Статті в журналах: "KANAI AND TAJIMI PARAMETERS"

1

Chen, Huiguo, Ting Zhong, Guocui Liu, and Junru Ren. "Improvement of and Parameter Identification for the Bimodal Time-Varying Modified Kanai-Tajimi Power Spectral Model." Shock and Vibration 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/7615863.

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Based on the Kanai-Tajimi power spectrum filtering method proposed by Du Xiuli et al., a genetic algorithm and a quadratic optimization identification technique are employed to improve the bimodal time-varying modified Kanai-Tajimi power spectral model and the parameter identification method proposed by Vlachos et al. Additionally, a method for modeling time-varying power spectrum parameters for ground motion is proposed. The 8244 Orion and Chi-Chi earthquake accelerograms are selected as examples for time-varying power spectral model parameter identification and ground motion simulations to verify the feasibility and effectiveness of the improved bimodal time-varying modified Kanai-Tajimi power spectral model. The results of this study provide important references for designing ground motion inputs for seismic analyses of major engineering structures.

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2

Guenfaf, Lakhdar, and Mohamed Azira. "Generalized Minimum Variance Control for MDOF Structures under Earthquake Excitation." Journal of Control Science and Engineering 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/7458654.

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Control of a multi-degree-of-freedom structural system under earthquake excitation is investigated in this paper. The control approach based on the Generalized Minimum Variance (GMV) algorithm is developed and presented. Our approach is a generalization to multivariable systems of the GMV strategy designed initially for single-input-single-output (SISO) systems. Kanai-Tajimi and Clough-Penzien models are used to generate the seismic excitations. Those models are calculated using the specific soil parameters. Simulation tests using a 3DOF structure are performed and show the effectiveness of the control method.

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3

Palazzo, Bruno, and Luigi Petti. "Stochastic Response Comparison between Base Isolated and Fixed-Base Structures." Earthquake Spectra 13, no. 1 (February 1997): 77–96. http://dx.doi.org/10.1193/1.1585933.

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Random response of linear Base Isolated Systems, mounted on elastomeric bearings, subject to horizontal random excitations, is analyzed in comparison with the one of the fixed-base structures. Considering the superstructure motion described by its first modal contribution, a two-degree-of-freedom equivalent linear model, under stationary Gaussian excitations modelled by the modified Kanai-Tajimi power density spectrum, has been used in the analysis. The response sensitivity to design parameters for the superstructure and the isolators have been evaluated for a wide range of parameters. Optimum viscous damping and isolation degree values which minimize structural response are also obtained. Some implications of these results for the design and code requirements are discussed.

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4

Bhattacharyya, B., and S. Chakraborty. "Stochastic Sensitivity of 3D-Elastodynamic Response Subjected to Random Ground Excitation." International Journal of Structural Stability and Dynamics 03, no. 02 (June 2003): 283–97. http://dx.doi.org/10.1142/s0219455403000847.

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The present study deals with structural sensitivity of dynamic response having uncertainties in design parameters subjected to random earthquake loading. Earthquake is modeled as stationary random process defined by Kanai–Tajimi power spectral density. The uncertain design parameters are modeled as homogeneous Gaussian process and discretized through 3D local averaging. Subsequently the Cholesky decomposition of respective co-variance matrix is used to simulate random values of design parameters. The Neumann expansion blended with Monte Carlo simulation (NE-MCS) is explored for computing response sensitivity in frequency domain. Application examples related to a building frame and a gravity dam are presented serving to validate the NE-MCS technique in terms of its accuracy and effectiveness compared to direct Monte Carlo simulation and perturbation method.

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5

Azira, Mohamed, and Lakhdar Guenfaf. "Empirical multi-degree-of-freedom-generalized minimum variance control for buildings during earthquakes." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 1 (March 2018): 3–30. http://dx.doi.org/10.1177/1461348418760878.

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Structural control of a multi-degree-of-freedom building under earthquake excitation is investigated in this paper. The ARMAX model calculation is developed for a linear representation of multi-degree-of-freedom structure. A control approach based on the generalized minimum variance algorithm is developed and presented. This approach is an empirical method to control the story unit regardless of the coupling with other stories. Kanai-Tajimi and Clough–Penzien models are used to generate the seismic excitations. Those models are calculated using the specific soil parameters. In order to test the control strategy performances under real strong earthquakes, the structure has been subjected to EL Cento earthquake. RST controller form shows the stability conditions and the optimality of the control strategy. Simulation tests using a 3DOF structure are performed and show the effectiveness of the control method using of the empirical method.

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6

Sun, Huang Sheng, and Li Nuo Cheng. "Connecting Parameter Study on Adjacent Structures Linked by Dampers." Advanced Materials Research 243-249 (May 2011): 3832–38. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3832.

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In order to research the optimal parameters of dampers linking adjacent structures for seismic mitigation, two SDOF systems connected with visco-elastic damper (VED) are taken as research object and the primary structural vibration frequency ratio, connection stiffness and linking damping ratio as research parameters. Modified Kanai-Tajimi spectrum is selected to model the earthquake excitation. The peak distribution of power spectral density curves are analyzed, then the formulas of structural mean squared displacement (MSD) and research parameters is derived based on random vibration theory. Then the relationship of the adjacent structural seismic response versus the research parameters was presented. The optimal value of the linking visco-elastic damper damping ratio and stiffness ratio are investigated. Finally, the seismic responses of example structures with or without connecting dampers are contrastively analyzed. The dependence of response mitigation effective on research parameters is highlighted. The results indicate fine earthquake-reduction effectiveness of dampers connecting adjacent structures. It is also shows that optimal parameters of damper cannot reduce the seismic responses of the primary structures connected to the best extent simultaneously. The damper parameters should be determined according to the best seismic mitigation effectiveness of the primary, auxiliary structure or the combined structure system.

