Numerical Simulation Of Seismic Behavior For Square Concrete-filled Steel Tube With Localised Corrosion

Concrete filled steel tubular(CFST)structure is widely used in bridges,power transmission stations,airports and other fields due to its good mechanical behavior.The deterioration of natural environment(e.g.acid rain)or environment itself(e.g.sea water)cause different degrees of corrosion on the surface of CFST during service,which leads to the decline of the mechanical properties of CFST.In this paper,the mechanical properties of locally corroded CFST subjected to static and quasi-static loads were analyzed.The main work listed as follows:(1)The constitutive model,element type and interaction relationship of CFST under monotonic loads were selected to establish a finite element model of concrete filled steel tubular columns using ABAQUS software.The correctness of the finite element analysis method adopted in this paper is verified by comparing the calculated results with the results obtained from the literature tests.(2)The effect of different distribution of single corrosion pit and two corrosion pits on the axial compressive behavior for concrete filled steel tubular columns was discussed by the validated finite element model modeling method.The results indicate that the distribution of corrosion pits has an influence on the axial compressive bearing capacity of concrete filled steel tubular columns.(3)Four simplified local corrosion models(equivalent global material property reduction model,equivalent local material property reduction model,equivalent global wall thickness reduction model and equivalent local wall thickness reduction model)were used to compare with the local pitting corrosion model,and the simplified locally corroded model which is close to the local pitting corrosion model in mechanical properties and deformation was selected as a simplified model to analyze the seismic performance of localized corroded CFST columns.(4)Constitutive relations,element types and interaction relations which is suitable for low-cycle reciprocating loads were selected to calculate the seismic performance of CFST by ABAQUS finite element software.Comparing the calculated results with the experimental results in the literature to verify the correctness of the finite element analysis method used in this paper.(5)Non-linear finite element analysis of seismic behavior for locally corroded square concrete filled steel tubular columns was carried out by using finite element software ABAQUS,considering the different impact factors such as corrosion rate,axial compression ratio,steel strength,concrete strength,slenderness ratio and steel tube wall thickness.In addition,the key influencing factors for correlation parameter of P-Δ hysteretic model were pointed out by parameter sensitivity analysis.Then the relevant parameters of P-Δ hysteretic model were calculated by non-linear regression method and the corresponding simplified calculation methods were obtained.Results from the analysis of non-linear regression shown that the simplified formulas were in good agreement with the numerical simulation results.