Seismic isolation of composite bridge with skewed deck

The seismic vulnerability of road bridges is currently a key issue in Italy due to the wide existing heritage of bridges designed according to not seismic rules or located in areas where an enhancement of hazard has been applied in the last decades. Surely the seismic upgrading by the substitution of bearings with seismic isolators is a resolute intervention that can solve further problems as the stresses due to the skewness of the decks. In fact sometimes the skewed bridge is the only alternative for viaduct that across the roadway not along the orthogonal direction, but skewness angles higher than 20° gives undesirable effects both for vertical loads and seismic actions. In this study, a steel-concrete composite bridge with skewed decks is analyzed to design the seismic upgrading introducing seismic isolation. The positive effect of the isolators also on the bridge response under gravitational loads is discussed evidencing the benefit through the high reduction of the bearings reaction due to the skewness that means the reduction of stresses on the piers.