GANZORIG TUVSHINZAYA

CFRP repair of steel girders with corrosion damage near the splicing plate

Takeshi MIYASHITA

The carbon fiber (CFRP) bonding method, which has features such as light weight, high strength, high elasticity, and high corrosion resistance, is attracting attention for corrosion damage to steel structures. However, there have only few cases where CFRP repair was performed for steel girder 　with corrosion damage near the splicing plate. Therefore, the Steel Structure Laboratory has been conducting research since H29 with the aim of acquiring basic data for this purpose. Through the research of H29, we can change the design and construction manual for CFRP repair. Furthermore, in the research that conducted in R1, in order to apply this change to the actual structure, a steel girder had been used and 4-point bending loading test was performed.
According to the experiment in R1, it was found that in order to establish a CFRP repair method, for example, it is necessary to understand the relationship between the amount of corrosion damage and the residual load bearing capacity. We investigated the CFRP repair of damaged steel girders.
In this study, parametric analysis was performed by DIANA analysis software and analysis parameters was the width and depth of the counterbore that simulates corrosion damage near the splicing plate. However, the analysis did not consider the effects of initial irregularities, and model the bolts of the spliced plate.
As a result of parametric analysis, it was confirmed as follows. First, from the results of the relationship between the load and the central buckling displacement, the plate thickness reduction amount and the residual load bearing capacity, the Mises stress contour diagram, the cases which the plate thickness reduction amount is lower than about 50% was found that the counterbore part was deformed by local buckling, and the bending load bearing capacity was significantly reduced accordingly. Therefore, when the amount of plate thickness reduction was about 50% of the base metal, the maximum load was reduced by about 94%. As a result, if the yield load of the steel girder was reduced to 94%, it was considered that repair would be necessary. Then, in order to improve the accuracy of parametric analysis, it was considered necessary to consider the effects of initial irregularities and bolts.