Vertical Vibration of a Rigid Foundation Resting on Sand

2009 ◽  
pp. 197-197-36
Author(s):  
MMK Ho ◽  
WJ Burwash
Keyword(s):  
Vertical Vibration ◽  
Rigid Foundation

Vertical vibration of an embedded rigid foundation in a poroelastic soil

2006 ◽  
Vol 26 (6-7) ◽  
pp. 626-636 ◽  
Author(s):  
T. Senjuntichai ◽  
S. Mani ◽  
R.K.N.D. Rajapakse
Keyword(s):  
Vertical Vibration ◽  
Rigid Foundation ◽  
Poroelastic Soil

A 3-DOF Inchworm Using Levitation Caused by Vertical Vibration

2014 ◽  
Vol 134 (11) ◽  
pp. 1716-1723 ◽  
Author(s):  
Akihiro Torii ◽  
Mitsuhiro Nishio ◽  
Kae Doki ◽  
Akiteru Ueda
Keyword(s):  
Vertical Vibration

scholarly journals Tilt Active Vibration Isolation Using Vertical Pendulum and Piezoelectric Transducer with Parallel Controller

2021 ◽  
Vol 11 (10) ◽  
pp. 4526
Author(s):  
Lihua Wu ◽  
Yu Huang ◽  
Dequan Li
Keyword(s):  
Piezoelectric Transducer ◽  
Vibration Isolation ◽  
Vertical Vibration ◽  
Open Loop ◽  
Negative Effects ◽  
Voltage Controller ◽  
Hysteresis Nonlinearity ◽  
Passive Vibration Isolation ◽  
Active Vibration ◽  
Active Vibration Isolation

Tilt vibrations inevitably have negative effects on some precise engineering even after applying horizontal and vertical vibration isolations. It is difficult to adopt a traditional passive vibration isolation (PVI) scheme to realize tilt vibration isolation. In this paper, we present and develop a tilt active vibration isolation (AVI) device using a vertical pendulum (VP) tiltmeter and a piezoelectric transducer (PZT). The potential resolution of the VP is dependent on the mechanical thermal noise in the frequency bandwidth of about 0.0265 nrad, which need not be considered because it is far below the ground tilt of the laboratory. The tilt sensitivity of the device in an open-loop mode, investigated experimentally using a voltage controller, is found to be (1.63±0.11)×105 V/rad. To compensate for the hysteresis nonlinearity of the PZT, we experimentally established the multi-loop mathematical model of hysteresis, and designed a parallel controller consisting of both a hysteresis inverse model predictor and a digital proportional–integral–differential (PID) adjuster. Finally, the response of the device working in close-loop mode to the tilt vibration was tested experimentally, and the tilt AVI device showed a good vibration isolation performance, which can remarkably reduce the tilt vibration, for example, from 6.0131 μrad to below 0.0103 μrad.

Study on human-induced vibration of a cable-stayed bridge without backstays located in abrupt valley

2021 ◽  
pp. 136943322110203
Author(s):  
Yanru Wu ◽  
Junxin Li ◽  
Qing Sun
Keyword(s):  
Empirical Formula ◽  
Dynamic Instability ◽  
Vertical Vibration ◽  
Comfort Level ◽  
Tuned Mass Dampers ◽  
Dynamic Simulations ◽  
Maximum Acceleration ◽  
Cable Stayed Bridge ◽  
Crowd Density ◽  
Lateral Modes

This research aims to assess the pedestrian comfort and to control human-induced vibration of an arch tower cable-stayed bridge without backstays located in canyon. Dynamic simulations of human-induced vibration were carried out with a mode-by-mode approach, and the results indicated that a total of seven lateral and vertical modes of the bridge may suffer from excessive vibrations at the design crowd density. Based on the periodic walking force, the structure response under pedestrian loads was evaluated performing dynamic analyses with two Finite Element models of the footbridge. A single tuned mass damper (STMD) control system was developed for control of human-induced vibration, which consisted of four tuned mass dampers mounted on the mid-span of bridge to enhance damping ratios of lively modes. The results indicate that the maximum acceleration for the first-order lateral and second-order vertical vibration at the design crowd density exceed the associated threshold values referring to the comfort level 1 (CL1) Criteria. The critical pedestrian number of lateral dynamic instability estimated by the Dallard’s empirical formula is much smaller than the dynamic design pedestrian number; and the Dallard’s empirical formula is applicable to estimate the critical pedestrian number of lateral dynamic instability for this bridge by comparing with Pedroe Inês footbridge. The damping ratios for both the vertical and lateral modes increase appreciably after installing the tuned mass dampers and no evidence of large-amplitude vibrations has been observed, leading to the realization of satisfactory comfort levels, which can provide reference for vibration reduction design of this kind of bridge.

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