Seismic risk-based design of simply-supported bridges in Italy

Current design codes are mostly based on a force-based seismic design approach, which accounts for the inelastic capacity of structures by means of a reduction coefficient, i.e. behavior factor. In recent years, there has been a growing interest in assessing the safety margin of code-compliant structures. By overcoming the constraints linked to computational efforts, structural reliability analysis has started to be diffused beyond academia and into practical engineering applications. Consequently, recent studies assessed the level of structural safety implicitly achievable by following design codes and pointed out how current code provisions lead to a non-uniform safety level. For the abovementioned reasons, the present contribution assesses the seismic structural safety of newly-designed bridges in Italy. This is done by quantifying the failure probability via the solution of the direct reliability problem, which corresponds to the evaluation of the probability of exceeding one (or more) limit state(s) of interest during the bridge’s design life. The work proposes a methodology for the risk-targeted design of bridges, considering as a reference different configurations of simply-supported bridges with circular single-column piers.