A simplified procedure to evaluate seismic vulnerability of R.C. circular bridge piers

In this paper a simplified procedure to evaluate the seismic vulnerability of R.C. circular piers of bridges with simply supported deck is presented. The methodology starts from the definition of the socalled capacity curve of the pier which take account of the following collapse modes: ultimate curvature, lapsplice failure of longitudinal bars, buckling of longitudinal bars, shear failure, unseating of the deck, second order effects. The vulnerability level of the pier is then evaluated by using a vulnerability index defined for this purpose. The proposed procedure is also able to obtained normalised curves useful to analyse the influence of a single parameter (e.g. transversal confinement, longitudinal bars, seismic mass, slenderness) on the vulnerability index in order to define the best structural intervention necessary to achieve the design seismic performance.