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7

Huang, Tian Li, and Wei Xin Ren. "Dynamic Reliability-Based Seismic Optimal Design of Base-Isolated Structures." Advanced Materials Research 243-249 (May 2011): 3765–69. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3765.

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This paper presents a dynamic reliability-based optimization technique for the seismic design of base-isolated structures. Firstly, the governing equation of multi-degree-of-freedom base-isolated structures is established. Then, the superstructure is unfolded by the first mode. Considering that the damping is non-classical and the total base-isolation system is un-symmetric, the complex modal analysis is adopted to uncouple the governing equation and the analytical solutions of stochastic seismic response under the Kanai-Tajimi spectrum loading are obtained. Taking the ratio between the first-order modal displacement standard deviation of the superstructure with base- isolated system and the fixed-base structure as the optimal objective function, the dynamic reliability of the isolated system displacement as the constraint, the optimal design parameters of the isolated system are obtained through the penalty function method. A 3-story building with isolated system illustrates the proposed dynamic reliability-based optimization method. It is believed that such an optimization technique provides an effective tool for the seismic design of base-isolated structures.

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8

Huang, Tian Li, and Wei Xin Ren. "Dynamic Reliability-Based Seismic Optimal Design of Structures with Tuned Mass Damper." Advanced Materials Research 243-249 (May 2011): 3770–74. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3770.

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This paper presents a dynamic reliability-based optimization technique for the seismic design of structures with tuned mass damper (TMD). Firstly, the governing equation of multi-degree-of-freedom structure with TMD is established. Then, the main structure is unfolded by the first mode. Considering that the damping is non-classical and the total main structure and TMD system is un-symmetric, the complex modal analysis is adopted to uncouple the governing equation and the analytical solutions of stochastic seismic response under the Kanai-Tajimi spectrum loading are obtained. Taking the ratio between the first-order modal displacement standard deviation of the structure with TMD and the one without TMD as the objective function, the dynamic reliability of the TMD system displacement as the constraint, the optimal design parameters of the TMD system are obtained through the penalty function method. A 10-story building with TMD system illustrates the proposed dynamic reliability-based optimization method. It is believed that such an optimization technique provides an effective tool for the seismic design of structures with TMD.

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9

MARANO, GIUSEPPE CARLO, GIUSEPPE ACCIANI, and LENONARDO GIUSEPPE CASCELLA. "NON-STATIONARY NUMERICAL COVARIANCE ANALYSIS OF LINEAR MULTI DEGREE OF FREEDOM MECHANICAL SYSTEM SUBJECT TO RANDOM INPUTS." International Journal of Computational Methods 04, no. 01 (March 2007): 173–94. http://dx.doi.org/10.1142/s0219876207001072.

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Structural response of linear multi degree of freedom (MDoF) system subject to random Gaussian dynamic actions is defined by mean of vector and covariance matrix in state space. In case of non-stationary inputs, second-order spectral moments evaluation needs the solution of the so-called Lyapunov matrix differential equation. In this work a numerical scheme for its resolution is proposed, with reference to input processes modeled as linear filtered white noise with time-varying parameters, which is a common situation in amplitude and frequency variable loads. Numerical computational effort is minimized by taking into account symmetry characteristic of state space covariance matrix. As application of the proposed method a multi-storey building is analyzed to obtain reliability associated to maximum inter-storey exceeded over a given acceptable limit. It is assumed to be subject to seismic input described by a amplitude and frequency nonstationary process, by using a generalized non-stationary Kanai Tajimi seismic model. Structure is assumed as a plane shear frame MDoF system. Structural reliability evaluation is referred to "first time out-crossing" and different numerical benchmarks are considered.

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10

Wang, Shiyu, and Ying Lei. "A Joint State-Parameter Identification Algorithm of a Structure with Non-Diagonal Mass Matrix Based on UKF with Unknown Mass." Buildings 12, no. 6 (June 14, 2022): 826. http://dx.doi.org/10.3390/buildings12060826.

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Inaccurate mass estimates have been recognized as an important source of uncertainty in structural identification, especially for large-scale structures with old ages. Over the past decades, some identification algorithms for structural states and unknown parameters, including unknown mass, have been proposed by researchers. However, most of these identification algorithms are based on the simplified mechanical model of chain-like structures. For a chain-like structure, the mass matrix and its inverse matrix are diagonal matrices, which simplify the difficulty of identifying the structure with unknown mass. However, a structure with a non-diagonal mass matrix is not of such a simple characteristic. In this paper, an online joint state-parameter identification algorithm based on an Unscented Kalman filter (UKF) is proposed for a structure with a non-diagonal mass matrix under unknown mass using only partial acceleration measurements. The effectiveness of the proposed algorithm is verified by numerical examples of a beam excited by wide-band white noise excitation and a two-story one-span plane frame structure excited by filtered white noise excitation generated according to the Kanai–Tajimi power spectrum. The identification results show that the proposed algorithm can effectively identify the structural state, unknown stiffness, damping and mass parameters of the structures.

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11

Lai, Yong-An, Chi-Hung Chang, Cho-Yen Yang, and Chia-Ming Chang. "Design of Optimal Passive Tuned Mass Damper with Static Output Feedback and Updating Iterative Procedure." Structural Control and Health Monitoring 2023 (June 3, 2023): 1–18. http://dx.doi.org/10.1155/2023/2558070.

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In this study, the optimal design issue of a passive tuned mass damper (TMD) was transformed into the nonsparse control gain matrix optimization problem, and a general passive TMD optimization design method to minimize structural mean square responses or impulse response is therefore proposed. The proposed optimization procedure combines the static output feedback (also known as direct output feedback) algorithm and the updating iterative procedure. The proposed method can be applied to variant design scenario, whether the main structure is single-degree-of-freedom (SDOF) or multidegree-of-freedom (MDOF) structures, undamped or damped structures, subjected to wind disturbances or earthquake excitations. In addition, the proposed method is capable to consider the excitation shaping filter, so the design results are more suitable for practical application. The design procedure of the proposed method is presented, and all the required weighting matrices are introduced and derived in detail. Firstly, the SDOF structures are used as the main structure to demonstrate the correctness of the proposed method. The numerical simulation results verify that the obtained optimal design parameters of TMD were found identical to some cases which contain the analytic solution. The accuracy and feasibility of the proposed design method are confirmed. Finally, a passive TMD is optimally designed for a 5-story MDOF structure subjected to Kanai–Tajimi spectrum comparable earthquakes and a 60-story high-rise MDOF structure subjected to Davenport spectrum comparable wind loads for demonstration.

