Seismic Performance Analysis Of RC Frame Structure With Columns Retrofitted By FRP

All the previous seismic damage investigation and analysis indicates that the failure mode of many cast-in-place reinforced concrete(RC) frame structures is characterized by the“strong beam-weak column”, which is just opposite to the aseismic design criteria in our country. A significant adjustment in Code for Seismic Design of Buildings(GB 50011-2010) is that the moment augment factor of column of frame structures at all levels is improved, which makes a lot of existing buildings can no longer meet the request of seismic code and would become potential safety hazard. Fiber reinforced polymer(FRP) composites have been widely used for seismic strengthening or rehabilitation of reinforced concrete structures during the past years, due to its excellent properties, such as light deadweight, high tensile strength, low elastic modulus, good corrosion resistance and convenient construction process, etc.Appropriate reinforcement of these existing frame structures with FRP can improve their seismic performance and solve the issues above. Consequently, the seismic performance analysis of RC frame structure with columns retrofitted by FRP has great theoretical significance and engineering application value.In the seismic retrofit research on FRP, the analytical investigation of seismic performance of whole RC structure with columns retrofitted by FRP is not yet abundant. On this basis, the seismic performance of FRP strengthened RC columns was studied as the basic work on member level, then the structural seismic performance of FRP strengthened whole RC frames was investigated and analyzed. On the member level, based on the quasi-static test of FRP strengthened full scale RC columns, analytical simulation of the calculation model of the RC columns retrofitted by FRP was conducted using FEM software ABAQUS to verify the rationality and the veracity of restoring model of FRP-confined concrete, through comparison between numerical simulation and the test results. On the structural level, firstly,the reinforced concrete structure of three-story frame was designed by usual structure design software PKPM and response spectra analysis was made. Then the finite element model of RC structure with columns retrofitted by FRP was conducted using ABAQUS software, and the dynamic time-history analysis was conducted by inputting three seismic waves selected,such as EI-Centro wave, Taft wave, and an artificial wave. Finally, changes of seismicperformance between bare and FRP strengthened frames were compared and analyzed.The research results indicate that the ductility and energy dissipation capability of the whole structure can be improved obviously with columns retrofitted by FRP composites,while there’s no obvious influence on the improvement of the bearing capacity. When plastic development degree in the structure is low, the weak lateral restriction effects from FRP make the maximum displacement of the top slightly less than the original structure; However, with the adequate plastic development in the structure, making best use of FRP, ultimate displacement of the structure is obviously higher than that of the pure frame, and the seismic performance is obviously improved than before. Therefore, the ductility and energy dissipation capability of the whole structure can be improved obviously with columns retrofitted by FRP composites. Appropriate reinforcement method can make structure resist higher levels of earthquake action. FRP retrofitted method aiming at improving ductility of structures can be applied widely in engineering practice.