| With the development of economy,a large number of long-span,high intensity and lightweight engineering structures are constantly emerged.Steel structures are widely used in various engineering fields,but the environmental conditions are more and more complex.Therefore,the safety performance of steel structures in harsh environments achieves more attention.Due to the corrosion,a lot of accidents of the steel structure have emerged in recent ten years.Therefore,the loss of mechanical properties caused by the corrosion becomes a focused issue in recent years.The forms of corrosion can be summarized into four types: uniform corrosion,pitting corrosion,groove corrosion and edge corrosion.Pitting is the most common and destructive corrosion in steel structures,because pitting is very dangerous,universal and undetectable.In recent years,with the deepening of the understanding in mechanism of pitting and benefit from the further refinement of the statistical analysis of the accidents,the degradation of the ultimate strength of the steel plate caused by pitting achieves more and more attention.Based on the simulation of random pitting,this paper focus on the influence of ultimate bearing capacity of plate and the stress and strain under different loading conditions with different pitting shapes caused by local corrosion region.The result shows:1.By improving the present cellular automata,a new model is designed to simulate the corrosion of steel plate under marine environment,and the process of initiation and development of pitting on the steel plate under different corrosion volumes is simulated.The result shows that the process of pitting can be described in detail in three-dimensional space by cellular automata,and the simulation result is reliable by comparing with the relevant literature.2.Testing the reliability of the solid element in the FEA of the corrosion model,the sensitivity of the grid density,the reliability of the biaxial compression program used in the entity unit,and ensure the accuracy and reliability of the simulation results.The result shows it is reliable and quick to explore the ultimate bearing capacity by using FEA model with solid element.3.The distribution characteristics of stress inside the pitting are obviously different under different load conditions.The distribution characteristics of stress between the pitting is greatly influenced by the relative position of the pitting under different load conditions.The smaller the distance of the pitting is,the more obvious the stress concentration between the pitting is.The distribution characteristics of stress inside the pitting and between the pitting is obviously affected by the depth of the pitting.4.Under uniaxial compression,the effects of the pitting shape,the relative distance and the depth of the pitting on the stress and strain distribution of the local corrosion region are studied on the basis of the single pitting plate,the multiple pitting plate and the random pitting plate,and the changes of the compression of the pitting plate under the condition of random pitting are analyzed.The results show that the difference of ultimate bearing capacity of corroded plates with different etching pits increases by the increase of corrosion volume.When the corrosion volume reaches 10%,the plastic strain distribution of the plates are obviously different.5.Under biaxial compression,the influence of the stress and strain distribution of the local corrosion region based on the size and position of the pitting is studied under the different corrosion conditions(single pitting,multiple pitting and random pitting),and the influence of the random pitting on the biaxial compression corrosion plate is analyzed based on conclusions.The result shows that the corroded plate has a low bearing capacity with conical pitting and the difference between ultimate bearing capacities of corroded plates in different pitting shapes reaches the maximum when the corrosion volume reaches 10%. |
