Research Trends and Results

The design examples of wooden building to beconstructed in the region where tsunami attack may
occur
TSUCHIMOTO, Takahiro (DAg): HeadEvaluation System Division, Research Center for Land and Construction Management(Keywords): depth of water coefficient, tsunami refuge building, inundation height, wave pressure distribution, tsunami
prevention regional construction, displacement, buoyancy, topple down
1. Background of deliberation
Great many wooden buildings suffered damage by thetsunami triggered by the 2011 Great East Japan
Earthquakes. The results of comparison made with its
actual damage situation(1) and external force and proof
stress of wooden buildings which were worked out fromthe tsunami refuge building guideline does not agree eachother(2). So an appropriate depth of water coefficientmeeting the damage situation was calculated whichsuggested the possibility to set in between 1.0 and 1.5(3) .
On the other hand, in the regions where they havesuffered devastating damages by the tsunami, majorities
are drawing up their reconstruction plan to move houses
to the high ground, but there still is a large number ofpeople who would prefer to live in a place where they canview the seashore. Meanwhile, for the regions where
they are likely to be hit by the tsunami triggered by thepredicted Tokai-Tonankai earthquake, the proactive
program would become necessary.
And so, the deliberation of drawing design methods
regarding the wooden buildings and wooden tsunami
refuge buildings to be constructed within the regions ofpossible tsunami attack.
2. Calculation of the external force
Wave pressure and wave power of tsunami wascalculated based on the wave pressure distribution whichis the product of depth of water coefficient andhydrostatic pressure set in the tsunami refuge building
guideline(4). For the depth of water coefficient, figure 1.5
was used which was drawn from the Notification of theMinistry of Land, Infrastructure, Transport and Tourism
2011, No. 1318, based on the Act regarding tsunami
prevention regional construction, in which it is applied tothe locations where reduction of wave pressure blockedby other facilities is expected and at the same time morethan 500 meters away from the seashore and rivers.
Openings of the building are presumed be damaged, andbuoyancy resulting from dead air space between theceiling height of the floor lower than inundation heightand inundation height whichever is lower and the bottom
end of the partition wall was also considered. The fixedload of the building is reduced by specific gravity ofwater and the movable load was not included in theweight of the building because they would be washedaway. Other issues like consideration of pressure-resistantmaterials and floating wreckage, were made inaccordance with the tsunami refuge building guideline(5).
3. Verification of wooden building proof stress
With regard to the horizontal load which affects to theparts of the wooden building, shear proof stress of thebuilding frame, tension proof stress of joint parts andshear proof stress of anchor bolts were verified.
The ultimate shear proof stress of the wooden building
was calculated using the figure 1.5 times of allowable
proof stress.
Also toppling down and sliding of the whole building
against horizontal load were verified. Furthermore,tension proof stress of joint parts and anchor bolts against
buoyancy were verified. See document (5) for moredetail.
4. Design examples
Followings illustrate the outlines of design examples.
4.1 Two-story wooden house (inundation height: 2meters, depth of water coefficient: 1.5)

4.2 Two-story wooden house (inundation height: 3
meters, depth of water coefficient: 1.5)

Research Trends and Results

4.3 Wooden tsunami refuge building (inundation height:
4 meters, depth of water coefficient: 1.5, refuge floor:
roof terrace (4th floor)))【References】(1)

National Institute for Land and Infrastructure Management
document No. 636, Building Department document No. 132，
The 2011 earthquake off the Pacific coast of Tōhoku, (flash) (theGreat East Japan Earthquake)
http://www.nilim.go.jp/lab/bcg/ siryou/tnn/tnn0636.htm ，
http://www.kenken.go.jp/japanese/contents/topics/20110311/0311quickreport.html, 2011.
(2) TSUCHIMOTO Takahiro, NAKAGAWA Takafumi, ARAKI
Yasuhiro, TSUDA Chihiro: ” Damage to Wood Buildings during
The Great Tohoku Earthquake Part 3- Damage due to tsunami”, 11th
Proceedings of World Conference on Timber Engineering, 2012.
(3) TSUCHIMOTO Takahiro, NAKAGAWA Takafumi, ARAKIYasuhiro, KAWAI Naoto: ”Damage Due to Tsunami and Tsunami
Resistance Performance of Wood Houses during The Great Tohoku
Earthquake”, Proceedings of 15th World Conference on EarthquakeEngineering, 2012
(4) Cabinet Office: The guideline regarding tsunami refuge building
http://www. bousai.go.jp/oshirase/h17/tsunami_hinan.html, 2005.6(5) The Japan Building Disaster Association: Commentaries regarding
the structural requirements for the tsunami refuge building, 2012
. http://www.kenchiku-bosai.or.jp/ seismic/tsunami_text.html