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Chunxiang Li - One of the best experts on this subject based on the ideXlab platform.
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Multiple active–passive tuned mass dampers for structures under the Ground Acceleration
Earthquake Engineering & Structural Dynamics, 2020Co-Authors: Chunxiang LiAbstract:An Erratum has been published for this article in Earthquake Engineering and Structural Dynamics 2003; 32(15):2451. Multiple active–passive tuned mass dampers (MAPTMD) consisting of many active–passive tuned mass dampers (APTMDs) with a uniform distribution of natural frequencies have been, for the first time here, proposed for attenuating undesirable oscillations of structures under the Ground Acceleration. The MAPTMD is manufactured by keeping the stiffness and damping coefficient constant and varying the mass. The control forces in the MAPTMD are generated through keeping the identical displacement and velocity feedback gain and varying the Acceleration feedback gain. The structure is represented by the mode-generalized system corresponding to the specific vibration mode that needs to be controlled. Through minimization of the minimum values of the maximum dynamic magnification factors (DMF) of the structure with the MAPTMD (i.e. through implementation of Min.Min.Max.DMF), the optimum parameters of the MAPTMD are investigated to delineate the influence of the important parameters such as mass ratio, total number, normalized Acceleration feedback gain coefficient and system parameter ratio on the effectiveness (i.e. Min.Min.Max.DMF) and robustness of the MAPTMD. The optimum parameters of the MAPTMD include the optimum frequency spacing, average damping ratio and tuning frequency ratio. Additionally, for the sake of comparison, the results for a single APTMD are also taken into account in the present paper. It is demonstrated that the proposed MAPTMD can be employed to significantly reduce the oscillations of structures under the Ground Acceleration. Also, it is shown that the MAPTMD can render high robustness and has better effectiveness than a single APTMD. In particularly, if and when requiring a large active control force, MAPTMD is more promising for practical implementations on seismically excited structures with respect to a single APTMD. Copyright © 2003 John Wiley & Sons, Ltd.
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performance of tuned tandem mass dampers for structures under the Ground Acceleration
Structural Control & Health Monitoring, 2017Co-Authors: Yunzhi Yang, Chunxiang LiAbstract:Summary It is widely acknowledged that the tuned mass damper (TMD) is one of the most effective and simplest passive control devices, but its limited control performance is still a troubling problem. In order to surmount the shortage of TMD, the tuned tandem mass dampers (referred herein to as TTMD) have been proposed for mitigating the undesirable oscillation of structures under the Ground Acceleration. Based on the formulation of the mode-generalized system in the specific vibration mode being controlled, the analytical expression is then derived for the dynamic magnification factor of the structure furnished with a TTMD. The optimum criterion can thereby be defined as minimization of the minimum values of the maximum dynamic magnification factor with a set of optimization variables embedded so as to give full play to the control device potential. The optimization implementation of TTMD is carried out by the MATLAB-based coding and debugging. For the purpose of a mutual authentication to the optimization results, three metaheuristic algorithms, namely, genetic algorithm, particle swarm optimization, and simulated annealing, are concurrently taken into consideration. Results demonstrate that the proposed TTMD endows with the superior stroke performance with respect to TMD.
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hybrid active tuned mass dampers for structures under the Ground Acceleration
Structural Control & Health Monitoring, 2015Co-Authors: Chunxiang LiAbstract:Summary The hybrid active tuned mass dampers (HATMD)—a new control system—have been proposed to attenuate undesirable oscillations of structures under the Ground Acceleration. Based on the authors recent exploration, the performance of the active tuned mass damper (ATMD) with the negative normalized Acceleration feedback gain factors (NNAFGF) scheme is better than that with the positive NAFGF (PNAFGF) scheme; therefore, the active control forces of the HATMD are generated by combined use of both the NNAFGF and PNAFGF schemes. In the light of the mode-generalized system in the specific vibration mode being controlled (simply referred here to as the structure) and accordingly deduced formulae, the expression then is defined for the dynamic magnification factor (DMF) of the structure furnished with the HATMD. Naturally, the criterion for the optimum searching can be determined as the minimization of the minimum values of the maximum DMF. By resorting to the selected criterion and utilizing a genetic algorithm, the effects of varying the key parameters on the optimum performance of the HATMD have been scrutinized both to arrive at the parameter combinations that make it best work and to make an attempt to shed light on the particular phenomena that for it there may exist. Furthermore, for the purpose of comparison, this study simultaneously investigates the optimum performance of both the ATMD and active–passive tuned mass dampers (APTMD) employing the proposed NNAFGF scheme. It is found in terms of numerical results that the HATMD outperforms both the ATMD and APTMD. Copyright © 2014 John Wiley & Sons, Ltd.
