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RISS 인기검색어
- 검색키워드
- 저자 : Ramin Sedaghati (검색결과 3 건)
- 무료
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Semi-active control of seismic response of a building using MR fluid-based tuned mass damper
Ashutosh Bagchi,Kambiz Esteki,Ramin Sedaghati 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.5
While tuned mass dampers are found to be effective in suppressing vibration in a tall building, integrating it with a semi-active control system enables it to perform more efficiently. In this paper a forty-story tall steel-frame building designed according to the Canadian standard, has been studied with and without semi-active and passive tuned mass dampers. The building is assumed to be located in the Vancouver, Canada. A magneto-rheological fluid based semi-active tuned mass damper has been optimally designed to suppress the vibration of the structure against seismic excitation, and an appropriate control procedure has been implemented to optimize the building\'s semi-active tuned mass system to reduce the seismic response. Furthermore, the control system parameters have been adjusted to yield the maximum reduction in the structural displacements at different floor levels. The response of the structure has been studied with a variety of ground motions with low, medium and high frequency contents to investigate the performance of the semi-active tuned mass damper in comparison to that of a passive tuned mass damper. It has been shown that the semi-active control system modifies structural response more effectively than the classic passive tuned mass damper in both mitigation of maximum displacement and reduction of the settling time of the building.
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Fan Lin,Masoud Hemmatian,Ramin Sedaghati,Farhad Aghili 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.4
Excessive vibration may cause premature fatigue failure on structural components if it is not properly controlled. One effective way to attenuate vibration is to attach a tuned vibration absorber to the main structural component. Passive tuned vibration absorbers are mainly effective to attenuate vibration at a specific range of frequencies and thus they become infective under varied environmental conditions which can significantly alter the tuning frequencies. The present study aims at development of a wide-bandwidth and light-weight adaptive tuned vibration absorber (ATVA) featuring a magnetorheological elastomer (MRE) which is tuned to absorb the vibrations of a flexible beam. The accelerance transfer function is derived for both beam with and without ATVA. The effectiveness of the ATVA to control vibration of the flexible beam caused by external excitation under wide range of frequencies is demonstrated. The proposed ATVA consists of C-Shape frame with winding coils, two isometric MRE specimens with 40% volume fraction, and active mass. An empirical model for the MRE has been developed through an experimental identification method in order to predict the MRE's elastic modulus under various levels of excitation frequencies and applied magnetic fields. Using MRE models and magneto-circuit analysis, the frequency bandwidth of the ATVA is analytically obtained. The analytical model is then used to develop a multidisciplinary design optimization formulation to minimize the mass and maximize the frequency bandwidth of an ATVA featuring MRE given several geometrical and physical constraints. Finally, a tuning algorithm has been presented to determine the required applied magnetic flux density to the MRE layers based on the identified phase difference between the absolute acceleration of the host and relative acceleration of the host and ATVA's resonator.
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Gamaleddine Elnashar,Rama B. Bhat,Ramin Sedaghati 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
Increased road traffic combined with heavy vehicle loads leads to deterioration of pavements and reduces the life span of the paved roads. As a result, large amounts of financial resources are spent each year to improve and maintain road infrastructure around the world. Vehicle dynamics and pavement dynamics are strongly coupled through their contact points. This research focuses on the dynamic analysis of pavement-vehicle interaction system and the effect of coupling action on the response. The system response due to the moving vehicular load on rough road supported by a linear visco-elastic foundation was investigated. The vehicle is modeled as a two-degree-offreedom quarter-vehicle model, and the pavement-foundation system is described by a simply supported Euler-Bernoulli beam resting on Pasternak foundation, while the tire is coupled to the flexible pavement with a single point contact. Galerkin method was used to develop a system of governing differential equations for a coupled system in the time domain. Direct numerical integration method using Newmark-β based on linear average acceleration method was then used to solve the governing equations and evaluate the response of the coupled system. The results were validated with previous research works and compared with conventional uncoupled systems. Finally, the effects of parameters such as vehicle speed, road roughness, soil stiffness and suspension damping on the responses were investigated.
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