Experimental Research On Influence Factors Of Seismic Performance Of Reinforced Concrete Columns Strengthened With TRC Under Chloride Environment

Textile Reinforced Concrete(TRC)is a new type of composite material composed of textiles and fine-grain concrete.Because of its superior capacities of load-bearing,crack resistance,seepage resistance and corrosion resistance,TRC is increasingly valued by many scholars.At present,there are few researches about the influence factors of seismic performance of TRC reinforced columns and the effect of TRC reinforcement on the seismic performance of corroded RC columns in harsh environment.Therefore,in this paper,the influence factors of the seismic performance of TRC-reinforced columns in the chloride erosion environment are studied experimentally,and the seismic performance of TRC-reinforced corroded columns in the erosion environment is discussed.A total of 14 reinforced columns have been designed and manufactured,and the axial pressure ratio,shear ratio,stirrup ratio,and cross section form on the effect of TRC reinforcement were investigated.The steel bars were rusted by electrochemical method to study the influence of different initial rust levels on the seismic performance of reinforced columns.Finally,based on the experimental results,the restoring force model of columns reinforced with TRC under chlorine erosion environment was established.Specific results are summarized as follows:After the erosion of chloride dry-wet cycle,the yield load and peak load of the TRC-strengthened columns decreased slightly,but their yield displacement increased slightly,and the ductility was also similar.When the corrosion of the steel bars was low,the seismic performance of columns has been improved to a certain extent,and a certain degree of chloride erosion can improve the integrity of the TRC reinforcement layer and the concrete.For columns reinforced with TRC in the chloride erosion environment,the yield load and ultimate bearing capacity of the column improve with the axial compression ratio increases,but the ductility and deformation capacity deteriorate and the energy dissipation capacity decreases.The large-shear span has a slower rate of stiffness degradation,with the good ductility and seismic deformation resistance under the action of reciprocating loads.As the spacing between stirrups decreases,the ductility and deformability of the reinforced columns increase,and seismic performance improves.Compared with the square and rectangular columns reinforced with TRC,The circular column reinforced with TRC has earlier yield and lower bearing capacity,but it has superior ductility anddeformation ability,while the rectangular column reinforced with TRC has a faster rate of bearing capacity and stiffness degradation.For columns reinforced with TRC after steel corrosion,the seismic performance is related to the initial corrosion of the steel bars when subjected to chloride erosion again.With the increase of the initial corrosion of steel bars,the yield load and peak load of the columns both show a decreasing trend,and the ductility and energy dissipation capacity increase first and then decrease.TRC reinforcement can improve the column failure morphology,increase the yield load and ultimate bearing capacity significantly,and the columns reinforced with TRC have better ductility and seismic deformation resistance.In the case of severe steel corrosion,TRC can also play a restraining role and improve the normal serviceability of such components in earthquakes.Based on the restoring force model of intact reinforced concrete columns and experimental values,the calculation formula by considering the effects of axial compression ratio,shear span ratio and stirrup ratio can describe the restoring force model of columns reinforced with TRC under chlorine erosion environment,and the calculated results are in good agreement with the experimental results.