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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS002 Oral Presentation 1768
Forces on the structures in urban area due to tsunamis
Dr. Yoshinori Shigihara
Civil and Enviromental Engineering National Defense Academy
Koji Fujima, Charles Simamora
The Indian Ocean Tsunami of December 26, 2004 caused significant damage to coastal areas. The
tsunami created breaking waves run up the shoreline as surges, or bores. They inundated in urban
area, and broke down most kinds of structures such as residential houses, industrial plant and cargo
transporter. Since the best way to preserve the human life from the tsunami is that people run away to
a higher place as much as possible, a refuge building in coastal region may exert great effect for saving
life. In order to evacuate people safety in the buildings, structure of the building must hold against the
gigantic tsunami load. Therefore, estimation method of force against tsunami on the structures is
required. The objective of this study is to investigate tsunami forces on the structures in urban area. We
carry out laboratory experiments, analytical and numerical model are developed to simulate the
behavior of tsunami. Two dimensional wide wave tank (11m in length and 7m in width) used for the
experiment is 60cm depth with 1/3 slope connected to 5cm shelf region, the solitary wave is generated
from the wave generator. The structure models are installed on-shore, we measured total force against
tsunamis, pressure, time history of the water level in off-shore, time history of inundation depth and
vector of velocity in time on-shore. The maximum measured force related to distance from the shoreline
and that related to occupied rate of buildings are discussed. Also, to determine the tsunami force
quantitatively, we introduce relationships among tsunami forces, water level on-shore and current
velocity around the structures. Results of the laboratory experiments are simulated with Finite
Difference Method (FDM) and Finite Volume Method (FVM), and both model results are compared to
clarify which numerical models well simulate the tsunami force. In order to discuss the accuracy of
simulation model, suitable grid size, grid number and grid shape in numerical domain are investigated.
Keywords: tsunami, structure, tsunami force