seismic performance of the structure after FRP reinforcement, domestic and foreign scholars have carried on a lot of research to FRP reinforcement technology, but these studies mainly focus on the level of materials and components, and it can not reflect the seismic performance of the structure after FRP strengthening at the structural level.Aiming at the shortage of the research on the FRP confined concrete structures, this thesis draw support from the nonlinear beam column element based on flexibility and the fiber models on the Open Sees platform, and simulated the time history response of FRP reinforced concrete structures under strong earthquake action.T his thesis takes the research of constitutive model of FRP confined concrete as the starting point, and then the simulation and research of seismic performance of FRP confined concrete column was studied as the base. Finally, the simulation and research of seismic performance of the FRP confined concrete frame structure has been studied by using fiber models combined with the programed computing module of constitutive model of FRP confined concrete on the base of Open Sees. The main research contents of this paper are as fol lows:(1) On the material level, the constitutive model of the typical FRP confined concrete materials is introduced. Then, the effective utilization coefficient of FRP is taken into the constitutive model of FRP confined concrete, which makes the calculation of ultimate state of FRP confined concrete column more accurate by considering the impact of the material properties to the ultimate state of FRP confined concrete. The confinement of stirrup has been considered in t he FRP confined concrete column, and then the constitutive model of FRP confined concrete circular cylinder and rectangular column is presented.(2) On the component level, on the base of Open Sees computing module of FRP confined concrete material has been programmed. By using the fiber mod els the mechanical properties of FRP confined concrete column under different mechanical conditions are simulated and analyzed. The influence of parameters on seismic behavior of FRP confined concrete column is discussed, and the parameters included constitutive relationship of the reinforcement, the thickness of FRP material, axial compression ratio, concrete strength, longitudinal reinforcement ratio, the corner radius and aspect ratio.(3) On the structural level, firstly, the accuracy of the fiber mod el is demonstrated by the simulation of a FRP reinforced concrete frame structure. Based on this, a reinforced concrete frame structure is designed, and in the case of the same total amount of FRP, three reinforcement schemes are adopted to reinforce the f rame structure. The elastic plastic dynamic response of the structure before and after reinforcement is obtained by using fiber models. Through the analysis and comparison of the top floor displacement, base shear and inter-story drift ratio of the structure reinforced by different schemes, the influence of different reinforcement schemes on the seismic behavior of the structure is obtained, and finally the most suitable reinforcement scheme is presented.