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Conventional tuned mass damper (TMD) is a popular and generally accepted vibration control device in the field of passive structural control. However, it was found that the control efficacy of a conventional TMD may significantly degrade when the TMD’s frequency does not tune to its desired value. In addition, the vibration energy of controlled structure transferred into the TMD is dissipated by viscous or friction damper and becomes waste heat. In this paper, a new type of TMD, called electromagnetic TMD inerter (EM-TMDI) is developed by replacing the viscous dampers with electromagnetic rotary transducers so that a more flexible viscous damping can be achieved and part of the energy originally dissipated by the dampers could be harvested. A flywheel with variable mass moment of inertia will be introduced into the transmission system of the TMD to adjust TMD’s frequency to mitigate the frequency detuning effect and to enhance the control efficacy of TMD system. The theoretical derivation is performed to generate the relationship between the DC motor and the transmission system of the EM-TMDI. Optimal design method considering the inerter of rotary transducers will be developed. This study first designed and manufactured a scale-down, double-deck EM-TMDI. A series of shaking table tests were conducted at NCREE Tainan laboratory to verify the capability of inerter to change TMD’s frequency.

Nuclear containment structure is one of the most important infrastructure systems ensuring the safety of a nuclear power plant. In this paper, the structural behavior of cylindrical concrete containment structure was investigated using two 1/13-scaled nuclear containment specimens subjected to reversed cyclic loadings. The presentation will first describe the experimental program, including the dimensions, the reinforcement detailing, the test setup, and the loading method. Second, the experimental results of the specimens are discussed including the cracking patterns, the total load versus displacement curves, and the failure modes. Third, the test results were compared to the analytical results predicted at the University of Houston using a 3D finite element program with the CSMM-based shell elements. The predicted results agree very well with the experimental data.

The more the development of super high-rise buildings, the faster the speed of elevator in order to shorten the riding time of elevator and the waiting time of passengers. With the increase of elevator speed, the horizontal vibration of passenger car becomes more significant resulting in the decrease of serviceability and safety of elevator, and the discomfort of passengers. The horizontal vibration is mainly generated from the elevator wheels running on rough and winding guide rails. In this paper, a four degree-of-freedom (DOF) elevator system was established to examine the characteristics of the excitations and to analyze the dynamic responses of the elevator. An active mass driver (AMD) was developed to reduce the horizontal acceleration of passenger car in the elevator based on H∞ direct output feedback control algorithm. The optimal control force is obtained from the multiplication of direct output measurements by a pre-calculated time-invariant gain matrix. To achieve optimal control performance, the strategy to select both control parameters γ and α was investigated extensively. Numerical verification results show that decrease in γ or increase in α yields better control performance with an acceptable magnitude of control force. The selective ranges of γ and α making a controlled system become overdamped or unstable were found. To assure system stability and control efficiency, the upper bound of α were derived and illustrated graphically. An optimum design flowchart was also proposed. Finally, a full-scaled high-speed elevator system was investigated to prove the applicability and control effectiveness of the proposed AMD system.Copyright © 2011 by ASME