Time-varying Seismic Recoverability Analysis Of RC Framework In Chloride Ion Environment

In recent years,the concept of structural resilience has received extensive attention.The introduction of seismic resilience theory into building structures can provide a new design theory and approach for the seismic design of structures.Therefore,researchers have started to focus on this.the study.In this paper,a reinforced concrete（RC）frame structure is taken as an example to study the recoverability of this type of frame structure that has been corroded by chloride ions.Reinforcing steel will corrode under the erosion of chloride ions,which will cause more serious damage to the structure than expected under the action of extreme events such as earthquakes,resulting in huge economic losses and greater social impact.Therefore,it is particularly important to consider the effect of steel corrosion when performing seismic recovery analysis of RC frame structures with different service ages in a chloride ion corroded environment.However,the commonly used recoverability analysis methods do not take this phenomenon into consideration.Therefore,the degradation degree of RC frame structure under chloride ion erosion is underestimated,so that the vulnerability of the structure is underestimated,which leads to the seismic potential of the RC frame structure.The recovery analysis and evaluation are too high,which has a certain impact on the decision-makers to formulate response disaster mitigation strategies.In view of this,this article considers the influence of steel corrosion on the seismic resilience of the structure.Through the improvement of the damage function of the RC frame structure of different service ages,the seismic resilience of the RC frame structure of different service ages under the chloride ion erosion environment is studied.The research content is as follows:（1）Discuss and analyze the principle of corrosion of steel bars by chloride ions and related basic theories.Using Fick’s second law,the functional relationship of chloride ion on steel corrosion is obtained through principle conversion based on the time-varying characteristics of corrosion current.Then,a comprehensive study of the mechanical properties of the corroded steel bars was carried out,and the law and expression of the damage and deterioration properties of the corroded steel bars with the erosion time were obtained.（2）Based on the changes in the mechanical properties of corroded steel bars in the research content（1）,the damage index of the frame structure is linked to the residual seismic capacity corresponding to the peak ground acceleration from the initial damage limit state to the collapse limit state of the structure,and the corroded reinforced concrete frame is established Structural damage index,on this basis,through comprehensive consideration of structural loss function,recovery function and recovery time,finally establishes a time-varying seismic recovery analysis method for corroded reinforced concrete structures.（3）In this paper,the numerical model of RC frame structure is constructed by using OPENSEES finite element software.The comprehensive loss results of RC frame structure are analyzed and analyzed.The time-varying vulnerability of the frame structure is analyzed.Based on this,the corresponding analysis and discussion of its function index and function recovery process are carried out to verify the feasibility of the seismic time-varying recoverability of the structure built in this paper.