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- MakaleYalnız künye2022Optimization of multiple tuned mass dampers for a two-span continuous railway bridge via differential evolution algorithm
Araz, Onur; Kahya, Volkan
The study aims at proposing a methodology for optimization of multiple tuned mass dampers (MTMD) in reducing the multi-resonance vibrations of continuous bridges due to moving train loads. The equations of motion for time-domain analysis are derived for obtaining train-induced vibrations of a two-span continuous railway bridge with equipped MTMD-1 and MTMD-2 devices when the vehicle-bridge interaction (VBI) is considered. The bridge and the train are modeled as a Bernoulli-Euler beam with constant section and a series of moving sprung masses of identical length, respectively. To reduce the multiple resonance vibrations of a two-span continuous railway bridge, the MTMD-1 and MTMD-2 are tuned to the first mode and the second mode of the bridge, and they are attached to the midspan of each span, respectively. The optimum parameters of the both MTMD systems are investigated using the differential evolution (DE) method. The criterion chosen to obtain the optimum parameters is the minimization of the first two resonance peaks of the bridge. The influence of the different mass ratios and the number of TMD units in the MTMD system on the optimum parameters of the both MTMD systems and corresponding displacement responses of the bridge are also investigated. The results show that the VBI effect does not have much effect on the resonant train speeds and the control performance of TMDs. Therefore, the optimum parameters of TMDs can be obtained quickly by modeling the train as a series of moving forces for the vibration control of railway bridges.
- MakaleAçık Erişim2021Optimization of non-traditional tuned mass damper for damped structures under harmonic excitation
Kahya, Volkan; Araz, Onur
Tuned mass dampers (TMDs) are used to reduce dynamic vibrations of structures under environmental loads such as wind or seismic excitation. In this paper, the optimum design of nontraditional tuned mass dampers (NT-TMD) attached to a damped main structure under harmonic excitation was investigated. Unlike the traditional TMD, the damping element in NT-TMD is directly connected to the ground. In this study, the effectiveness of NT-TMD on the attenuation of vibrations on the damped main system under harmonic load is investigated. The optimum parameters of the NT-TMD are obtained by using the hybrid pattern search (HPS) technique. According to numerical results, it is seen that non-traditional TMD is more effective than traditional TMD in reducing vibration.
- MakaleYalnız künye2021Design of series tuned mass dampers for seismic control of structures using simulated annealing algorithm
Araz, Onur; Kahya, Volkan
The effectiveness of the series tuned mass dampers (STMDs) in reducing the dynamic vibrations of the structures under the ground motion is investigated, and their optimum parameters are obtained based on the simulated annealing (SA) optimization. The STMD is one of the most well-known passive control devices which consists of two TMD units arranged in series. However, only a few studies are available on the control performance and optimum parameters of the STMDs for structural systems subjected to ground motion. Thus, the goal of this study is to carry out a thorough optimization analysis based on the SA algorithm for the structures equipped with an STMD under the effect of ground motion. The objective function is selected as the reduction of the displacement response of the structure. It is proved that the optimum STMD has better effectiveness than the optimum TMD in suppressing the maximum story displacement of the structure. Further, the effect of the frequency shift on the effectiveness of the optimally designed STMD is investigated.
- MakaleYalnız künye2020Series tuned mass dampers in vibration control of continuous railway bridges
Araz, Onur; Kahya, Volkan
This paper presents the applicability of series tuned mass dampers (STMDs) to reduce the multiple resonant responses of continuous railway bridges under high-speed train. The bridge is modeled by two-span Bernoulli-Euler beam with uniform cross-section, and a STMD device consisting of two TMD units installed on the bridge to reduce its multiple resonant vibrations. The system is assumed to be under the action of a high-speed train passage which is modeled as a series of moving forces. Sequential Programming Technique (SQP) is carried out to find the optimal parameters of the STMD that minimizes the maximum peak responses of the bridge. Comparisons with the results available in the literature are presented to demonstrate the effectiveness and robustness of STMD system in reducing the multiple resonant responses of the continuous railway bridges under high-speed trains.
