In this study, the differences of the three-dimensional seismic response behaviors of the steel I girder bridges that constructed in many cases were clarified. And, The design issues of the steel I girder bridges under the L2 earthquakes are summarized. Of comparing the result of the design with the result of the entire bridge dynamic analysis, it was confirmed that the L2 seismic responses of the members exceed the allowable design level for the L1 earthquakes. These exceeding responses are considered to be problems for the existing bridges, but, the damages of the bridge members are consistent with the damages of the steel I girder bridges caused by past large-scale earthquakes.
