Performance Analysis And Evaluation Of Corrosion-damaged Grid Structure

With the progress of the times,people’s demand for buildings is growing day by day,and space steel structure has become the preferred structural form for large public buildings and industrial buildings.There are many types,from grid frames,grid shells to cable membranes,are common structural forms,but due to the complexity of the spatial grid structure,it is vulnerable to the influence of the external environment when serving,especially the impact of rust damage,and rust will accumulate with the increase of service time,seriously affecting the normal working performance of the structure,and may even endanger the durability and safety of the structure.Therefore,in practical engineering applications,effective measures must be taken to prevent the occurrence of such damage to ensure the safety and reliability of the structure.Therefore,it is particularly important to study the components and structures of rusted spatial grid structures.The most reliable way to study rust is through testing,but the surface morphology distribution of rusted steel and structural rust working conditions are random,the test results are discrete,compared with the test method,finite element analysis has the advantage of time and cost,and can more accurately control material parameters,boundary conditions and loading methods and other factors,so as to better simulate the actual engineering situation.Therefore,with the help of the finite element method,ANSYS finite element software is used to study the working performance of the steel components and structures of the rust space grid,and the appropriate verification and correction are made when the model is established to ensure the accuracy and reliability of the settlement results,and the working performance of the rust structure with different rust degrees and rust conditions is obtained through analysis.This thesis studies the working performance analysis of the research object after rust in the atmospheric corrosion environment during service from two different perspectives: steel components and space grid structure,and the main work content is as follows:(1)Taking the most common round steel pipe components in the spatial grid structure as the research object,through ANSYS finite element software,the finite element model of the axial compression member of the round steel pipe was established and the rationality of the model was verified by considering the double nonlinearity of the steel,and the corrosion working conditions of two different types of rust were set uniformly rusted and random pitting,and the volume ratio before and after rust was used as the rust rate to study the influence of rust type and rust degree on the ultimate bearing performance of round steel pipe components.(2)Based on the existing atmospheric corrosion model and mechanical degradation law of steel,the time-varying atmospheric corrosion model of steel is determined by considering the effect of the life period of anti-corrosion coating on the surface of steel.Through the nonlinear whole-process analysis method,the loaddisplacement curve of the grid structure is drawn,the ultimate bearing capacity change law of the rust grid structure is studied,the easy rust position of the structure in the actual project is summarized,three different rust conditions are set,and the change law of the ultimate bearing capacity of the grid structure is studied at different rust locations and different rust degrees.(3)The nonlinear dynamic time-history analysis of the structure is carried out,and the incremental dynamic analysis and seismic vulnerability analysis are used to evaluate the damage of the rusted structure under the action of earthquakes,and the level of seismic damage state and quantitative behavior limit are divided.With the peak seismic acceleration as the seismic demand parameter and the maximum node displacement response as the seismic capability index of the structure,different damage grades of the structure under earthquake action are determined and the limit values are quantified,and the seismic vulnerability of the structure is further analyzed and the time-history analysis results of different rust degrees are compared.The damage state of the grid structure under the action of earthquake will change with the increase of rust degree,which in turn increases the possibility of structural failure.By comparing the structural vulnerability curves of different ages,it is found that with the increase of structural rust degree,the ground motion strength that the structure can withstand gradually decreases,and the seismic displacement response is enhanced under the same seismic intensity,and the change of the vulnerability curve gradually increases,that is,the probability of structural failure is increasing.Therefore,in the design and construction process of the grid structure,it is necessary to fully consider the anti-corrosion measures and periodic repair and maintenance of the structure,eliminate potential safety hazards in time,and improve the durability and seismic performance of the structure.