Analysis Of Corrosion On Bearing Capacity Of CFST Arch Rib

Concrete filled steel tube arch bridge s have the advantages of short construction time,strong spanning a bilit y and good landscape.Most of them are built in mountainous areas,rivers and other areas with abundant water and gas.With the increase of service time,the steel tube will suffer from pitting corrosion,local corrosion and even full section corrosio n due to the influence of air moisture,salt and corrosive gases.Corrosion of steel pipe will reduce the effective bearing area of steel pipe,lead to the increase of steel pipe stress and the reduction of hoop effect.At present,the research on the corrosion of concrete-filled steel tube arch bridge is mainl y focused on the anti-corrosion measures,but the research on the residual bearing capacit y of concrete-filled steel tube arch bridge after corrosion was still in its infancy.For this reason,the inf luence of uniform corrosion on the bearing capacit y of concrete-filled steel tubular arch bridge s were studied in this paper.The main contents are as follows:(1)Aiming at the problem that the existing stress in steel tube and core concrete before corros ion can’t be considered b y traditional section reduction method and stiffness reduction method,a "composite element +multi-scale" modeling method was proposed to simulate steel pipe corrosion on arch rib section u nder stress.Example was given to verify the correctness of the method proposed in this paper.(2)Based on the displacement relationship between master and slave nodes,the element stiffness matrix of composite beam was derived,and the calculation program was compiled b y using the APDL languag e of general finite element software ANSYS,and the corrosion multi-scale models of single circular tube and dumbbell steel pipe arch ribs were established to realize the simulation of "stress corrosion" of arch ribs with two cross-sections.Experiment s had been carried out were used to verify the correctness of the program in this paper.On this basis,the bearing capacit y,failure mode and stress state of corroded single circular tube and dumbbell CFST arch rib were studied.(3)The influence of uniform corrosion on the bearing capacit y of single circular tube and dumbbell concrete filled steel tube arch rib was anal yzed,and the attenuation law of bearing capacit y of corroded arch rib under different arch axis coefficient,steel tube strength,concrete s trength grade,load form and steel ratio was studied.The results show that the bearing capacit y of the two cross-section forms of arch ribs ha ve the same variation law,but the bearing capacit y reduction rate of dumbbell arch ribs are smaller than that of single circular tube arch ribs.(4)According to the anal ysis results of single circular tube and dumbbell CFST arch steel tube,the maximum corrosion rate of arch ribs of two cross-section forms was given with the limit of 10% reduction of ultimate bearing capacit y.By using the method of regression anal ysis,the formulas for calculating the reduction rate of bearing capacit y of two kinds of concrete-filled steel tubular arch ribs under uniform corrosion were fitted.Based on the parameter anal ysis data,the naive Bayesian model was used to verify the reliabilit y of the maximum corrosion rate of single pipe arch ribs calculated b y the formula.