Reliability of Bridges under Seismic and Tsunami Hazards

Abstract

In the Tohoku-region, where the effects of the seismic shocks and the tsunami waves due to 2011 Great East Japan earthquake were felt with very high intensity, many structures and infrastructures were severely damaged or washed away. Because tsunami effects have not been taken into consideration in the seismic design and retrofit specifications in Japan, code provisions regarding tsunamis need to be established based on the failure mechanisms observed in the tsunami-induced damage to bridges. In this paper, using both analytical fragility curves and tsunami hazard curves, the basic procedure to estimate the failure probability associated with tsunami hazard is presented. The tsunami fragility of a concrete girder bridge is estimated based on Monte Carlo Simulation (MCS). Seismic reliability of bridge is compared with tsunami reliability of the same bridge. The need to consider the tsunami effect in the design of concrete girder bridge is discussed in an illustrative example.