Study On Performance-based Seismic Capacity Of Corroded RC Frame

Reinforced concrete (RC) frame structure is widely used in the world for itsadaptive plane, good mechanical performance and high economic benefits. With timepassing by, the problem of durability of RC frame becomes more prominent. The steelcorrosion is one of the most influential factors that affect the durability, which hasbecome a focus research subject. It not only decreases the section of steel but alsodegenerates the mechanical property, and deteriorates the property of components andstructure, harming the reliability of structure.In this dissertation, the influence of corrosion on the capacity, stiffness, thedeformation ability, ductility and hysteretic energy-dissipated capacity were studiedaccording to the arrangement and analysis of some test results of corroded RC framecolumns, and a decay model of seismic performance index system of the RC frames wasestablished. The results showed that with corrosion enhancing, the bearing capacitydecreases, the stiffness degradation aggravates, the ductility becomes worse, and theenergy-dissipated capacity decreases. The research results can provide a reference to theassessment of the time-dependent seismic reliability of existing RC frames and supportthe perfecting of related codes theoretically.The settlement of restoring force model is an important premise for dynamicanalysis. Due to the restoring force model of corroded RC structure is obviouslydifferent from optimum structure, and it is necessary to establish the restoring forcemodel for corroded structure. After concluding and analyzing the advantages and shortcomings of some existed models, a skeleton curve of restoring force model withdescent segment was built. Considering strength and stiffness degradation based on theprinciple of energy dissipation, the method to calculate feature points on the skeletoncurve and degradation index value was given. After ensuring the hysteretic rules,restoring force model of corroded RC frame columns was established. The verificationof some test results showed that this model could describe the hysteretic characteristicsof corroded RC frame columns well. The research results can provide a reference to theseismic damage assessment.For research of the seismic performance of corroded RC frames, this paper madeseismic response analysis for different corrosion ratio RC frame structures with differentseismic wave, and then compared the deformation under frequent and rare earthquake,respectively. The results showed that corrosion caused greater impact to elastic-plasticdeformation under rare earthquake than elastic deformation under frequent earthquake.The max interlayer deformation would exceed the limit in the codes with theaggravation of corrosion, leading a higher probability of collapse. The research resultscan provide theoretical basis and suggestion for the assessment of the seismicperformance of corroded frames.