Research On Seismic Behavior Of RC Column Strengthened With Self Compact Concrete Filled Steel Jacket

At present,China’s construction industry is developing rapidly,which is accompanied by the demolition and reconstruction of a large number of old buildings.At the same time,China is in the Pacific Rim earthquake zone and the Eurasian earthquake zone.Buildings are affected by earthquakes all year round,and old buildings are designed during construction.With low construction standards and construction defects,direct demolition and reconstruction will cause a lot of waste of resources and environmental pollution,which is inconsistent with the current green economy and the trend of green development.At this time,reconstruction and reinforcement technology came into being.The steel casing self-compacting concrete reinforcement technology studied in this paper is mainly aimed at columns,which are important vertical stress members in the building,specifically by drilling and planting reinforcement on the outer surface of the reinforced concrete column,and then sheathing the steel casing outside the reinforced concrete column The use of self-compact concrete to fill the gap between the steel casing and the reinforced concrete column has achieved the purpose of reinforcement and transformation.This paper mainly studies the seismic performance of this reinforcement method in order to provide a reference and theoretical basis for practical engineering projects.conclusion as below:(1)The low-cycle reciprocating test of 12 column test specimens(including 1 original reinforced concrete column test specimen and 11 steel casing reinforced column test specimens)has been completed.The main influencing factors considered are the axial compression ratio and the reinforcement Rate,defect rate,strength of reinforced concrete,and section form of reinforced steel casing.After the test was completed,the loading phenomena and failure modes of 12 specimens were obtained.At the same time,the test data were sorted out,and the hysteresis curve and skeleton curve of the specimen were analyzed to obtain the strength,stiffness,ductility,and energy consumption of the specimen.Seismic performance indicators.At the same time,combined with theoretical analysis and regression analysis,a simplified tri-fold line skeleton model and stiffness degradation law of steel tube reinforced column specimens were obtained to form a restoring force model.From the above results,it is shown that the steel casing self-compacting concrete reinforcement method can effectively reinforce the reinforced concrete columns,exert the role of the steel tube’s restraining hoop,and delay the development of internal concrete cracks.In addition,the steel casing self-compacting concrete reinforcement can also significantly improve The bearing capacity of reinforced concrete columns;the hysteresis curve of the reinforced column test piece is fuller than the reinforced concrete column test piece,and the equivalent viscous damping coefficient is also significantly increased,indicating that the reinforcement increases the energy dissipation capacity of the column;It is obvious that the lifting amplitude is obvious,and the ability of the column specimen to resist deformation is increased,and the degradation of stiffness and strength is relatively slow,indicating its good seismic performance;considering the degradation of stiffness,combined with the regression analysis method,the proposed restoration The force model can better reflect the hystereticperformance and stiffness degradation of the test piece,and can provide a reference for the elastoplastic analysis of the specimen.The energy consumption,bearing capacity and non-linearity of steel casing reinforced column specimens and concrete original column specimens under different seismic waves and the same seismic intensity were investigated.Based on the low-cycle reciprocating test,a simplified tri-fold line model of reinforced concrete,the original column test piece and the steel casing reinforced column test piece is obtained in this paper.It is input into SAP2000,and the connection method and loading mode consistent with the test are used to verify The correctness of the model established.Then,time-history analysis is performed,and a typical seismic wave input model on the first,second,and third sites is selected.It was found that the reinforced column specimens showed good energy dissipation and ductility under different seismic waves,and could resist large deformation.Under the same seismic intensity,the seismic performance of reinforced column specimens was better than that of the original concrete column specimens.