| corrosion is the main factor affecting the durability of RC structures.The RC structure located in the coastal area is affected by the atmospheric environment of the coastal area.The chloride ion concentration is higher and the pitting corrosion of the steel bar is more serious.As a result,the structure often deteriorates before the design life is reached.In recent decades,domestic and foreign scholars have realized the influence of corrosion on the safety and durability of structures.Through experiments,numerical simulations,theoretical analysis and other methods,a lot of research has been done on the corrosion problems from materials to components to structures.However,due to the test method,the difference in thickness,length,and original constitutive relationship of the steel used in the test,the statistical results obtained are not uniform,especially the statistical results of the corroded steel ductility are very different.In this paper,the specific results are as follows:(1)Through literature research,this paper summarizes the physical characteristics of corroded steel bar,summarizes the area change rule of corroded steel bar cross section and its arrangement rule in space,and gives the random distribution function of the area change of corroded steel bar cross section and the calculation method of rust pit diameter.Based on this,based on the general finite element software MSC.MARC,through numerical simulation and monte carlo method,a method of mass modeling of pitting reinforcement is proposed.(2)Based on the numerical simulation method of corroded steel bars,the mechanical properties of corroded steel bars are analyzed by means of parametric analysis.First,the corroded steel bar with a diameter of 14 mm and a spacing length of 50 mm was simulated,and the decay law of the mechanical properties of the steel bar at various corrosion rates was obtained.The results were compared with the test results in the corresponding literature to verify the effectiveness and rationality of the modeling method and the mass calculation.Secondly,the influence of different constitutive relations,diameter and length on the ductility of corroded reinforcement is further tested by numerical simulation.The stronger the flexural ratio is,the slower the ductility decline is.The thinner the diameter,the weaker the ductility;The longer the length of reinforcement,the weaker the ductility.Finally,the ductility decline formulas of reinforcement proposed by different scholars are compared,and the differences are analyzed.It is proved that the numerical simulation method of corroded reinforcement proposed in this paper is applicable to the reinforcement with arbitrary diameter,length and original constitutive structure.The mechanical properties of steel bars at different corrosion rates can be obtained by this method,which is not only true and accurate,but also more general than the empirical formulas summarized by other scholars for specific steel bars.(3)Based on the reinforcement constitutions obtained by the pitting corrosion simulation method in this paper,the seismic behavior of corroded RC members is numerically simulated.A group of RC member tests with long-term corrosion of 26 years were selected.In the model,the numerical simulation method of pitting reinforcement in the paper and the empirical formula in the literature were used to calculate the constitutive structure of the reinforcement in the fiber beam,respectively.It was found that when the constitutive structure obtained by the simulation method in the paper was used,the simulation results of the seismic performance of the corroded beam were more accurate.The numerical simulation method for corroded steel bar presented in this paper has good practicability,especially for the calculation results of the ductility of steel bar.This method can be used to evaluate the seismic performance of rusted components effectively and provide a reference for the study of time-varying seismic performance of RC frame components in coastal areas. |
