Influence Of Inhomogeneous Longitudinal Reinforcement Corrosion On Mechanical Performance Of RC Columns In The Marine Chloride Environment

The durability of reinforced concrete(RC)structure is attracting more and more attention around the world.The steel bar corrosion caused by chlorine ion is one of the main deterioration phenomena of RC structure in marine chloride environment.In the actual engineering,the corrosion state of steel bar in RC columns is different and even the inhomogeneous corrosion of steel bar may occur due to the complexity of the service environment of the structure.At present,the research on the mechanical performance of RC columns with inhomogeneous corrosion of steel bar is insufficient.Based on the above background,this paper conducts research on the mechanical performance of corroded RC columns through experimental investigation and numerical simulation and makes quantitative evaluation of loading capacity.In this study,13 columns are designed according to the experimental parameters.The steel bar corrsion is simulated by using electrochemical method and the mechanical performance of RC columns is investigated by loading test.In addition,the mechanical performance of corroded RC columns is also investigated by numerical simulation using finite-element-analysis software DIANA.Based on the results of experimental investigation and numerical simulation,this paper obtains some beneficial conclusions.1.The total crack width of corrosion induced by the expansion of corrosion product increases with the mass loss ratio of the steel bar.According to the test result,a quadratic regression formula between the total crack width and the mass loss ratio of corrosion steel bar is developed,which provides some basic research data for the establishment of damage-evaluation system for concrete structure.2.For the column with large eccentric compression,the cross-section reduction caused by the corrosion of tension steel bar reduces the nominal yield strength and directly causes the decline of loading capacity.The bonding degradation caused by corrosion may also causes the following consequences:1)the decrease of the flexural crack-induced load and the decrease of the number of crack;2)the damage of the working ability between steel bar and concrete and the reduction of the stiffness of the specimen;3)the deformation concentration of the specimen.3.For the column with large eccentric compression,the corrosion of compression steel bar reduces the ductility of the specimen,which may results in brittle fracture.4.For the column with small eccentric compression,the loading capacity of specimen is mainly affected by the corrosion of compression steel bar.The deformation concentration caused by tension steel bar corrosion and the damage of concrete caused by compression steel bar corrosion increase the area of crushing concrete and make destruction more severe.5.It is concluded that the column with the eccentric compression basically meets the plane section assumption in the case of moderate corrosion level.Therefore,the mechanical performance of the RC columns can be evaluated according to the conventional bending theory.6.By referring to the two-steps approach developed by Abul K.Azad and Mohammed a.a.1-osta,this paper makes quantitative evaluation of the loading capacity of corroded RC columns.Based on the experiment result,the reduction coefficient is obtained and the applicability is verified by relevant data.