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12

Lin, Y. K., and Yan Yong. "Evolutionary Kanai‐Tajimi Earthquake Models." Journal of Engineering Mechanics 113, no. 8 (August 1987): 1119–37. http://dx.doi.org/10.1061/(asce)0733-9399(1987)113:8(1119).

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13

Alotta, G., M. Di Paola, and A. Pirrotta. "Fractional Tajimi–Kanai model for simulating earthquake ground motion." Bulletin of Earthquake Engineering 12, no. 6 (April 13, 2014): 2495–506. http://dx.doi.org/10.1007/s10518-014-9615-z.

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14

Dalla Chiesa, Daniela, and Letícia Fleck Fadel Miguel. "Geração de uma excitação sísmica através do espectro de Kanai-Tajimi." Revista Brasileira de Computação Aplicada 9, no. 1 (May 28, 2017): 31. http://dx.doi.org/10.5335/rbca.v9i1.6660.

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O presente artigo apresenta os resultados da implementação de uma rotina computacional, no programa MATLAB, para a geração de uma excitação sísmica e análise da resposta dinâmica de um edifício, com n graus de liberdade, sujeito a esse tipo de carregamento. Deﬁne-se a excitação sísmica como um processo estocástico estacionário unidimensional, passando por um processo de ruído branco Gaussiano através do ﬁltro de Kanai-Tajimi, cuja função densidade espectral de potência permite a geração da aceleração do solo no domínio da frequência. A aceleração do solo é, então, passada para o domínio do tempo gerando um acelerograma sísmico artiﬁcial. De posse do acelerograma resolve-se, com a aplicação do método de Newmark, a equação de movimento dinâmico estrutural e encontram-se os deslocamentos, velocidades e acelerações referentes a cada andar do edifício. Por ﬁm, uma análise dos valores máximos, em módulo, dos deslocamentos, acelerações e dos deslocamentos relativos entre os andares é ilustrada. Os resultados encontrados estão condizentes com a literatura conﬁrmando, assim, a eﬁciência da rotina implementada.

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15

Ge, Xinguang, Chuangdi Li, Iftikhar Azim, Jinghai Gong, and Yuxiang Li. "Structural dynamic responses of linear structures subjected to Kanai-Tajimi excitation." Structures 34 (December 2021): 3958–67. http://dx.doi.org/10.1016/j.istruc.2021.08.092.

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16

Rofooei, F. R., Aghababaii Mobarake, and G. Ahmadi. "Generation of artificial earthquake records with a nonstationary Kanai–Tajimi model." Engineering Structures 23, no. 7 (July 2001): 827–37. http://dx.doi.org/10.1016/s0141-0296(00)00093-6.

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17

Bai, Zhi Qiang, Wen Feng Liu, and Huan Qiang Luan. "Study on Reliability of Structure with Energy Dissipation Dampers." Advanced Materials Research 383-390 (November 2011): 6396–403. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.6396.

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In this paper, Kanai-Tajimi spectrum as earthquake random excitation is applied. A Structure with Viscoelastic Dampers is analyzed by random method and reliability of energy dissipation is presented. The effect of energy dissipation of viscoelastic dampers added to building is studied under four working situations. The result of calculation indicates that the reliability of energy dissipation will be higher if more dampers are installed. Supposing that the quantity of dampers is fixed, the reliability of energy dissipation will be decrescent if energy dissipation degree is larger. If the reliability of energy dissipation is fixed, the dampers parameter is the determinant factor.

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18

Fan, F.-G., and G. Ahmadi. "Nonstationary Kanai-Tajimi models for El Centro 1940 and Mexico City 1985 earthquakes." Probabilistic Engineering Mechanics 5, no. 4 (December 1990): 171–81. http://dx.doi.org/10.1016/0266-8920(90)90018-f.

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19

Jin, X. L., Z. L. Huang, and A. Y. T. Leung. "Nonstationary seismic responses of structure with nonlinear stiffness subject to modulated Kanai-Tajimi excitation." Earthquake Engineering & Structural Dynamics 41, no. 2 (April 26, 2011): 197–210. http://dx.doi.org/10.1002/eqe.1125.

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20

Ge, Xinguang, Jinghai Gong, Chenjun Zhao, Iftikhar Azim, Xuefeng Yang, and Chuangdi Li. "Structural dynamic responses of building structures with non-viscous dampers under Kanai–Tajimi spectrum excitation." Journal of Sound and Vibration 517 (January 2022): 116556. http://dx.doi.org/10.1016/j.jsv.2021.116556.

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21

Amiri, G. Ghodrati, and A. Bagheri. "Simulation of earthquake records using combination of wavelet analysis and non-stationary Kanai-Tajimi model." Structural Engineering and Mechanics 33, no. 2 (September 30, 2009): 179–91. http://dx.doi.org/10.12989/sem.2009.33.2.179.

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22

Spanos, P. D., and S. M. Miller. "Hilbert Transform Generalization of a Classical Random Vibration Integral." Journal of Applied Mechanics 61, no. 3 (September 1, 1994): 575–81. http://dx.doi.org/10.1115/1.2901498.