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estimating double tuned mass dampers for structures under Ground Acceleration using a novel optimum criterion
Journal of Sound and Vibration, 2006Co-Authors: Chunxiang LiAbstract:The double tuned mass dampers (DTMD), consisting of one larger mass block (i.e. one larger tuned mass damper (TMD)) and one smaller mass block (i.e. one smaller TMD), have been proposed to seek for the mass dampers with high effectiveness and robustness for the reduction of the undesirable vibrations of structures under the Ground Acceleration. The structure is represented by the mode-generalized system corresponding to the specific vibration mode that needs to be controlled. In light of the developed dynamic magnification factors (DMF) of the DTMD structure system, the criterion used for assessing the optimum parameters and effectiveness of the DTMD is selected as the minimization of the minimum values of the maximum DMF of the structure with the DTMD. With resorting to the maximum DMF of both the larger and smaller TMDs in the DTMD, the stroke of the DTMD is simultaneously investigated too. It is highlighted that a novel optimum objective function has been proposed in order to acquire high robust control system. Consequently, the two types of optimum goal functions (including the optimum goal function commonly used) have been applied for the optimum searching of the DTMD. The numerical results indicate that the DTMD designed in terms of the second type of optimum objective functions (i.e. the novel optimum objective function) practically provides the same effectiveness and robustness to the changes in the drift frequency ratio (DFR) as the multiple tuned mass dampers (MTMD) with the distributed natural frequencies with the total number of the TMD units equal to five and with equal total mass ratio. Likewise, the DTMD designed with resort to the second type of optimum objective functions can practically attain the same effectiveness as the TMD with equal total mass ratio. More importantly, in the robustness to the changes in the DFR, the DTMD is significantly better than the TMD, whereas in the robustness to the natural frequency tuning (NFT), measured by the frequency band width coefficient (FBWC), the DTMD is significantly better than the MTMD, thus manifesting that the DTMD is an advanced control device.
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evaluation of multiple dual tuned mass dampers for structures under harmonic Ground Acceleration
International Journal of Structural Stability and Dynamics, 2006Co-Authors: Chunxiang LiAbstract:The multiple dual tuned mass dampers, referred to as the MDTMD, consisting of several units of dual tuned mass dampers (DTMD) are proposed for the first time herein, aimed at the effectiveness and robustness of the system for suppressing the undesirable vibrations of structures under the Ground Acceleration. The total number of dampers can be arbitrary and their natural frequencies are uniformly distributed. Ten typical types of the MDTMD can be devised by varying the system parameters. Employing the criteria chosen for optimum searching, parametric studies were carried out to evaluate the performance of the MDTMD of Type I-1 for its convenience in manufacturing, in which the larger mass blocks (LMBs) are assumed to have identical stiffness, but unequal masses, and the smaller mass blocks (SMBs) have identical stiffness and damping coefficient, but unequal masses and damping ratios. By adopting the maximum dynamic magnification factor (DMF) for each LMB and SMB used in estimating the stroke, an evaluation is also made for the stroke of the MDTMD. The numerical results indicate that the MDTMD (I-1) can provide better effectiveness and higher robustness in comparison with the dual tuned mass dampers (DTMD) and other MTMD systems of similar complexities. However, the stroke of the MDTMD is greater than that of the DTMD and the stroke of each SMB in the MDTMD is larger than that of the mass blocks (MBs) in the arbitrary integer and odd number based MTMD.
Yiben Tsai - One of the best experts on this subject based on the ideXlab platform.
