Modelling for seismic analysis of an existing segmental cantilever bridge

Many segmental bridges were constructed in Europe during the 1970s using the Dywidag bars prestressing technique. These bridges were built through the balanced method of hammer elements using caissons section with variable dimensions and span lengths generally ranging between 70 and 100m. In Italy, some of these types of bridges are in high seismic hazard area but were designed according to outdated codes considering a significantly lower seismic demand. The numerical model is particularly complex especially regarding the restraints: if the end span is connected to a column vertical bilateral restraints were used instead of simple bearings. Furthermore, the restraints were realized to accommodate small horizontal displacements to mitigate the temperature effect and avoiding high displacements induced by seismic actions. These solutions are difficult to be considered in linear models due to the nonlinear response of the bearings. In this paper the seismic behaviour of a typical cantilever segmental bridge is analysed through a FE model discussing the effect of the nonlinear behaviour of the bearings that is not always negligible.