# Development of Vibration Control Structure on Suspended Ceiling Using Pulley Mechanism  
[PERSON]  
1 Department of Architecture and Civil Engineering, Toyohashi University of Technology,  
Toyohashi 441-8580, Aichi, Japan; [EMAIL_ADDRESS]  
[PERSON]  
2 Building Research Department of Research Institute, Hazama Ando Corporation,  
Tsukuba 305-0822, Ibaraki, Japan; sakai.shigeki@ad-hzm.co.ip  
[PERSON]  
1 Department of Architecture and Civil Engineering, Toyohashi University of Technology,  
Toyohashi 441-8580, Aichi, Japan; [EMAIL_ADDRESS]  
in Korea [9]. In addition, the failure and collapse of ceiling panels would cause, not only blocking evacuation paths and impending continuous operation of the building, but also human damage. During the 2011 Great East Japan Earthquake, there were more than 75 casualties caused by the collapsing of approximately 2000 SCSs [10; 11]. The SCS is composed mainly of hanger elements, carrying ceiling runners, and ceiling panels. Based on the structure of the ceiling runner, the SCS can be classified into two types [12]: the direct-hung suspended ceiling system (direct-SCS) and indirect-hung suspended ceiling system (indirect-SCS). Figure 1 shows the schematic diagram of the SCS. The key difference between them is the connection of the cross runner and hanger elements. In the direct-SCS (Figure 1a), the primary runners are directly suspended from wires attached to the structural system above, and cross joints are applied to the secondary runners to insert between the span of the primary runners. Meanwhile, the indirect-SCS (Figure 1b,c) uses hanger bolts to suspend primary runners from the above floor, and primary runners and secondary runners are connected using clips. On the one hand, as the direct-SCS is widely used because of its convenience when changing the ceiling panels, relocating the attached air conditioner unit, and the lighting equipment in the practice, most of the previous studies focused on evaluating and understanding the seismic response of the direct-SCS by using a shake table for more than two decades. The main finding from those experiments was about the connection failure of the ceiling grid members due to the collision between ceiling panels and the surrounding structures, including walls. To overcome this issue and improve the seismic performance, several studies were performed on the hanger connection [12; 13], the perimeter [14; 15; 16], retainer clip [17], and the cross joint [18; 19]. In addition to these studies, few researchers proposed and investigated the feasibility of a pendulum-type ceiling system that does not use any rigid elements and is completely separated from the surrounding wall, with an aim to reduce ceiling damage in the earthquake [20; 21]. Similarly, [PERSON] [22] presented the application of flexible braces (lightweight steel) integrated into the SCS to absorb the input energy. On the other hand, research on the indirect-SCS is recently becoming active. Based on their response behavior in the earthquake, the indirect-SCS can be divided into two types [23]: a continuous panel ceiling and a lay-in panel type (Figure 1). In the case of the lay-in panel SCS, the seismic performance decreases rapidly, owing to the lack of lateral stiffness when one panel falls, which is due to the unfastening of the ceiling runner. Figure 1: Type of suspended ceiling systems: (**a**) Direct-hung suspended ceiling system; (**b**) indirect-hung suspended ceiling system with lay-in panel; (**c**) indirect-hung suspended ceiling system with continuous panel. Therefore, the continuous panel SCS has been certified to perform low fragility because the larger area panels are fixed on the bottom surface of runners and the entire ceiling moves together [24]. The superiority of the continuous ceiling panel was also verified based on the seven types of direct and indirect SCSs using an array of two shaking tables [9].