# Development of Vibration Control Structure on Suspended Ceiling Using Pulley Mechanism
## 6 Conclusions  
This paper proposed an innovative passive vibration control structure for an indirect suspended ceiling system using pulley tackle mechanisms, named the pulley-damper ceiling system (PDCS), and provided detailed information on the system configuration. A preliminary experimental investigation of the dynamic characteristics of the proposed system was conducted. A main goal was to understand the behavior of the entire system under seismic motion and evaluate the feasibility. The results obtained in this study are summarized below:  
* The fundamental concept to integrate passive damper system-employed pulley tackle mechanisms into a SCS was presented, which amplifies the SCS displacement in proportion to the number of stretched wire and its installing angle, and transmits to the damper. Moreover, theoretical formulation, considering the amplification mechanism and the elasticity of the wire-cable by modeling as equivalent truss elements, was established.
* Shake table tests using a full-scale SCS specimen of 4020 mm \(\times\) 3200 mm in area were demonstrated using simulated earthquake ground motion to evaluate the vibration reduction effect of the PDCS. Conventional SCS (Case C), reinforced SCS with the steel brace (Case CB), and damped SCS using PDCS (Case CWD) were constructed. In addition, in the case of Case CWD, two configurations were prepared to investigate the influence of the system installing angle (horizontal: Case CWD0 and diagonal: Case CWD60) to the response reduction effect. The average response ratio of the maximum displacement in Case CWD0 and Case CWD60 to Case C were 0.04 and 0.21, respectively. Additionally, the average response ratio of the maximum displacement in Case CWD0 and Case CWD60 to Case CB were 0.19 and 0.15, respectively. It was confirmed that both acceleration and displacement could be controlled with high efficiency compared to the unbraced SCS and braced SCS.
* A non-linear rotational damper comprises of two fluid viscous dampers, and the cable bobbin was developed for the proposed system to follow up the large wire stroke. The damper successfully worked during shake table excitations and the theoretical amplification effect was observed.
* The analytical model of the full SCS specimens and formulation of the constitute equation in the DPDS were verified by comparing the experimental and analytical results. The friction force on the pulley was equivalently converted as a bilinear hysteresis model. The analytical model accurately simulated the experimental time history responses of both displacements with 0.83 \(R^{2}\) and acceleration with 0.91 \(R^{2}\), including the dynamic behavior of the damper.  
Conceptualization, T.S.; methodology, S.S.; software, T.S.; validation, R.M. and S.S.; formal analysis, R.M.; investigation, R.M.; data curation, R.M.; writing--original draft preparation, R.M.; writing--review and editing, T.S.; visualization, R.M.; supervision, T.S.; project administration, S.S.; funding acquisition, T.S. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors gratefully thank the practice committee of the development of the ceiling vibration control system: [PERSON] (Sato Kogyo Co., Ltd.), [PERSON] (Toda Corp.), [PERSON] (Nishimatsu Construction Co., Ltd.), [PERSON] (Maeda Co., Ltd.), and [PERSON] (Kumagai Gumi Co., Ltd.).  
The authors declare no conflict of interest.