Suchergebnisse

Abstract. Tsunami fragility functions describe the probability of structural damage due to tsunami flow characteristics. Fragility functions developed from past
tsunami events (e.g., the 2004 Indian Ocean tsunami) are often applied directly,
without modification, to other areas at risk of tsunami for the purpose of
damage and loss estimations. Consequentially, estimates carry uncertainty
due to disparities in construction standards and coastal morphology between
the specific region for which the fragility functions were originally
derived and the region where they are being used. The main objective of
this study is to provide an alternative approach to assessing tsunami
damage, especially for buildings in regions where previously developed
fragility functions do not exist. A damage assessment model is proposed in
this study, where load-resistance analysis is performed for each building by evaluating hydrodynamic forces, buoyancies and debris impacts and comparing them to the resistance forces of each building. Numerical simulation was performed in this study to reproduce the 2011 Great East Japan tsunami in Ishinomaki, which is chosen as a study site. Flow depths and velocities were calculated for approximately 20 000 wooden buildings in Ishinomaki. Similarly, resistance forces (lateral and vertical) are estimated for each of these buildings. The buildings are then evaluated for their potential of collapsing. Results from this study reflect a higher accuracy in predicting building collapse when using the proposed load-resistance analysis, as compared to previously developed fragility functions in the same study area. Damage is also observed to have likely occurred before flow depth and velocity reach maximum values. With the above considerations, the proposed damage model might well be an alternative for building damage assessments in areas that have yet to be affected by modern tsunami events.

Abstract. Modern tsunami events have highlighted the vulnerability of port structures to these high-impact but infrequent occurrences. However, port planning rarely includes adaptation measures to address tsunami hazards. The 2011 Tohoku tsunami presented us with an opportunity to characterise the
vulnerability of port industries to tsunami impacts. Here, we provide a
spatial assessment and photographic interpretation of freely available data
sources. Approximately 5000 port structures were assessed for damage and
stored in a database. Using the newly developed damage database, tsunami
damage is quantified statistically for the first time, through the development of damage fragility functions for eight common port industries.
In contrast to tsunami damage fragility functions produced for buildings
from an existing damage database, our fragility functions showed higher
prediction accuracies (up to 75 % accuracy). Pre-tsunami earthquake damage was also assessed in this study and was found to influence overall damage assessment. The damage database and fragility functions for port industries can inform structural improvements and mitigation plans for ports against future events.