Experimental Study On Axial Compression Of Damaged RC Short Column Reinforced By GFRP And Steel Fiber Mortar

GFRP(Glass Fiber Reinforced Polymer)has light weight,high strength and corrosion resistance,while steel fiber mortar has good crack resistance and good elongation and other superior properties.Based on the need to strengthen the old building column members and widen the scope of application of steel fiber mortar,this study proposes a new concept of GFRP casing and steel fiber mortar to strengthen damaged RC columns and GFRP strip and steel fiber mortar to strengthen damaged RC columns.Eight RC specimens were designed and manufactured,the process of force destruction and destruction patterns of RC column test pieces under the action of axis pressure were studied and analyzed.The data collected through experiments were used to analyze the load-displacement curve of the RC specimen,the load-strain curve of the steel bar and the axial bearing capacity,and to study the effects of RC specimens with different damage levels on their axial compression performance after reinforcement.The study found that With the increase of damage level,the steel bars of RC columns are in elastic,elastic-plastic and yield stages respectively.Three GSFRC test specimens were designed and manufactured,the process of force destruction and destruction patterns of the GSFRC test specimens under the action of axial pressure were studied and analyzed.Collected data through experiments,analyzed the load-displacement curve of the GSFRC test specimen,the load-strain curve of the GFRP pipe,the lateral deformation coefficient of the GFRP pipe,and the axial compression capacity,and studied the effects of reinforcement methods and GFRP pipe thickness on the axial compression performance of the GSFRC test specimen.The study found that the axial load-bearing capacity of the GSFRC test piece gradually increased with the increase of the thickness of the GFRP tube.Compared with the SFRC test piece,the axial load-bearing capacity of the GSFRC test piece was significantly improved,but its ductility was not as good as the SFRC test piece.One SFRC specimen and three GSSFRC specimens were designed and manufactured,the process of force destruction and destruction patterns of the GSSFRC specimens and SFRC specimen under the action of axial pressure were studied and analyzed.By collecting data through experiments,the load-displacement curves of GSSFRC specimens and SFRC specimens,the load-strain curve of steel fiber mortar,and the axial compression capacity were analyzed,and the influence of the degree of damage on the axial compression performance of GSSFRC specimens was studied.By comparing and analyzing the load-displacement curve and axial compression capacity of SFRC test specimens,GSFRC test specimens,and GSSFRC test specimens,the differences in axial compression performance of SFRC,GSFRC,and GSSFRC reinforced columns were studied.The study found that the axial load-bearing capacity of the GSSFRC specimen gradually decreased with the increase of the damage degree,and the axial load-bearing capacity of the GSFRC specimen increased the most,followed by the GSSFRC specimen,SFRC specimen is the smallest,and the ductile of GSSFRC specimen is the most,SFRC test piece is second,GSFRC test piece is the worst,showing brittle failure.Based on the existing domestic and foreign FRP pipe-constrained concrete strength calculation models and some FRP cloth-reinforced concrete models,the correlation coefficients were regression-fitted,and a method for calculating the axial bearing capacity of two types of composite reinforced columns,GSFRC and GSSFRC,was proposed.The theoretical calculation results are in good agreement with the actual experimental results.It can provide a reference for the engineering application of reinforced columns.