11th World Congress on Computational Mechanics (WCCM XI)
5th European Conference on Computational Mechanics (ECCM V)
6th European Conference on Computational Fluid Dynamics (ECFD VI)
July 20 - 25, 2014, Barcelona, Spain

COLLAPSE ANALYSIS OF BUILDINGS SUBJECTED TO
SEISMIC EXCITATION, TSUNAMI, AND DEBRIS COLLISION
Daigoro Isobe¹ and Yuan Qi Dong²
1

Division of Engineering Mechanics and Energy, University of Tsukuba
Tennodai 1-1-1, Tsukuba-shi, Ibaraki 305-8573, JAPAN, isobe@kz.tsukuba.ac.jp
http://www.kz.tsukuba.ac.jp/~isobe/
2
Graduate School, University of Tsukuba, JAPAN, s1220927@u.tsukuba.ac.jp

Key Words: Structural Collapse Analysis, Tsunami, Debris Collision, ASI-Gauss Technique.
The Great East Japan Earthquake and the following tsunami which occurred on the 11th ofMarch, 2011, caused a big disaster along the ocean-side of Tohoku area. The big tsunami
carried different kinds of debris such as ships and cars up the stream, which caused additional
damages to the buildings in the area [1][2]. In this study, a structural collapse analysis of asteel building is performed using a finite element code based upon the ASI-Gauss technique[3]. A seismic excitation recorded in Kesennuma-shi is first applied to the steel building
model, followed by an input of the drag force and buoyant force due to tsunami wave. At thelast phase of the analysis, a debris model with a velocity is collided, as shown in Fig. 1, andthe collapse behavior of the building is analyzed.

Fig. 1 Drag force and buoyant force applied to the building and tsunami debris
The story drift angle and the drag force applied to the building during the sequence are bothinvestigated, and are compared between models with and without a wall placed under waterlevel. The latter model tends to withstand both the tsunami and the debris collision while theone with a wall is totally washed up by tsunami after a direct hit from the debris (see Fig. 2).
However, the impact force of debris and continuous application of the drag force on thecollided debris leads to a severe damage of the building with a story drift angle of about 0.036
rad (see Fig. 3), even if the building of the latter case has survived the tsunami itself. This
indicates that the anti-collision as well as anti-tsunami considerations are both similarly
important in the structural design of a tsunami refuge building.

Daigoro Isobe and Yuan Qi Dong.

Story drift angle [rad]0-0.02-0.04-0.06

Model with wallunder water level-0.08

Model without wallunder water level

-0.1
150

Fig. 2 Behavior of the building after collision withtsunami debris (model with a wall placed
under water level)

155

160
Time [s]165170Fig. 3 Story drift angle of the building
at the 1st floorREFERENCES[1] Technical Note of the Port and Airport Research Institute, An Investigation Report on theSeismic and Tsunami Damages of Port, Coast and Airport due to 2011 Great East-JapanEarthquake, 2011, in Japanese.
[2] Report on Field Surveys and Subsequent Investigations of Building Damage Following
the 2011 Off the Pacific Coast of Tohoku Earthquake, Technical Note of National
Institute for Land and Infrastructure Management No. 636, Building Research Data No.
132, 2011, in Japanese.
[3] K.M. Lynn and D. Isobe, Finite Element Code for Impact Collapse Problems of Framed
Structures, International Journal for Numerical Methods in Engineering, Vol.69, No.12,
pp.2538-2563, 2007.

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