| China is a country prone to earthquakes.In the process of post-disaster reconstruction,the demolishing of all the earthquake damaged structures will cause huge economic and resource consumption,which will seriously affect the recovery speed of production and living.Some old structures in service can no longer meet the requirements of the current seismic code,and there are deterioration of material properties such as steel corrosion.Therefore,the safety of such structures in the emergency stage and the repair ability in the recovery stage are worthy of further study.In order to provide a theoretical basis for the treatment and decision-making of damaged buildings after earthquake,the residual seismic performance of damaged RC members and frame structures was studied in this paper.The main work contents and results are as follows:（1）118 hysteretic test results of RC columns were selected from the Pacific Earthquake Engineering Center database,and the models for the strength degradation coefficient,stiffness degradation coefficient and residual deformation coefficient of damaged members corresponding to the normalized rotation angle were then proposed.Furthermore,considering the residual deformation,a method to determine the tri-linear restoring force skeleton curve of the plastic hinge of the earthquake damaged RC members was proposed.Based on the Open Sees simulation platform,the concentrated plastic hinge models of damaged RC beam and column specimens were established,respectively.The simulation results were in good agreement with the existing experimental results,which verified the effectiveness and applicability of the proposed restoring force model and modeling method.（2）The combining effects of steel corrosion and earthquake on the seismic performance of RC columns during service period was investigated.The two effects were assumed independent,the restorative force skeleton curve of concentrated plastic hinges was modified twice,and the RC column model with different axial compression ratios was established.The finite element results showed that the maximum bearing capacity of RC columns subjected to earthquake damage after 40 ～50 years of service in general atmosphere increased by 2.59%～6.15%,compared with the RC columns without considering the deterioration of materials.With the same corrosion amount,the greater the axial compression ratio,the greater the ductility coefficient and average energy dissipation coefficient decrease.（3）Taking the six-story three-span RC frame as the research object,seismic vulnerability analysis and performance redundancy analysis were carried out on a intact frames and the five earthquake damaged frames.The results showed that the degradation of stiffness,bearing capacity and deformation capacity of RC frame structure increases with the increase of damage degree,and the degradation rate of seismic performance was obviously accelerated when the structure damage degree transformed from moderate to severe.（4）Collapse Margin Ratio（CMR） and Seismic Performance Index（SPI）were selected to quantify the residual rate of seismic performance of RC frame after earthquake.The variation trend of the residual rate determined by the two methods is consistent.However,the calculation results based on SPI were lower.In the vulnerability analysis,the capacity limit used is essentially an index to measure the sound structure.When determining SPI,it is directly based on the capacity spectrum of the damaged structure,so the evaluation of seismic performance residual rate is more conservative and the calculation is simple.Considering corrosion,the residual rate of seismic capacity of X-D3 frame with moderate damage is 0.77,which is 8.0%lower than that of D-3 with the same seismic damage degree.This indicates that the influence of steel corrosion cannot be ignored when evaluating the seismic capacity of the existing damaged structure. |
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