Seismic Performance Of Strengthened And Repaired Large Scale Square Section RC Column Using FRP

FRP has studied widely in seismic strengthening and repairing of reinforced concrete column in recent years,but the experimental study on seismic strengthening and repairing of large scale column is a little.In this study,seismic behavior of FRP strengthening and repairing of large scale reinforced concrete columns were studied through experiment,Finite element analysis(FEA)and theoretical analysis.(1)Firstly,the pseudo-static experiment was conducted through four large scale RC columns with two cross section sizes,two of these columns were pre-damaged under cyclic lateral load and then repaired using FRP and Engineering Cementitious Composite(ECC)and retested,two others of these columns were strengthening with the same amount of FRP.The cross section size of these RC columns are 495mm?495mm and 700mm?700mm respectively.The experiment results showed that the carrying capacity,ductility and energy dissipation of FRP strengthening columns were significantly improved,but these behaviors decrease with increasing the cross section size.The ductility of repaired RC columns were restored or improved,but the carrying capacity decrease with increasing the cross section size and damaged level.(2)Secondly,the hysteretic behaviors of unstrengthening,strengthening and repairing column were simulated through Opensees,the further parameter studies include axial load ratio,strength of ECC,amount of ECC and damaged levels were investigated.Finite element results agreed well with the experiment results.(3)The ultimate drift ratio assessment of FRP strengthening large scale columns were studied through comparing three models which were proposed by Ozcan,Libenben and Yuan.Results showed that model which was proposed by Yuan showed a better prediction than Libenben and Ozcan model.Afterward,the ultimate drift ratio assessment of FRP repaired column was studied through literatures,Ozcan proposed a model to predict ultimate drift ratio through six FRP repaired RC columns,the accuracy of the model was verified through a reliable database from literatures.Analysis results show that the predicted model overestimated the experiment results.The model was modified through analysis,the predicted results of modified model showed a better prediction than Ozcan model,the further verification of the modified model was done through experimrntal results in this study,the results showed a better prediction.Afterward,the predicted model for design was proposed.Finally,the ultimate capacity of the strengthened and repaired specimens were derivated.