Comments on bridge girder seating length under current design regulations

This paper investigates the adequacy of the required seating length of bridge girders in the current Japanese bridge design code under strong earthquakes. The seating length was developed without considering the effect of soil-structure interaction (SSI). In this study, spatially varying earthquake ground motion time histories are simulated corresponding to the Japanese design spectrum, and any two of them are compatible with an empirical coherency loss function. Two bridge structures on half space are considered The study reveals that although the Japanese design specification is currently the most advanced and strictest regulation and implicitly includes the effect of spatial variation of ground motions, the required seating length may still not be adequate, especially when the neighbouring bridge structure is flexible and when both structures experience different SSI.