Studies On Load Carrying Mechanism Of Existing Rc Frames Including Corrosion Effects To Resist Progressive Collapse

There are a large number of experimental research and theoretical analysis on the progressive collapse resistance of new intact structure have been carried out by domestic and foreign scholars.However,with the increase of the use time of the components,durability problems are becoming more and more prominent.The corrosion of steel reinforcement is one of the main problems in the durability damage of the structure,and it has great influence on the building structure progressive collapse resistance.In view of less research on the progressive collapse resistance of the existing RC frame structures considering the corrosion of reinforced,this paper has carried out a series of high fidelity finite element analysis.Basing on the experimental study on the progressive collapse resistance of reinforced concrete structures under condition of failure medium column,the appropriate constitutive relation has been chosen and the commercial finite element software DIANA has been used to simulate the existing specimens.The result shows that the finite element model can simulate the development and failure mode of the fracture in the various stages during the Push-down loading process.Besides,the switch of beam mechanism,compressive arch effect,catenary action and membrane action of specimens are all consistent with the experimental results.According to existing data statistics and experimental analysis,this paper will take the specimens using time of every 10 years in 0?70 years as a variable,and consider some factors including that corrosion of reinforcement has weakened the strength,elongation and effective area,reduced the strength of concrete protection layer,the strength of core concrete,and the strength of concrete bond slip.Therefore this paper make research and discussion of the progressive collapse behavior of existing RC frames in different period.Based on the existing classical formula,the theoretical analysis model of the main resistance mechanism of the reinforced concrete structure with reinforced concrete structure is proposed.The results show that the yield load,the first peak load and the ultimate load decrease continuously with the increase of service cycle;the effect of compressive arch action,tensile catenary action,compressive membrane action and tensile membrane action decrease gradually with the increase of the use time of the specimens,or even quit the work.The theoretical calculation model and the finite element simulation result are in good contrast,and the error meets the engineering precision requirement,which can be used as the prediction tool for the anti-collapse bearing capacity of the active structure.