Seismic bridge design according to Eurocode 8 and SIA 160

A case study of comparative seismic design of a reinforced concrete multi-span box girder bridge is presented. The bridge has a floating support system in the longitudinal direction. The seismic action effects are calculated by the equivalent lateral force method and by the multi- modal response spectrum analysis method. Three different design cases of the bridge are compared: "Limited ductility" and "Ductile behaviour" according to Eurocode 8, as well as "Nominal ductil- ity" according to Swiss Standard SIA 160. The study shows that the requirements of Eurocode 8 are more stringent than current Swiss Standards, causing a considerable increase in the seismic ac- tion. Even in zones of moderate seismicity, the seismic design situation according to Eurocode 8 will govern the dimensioning of bridge columns.