In recent years base isolation has become an increasingly applied structural design technique to protect bridges and buildings from severe earthquakes. Main goal of base isolation is to produce a substantial decoupling of the superstructure from the substructure resting on the shaking ground, minimizing the internal state of stress during an earthquake by increasing the period of the structure and by acting as energy dissipation device (Naiem & Kelly, 1999). This structural solution also has the benefit of giving better distribution of the seismic forces between the various elevation supports. In the specific field of bridges, base isolation techniques were initially confined to long structures, but in several countries – due to more severe seismic codes – base isolation has been recently applied also to small and medium-size bridges. In this paper, results of an experimental/analytical study focused on the dynamic behavior of a 75m long, reinforced concrete (RC), post-tensioned, based isolated bridge are discussed.