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Integrals which represent the spectral moments of the stationary response of a linear and time-invariant system under random excitation are considered. It is shown that these integrals can be determined through the solution of linear algebraic equations. These equations are derived by considering differential equations for both the autocorrelation function of the system response and its Hilbert transform. The method can be applied to determine both even-order and odd-order spectral moments. Furthermore, it provides a potent generalization of a classical formula used in control engineering and applied mathematics. The applicability of the derived formula is demonstrated by considering random excitations with, among others, the white noise, “Gaussian,” and Kanai-Tajimi seismic spectra. The results for the classical problem of a randomly excited single-degree-of-freedom oscillator are given in a concise and readily applicable format.

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23

Amiri, G. Ghodrati, A. Bagheri, and M. Fadavi. "New method for generation of artificial ground motion by a nonstationary Kanai-Tajimi model and wavelet transform." Structural Engineering and Mechanics 26, no. 6 (August 20, 2007): 709–23. http://dx.doi.org/10.12989/sem.2007.26.6.709.

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24

Zhou, Yao, Zhi Wei Wang, and Yuan Feng Wang. "Seismic Analysis of Separated Platform Subway Station Structure." Advanced Materials Research 163-167 (December 2010): 4138–41. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.4138.

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As separated platform subway station structures are close to the bridge piles, its seismic performance need to be analyzed. An artificial earthquake record is used to analyze seismic performance of the subway station structure. The artificial earthquake record with the Kanai–Tajimi model and trigonometric series superprosition method is generated. It is shown that the influences of the stresses of arch springing and basement are significant under horizontal direction earthquake. Under horizontal direction earthquake, the horizontal stresses of arch springing and basement are 1.46 and 1.61 times than the original stresses and their vertical stresses are 1.34 and 1.59 times than the original stresses. It is shown that the influences of the horizontal stress of soleplate and the vertical stresses of arch springing and basement are significant under vertical direction earthquake. Under vertical direction earthquake, the horizontal stresse of soleplate is 3.30 times than the original stress, while vertical stresses of arch springing and basement are 2.78 and 2.72 times than the original stresses.

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25

Er, G. K., K. Wang, and V. P. Iu. "Probabilistic Solutions of the In-Plane Nonlinear Random Vibrations of Shallow Cables Under Filtered Gaussian White Noise." International Journal of Structural Stability and Dynamics 18, no. 04 (March 28, 2018): 1850062. http://dx.doi.org/10.1142/s0219455418500621.

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The probabilistic solutions of the responses of shallow cable are studied when the cable is excited by filtered Gaussian white noise. The nonlinear multi-degree-of-freedom system is formulated which governs the random vibration of cable. The state-space-split (SSS) method and exponential polynomial closure (EPC) method are adopted to analyze the probabilistic solutions of cable systems in order to study the effectiveness and computational efficiency of SSS-EPC procedure in analyzing the probabilistic solutions of the cable systems under the excitation of filtered Gaussian white noise. Numerical results obtained by SSS-EPC method, Monte Carlo simulation, and equivalent linearization method are compared to examine the computational efficiency and numerical accuracy of SSS-EPC method in this case. Thereafter, the behaviors of probabilistic solutions of the cable systems are studied with different values of peak frequency and seismic intensity of excitation when the cable is excited by Kanai–Tajimi seismic force. Some observations and discussions are given by introducing a probabilistic quantity to show the influence of excitations on the probabilistic solutions.

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26

Lee, C. L., R. K. L. Su, and Y. P. Wang. "AGV-induced floor micro-vibration assessment in LCD factories by using a regressional modified Kanai-Tajimi moving force model." Structural Engineering and Mechanics 45, no. 4 (February 25, 2013): 543–68. http://dx.doi.org/10.12989/sem.2013.45.4.543.

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27

Wang, Kun, Guo-Kang Er, and Vai Pan Iu. "Seismic analysis of nonlinear offshore moored floating structures." Advances in Structural Engineering 21, no. 9 (December 7, 2017): 1361–75. http://dx.doi.org/10.1177/1369433217744356.

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This article presents a numerical model for solving the nonlinear random vibrations of offshore moored floating structures under seismic excitation. The offshore moored floating structure consists of the floating platform and mooring cables. The floating platform is considered as a rigid body with 3 degrees of freedom. The nonlinear equations of motions of the mooring cables are established using the nonlinear cable elements that are formulated based on the extended Hamilton principle. The nonlinear hydrodynamic drag forces that act on both the floating platform and cables are considered. In order to carry out the random vibrational analysis, the connection conditions between the floating structure and mooring cables are given to formulate the equations of motions of the whole system. Finally, the moored floating structure under horizontal seismic ground accelerations with Kanai–Tajimi model are analyzed using Monte Carlo simulation method. The probability density functions of the displacements of the moored floating structure and the maximum tensile force in cables are presented. The influences of different sag-to-span ratios or inclined angles of the mooring cables on the mean value and standard deviation of the displacements of the floating structure and the maximum tensile force in cables are analyzed.

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28

Jian, Fan, Zhang Yanping, and Long Xiaohong. "Establishment of a Time-Varying Modified Kanai-Tajimi Non Stationary Stochastic Model of Seismic Records Based on the S-transform." Journal of Earthquake Engineering 18, no. 6 (July 2014): 876–90. http://dx.doi.org/10.1080/13632469.2014.916631.

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29

Ruiz, Sonia E., and Emilio Rosenblueth. "Discussion of “ Evolutionary Kanai‐Tajimi Earthquake Models ” by Y. K. Lin and Yan Yong (August, 1987, Vol. 113, No. 8)." Journal of Engineering Mechanics 115, no. 4 (April 1989): 884–85. http://dx.doi.org/10.1061/(asce)0733-9399(1989)115:4(884).

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30

Lin, Y. K., and Yang Yong. "Closure to “ Evolutionary Kanai‐Tajimi Earthquake Models ” by Y. K. Lin and Yan Yong (August, 1987, Vol. 113, No. 8)." Journal of Engineering Mechanics 115, no. 4 (April 1989): 886–87. http://dx.doi.org/10.1061/(asce)0733-9399(1989)115:4(886).

