Study On Mechanical Properties Of Large Eccentric Columns Strengthened By TRC In Dry-wet Cycle Of Chloride Salt

Reinforced concrete columns located in the tidal zone of sea water are eroded alternately by chloride salts.This harsh environment can easily lead to corrosion of steel bars and deterioration of concrete.The durability of RC columns decreases continuously.It is necessary to repair and reinforce them to ensure their good service condition.Textile Reinforced Concrete(TRC)has the advantages of strong corrosion resistance,high specific strength and good crack control effect.In recent years,many scholars have studied the use of this new composite material to repair and reinforce RC members.As an important bearing component of structure,the bearing capacity of RC column in practical engineering application mainly depends on the interaction of bending moment and axial force.In this paper,the mechanical properties of large eccentric columns strengthened by TRC under chloride salt dry-wet cycling are studied.The effects of the number of reinforcement layers,reinforcement methods,eccentricity,volume fraction of short-cut fibers,chloride salt dry-wet cycling times and pre-loaded stress level on the mechanical properties of reinforced columns are considered.The specific research contents are as follows:(1)The bearing capacity of specimens increases with the increase of TRC reinforcement layers,but the relationship between them is not linear.Compared with TRC longitudinal reinforcement method,the reinforcement effect of transverse reinforcement on large eccentric compressive short columns is not ideal.The development mode of transverse cracks on the concrete surface of tension side will be improved by adding short-cut fibers into TRC matrix,and the bearing capacity of specimens will also increase.(2)It is found that the larger the eccentricity of load,the more obvious the bearing capacity of TRC strengthened columns is.Compared with the unreinforced specimens,the ductility of the specimens decreases,which reduces the effect of longitudinal bending on RC columns with larger slenderness,improves the performance of large eccentric columns in the normal service stage,and damages the microstructure of TRC with the increase of chloride salt dry-wet cycle times,thereby weakening the reinforcement effect of TRC.(3)Under the coupling action of Chloride Erosion and load,the mechanical properties of TRC strengthened specimens deteriorated with the increase of the load stress level.Rehabilitation and reinforcement in practical engineering can eliminate the adverse effects caused by the previous stress history by unloading.(4)By analyzing the load-bearing mechanism of TRC reinforced large eccentric columns and considering the damage caused by chloride corrosion environment to TRC,a formula for calculating the normal section load-bearing capacity of TRC reinforced large eccentric columns is proposed.The error between experimental results and theoretical values is small,which verifies the accuracy of the calculation model.