# Development of Vibration Control Structure on Suspended Ceiling Using Pulley Mechanism
## 4 Full-Scale Shake Table Test
### Measurement Plan and Input Excitations  
A total of 27 accelerometers, in a triaxial direction and with 9 locations (four of each on the specimen top and ceiling panel, and the shake table surface), and 4 laser displacement sensors (two of each in the X-direction and Y-direction) were used for monitoring the outputs in the tests with 500 Hz sampling frequency. During the excitation with the damper system, one draw-wire displacement sensor, and four tension measuring plates with strain gauges were installed for each pulley-damper system. The location and details of these instruments are shown in Figure 13.  
Figure 11: Overall view of the SCS specimen on the shake table. Figure 12: Schematic view of overall specimen: (**a**) Plan view; (**b**) cross-section view in X-direction; (**c**) cross-section view in Y-direction. White noise with random phase tests (frequency range: 0.1 Hz to 49 Hz) were conducted for the initial tests to analyze the dynamic properties of the SCS and the test steel frame. Then, earthquake excitation tests using a simulated earthquake ground motion with random phases, based on the design spectrum specified in the Building Standards Law of Japan, were carried out. The amplitude was gradually scaled according to the condition of the specimens. Figures 14 and 15 show the acceleration time histories and spectrum of the input motions given to the shake table. for example, Case CW and Case CWD, a distinct peak point was not confirmed. That is, the implementation of PDCS into the SCS provides a great effect to suppress vibration and prevent resonance damage to the ceiling. Figure 16: Amplitude of acceleration transfer function under white noise wave. Figure 14: White noise wave used in shake table test: (**a**) Acceleration time histories; (**b**) Fourier amplitude spectrum. Figure 15: Simulated earthquake wave used in shake table test: (**a**) Acceleration time histories; (**b**) spectral acceleration. As shown in Figure 17a and Table 3, Case CB, which was rigidly fixed to the floor above by the steel brace, exhibited the largest response reduction, of an average of 3% for the unreinforced Case C. Similarly, the specimens applying the proposed system, Case CWD0 and Case CWD60, effectively reduced the displacement response to 6% in Case CWD0 and 27% in Case CWD60, respectively, compared to Case C. Case CW0 mitigated the displacement response more than Case CW60, because the horizontal stiffness given by the stretched wire of Case CW0 is larger than that of Case CW60. Figure 17b compares the displacement time history of the ceiling panel for each case under the simulated earthquake motion at PGA 2 m/s/s. As the displacement time history demonstrates, the displacements in Case CWD0 and CWD60 were much smaller than Case C, between 20 to 40 s, and they suppressed the shaking faster than Case C.  
Figure 18a displays the relationship between the maximum acceleration response at the ceiling panel and the peak ground acceleration (PGA) at the shake table surface for simulated earthquake waves up to PGA 5 m/s/s. The ratio of the maximum acceleration response for each test case to Case CB under major PGs is presented in Table 4.  
As shown in Figure 18a and Table 4, the acceleration response of Case CB was amplified twice as compared with Case C; meanwhile, the Case CB provided great displacement reduction effect. Moreover, in the Case CB, the buckling of the hanger bolts after the excitation of the simulated earthquake motion at PGA 6 m/s/s was observed due to the large acceleration response. The accelerations in other cases were reduced to almost 20% of Case CB, and there were no significant differences at the maximum acceleration response between Case CWD0 and Case CWD60. Figure 19 displays the amplification factor of PDCS under the simulated ground motion at different PGAs. This amplification factor is the ratio of the maximum damper displacement to the maximum ceiling panel displacement. The theoretical amplification factor for Case CW0/CWD0 and Case CW60/CWD60 are 5.0 and 2.5, respectively.