Experimental Study On Confinment Performance Of Corroded Reinforced Concrete Columns Strengthened With TRC

In buildings,Bridges and other structures,reinforced concrete columns are not only the components that bear vertical loads,but also the most important components that resist lateral forces.In coastal or saline-alkali areas,reinforced concrete columns are easily eroded by chloride ions,resulting in different degrees of corrosion of internal steel bars.Steel corrosion will lead to the reduction of section area and tensile performance,especially the restraint performance of stirrup corrosion on concrete is reduced,so that the bearing capacity,lateral resistance and deformation capacity of concrete column are reduced,which is easy to damage under the action of earthquake,and then cause local damage or even whole collapse of the structure.In addition,after the reinforcement rusts in the reinforced concrete column,as a result of the corrosion expansion can cause the concrete protection layer to crack the destruction,further aggravates the outside corrosive medium invasion and the reinforcement corrosion degree.Therefore,it is necessary to study the effect of stirrup corrosion on the restraint performance of concrete and how to strengthen it effectively.Fabrics and fine aggregate Concrete(High performance mortar)of composite fabric Reinforced Concrete(Textile Reinforced Concrete,the TRC)is a new type of fiber Reinforced Concrete composite material,the material has thin wall,high strength and high crack and has the advantages of good corrosion resistance,especially suitable for the chlorine salt performance of Reinforced Concrete member bearing reinforcement corrosion environment,but at the moment about the TRC reinforcement corroded Reinforced Concrete member bearing performance of related research is less,especially used in the study of corroded Reinforced Concrete columns reinforcement.Therefore,it is necessary to study the restraint behavior of TRC reinforced concrete columns.Based on the national natural science fund "Fabric reinforced concrete template and mechanical properties of composite beam slab life cycle research(51478408)" and "History of circulating load bending shear failure seismic performance of RC column and earthquake damage mechanism research(51508154)",An experimental study on the restraint performance of TRC strengthened corroded reinforced concrete column was carried out.The main contents are as follows:(1)The axial compression test was carried out on 30 corroded reinforced concrete columns with different design parameters to study the influence of section size,corrosion rate,stirrup reinforcement ratio and different corrosion objects(including corrosion stirrups and joint corrosion of stirrups and longitudinal bars)on the restraint action of concrete columns.Using electrochemical corrosion of reinforced concrete column with different design parameters to accelerate the corrosion,and the different degree of corrosion of reinforced concrete column specimens with axial compression test,analysis of stirrup ratio,rust and corrosion rate of parameters such as column specimen failure pattern,axial compression bearing capacity,deformation,ductility and the influence of the load-deformation curve;Based on the test results,the relationship between the corrosion rate and the bearing capacity and ductility of reinforced concrete columns is presented,and a stress strain relation model of concrete with stirrup restraint considering the influence of corrosion degree is established.(2)Through to the group of 16 different fiber(calcium carbonate whisker or PVA fiber),the high performance of fine aggregate concrete(high performance cementbased materials)respectively for compressive strength,flexural and splitting tensile performance test and resistance to chloride ion permeability test,analysis of fiber types and dosage on the mechanical properties of concrete matrix and the influence of the chloride ion erosion resistance.Concrete specimens of compressive strength,flexural and splitting tensile test results show that the mixed with proper amount of calcium carbonate whisker fiber and PVA fiber is beneficial to improve the mechanical properties of substrate material,mixed 1.2% volume content of calcium carbonate whisker,PVA fiber dosage of 1.6% volume and mechanical properties of concrete matrix to improve the effect is relatively good,its compressive strength,flexural and splitting tensile strength than those not doped fiber contrast specimen increased by 14%,44% and 48% respectively.Different fiber reinforced fine aggregate concrete matrix electric flux test and determination of chloride ion penetration depth of the test results show that the mixed with proper amount of calcium carbonate whisker fiber and PVA fiber can effectively improve the chloride ion erosion resistance of matrix,and the double mixing 1.2% calcium carbonate whisker,1.6% PVA fiber resistance to chloride ion permeability of matrix,the best power value and its color depth of chloride ion doped fiber than contrast specimen decrease by 20.1% and 29.5% respectively,with good resistance to chloride ion permeability.(3)Using high-performance TRC composites of 16 groups of reinforcement of reinforced concrete columns with different corrosion degree,and the different TRC reinforced column axial compression performance test,the study of corrosion ratio and stirrup ratio and section size of TRC composites reinforcement corroded reinforced concrete column the influence of axial compression performance,and TRC reinforcement corroded reinforced concrete was developed based on the test results of stress-strain relation model.The results show that TRC reinforcement can effectively improve the low ductility failure characteristics of corroded reinforced concrete columns,and improve the bearing capacity and deformation capacity of corroded columns.The proposed stress-strain relationship model for TRC reinforcement of corroded reinforced concrete columns considers the double constraint of TRC reinforcement layer and corroded stirrups on core concrete,and the model calculation results are in good agreement with the test results,which can be used to describe the stress-strain relationship of TRC reinforcement of corroded reinforced concrete columns.