EXPERIMENTAL STUDY ON DAMAGED COLUMNS STRENGTHENED WITH GFRP STRIP AND STEEL FIBER MORTAR UNDER AXIAL COMPRESSION

Through the axial compression test of one RC square-section short column and four RC square-section short columns strengthened with composite reinforcement, the axial compression performance of the damaged RC square-section short column strengthened with GFRP sleeve and steel fiber mortar was studied. The restraint effect of GFRP strips on RC columns strengthened with steel fiber mortar was analyzed; under different damage conditions, the bearing capacity, stiffness and ductility of RC columns strengthened with GFRP strips and steel fiber mortar were analyzed. The test results showed that GFRP strip could significantly improve the bearing capacity and ductility of RC columns strengthened with steel fiber mortar; the bearing capacity of damaged RC columns was significantly improved after GFRP strip and steel fiber mortar composite reinforcement, under the same conditions, the improvement rate of the bearing capacity of the composite reinforced column decreaseed with the increase of the degree of damaged RC columns, and the reinforcement effect was obvious in a certain degree, the reinforcement effect was weakened beyond this degree of damage. The axial compression stiffness of the specimen decreased with the increase of damage degree.On the basis of experimental study, the calculation formula of axial bearing capacity of composite reinforced RC short column with square-section was established,and the results were in good agreement with the experimental data.