Abstract
The purpose of this research is to investigate seismic performance for the large earthquakes and the effects of the concrete fill method as the retrofitting works of existing steel bridge frame piers with circular column. First, the design and the structural condition of their piers were surveyed. Next, pushover analyses and earthquake response analyses by using FEM were carried out on selected piers from the survey. As the results, although damage to some of their piers without retrofitting by concrete fill in the large earthquakes was serious, the damage was not significant with retrofitting by concrete fill. Moreover, it was found that the application of the method increased the response in the large earthquakes in case of the 2-story type of frame pier.
