Seismic Motion Analysis of Furniture Placed in a Reinforced Concrete Building
using FEM
Koichi Kobayashi1, Toshiki Miura2, Takuzo Yamashita3 and Daigoro Isobe41

Graduate School, University of Tsukuba
Ibaraki 305-8573, Japans1720934@s.tsukuba.ac.jp

2

Graduate School, University of Tsukuba
Ibaraki 305-8573, Japans1620924@s.tsukuba.ac.jp
3E-Defense, National Research Institute for Earth Science and Disaster Resilience
Hyogo 673-0515, Japan
tyamashi@bosai.go.jp
4
Division of Engineering Mechanics and Energy, University of Tsukuba
Ibaraki 305-8573, Japan
isobe@ kz.tsukuba.ac.jp

Japan is one of the countries frequently hit by earthquakes. In Great East-Japan Earthquake
occurred in 2011, indoor furniture and interior equipment were severely damaged although
there appeared little damages on buildings. Improperly secured furniture, especially on theupper floors of high-rise buildings under seismic excitation, can become dangerous objects forhuman life. Many tumbled furniture could become fatal obstacles that obstruct people fromevacuating. Therefore, it is important to know the overturning behaviors of furniture underseismic excitations, as well as the behaviors and damages of the building itself. From thisbackground, various shake-table tests for such specimen had been carried out, although suchtests can be too costly to conduct repeatedly.
To restrain the costs, numerical simulation techniques such as discontinuous element method(DEM) had been often applied to investigate the motion behaviors of furniture. Its calculation
cost is very small; however, there are physically uncertain properties that have to be fixed in
the models and it is difficult to obtain the deformations and stress distributions of the models.
The finite element method (FEM), on the other hand, is an effective means to evaluate thedeformations and stress distributions of the models and requires less number of parametersthan the DEM. In this research, the behaviors of furniture under seismic excitation are
simulated, using the code in which the frictional contact algorithm based on the sophisticatedpenalty method is introduced to Adaptively Shifted Integration (ASI) - Gauss code [1,2].

Fig. 1 Behaviors of quake-proof furniture under seismic excitation on the tenthfloor of a reinforced concrete buildingFirst, we simulated the behaviors of quake-proof furniture placed on the first floor and thetenth floor of a medium-rise reinforced concrete building subjected under a seismic excitation(Fig. 1). According to the numerical results, large motions appeared in the furniture placed on
upper floors and the attached quake-proof equipment were less useful in those cases.
Furthermore, the most effective means to suppress the motions was to attach the quake-proof
equipment near the centroid position of furniture. Secondly, we conducted a seismic motion
analysis of furniture placed on each floor of a medium-rise reinforced concrete building. As aresult, the motions of furniture became larger as the location went higher (Fig. 2).

Fig. 2 A seismic motion analysis of furniture placed on each floor of a medium-risereinforced concrete building

References[1] D. Isobe, Z.H. He, M. Kaneko and M. Hori: Motion Analysis of Furniture under Sine
Wave Excitations, Proceedings of the International Symposium on Reliability Engineeringand Risk Management (ISRERM2012), (2012), pp.230-233, Yokohama, Japan.
[2] D. Isobe, T. Yamashita, H. Tagawa, M. Kaneko, T. Takahashi and S. Motoyui: MotionAnalysis of Furniture under Seismic Excitation using FEM, Journal of Structural andConstruction Engineering, AIJ, Vol. 80, No. 718, (2015), pp.1891-1900, in Japanese.