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31

Dalla Chiesa, Daniela, and Letícia Fleck Fadel Miguel. "Determinação da probabilidade de falha em um edifício submetido a uma excitação sísmica." Revista Interdisciplinar de Pesquisa em Engenharia 5, no. 1 (January 15, 2019): 22–29. http://dx.doi.org/10.26512/ripe.v5i1.19114.

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Este artigo apresenta uma metodologia para a determinação da probabilidade de falha em edifícios submetidos a uma excitação sísmica. Incertezas nos parâmetros do movimento do solo e da estrutura são consideradas nesse procedimento. A excitação sísmica é modelada como um processo estocástico estacionário unidimensional, utilizando a função densidade espectral de potência de Kanai-Tajimi, e são atribuídas aleatoriedades na frequência, amortecimento e pico de aceleração do solo. A estrutura analisada corresponde a um edificio, com 10 pavimentos, no qual a obtenção da resposta dinâmica é calculada levando-se em conta as aleatoriedades em sua massa, rigidez e razão de amortecimento. Para ilustrar a proposta, são realizadas 3.000 simulações computacionais, no programa MATLAB, considerando três tipos de solos, em uma região que poderia estar situada na zona sísmica 3 do Peru. Os valores máximos médios, em módulo, para o deslocamento e a aceleração em cada andar do edifício, o deslocamento relativo entre os andares e a probabilidade de falha são determinados. Considera-se como estado limite para dano estrutural um valor máximo para o deslocamento relativo entre os andares. Os resultados mostram que altas probabilidades de falhas são observadas em solos com frequências situadas entre as frequências naturais dos dois primeiros modos de vibrações da estrutura.

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32

Brandão, Francisco Da Silva, and Letícia Fleck Fadel Miguel. "A New Methodology for Optimal Design of Hybrid Vibration Control Systems (MR + TMD) for Buildings under Seismic Excitation." Shock and Vibration 2023 (September 4, 2023): 1–14. http://dx.doi.org/10.1155/2023/8159716.

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This study proposes a new methodology, based on the optimization procedure by a metaheuristic algorithm, for designing a hybrid vibration control system to mitigate the dynamic response of buildings under nonstationary artificial earthquakes (NSAEs). For illustration purposes, a 10-story shear building is studied. The hybrid control system involves the use of an MR damper (MR) and a tuned mass damper (TMD) located in different places of the structure. To describe the behavior of the MR, the modified Bouc–Wen model (MBW) was used. To calculate the damping force of the MR, the clipped optimal control associated with linear quadratic regulator (LQR), CO-LQR, was considered. The optimization was performed using the whale optimization algorithm (WOA) and seismic load generated by the Kanai–Tajimi spectrum. Different control scenarios were evaluated: MR-OFF, MR-ON, CO-LQR, STMD, and CO-LQR (MR + TMD) to determine the best control scenario that can effectively control the structure. Overall, the optimized hybrid control scenario (MR + TMD) was the only one able to adapt all story drifts to the control criterion of the consulted normative. Then, CO-LQR (MR + TMD), designed via the methodology proposed in this work, proved to be the best alternative to control the seismic response of this building.

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Liu, Liangkun, Yuze Zheng, Zhaodong Pan, and Qing Lyu. "Energy Dissipation and Performance Assessment of the Connected Structure with a One-Side Damping Layer." Buildings 12, no. 9 (September 13, 2022): 1438. http://dx.doi.org/10.3390/buildings12091438.

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Due to aesthetic demands and the necessity for multi-functionality, a unique structure with one or multiple links connecting adjacent buildings has attracted the attention of researchers. In order to improve vibration control, this study investigates the seismic mitigation performance of a connected structure with a one-side damping layer. The simplified shear model is employed to derive the structure’s motion equation. Based on the Kanai-Tajimi filtered spectrum model, the seismic response variances are calculated using the Lyapunov equation. To investigate the seismic energy distribution and mitigation performance, three models of the connected structure with a damping layer are analyzed using the index of the mean kinetic energy. The results shows that the stiffness and damping coefficient affects the vibration energy, while the excessive stiffness of the damping layer is shown to be detrimental to the damping effects. In sum, the novel connected structure shows excellent damping ability and effectively reduces the vibration energy. Damping layers placed at a lower position with a stiffer structure are shown to enhance the damping effect and lead to more energy dissipation through the damping layer. Thus, this study concludes that the introduction of a One-Side damping layer into the connected structure is an excellent alternative strategy for adjusting the energy distribution of the connected structure and meeting the design requirements.

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WANG, SHUAI, HONG-CHUN YUAN, and HONG-YI FAN. "FRESNEL OPERATOR, SQUEEZED STATE AND WIGNER FUNCTION FOR CALDIROLA–KANAI HAMILTONIAN." Modern Physics Letters A 26, no. 19 (June 21, 2011): 1433–42. http://dx.doi.org/10.1142/s0217732311035778.

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Based on the technique of integration within an ordered product (IWOP) of operators, we introduce the Fresnel operator for converting a kind of time-dependent Hamiltonian into the standard harmonic oscillator Hamiltonian. The Fresnel operator with the parameters A, B, C, D corresponds to classical optical Fresnel transformation, these parameters are the solution to a set of coupled partial differential equations set up in the above-mentioned converting process. In this way, the Caldirola–Kanai Hamiltonian has been easily converted into the standard harmonic oscillator Hamiltonian. And then the exact wave function solution of the Schrödinger equation governed by the Caldirola–Kanai Hamiltonian is obtained, which represents a squeezed number state. The corresponding Wigner function is derived by virtue of the Weyl ordered form of the Wigner operator and the order-invariance of Weyl ordered operators under similar transformations.

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35

Ahmadi Taleshian, Hamed, Alireza Mirzagoltabar Roshan, and Javad Vaseghi Amiri. "Use of viscoelastic links for seismic pounding mitigation under random input." International Journal of Structural Integrity 11, no. 3 (November 19, 2019): 471–96. http://dx.doi.org/10.1108/ijsi-06-2019-0055.

