Calculation And Simulation Analysis On Degradation Of Mechanical Behaviors Of Corroded Reinforced Concrete Pier Members

Reinforced Concrete(RC)structures are vulnerable to chloride ions corrosion in marine environment.The corrosion of reinforcement is the main reason for mechanical behaviors degradation of RC structures,which significantly reduces the service life of the structures.As the degradation of the mechanical behaviors of corroded RC structures becomes severe,the risk of failure of the structure increases,which may cause catastrophic consequences.In the marine environment,chloride ions are known as reinforcement corrosion killers.A large amount of chloride ions penetrate through the concrete and accumulate to the surface of the reinforcement,and finally destroy the passivation film of the reinforcement and accelerate the corrosion of the reinforcement.Reinforcement corrosion in concrete structures may lead to reduction of the effective cross-sectional area and degradation of the mechanical behaviors of reinforcement,cracking and spalling of the concrete cover,degradation of the mechanical behaviors of confined concrete by stirrups,and loss of bonding between reinforcement and concrete,etc.These phenomena eventually result in degraded loading-carrying performance of corroded RC structures.Therefore,it is necessary to study the effect of reinforcement corrosion on the mechanical behaviors degradation of concrete structures.In this paper,the theoretical study about the mechanical behaviors degradation of the confined concrete by corroded stirrups and the finite element analysis about the mechanical behaviors degradation of the partially corroded RC piers are carried out respectively,and also compared with the existing experimental results.The study of mechanical behaviors of axial compression confined concrete is particularly important and is the basis of the theoretical analysis of RC structures.For the RC structure in the marine environment,reinforcements are usually corroded,and the corrosion of the stirrups will lead to the degradation of the mechanical behaviors of the confined concrete.For the corroded RC member in the earthquake-prone area,the degradation of the mechanical behaviors of the confined concrete will obviously reduce the seismic performance of the RC structure.In this paper,the stress-strain relationship model of confined concrete by corroded stirrups is studied firstly based on the Mander model,the effect of stirrups corrosion is considered.The theoretical formulas for calculating the axial compressive strength and the strain value corresponding to maximum stress of the confined concrete by stirrups are given respectively,which consider the coupling effects of different stirrups corrosion levels and concrete strengths.The stress-strain relationship model of confined concrete by corroded stirrups is proposed,which provides the basis for theoretical analysis and research of corroded RC structures.Finally,the theoretical calculation model of ultimate bearing capacity of corroded stirrups confined concrete short column is given.A comparative analysis of theoretical and experimental results shows that the proposed model can be used to evaluate the degradation of the mechanical behaviors of the confined concrete by corroded stirrups.With the improvement of computer performance and the development of RC structure research,finite element analysis software has gradually become an effective tool to study the performance of RC structure,and has been widely accepted and applied by most researchers.In this paper,the nonlinear finite element analysis of partially corroded RC pier members is firstly performed using ABAQUS software on the basis of experiments.Corrosion damage of reinforcement and cover concrete materials and loss of bonding between corroded reinforcement and concrete are considered in the pier finite element model,the four-node bond slip element is also introduced to simulate the bond-slip between corroded reinforcement and concrete.Meanwhile,the partially corroded RC pier finite element models are loaded with six models per group for axial compression and cyclic loading,respectively.Finite element analysis results are compared and validated by experimental results,and they are in good agreement,which indicates that the mechanical behaviors degradation of corroded RC piers can be well simulated using ABAQUS finite element software as well as the setting of relevant parameters,the selection of material relations,and the consideration of corrosion damage in the model.