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    A New Tuned Mass Damper Design Method based on Transfer Functions
    (Korean Society Of Civil Engineers-Ksce, 2019) Cetin, Huseyin; Aydin, Ersin
    Tuned mass damper (TMD) is an effective passive device in reducing harmful vibrations as long as they are designed correctly. An optimal TMD design method is proposed based on transfer functions and also differential evolution (DE) algorithm is used. The method includes optimization of all parameters which are the mass, stiffness and damping coefficients of a TMD. By using random vibration theory, the mean-square of top floor absolute acceleration, top floor displacement and the sum of mean-squares of interstorey drifts have been chosen as objective functions to be minimized with respect to upper and lower limits of TMD parameters. In the classical design, the mass is usually chosen by the designer to find the optimum values of the stiffness and damping coefficient. In addition to optimizing stiffness and damping coefficients, in this study TMD mass quantity is also optimized by using DE algorithm to minimize objective functions for TMD design. After that, structure system with TMD is tested under six near fault and three far fault ground motions by evaluating responses of the structure. The results obtained here are compared with the methods available in the literature for verification. Numerical results show that the proposed method is effective for optimal TMD design.
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    A Novel Design Method of Single TMD Exposed to Seismic Effects
    (CRC Press, 2023) Cetin, Huseyin; Aydin, Ersin; Ozturk, Baki
    A tuned mass damper (TMD) can be an effective passive device for decreasing hazardous vibrations, when it is properly designed. In this chapter, the differential evolution (DE) algorithm is used to suggest an optimal TMD design technique based on transfer functions. Random vibration theory and the probabilistic critical excitation method are used to generate the governing equations in the frequency domain. The process involves optimizing all of a TMD's properties, including mass, stiffness, and damping coefficients. The mean-square of top floor absolute acceleration and top floor displacement have been chosen as objective functions to be minimized with respect to the upper and lower limits of TMD parameters. Shear building models with single and multiple TMD are tested using different earthquake acceleration records in order to understand the performance of the suggested technique. In addition, the findings are compared to those of other studies in the literature. © 2024 selection and editorial matter, Ehsan Noroozinejad Farsangi, Mohammad Noori, Tony T.Y. Yang, Paulo B. Lourenço, Paolo Gardoni, Izuru Takewaki, Eleni Chatzi, and Shaofan Li; individual chapters, the contributors.
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    DESIGN OF VISCO-ELASTIC SUPPORTS FOR TIMOSHENKO CANTILEVER BEAMS
    (Konya Teknik Univ, 2023) Aydin, Ersin; Kebeli, Yunus Emre; Cetin, Huseyin; Ozturk, Baki
    The appropriate design of supports, upon which beams are usually placed as structural components in many engineering scenarios, has substantial significance in terms of both structural efficacy and cost factors. When beams experience various dynamic vibration effects, it is crucial to contemplate appropriate support systems that will effectively adapt to these vibrations. The present work investigates the most suitable support configuration for a cantilever beam, including viscoelastic supports across different vibration modes. Within this particular framework, a cantilever beam is simulated using beam finite elements. The beam is positioned on viscoelastic supports, which are represented by simple springs and damping elements. These supports are then included in the overall structural model. The equation of motion for the beam is first formulated in the temporal domain and then converted to the frequency domain via the use of the Fourier Transform. The basic equations used in the frequency domain are utilized to establish the dynamic characteristics of the beam by means of transfer functions. The determination of the ideal stiffness and damping coefficients of the viscoelastic components is achieved by minimizing the absolute acceleration at the free end of the beam. In order to minimize the objective function associated with acceleration, the nonlinear equations derived from Lagrange multipliers are solved using a gradient-based technique. The governing equations of the approach need partial derivatives with respect to design variables. Consequently, analytical derivative equations are formulated for both the stiffness and damping parameters. The present work introduces a concurrent optimization approach for both stiffness and damping. Passive constraints are established inside the optimization problem to impose restrictions on the lower and higher boundaries of the stiffness and damping coefficients. On the other hand, active constraints are used to ascertain the specific values of the overall stiffness and damping coefficients. The efficacy of the established approach in estimating the ideal spring and damping coefficients of viscoelastic supports and its ability to provide optimal support solutions for various vibration modes have been shown via comparative experiments with prior research.
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    On the Efficacy of a Novel Optimized Tuned Mass Damper for Minimizing Dynamic Responses of Cantilever Beams
    (Mdpi, 2022) Ozturk, Baki; Cetin, Huseyin; Dutkiewicz, Maciej; Aydin, Ersin; Farsangi, Ehsan Noroozinejad
    This study examines the optimal design of a tuned mass damper (TMD) in the frequency domain so that the dynamic response of cantilever beams can be decreased. Random vibration theory is applied to identify the mean square acceleration of the endpoint of a cantilever beam as the objective function to be reduced. In addition, to determine the optimal TMD coefficient of mass, stiffness, and damping, a differential evolution (DE) optimization algorithm is employed. The upper and lower limit values of these parameters are taken into account. A majority of the previous studies have concentrated on determining just the stiffness and damping parameters of TMD. Nonetheless, in this study there is also the optimization of TMD mass parameters to determine the mass quantity. In addition, there has been inefficient use of the stochastic DE optimization algorithm method for the optimization of TMD parameters in previous studies. Hence, to obtain optimal TMD parameters, this algorithm is precisely used on the objective function. Tests are carried out on the cantilever beam with the TMD system following this optimization method with harmonic base excitations that resonate the foremost modes of the beam and white noise excitation. The method proposed here is reasonably practical and successful regarding the optimal TMD design. When a TMD is designed appropriately, the response of the cantilever beam under dynamic interactions undergoes a considerable reduction.
