Collapse Simulation of Wide-Area Suspended Ceiling System
Using the ASI-Gauss Code
Daigoro Isobe1, Takashi Fujiwara2, Takuzo Yamashita3,Hiroyuki Tagawa4 and Tomohiro Sasaki5
1

Division of Engineering Mechanics and Energy, University of Tsukuba
Ibaraki 305-8573, Japan
isobe@kz.tsukuba.ac.jp
2

Samsung Japan Corporation
Tokyo 108-8240, Japanf.takashi@samsung.com
3
E-Defense, National Research Institute for Earth Science and Disaster Resilience
Hyogo 673-0515, Japan
tyamashi@bosai.go.jp
4
Mukogawa Women’s University
Hyogo 663-8137, Japan
tagawa@mukogawa-u.ac.jp
5Technical Research Institute, Obayashi CorporationTokyo 204-8558, Japansasaki.tomohiro@obayashi.co.jp
Many ceiling collapse damages were observed in wide-area structures such as gymnasiums
during the 2011 Great East-Japan Earthquake [1] and the 2016 Kumamoto Earthquake [2].
The prevention of ceiling collapse phenomena is an important issue not only to save people’s
lives, but to keep these facilities to be safely used as shelters after earthquakes.
In this paper, a numerical analysis to simulate the ceiling collapse in a full-scale gymnasium
specimen, which was tested at the E-Defense shaking table facility in 2014 [3,4], wasconducted. A numerical model consisted of steel structural frames and suspended ceilings
were constructed. All the members were modeled using linear Timoshenko beam elements
and the adaptively shifted integration (ASI) - Gauss code [5] was applied. Hangers andhanging bolts were modeled in one piece. The plaster boards were assumed as rigid in out ofplane direction and only the mass of rock wool boards was considered. Their strength wereneglected. Clips and screws were modeled with minute, small elements. Each plaster board
was modeled separately to consider local contact between plaster boards, which wassimulated by modeling the screws slightly apart. Elasto-plastic buckling of braces andhanging bolts were considered by modeling them with eight beam elements each and two
hinge elements on both ends. The clips connecting ceiling joists and ceiling joist receivers are
small and delicate components that may be detached during repeated excitation. Once there isa local detachment of clips, a change in the load distribution may cause a chain reaction ofdetachments, which ends in a drop of plaster boards. Furthermore, the detachments of hanging
bolts that are connected to the structural members composing the roof, and failure of screws
on plaster boards are assumed to be other main causes of the ceiling collapse. The results ofsome preliminary tests [6-9] conducted to see the actual strength of these components areimplemented in the analysis for criteria.
The numerical result was validated by the experimental result [3,4], which was performed at
the E-Defense under an input of two continuous K-NET Sendai 50% waves. The acceleration

responses, the spectrum and the displacement responses obtained on the roof matched wellwith the experimental result. According to the results, the plaster boards near walls pattereddown occasionally at the first peak of the first wave. These were due to detachment of clips
and screws caused by collisions to the walls. Then, the clips near roof top began to get loose
due to buckling of hanging bolts caused by vertical excitation, which ends, at the first peak of
the second wave, in drop of plaster boards in a wide range (Fig. 1). The numerical result had
shown the collapse of the ceilings progressed owing to the detachment of clips that connected
the ceiling joists to the ceiling joist receivers, which eventually led to a large-scale collapse ofthe ceilings.

Fig. 1 Collapse of ceilings in a gymnasium during seismic excitation

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