Yuanfeng Duan

Bio: Yuanfeng Duan is an academic researcher from Zhejiang University. The author has contributed to research in topics: Damper & Vibration control. The author has an hindex of 15, co-authored 67 publications receiving 761 citations. Previous affiliations of Yuanfeng Duan include Hong Kong Polytechnic University.

State-derivative feedback control of cable vibration using semiactive magnetorheological dampers

Abstract: This paper presents the theoretical and in situ experimental studies on state-derivative feedback control of bridge cable vibration using semiactive magnetorheological (MR) dampers. Numerical simulations of state derivative feedback control for a stay cable in the cable stayed Dongting Lake Bridge are conducted under sweeping sine excitation and sinusoidal step relaxation excitation. Good agreement between the simulation and experimental results were obtained. The real time control test on a prototype cable in the bridge site shows that the damping capacity obtained from the semiactive control test agrees well with the simulation result.

Inertial mass damper for mitigating cable vibration

Abstract: Summary Stay cables used in cable-stayed bridges are prone to vibration due to their low-inherent damping characteristics. Many methods have been implemented in practice to mitigate such vibration. Recently, negative stiffness dampers have gained attention because of their promising energy dissipation ability. The viscous inertial mass damper (VIMD) has been shown to have properties similar to negative stiffness dampers. This paper examines the potential of the VIMD to enhance the damping, and mitigate the vibration, of stay cables. First, a control-oriented model of the cable is employed to formulate a system level model of the cable–VIMD system for small in-plane motion. After carefully classifying and labeling the mode order, the modal characteristics of the system are analyzed, and the optimal damper parameters for the several lower frequency modes are determined numerically. The results show that the achievable modal damping ratio can be up to nearly an order of magnitude larger than that of the traditional linear viscous damper; note that the optimal parameters of the VIMD are distinct for each mode of interest. These results are further validated through analysis of the cable responses due to the distributed sinusoidal excitation. Finally, a case study is conducted for a cable with a length of 307 m, including the design of practical damper parameters, modal-damping enhancement, and vibration mitigation under wind loads. The results show that the VIMD is a promising practical passive damper that possesses greater energy dissipation capacity than the traditional viscous damper for such cable–damper systems.

Cable Vibration Control using Magnetorheological Dampers

Abstract: As the world's first implementation of magnetorheological (MR) smart damping technique in bridge structures, a total of 312 semi-active MR dampers (RD-1005, Lord Corporation) have recently been installed for rain-wind-induced cable vibration control on the cable-stayed Dongting Lake Bridge, China. This project has undergone several stages of in situ experiments and tests: (i) modal tests of undamped cables, (ii) forced vibration tests of MR-damped trial cables, (iii) monitoring of MR-damped and undamped cable responses under rain-wind excitations, (iv) comparative tests using different damper setups, (v) full installation, and (vi) field measurements and real-time control tests after the installation. After outlining the above six stages of the whole project and addressing the experience and lessons learned from both open-loop control and closed-loop control practices, this study focuses on the design considerations of implementing MR dampers for cable vibration control, taking into account the effects of the damper stiffness, damper mass, stiffness of damper support, nonlinearity of the damper, and sag and inclination of the cable. The research efforts make it possible to develop elaborate MR dampers specific for application to bridge stay cables.

Steel stress monitoring sensor based on elasto-magnetic effect and using magneto-electric laminated composite

Abstract: Monitoring of stresses in in-service steel structural components is challenging, but crucial to structural safety and health evaluation. Elasto-magnetic (EM) sensors are promising for stress monitoring of steel structural components, because of their great capabilities for actual stress measurement, noncontact monitoring, and long service life. However, the low sensitivity, low signal-to-noise ratio, slow response, and complicated installation of the EM sensors limit their application flexibility. This paper presents a steel stress monitoring sensor (SSMS) using a magneto-electric (ME) sensing unit to overcome the drawbacks intrinsic in the conventional EM sensors. The ME sensing unit is made of a ME-laminated composite of Terfenol-D magnetostrictive alloy and 0.7Pb_Mg1/3Nb2/3_O3−0.3PbTiO3 (PMN-PT) piezoelectric crystal. The theoretical analysis and experimental characterization conducted on the ME sensing unit show high sensitivity, real-time response, and good linearity. Stress monitoring of a steel bar under tension is implemented for the SSMS with a pulse excitation of magnetization. The results demonstrate that the SSMS is feasible for real-time stress monitoring of steel structural components with high sensitivity, fast response, and ease of installation.

