Risk assessment of bridge’s piers subjected to multiple earthquakes: comparison between different approaches .

Frequently, buildings or infrastructures are in regions prone to earthquake excitations. These structures are continuously exposed to earthquakes in the form of main shocks throughout their service life. Repeated shocks can cause reduction of structural capacity and may lead to collapse and, as consequence, to a devastating impact on urban context both for human losses and economic stability. Considering the prospect of future destructive events, risk assessment has to focus on probabilistic models which can use the limited available information to best predict future scenarios and consider the high uncertainty involved in the analysis. The present study proposes a comparison between three probabilistic approaches for the seismic risk estimation. In all three methods the probability of occurrence of seismic shocks and the effect induced on the structure are evaluated separately by applying total probability theorem. In the first one, conceived by Ghosh et al., the accumulation of damage is based on predictive regression models. Iervolino et al., describes the progressive structural degradation using a homogeneous Markov process in discrete time. The last methodology includes the seismic risk assessment through the classic frequentist approach. The results deriving from the mentioned above methods are reported, compared and finally discussed.