Seismic Resilience Assessment And Maintenance Methods Of RC Frame Structures Under Salt Erosion

In recent years,researchers have been concerned with the seismic resilience of structures under salt-erosion environments.As an important part of the resilience assessment,loss estimation,particularly considering the structural loss caused by salt erosion,become a research hotspot.There is little resilience research on the impact of salt-erosion environments at the present stage.The methods underestimate the direct loss caused by the long-term erosion of chlorine salt on a structure.Furthermore,most of these methods ignore the indirect loss caused by the combined influence of chlorine salt and earthquakes,which results in an incomplete loss estimation and an overly high evaluation of a structural resilience.Therefore,this paper introduces the erosion effect of chlorine salt on structure into the assessment of structural resilience after earthquake,and discusses the loss caused by the cumulative effect of chloride erosion and earthquakes on deteriorating RC structures.The research results can provide a theoretical reference for the assessment of the resilience of RC structures under salt erosion.Based on the loss estimation of RC frame structure under salt erosion,this study aims to establish the seismic resilience assessment and maintenance method of RC structure under salt erosion.The main research contents are as follows:（1）The present study considered the reinforcement corrosion increasing with the service time of the structure,and established a reinforcement damage function based on the loss of corroded sections by defining the replacement cost of the degraded structure and combining it with quantitative analysis.Furthermore,a post-earthquake loss estimation function of a structure under salt erosion was established by considering the cumulative effect of chlorine salt erosion and earthquakes.According to the degree of structural damage and the duration of the impact after an earthquake,a sigmoidal function was used to simulate the structural recovery path.Finally,the assessment system for an RC structure resilience under salt erosion was obtained with a timevarying function.（2）In order to verify the above established the applicability of resilience assessment system,this paper designed a three-story RC structure example model.The fragility analysis of RC frame structure calculation model based on the incremental dynamic analysis method in the Opensees software,and obtained structural loss rate.Finally,the resilience of the structure under salt erosion was analyzed.The results demonstrate the feasibility of the proposed method for resilience assessment of degraded structures under salt erosion.（3）In order to maximize the resilience and minimize the total maintenance cost as the goal,the dual-objective maintenance method was established.Pareto optimization analysis is performed on the RC frame structure with MATLAB software.According to the calculation results,the effectiveness and practicability of dual-objective maintenance method based on recoverability and total maintenance cost are further discussed.