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    Optimal Design and Distribution of Viscous Dampers for Shear Building Structures Under Seismic Excitations
    (Frontiers Media Sa, 2019) Cetin, Huseyin; Aydin, Ersin; Ozturk, Baki
    Viscous dampers (VDs) are effective and widely used passive devices for the protection of civil structures, provided that appropriate design is carried out. For this purpose, optimal design and optimum distribution of VDs method are presented for a shear building under the critical excitation by using random vibration theory in the frequency domain. In the optimization, by using Differential Evolution (DE) algorithm and the top floor displacement are evaluated as objective functions taking into consideration upper and lower limits of VDs damping coefficients, so that optimal damper placement and properties of the shear building can be determined. In this design, the VDs-shear building system is tested under the three different ground motions being compared to some methods in the literature and uniformly distributed VDs placed at each story. It is shown that the results of the study are both compatible and very successful in reducing the response of the structure under the different ground motions.
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    Optimal viscous damper placement to prevent pounding of adjacent buildings
    (European Association for Structural Dynamics, 2020) Cetin, Huseyin; Ozturk, Baki; Aydin, Ersin
    Structural pounding is prevalent in general during earthquake shaking for adjacent structures in earthquake prone cities. In this study, the prevention of pounding effect is targeted by the optimal placement of viscous damping elements within the adjacent buildings. One of the important reasons of the pounding phenomenon is the out of phase vibrations of adjacent structures. A couple of adjacent structures which have different heights are modeled as shear buildings to set the proposed method. The relative displacement, defined as the extraction of horizontal displacements of adjacent structures at the top level of the shorter building, are chosen as the objective function to be minimized. In addition, reduction of relative displacement of the buildings and the effects of various vibration characteristics of each building is investigated based on transfer functions. Equations of motion of a structure, which are uncoupled when each structure is considered alone, become coupled when damping elements are placed in between the adjacent structures. The first mode response of the structures is considered while the transfer function response is derived. Optimal designs are determined for different total damping levels and different vibration characteristics of adjacent structures. The results of numerical analyses reveal that optimal designs effectively decrease the relative displacements between adjacent structures. Optimal designs are compared with the uniform design and without damper cases. The numerical analyses show that the proposed optimal damper design method in this study is vigorously effective for the prevention of pounding of adjacent buildings. © 2020 European Association for Structural Dynamics. All rights reserved.
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    Optimum vertical location and design of multiple tuned mass dampers under seismic excitations
    (Elsevier Science Inc, 2022) Ozturk, Baki; Cetin, Huseyin; Aydin, Ersin
    An efficient optimum vertical location and design method of multiple tuned mass dampers (MTMDs) is proposed in order to reduce the response of building structures under seismic excitation. Governing equations are derived in frequency domain in terms of random vibration theory and probabilistic critical excitation method. In order to determine the location and optimum parameters of each tuned mass damper (TMD) which are mass, stiffness and damping coefficient, both top storey mean square absolute acceleration and displacement of shear building are chosen as the objective functions to be minimized via Differential Evolution (DE) optimization method. It is assumed that there is one TMD on each storey at the initial stage of the method. During the optimization, if the mass or stiffness parameters convergence to zero on a specific storey, then TMD is eliminated, so that optimum placement can be achieved. The sum of the critical effects corresponding to the selected bandwidths in the first, second and third frequency peak regions of the structure is taken into account, thus the high mode behaviors are also controlled. In order to understand the performance of proposed method, shear building model with multiple TMD is tested using different earthquake acceleration records and the findings are compared with some other studies available in the literature. The results show that the optimal MTMD design obtained from proposed method is very effective in reducing the dynamic response of building structure.
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    Optimum Viscous Damper Distribution for Seismic Rehabilitation of Building Structures with Soft Story Irregularity
    (Springer Science and Business Media Deutschland GmbH, 2024) Koroglu, Arcan; Ozturk, Baki; Cetin, Huseyin; Aydin, Ersin
    Viscous dampers (VDs) are remarkably effective passive energy dissipation devices successfully implemented in building structures to reduce seismic demands during earthquake excitations. Viscous dampers can be utilized to enhance the resilience of structures against earthquake excitations. Besides that, they can be used for seismic rehabilitation of existing structures. Viscous dampers influence the dynamic response of the building structures that they are attached to; therefore, their allocation is vital. Furthermore, the optimum design of viscous dampers is another critical concept since they are expensive devices; thus, their optimum distribution results in a more economical method. This study suggests a methodology to rehabilitate existing building structures with soft story irregularities via optimum viscous damper distribution using the Particle Swarm Optimization (PSO) algorithm. Soft story irregularity causes significantly large peak inter-story drift ratios (IDR) and abrupt changes in peak inter-story drift ratios between adjacent stories. The primary objective of this study is to limit the peak inter-story drift ratios to an allowable limit. In the scope of this study, the suggested procedure was tested on shear buildings with soft story irregularity under different earthquake ground motions. The results of this study show that it is possible to keep peak inter-story drift ratios at an allowable limit with an optimum viscous damper distribution for shear buildings with soft story irregularity. Moreover, this study shows that the Particle Swarm Optimization algorithm can be successfully implemented on optimum viscous damper design problems in building structures. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.