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Purpose The purpose of this paper is to study the effects of viscoelastic links between two adjacent buildings for pounding mitigation under white-noise seismic input. Design/methodology/approach A formulation is first extracted for the effective modal damping ratios of the system. Then, two single DOF linear buildings connected by viscoelastic links are considered with both classical and non-classical damping schemes. The inelastic behavior is also taken into account by using equivalent natural frequencies and damping ratios of the buildings. The effect of ground dominant frequency and damping on the displacement response is also investigated by using Kanai‒Tajimi filtered white noise as the random input. Findings The difference between classical and non-classical damping is shown to be less than 20 percent, implying the permission in using the simpler classical damping scheme. Finally, the problem is extended to two-storey buildings, where using viscoelastic links only at the top story level of the buildings is shown to be sufficient for controlling individual, as well as relative, motions of the structures. Originality/value Results demonstrate that the use of link with a moderate stiffness may reduce the stiffer building displacement up to approximately 20 percent in comparison to the free displacement, while the seismic pounding of the adjacent buildings is effectively controlled. Further, an upper limit of link stiffness is obtained for preventing the increase in the stiffer building displacement, which may be exceeded by the minimum link stiffness necessary for pounding prevention if small gap size exists.

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Zelaya, Kevin, and Oscar Rosas-Ortiz. "Exact Solutions for Time-Dependent Non-Hermitian Oscillators: Classical and Quantum Pictures." Quantum Reports 3, no. 3 (August 21, 2021): 458–72. http://dx.doi.org/10.3390/quantum3030030.

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We associate the stationary harmonic oscillator with time-dependent systems exhibiting non-Hermiticity by means of point transformations. The new systems are exactly solvable, with all-real spectra, and transit to the Hermitian configuration for the appropriate values of the involved parameters. We provide a concrete generalization of the Swanson oscillator that includes the Caldirola–Kanai model as a particular case. Explicit solutions are given in both the classical and quantum pictures.

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Dialosa, Kukuh, Rustadi Rustadi, Bagus Sapto Mulyatno, and Cecep Sulaeman. "ANALISIS TINGKAT RESIKO DAMPAK GEMPABUMI DI KABUPATEN CILACAP MENGGUNAKAN METODE DSHA DAN DATA MIKROTREMOR." Jurnal Geofisika Eksplorasi 4, no. 3 (January 17, 2020): 73–89. http://dx.doi.org/10.23960/jge.v4i3.42.

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Soil mechanical research has been done in Cilacap Regency using DSHA method and microtremor data. This study aims to analyze the local land response to earthquakes based on the dominant frequency parameters (f0), amplification factor (A0), wave velocity VS30 and seismic hazard analysis through deterministic approach. This research uses 193 microtremor measurement points using a short period TDS-303 type (3 component) seismometer. Microtremor data were analyzed using the Horizontal to Vertical Spectral Ratio (HVSR) method in geopsy software. DSHA analysis refers to the source of the Lembang Fault earthquake and Java Subduction zone for deterministic calculations. Based on the analysis of HVSR method, Cilacap Regency is located on land type 1 (frequency 0-1.33 Hz) and soil type 2 (frequency 1,33-5 Hz) according to Kanai Classification (1983), dominated amplification value 1,104 to 8,171 times, then Dominated by soil class E (VS30 value 183 m / s) and soil class D (183 m / s VS30 366 m / s) according to NEHRP Classification (2000). This indicates that Cilacap Regency has high vulnerability to earthquake disaster. Based on the estimated value of PGA calculation method of DSHA, from the calculation of earthquake source Subduction obtained Java PGA bedrock 0,045 g - 0,0671 g and PGA surface rock 0,1926 g - 0,4855 g and calculation of Lembang Fault obtained PGA bedrock 0, 09 g - 0.025 g and PGA surface rocks 0.017 g - 0.089 g. Based on risk map analysis (combination of dominant frequency analysis, amplification, susceptibility factor and ability factor), the highest risk areas are Kec. Adipala, Kasugihan, Binangun, Nusawungun, Cil. Middle, Cil. South, Cil. North, allegedly the soil layer constituent area is a layer of thick and soft sediments. While the low risk of Kec. Majenang and Dayeuh Luhur.

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Gasser, Christian, Markus Goldgruber, and Christian Bucher. "Seismic Fragility Curves of an Arch Dam With Special Regard to Ultimate Limit State." ASCE-ASME J Risk and Uncert in Engrg Sys Part B Mech Engrg 5, no. 4 (September 25, 2019). http://dx.doi.org/10.1115/1.4044151.

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Abstract The seismic safety of an arch dam is analyzed by calculating fragility curves for different damage and failure mechanisms. The model includes fluid–structure–foundation interaction and considers contact and material type nonlinearities. The ultimate limit state (failure) is studied by means of a plastic-damage concrete model, especially developed for cyclic loadings. The time histories of the ground motions are generated randomly by means of Kanai–Tajimi filter. Moreover, ten parameters of the model are considered as random variables, including the water level. To the best knowledge of the authors, for the first time, water-level variability is accounted for in a probabilistic seismic analysis of a dam. It is studied if it is admissible to increase the efficiency of the Monte Carlo simulation (MCS) by assuming lognormal distributions for the fragility curves. In general, the aim of this work is to show the possibilities and difficulties of probabilistic seismic analysis tools when applied to a sophisticated mechanical model of a real structure.

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Zhang, Shangrong, Yuchen Hu, Xinyu Liu, Ping Tan, and Xiangjun Guo. "Hybrid Isolation Strategy for Seismically Isolated Multi-Tower Building with a Large Podium." International Journal of Structural Stability and Dynamics, January 24, 2022. http://dx.doi.org/10.1142/s0219455422500614.