- MakaleAçık Erişim2020A simple design method for multiple tuned mass dampers in reduction of excessive vibrations of high-speed railway bridges; [Yüksek hızlı demiryolu köprülerinde aşırı titreşimlerin azaltılmasında paralel bağlı ayarlı kütle sönümleyiciler için basit bir tasarım yöntemi]
Kahya, Volkan; Araz, Onur
In this study, a simple method is proposed to obtain the optimum design parameters of vibration absorbers consisting of several tuned mass damper units connected each other in parallel. The method is essentially the extension of the formulas proposed by Den Hartog for single degree-of-freedom tuned mass dampers to multiple tuned mass dampers. To demonstrate the effectiveness of the proposed method, an application to high-speed rail bridges are made. The bridge is modeled as a simple Euler-Bernoulli beam, and the train is modeled as a series of moving loads. The equations of motion are solved numerically by the Newmark method. The results of the study showed that multiple tuned mass dampers designed by the proposed method show good performance in reducing the resonance vibrations in high-speed rail bridges.
- MakaleYalnız künye2019A SEQUENTIAL APPROACH BASED DESIGN OF MULTIPLE TUNED MASS DAMPERS UNDER HARMONIC EXCITATION
Kahya, Volkan; Araz, Onur
This study evaluates the response reduction effect of single-degree-of-freedom (SDOF) primary systems with multiple tuned mass dampers (MTMDs) under harmonic excitation. To design MTMD, TMD properties are re-calibrated based on the natural frequencies of the system on which the number of TMDs is one less than the current system. This is a sequential approach that does not require any iteration for each step. Instead it requires starting from the case with single TMD, and then increasing the numbers of TMDs one more at a time until the desired number is reached. Using the obtained design parameters, the effectiveness and robustness of the MTMDs are studied in comparison to MTMDs designed by previous works available in the literature. As a result, the proposed design procedure produces an effective multiple tuned mass damper to be utilized in a SDOF system under harmonic excitation. Additionally, the proposed approach provides a simple way to design the MTMD system than the traditional optimization methods, thus it significantly reduces the computation effort in the design process.
- MakaleAçık Erişim2018Effects of manufacturing type on control performance of multiple tunedmass dampers under harmonic excitation
Kahya, Volkan; Araz, O.
Using different optimization techniques, the optimum characteristics of multiple tuned mass dampers (MTMD) for reducing the dynamic response of primary structure due to various excitations are studied by many researchers. In this paper, the five practical MTMD models are considered which consist of different combinations of the mass, damping, stiffness coefficient and damping ratio in the MTMD. The criteria selected for the optimality is the minimization of the maximum value of the displacement dynamic magnification factor (DMF) of the primary structure with the MTMD system under external harmonic excitation. The optimum parameters of the MTMD systems are investigated using Sequential Quadratic Programming (SQP). Results obtained illustrate that the optimum MTMD-1 and MTMD-4 have nearly the same control performance and provide higher effectiveness than all the other types of MTMDs of the same mass ratio in reducing the displacement response of primary structure. Finally, a robustness analysis of optimally designed MTMD systems to investigate their performance under errors in the tuned frequencies is also performed in detail.
- MakaleYalnız künye2017Series tuned mass dampers in train-induced vibration control of railway bridges
Kahya, Volkan; Araz, Onur
This paper presents the series multiple tuned mass dampers (STMDs) to suppress the resonant vibrations of railway bridges under the passage of high-speed trains (HSTs). A STMD device consisting of two spring-mass-damper units connected each other in series is installed on the bridge. In solution, bridge is modeled as a simply-supported Euler-Bernoulli beam with constant cross-section, and vehicle is simulated as a series of moving forces with constant speed. By the assumed mode method, the governing equations of motion of the beam-TMD device coupled system traversed by a moving train are obtained. The optimum values for the parameters of the STMD device are obtained for the criterion based on the minimization of the maximum dynamic displacement of the beam at its midspan. Single TMD and multiple TMDs in parallel are also considered for demonstration of the STMD device's performance. The results show that STMDs are effective in bridge vibration suppression and robust to parameters' change in the main system and the absorber itself.
- MakaleYalnız künye2015RESONANT VIBRATIONS OF TWO-SPAN RAILWAY BRIDGES UNDER HIGH-SPEED TRAINS
Kahya, Volkan; Araz, Onur; Turan, Muhittin
In this study, resonant vibrations of two-span railway bridges subjected to high-speed trains (HSTs) are studied. The continuous beam is modelled by using Bernoulli-Euler beam theory, and the train is considered as a series of moving concentrated loads. The dynamic response is obtained analytically by using the assumed mode method. Effects of the speed parameter and the span to car length ratio on the response are examined. Numerical results show that the above mentioned parameters play very important role on the dynamic behavior of two-span bridges.