Load-resistance analysis: An alternative approach to tsunami damage assessment applied to the 2011 Great East Japan tsunami

Abstract

Abstract. Tsunami fragility functions describe the probability of structural damage to tsunami flow characteristics. Fragility functions developed from past tsunami events (e.g. 2004 Indian Ocean tsunami) are often applied directly, without modifications, 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 were 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 city, which is chosen as a study site. Flow depths and velocities were calculated for approximately 20 000 wooden buildings in Ishinomaki city. Similarly, resistance forces (lateral and vertical) are estimated for each of these buildings. The buildings are then evaluated for its potential to collapse. 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 which have yet to be affected by modern tsunami events.

Estimating Impacts of Tsunami on Buildings around Ambon Bay of Indonesia

“…Assessing impacts of future tsunami on buildings is a challenging topic as the research would need to combine between the hydrodynamic forces of tsunami and the vulnerability aspects of the buildings (6)(7)(8). Exact impacts of tsunami on buildings would be difficult to assess in an extensive area, such as in the case of Ambon.…”