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attenuation relationships of peak Ground Acceleration and velocity for crustal earthquakes in taiwan
Bulletin of the Seismological Society of America, 2005Co-Authors: Yiben TsaiAbstract:Strong seismic Ground-motion data obtained by the Taiwan Strong Motion Instrumentation Program (tsmip) and Central Mountain Strong Motion Array (cmsma) are used to derive new attenuation relationships for the vertical and horizontal peak Ground Acceleration (pga) and peak Ground velocity (pgv) for crustal earthquakes in Taiwan. More than 7900 three-component accelerograms recorded from 51 crustal earthquakes in Taiwan, with M w magnitudes ranging from 4.0 to 7.1, have been analyzed to study the dependence of peak Ground motion parameters on magnitude, distance, regional and local site effects, through attenuation relationships. We first found that, for both pga and pgv, the attenuation relationships decay faster with distance for the vertical component than for the horizontal component. Also, the attenuation relationships decay faster with distance for the vertical pga than for the vertical pgv. We further compared the attenuation relationships for three subregions (chy, iwa, and nto) and the whole Taiwan region (twn). It is found that the chy area has higher Ground motion, either in pga or pgv, than the other areas, especially at near-source distances. This is because the chy area is located on a thick, recent alluvial plain. Comparison of our new attenuation relationships with strong-motion data from the 1999 Chi-Chi earthquake ( M w 7.7) and the 2003 Cheng-Kung earthquake ( M w 6.8) shows that the attenuation relationships developed for M w ≤7 can be extrapolated to make reasonable estimates of strong motion from larger M w ≥7 earthquakes. Finally, we analyzed the residuals to investigate variations of pga and pgv with respect to site conditions. The results show that (1) the residual contour maps, especially for the pgv, have high consistency with the regional geology and topography of Taiwan. (2) The pgv residual contours reveal that Taipei Basin, Changhua Plain, Chianan Plain, Pingtung Valley, Ilan Plain, and Taitung Longitudinal Valley have high residual values. Note that most major metropolitan areas all fall in high residual areas. (3) The site classification based on geologic criteria by Lee et al. (2001) can be simplified into three classes, that is, class E for soft soils, a combination of classes C and D for dense and stiff soils, and class B for rocks. These three site classes are mostly distributed, respectively, in the alluvial plains at an elevation less than 50 m, in terraces and hills at an elevation less than 1000 m, and in high mountainous areas.
Yih-min Wu - One of the best experts on this subject based on the ideXlab platform.
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Data Files from “Near Real-Time Mapping of Peak Ground Acceleration and Peak Ground Velocity Following a Strong Earthquake”
Bulletin of the Seismological Society of America, 2004Co-Authors: Yih-min Wu, Tzay-chyn Shin, Chien-hsin ChangAbstract:A list of 9631 three-component PGA and PGV recordings from 60 large and shallow events in Taiwan from our article, “Near Real-Time Mapping of Peak Ground Acceleration and Peak Ground Velocity following a Strong Earthquake,” is presented as a computer readable file on the attached CD-ROM. …
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near real time mapping of peak Ground Acceleration and peak Ground velocity following a strong earthquake
Bulletin of the Seismological Society of America, 2004Co-Authors: Yih-min Wu, Tzay-chyn Shin, Chien-hsin ChangAbstract:During a disastrous earthquake, the early assessment and timely reporting of the peak Ground Acceleration (PGA) and peak Ground velocity (PGV) maps will be crucial in an effective emergency response operation. In this study, we first derive an empirical relationship between M L and M W. The PGA and PGV attenuation relationships are deduced with data from the Taiwan Strong Motion Instrumentation Program (TSMIP) and the Taiwan Rapid Earthquake Information Release System (TREIRS). Site corrections of the attenuation relationships for shallow and large earthquakes in Taiwan region are also obtained. Peak values of earthquake strong Ground motion can be well determined in Taiwan as soon as the earthquake location is determined, and magnitudes are calculated by the TREIRS. This peak Ground motion value information can be immediately turned into the calculated PGA and PGV maps that can be issued within two minutes of the earthquake origin time. During any disastrous earthquake, these maps are found to be very useful for immediate seismic damage assessment and dispatching of emergency response missions. Manuscript received 1 December 2000.
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relationship between peak Ground Acceleration peak Ground velocity and intensity in taiwan
Bulletin of the Seismological Society of America, 2003Co-Authors: Yih-min Wu, Tzay-chyn Shin, Taliang Teng, Naichi HsiaoAbstract:Based on the strong-motion data set from the 1999 Chi-Chi, Taiwan, earthquake and a shaking damage statistics database, we investigated the correlations between strong Ground motions and earthquake damage (fatalities and building collapses) through a regression analysis. As a result, the current earthquake intensity scale I t is placed on a more reliable instrumental basis. This is necessary for the real-time seismic monitoring operation in Taiwan where programs for earthquake rapid reporting (RRS) and earthquake early warning (EWS) are actively pursued. It is found that the earthquake damage statistics give a much closer correlation with the peak Ground velocity (PGV) than with the peak Ground Acceleration (PGA). The empirical relationship between PGV and the intensity I t determined in this study can be expressed as \[I_{\mathrm{t}}=2.14{\times}\mathrm{log}_{10}(\mathrm{PGV})+1.89.\] This PGV-based intensity is particularly useful in real-time applications for damage prediction and assessment, as the damage impact of high PGV is much more important for mid-rise and high-rise buildings that are characteristic of a modern society. For smaller earthquakes ( M M
Vladimir Sokolov - One of the best experts on this subject based on the ideXlab platform.