Temperature Compensation of Elasto-Magneto-Electric (EME) Sensors in Cable Force Monitoring Using BP Neural Network.

Abstract: Techniques based on the elasto-magnetic (EM) effect have been receiving increasing attention for their significant advantages in cable stress/force monitoring of in-service structures. Variations in ambient temperature affect the magnetic behaviors of steel components, causing errors in the sensor and measurement system results. Therefore, temperature compensation is essential. In this paper, the effect of temperature on the force monitoring of steel cables using smart elasto-magneto-electric (EME) sensors was investigated experimentally. A back propagation (BP) neural network method is proposed to obtain a direct readout of the applied force in the engineering environment, involving less computational complexity. On the basis of the data measured in the experiment, an improved BP neural network model was established. The test result shows that, over a temperature range of approximately −10 °C to 60 °C, the maximum relative error in the force measurement is within ±0.9%. A polynomial fitting method was also implemented for comparison. It is concluded that the method based on a BP neural network can be more reliable, effective and robust, and can be extended to temperature compensation of other similar sensors.

Minimum Design Loads for Buildings and Other Structures

Abstract: Minimum Design Loads for Buildings and Other Structures provides requirements for general structural design and includes means for determining dead, live, soil, flood, wind, snow, rain, atmospheric ice, and earthquake loads, as well as their combinations, which are suitable for inclusion in building codes and other documents. This Standard, a revision of ASCE/SEI 7-05, offers a complete update and reorganization of the wind load provisions, expanding them from one chapter into six. The Standard contains new ultimate event wind maps with corresponding reductions in load factors, so that the loads are not affected, and updates the seismic loads with new risk-targeted seismic maps. The snow, live, and atmospheric icing provisions are updated as well. In addition, the Standard includes a detailed Commentary with explanatory and supplementary information designed to assist building code committees and regulatory authorities. Standard ASCE/SEI 7 is an integral part of building codes in the United States. Many of the load provisions are substantially adopted by reference in the International Building Code and the NFPA 5000 Building Construction and Safety Code. Structural engineers, architects, and those engaged in preparing and administering local building codes will find this Standard an essential reference in their practice. Note: New orders are fulfilled from the second printing, which incorporates the errata to the first printing.

Electrodynamics Of Continuous Media

Abstract: Thank you for reading electrodynamics of continuous media. Maybe you have knowledge that, people have look numerous times for their chosen books like this electrodynamics of continuous media, but end up in infectious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some malicious bugs inside their computer. electrodynamics of continuous media is available in our book collection an online access to it is set as public so you can get it instantly. Our book servers saves in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the electrodynamics of continuous media is universally compatible with any devices to read.

Magnetorheological fluid dampers: A review on structure design and analysis

Abstract: Magnetorheological fluid technology has gained significant development during the past decades. The application of magnetorheological fluids has grown rapidly in civil engineering, safety engineering, transportation, and life science with the development of magnetorheological fluid–based devices, especially magnetorheological fluid dampers. The magnetorheological fluid dampers could offer an outstanding capability in semiactive vibration control due to excellent dynamical features such as fast response, environmentally robust characteristics, large force capacity, low power consumption, and simple interfaces between electronic input and mechanical output. To address the fast growing demand on magnetorheological fluid damping technology in extensive engineering practices, the state-of-the-art development is presented in this article, which provides a comprehensive review on the structure design and its analysis of magnetorheological fluid dampers (or systems). This can be regarded as a useful complement to...