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The Compositive Passive Control method (CPC method) of “interlayer seismic isolation”[Formula: see text][Formula: see text][Formula: see text]“shock absorption between adjacent towers” is applied to Multi-Tower Building (MTB) with a large podium. Taking the total vibration energy of the structure as the optimal control objective, the response expressions of a multi-DOF layer shear model and an equivalent single-DOF layer shear model are derived. The rationality of the equivalent model is demonstrated from the perspective of mode characteristics and time history response. Based on the Kanai–Tajimi spectral seismic motion model, the control effect and the optimal control parameters of the CPC method are studied. Compared with the conventional seismic scheme and the interlayer seismic isolation scheme, the influence of the CPC method on the structure natural vibration characteristics and dynamic response under different parameters of the connecting control device is discussed and analyzed. The numerical analysis proves that the CPC method provides a significant damping effect compared with the interlayer seismic isolation scheme. It maintains the advantages of the interlayer seismic isolation scheme and reduces the defect of the response amplification caused by the interlayer isolation. This analysis constitutes a good reference for the follow-up study of the CPC method of MTB.

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Lu, Jubin, Liang Hu, Zili Xia, and Songye Zhu. "Conditional simulation of non-stationary spatially variable ground motions for long-span bridges across non-uniform site conditions." Advances in Bridge Engineering 3, no. 1 (August 19, 2022). http://dx.doi.org/10.1186/s43251-022-00059-w.

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AbstractNon-stationary spatially variable ground motions (SVGMs) are commonly modelled as multivariate oscillatory processes based on evolutionary power spectral density (EPSD) functions. The existing conditional simulation algorithms require the known EPSD functions. The EPSD functions are usually assumed to be identical for all locations, which is unreasonable for long-span bridges because variable soil conditions are practically observed at different bridge piers. This paper proposes a conditional simulation algorithm for non-stationary SVGMs in consideration of non-uniform site conditions. The spatial interpolation tool, termed inverse-distance-weighted (IDW) interpolation, is introduced to estimate the EPSD functions at sites without ground motion measurement. Subsequently, the covariance matrix of the random Fourier coefficients of the multivariate oscillatory processes can be calculated. The Kriging estimation is adopted to obtain the unknown random Fourier coefficients, from which the time histories of the non-stationary SVGMs can be conditionally simulated. The proposed conditional simulation algorithm is first validated through a numerical example, in which the EPSD functions of non-uniform sites are represented by a non-stationary Kanai-Tajimi spectrum with different soil parameters. Then, the algorithm is applied to the Jiuzhou Channel Bridge, a navigation channel bridge of the Hong Kong-Zhuhai-Macau Bridge (HZMB), with complex soil and water conditions. Based on the limited in-situ seismic measurement data, the site characteristics in the bridge area are analysed, and the ground motion time histories at all piers can be generated.

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Shen, Wenai, Zhentao Long, Heng Wang, and Hongping Zhu. "Power Analysis of Sdof Structures with Tuned Inerter Dampers Subjected to Earthquake Ground Motions." ASCE-ASME J Risk and Uncert in Engrg Sys Part B Mech Engrg, December 2, 2020. http://dx.doi.org/10.1115/1.4049212.

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Abstract Tuned inerter dampers (TID) have been demonstrated as efficient energy dissipation devices for seismic response control. However, its potential capability for energy harvesting remains largely unexplored. Here, we present a theoretical analysis of the power of a structure-TID system subjected to earthquake ground motions. The analytical solutions of the average damping power of the system are derived for considering white noise base excitations and the Kanai-Tajimi earthquake model, respectively. Comparisons of the numerical results of a Monte Carlo simulation and the theoretical predictions verify the accuracy of the analytical solutions. Besides, we uncover the influence of the TID parameters on the damping power and output power of the system. The optimal frequency ratio of the TID for maximizing its output power slightly differs from that for seismic response control, and the former varies with site conditions. In contrast, both the damping power and output power are not sensitive to the damping ratio of the TID. For short-period structures, a small inertance-to-mass ratio (µ) of the TID is beneficial to maximize its output power, while seismic response control requires a large µ. For long-period structures, the damping power and output power are not sensitive to the µ. Generally, a structure-TID system on a soft soil site absorbs more energy from a given earthquake and is capable of harvesting more energy than that on a hard soil site. This study may help develop new strategies for self-powered control and monitoring in civil structures.

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"Evolutionary Kanai-Tajimi type earthquake models." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 26, no. 6 (December 1989): 291. http://dx.doi.org/10.1016/0148-9062(89)91466-6.

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Karadeniz, H. "Stochastic Earthquake Analysis of Underwater Storage Tanks." Journal of Offshore Mechanics and Arctic Engineering 130, no. 3 (July 18, 2008). http://dx.doi.org/10.1115/1.2904946.

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In this paper, the problem and analysis method of underwater storage tanks resting on a horizontal seabed is presented under stochastic earthquake loading. The tank is axisymmetrical and has a flexible wall/roof. The finite element method is used for the response solution. A solid axisymmetrical finite element has been formulated to idealize the tank whereas an axisymmetrical fluid element is used for the idealization of the fluid domain. The Eulerian formulation of the fluid system is used to calculate the interactive water pressure acting on the tank during the free motion of the tank and earthquake motion. For the response calculation, the modal analysis technique is used with a special algorithm to obtain natural frequencies of the water-structure coupled system. For the stochastic description of the earthquake loading, the modified Kanai–Tajimi earthquake spectrum is used. Finally, the analysis method presented in the paper is demonstrated by an example.

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Basone, Francesco, Oreste S. Bursi, Fabrizio Aloschi, and Günter Fischbach. "Vibration mitigation of an MDoF system subjected to stochastic loading by means of hysteretic nonlinear locally resonant metamaterials." Scientific Reports 11, no. 1 (May 6, 2021). http://dx.doi.org/10.1038/s41598-021-88984-0.