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empirical model for estimating fourier amplitude spectra of Ground Acceleration in taiwan region
Earthquake Engineering & Structural Dynamics, 2000Co-Authors: Vladimir SokolovAbstract:SUMMARY A collection of Ground-motion recordings (1070 Acceleration records) of moderate (5.1)M L )6.5) earthquakes obtained during the execution of the Taiwan Strong Motion Instrumentation Program (TSMIP) since 1991 was used to study source scaling model and attenuation relations for a wide range of earthquake magnitudes and distances and to verify the models developed recently for the Taiwan region. The results of the analysis reveal that the Acceleration spectra of the most signi"cant part of the records, starting from S-wave arrival, can be modelled accurately using the Brune’s u-squared source model with magnitudedependent stress parameter *p, that should be determined using the recently proposed regional relationships between magnitude (M L ) and seismic moment (M 0 ) and between M 0 and *p. The anelastic attenuation Q of spectral amplitudes with distance may be described as Q"225 f 1.1 both for deep (depth more than 35 km) and shallow earthquakes. The source scaling and attenuation models allow a satisfactory prediction of the peak Ground Acceleration for magnitudes 5.1)M)6.5 and distances up to about 200 km in the Taiwan region, and may be useful for seismic hazard assessment. Copyright ( 2000 John Wiley & Sons, Ltd.
M. V. Rodkin - One of the best experts on this subject based on the ideXlab platform.
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Statistics and Spatial–Temporal Structure of Ground Acceleration Caused by Earthquakes in the North-Western Pacific
Pure and Applied Geophysics, 2020Co-Authors: V. F. Pisarenko, M. V. RodkinAbstract:The possibilities of statistical estimation of quantiles of predicted maximum peak Ground Acceleration are discussed. The estimation is based on the theory of extreme values. The quantiles of maximum peak Ground Acceleration are calculated for a spatial grid covering the territory of high seismicity regions of Japan, Kuril Islands, and Kamchatka. A new phenomenon is observed: spatial spots of increased Ground Acceleration showing essential inhomogeneity not only across the deep ocean trench, but as well along its extension. Some spots exist during all observation time (130 years), whereas some other can disappear or appear during this time interval. The position of majority of spots is correlated with the concentration of underwater sea mounts at the adjacent part of the oceanic plate. The subduction of these sea mounts could induce an increased seismicity. A correlation of spots with sites of increased ( M _ b − M _ w ) values is observed also, which can be caused by an increased friction between the plates. Stable spots of higher Acceleration are observed for different earthquake catalogs and various time periods. Our results make advisable using the extreme values theory technique for statistical estimation of seismic hazard, in particular, for characterization of seismic activity spots.
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statistics and spatial temporal structure of Ground Acceleration caused by earthquakes in the north western pacific
Pure and Applied Geophysics, 2020Co-Authors: V. F. Pisarenko, M. V. RodkinAbstract:The possibilities of statistical estimation of quantiles of predicted maximum peak Ground Acceleration are discussed. The estimation is based on the theory of extreme values. The quantiles of maximum peak Ground Acceleration are calculated for a spatial grid covering the territory of high seismicity regions of Japan, Kuril Islands, and Kamchatka. A new phenomenon is observed: spatial spots of increased Ground Acceleration showing essential inhomogeneity not only across the deep ocean trench, but as well along its extension. Some spots exist during all observation time (130 years), whereas some other can disappear or appear during this time interval. The position of majority of spots is correlated with the concentration of underwater sea mounts at the adjacent part of the oceanic plate. The subduction of these sea mounts could induce an increased seismicity. A correlation of spots with sites of increased (Mb − Mw) values is observed also, which can be caused by an increased friction between the plates. Stable spots of higher Acceleration are observed for different earthquake catalogs and various time periods. Our results make advisable using the extreme values theory technique for statistical estimation of seismic hazard, in particular, for characterization of seismic activity spots.
