Kouhei SAKURAI

Study on buckling strength of assembled compression members with corrosion defects

Eiji IWASAKI

Currently, the aging of existing infrastructure is a problem. Many structures have been constructed in a short period of time from 1955 to 1973. About 50 years have passed since then, and the ones built during this period have reached the end of their lives one after another. This is no exception to steel bridges．The number of bridges to be repaired or replaced is increasing. About 60% of the reasons for the replacement of steel bridges are corrosion of steel materials.
In assembled compression members, there are many corrosion defects of lattice material. However, the danger of the entire member due to corrosion defects in the lattice material has not been clarified. Therefore, in this study, I conducted a study on the buckling resistance of the entire member due to corrosion defects in the lattice material of assembled compression members.
In this study, assembled compression members of two-sided plate and two-sided lattice material used in Chosei Bridge is targeted. First, the target member is modeled and the buckling strength is calculated by linear buckling analysis. From this, the buckling resistance of each member in a healthy state is obtained. Next, in order to investigate the effects of corrosion defects, a model for corrosion defects is created and linear buckling analysis is performed. Based on this result, nonlinear elasto-plastic finite displacement is performed on the members affected by corrosion defects, and the degree of decrease in buckling strength is compared. Six patterns of corrosion defects in lattice materials were assumed for the analysis.
The findings obtained from this paper are shown below. Based on the results of the linear buckling analysis, elasto-plastic finite displacement was performed on the D2 member. The results are shown below. The buckling resistance decreased when the corrosion-deficient members were concentrated. In addition, elasto-plastic finite displacement analysis was performed assuming the corrosion defect positions at the center of the beam and the end of the beam. Comparing the results, the buckling resistance decreased significantly at the center of the beam.