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AbstractIn this paper, we intend to mitigate absolute accelerations and displacements in the low-frequency regime of multiple-degrees-of-freedom fuel storage tanks subjected to stochastic seismic excitations. Therefore, we propose to optimize a finite locally resonant metafoundation equipped with massive resonators and fully nonlinear hysteretic devices. The optimization process takes into account the stochastic nature of seismic records in the stationary frequency domain; the records are modelled with the power spectral density S0 and modified with a Kanai–Tajimi filter. Moreover, the massive superstructure of a fuel storage tank is also considered in the optimization procedure. To optimize the nonlinear behaviour of dampers, we use a Bouc–Wen hysteretic model; the relevant nonlinear differential equations are reduced to a system of linear equations through the stochastic equivalent linearization technique. The optimized system is successively verified against natural seismic records by means of nonlinear transient time history analyses. Finally, we determine the dispersion relations for the relevant periodic metafoundation.

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Fang, Chuangjie. "Frequency domain-based analytical framework for seismic performance of viscously damped outrigger systems based on continuous Timoshenko beam theory." Journal of Low Frequency Noise, Vibration and Active Control, March 29, 2023, 146134842311665. http://dx.doi.org/10.1177/14613484231166523.

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This paper proposes a frequency domain-based analytical framework for seismic performance of viscously damped outrigger systems. Based on a core–outrigger–damper–column simplified model, the global dynamic stiffness matrix is assembled from the core modeled as a Timoshenko beam, damped outriggers as complex rotational stiffness comprising outriggers, dampers, and perimeter columns, and inherent damping using Leung’s theory and modal damping construction. A general numerical method combining Wittrick-Williams algorithm and Newtonian iteration is developed to study the dynamic characteristic of such systems with multiple damped outriggers. The fast Fourier transformation (FFT) and the inverse Fourier transformation (IFFT) are then integrated with the principle of potential energy to obtain the equivalent nodal force and thus the time history response by transformations between time and frequency domains. Finally, the stochastic analysis is conducted via the transfer function resulting from the global stiffness matrix with the stochastic seismic excitation following Kanai-Tajimi spectrum. The proposed approach is verified by comparison with the finite element method through a case study of a tall building implemented with viscously damped outriggers. This study shows that the proposed analytical framework could serve as a powerful tool for evaluating the performance of viscously damped outrigger systems.

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Bamer, Franz, Denny Thaler, Marcus Stoffel, and Bernd Markert. "A Monte Carlo Simulation Approach in Non-linear Structural Dynamics Using Convolutional Neural Networks." Frontiers in Built Environment 7 (May 3, 2021). http://dx.doi.org/10.3389/fbuil.2021.679488.

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The evaluation of the structural response statistics constitutes one of the principal tasks in engineering. However, in the tail region near structural failure, engineering structures behave highly non-linear, making an analytic or closed form of the response statistics difficult or even impossible. Evaluating a series of computer experiments, the Monte Carlo method has been proven a useful tool to provide an unbiased estimate of the response statistics. Naturally, we want structural failure to happen very rarely. Unfortunately, this leads to a disproportionately high number of Monte Carlo samples to be evaluated to ensure an estimation with high confidence for small probabilities. Thus, in this paper, we present a new Monte Carlo simulation method enhanced by a convolutional neural network. The sample-set used for this Monte Carlo approach is provided by artificially generating site-dependent ground motion time histories using a non-linear Kanai-Tajimi filter. Compared to several state-of-the-art studies, the convolutional neural network learns to extract the relevant input features and the structural response behavior autonomously from the entire time histories instead of learning from a set of hand-chosen intensity inputs. Training the neural network based on a chosen input sample set develops a meta-model that is then used as a meta-model to predict the response of the total Monte Carlo sample set. This paper presents two convolutional neural network-enhanced strategies that allow for a practical design approach of ground motion excited structures. The first strategy enables for an accurate response prediction around the mean of the distribution. It is, therefore, useful regarding structural serviceability. The second strategy enables for an accurate prediction around the tail end of the distribution. It is, therefore, beneficial for the prediction of the probability of failure.

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Acosta, Andrés A., Eduardo Miranda, and Gregory G. Deierlein. "Response spectrum method for structures subjected to vertical ground motions: Absolute acceleration method." Earthquake Engineering & Structural Dynamics, August 8, 2023. http://dx.doi.org/10.1002/eqe.3988.

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AbstractAlthough a wide variety of response spectrum methods have been developed to estimate peak horizontal building responses, much less attention has been devoted to study the applicability of those methods for the vertical direction or to develop new methods to estimate peak vertical building responses. Vertical building responses can be significant for structures located close to the earthquake rupture, and for buildings with fundamental period of vibration within the range of most energy content of the vertical component of the ground motion (typically 0.05 to 0.15 s). The frequency content of the vertical component is significantly different to that in the horizontal components; thus, it is not clear if previous methods are applicable. We present a new alternative response spectrum analysis (RSA) method to estimate absolute accelerations in the vertical direction, which is a modified version of a previously studied modal combination rule developed for the horizontal components of motion. This formulation is derived based on the use of modal absolute accelerations, and we compare it to the traditional complete quadratic combination (CQC). In the proposed method, we develop simplified equations to estimate the necessary correlation coefficients for the vertical direction which are calibrated to fit empirical correlations computed from the vertical response of single degree of freedom systems subjected to a set of 90 vertical components of recorded ground motions. We also compute these correlations by using an improved power spectral density (PSD) function, which is as an enhanced version of the modified Kanai‐Tajimi PSD to represent the frequency content in the vertical direction which differs from that in the horizontal direction. To evaluate the proposed modal combination rule, we compare the RSA results to those obtained using response history analyses (RHA) of peak responses for a simplified model consisting of a prismatic bar fixed only at one end, as well as for 2D frames. We show that the proposed modal combination rule can estimate peak building responses with higher accuracy than the commonly used CQC modal combination rule, for any general building configuration at any structural location.

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