• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.141-148
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• 2002

MR 유체 감쇠기는 구조물의 진동을 감소시키기 위한 가장 유망하고 새로운 제진 (制振) 장치 중 하나이다. 이 장치는 기계적인 단순성, 높은 동적 범위, 적은 전력 요구량, 커다란 감쇠 능력, 강인성 등의 장점을 가지고 있기 때문에, 토목 구조 시스템의 내진(耐震) 및 내풍(耐風) 성능을 향상시키는데 매우 유용하다. 많은 연구자들이 MR 유체 감쇠기의 유사-정적 모델을 연구했지만 그 모델이 감쇠기의 설계를 위해서는 유용하다고 하더라도, 동적 하중에 대한 감쇠기의 거동을 모사하는 데는 충분하지 않다. 논문에서는 대용량 20톤 MR 유체 감쇠기의 동적하중에 대한 응답 해석 결과를 이용하여, Bouc-Wen 모델을 기반으로 하는 새로운 역학적 모델을 제안하였다. 이 모델은 MR 유체의 stiction현상과 관성 및 shear thinning 효과를 잘 묘사한다. 또한, 제안된 MR 유체 감쇠기의 동적 모델이 실험 결과와 매우 잘 일치함을 보였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.149-156
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• 2002

This paper examines the ASCE first generation benchmark problem for a seismically excited cable-stayed bridge, and proposes a new semi-active control strategy focusing on inclusion of effects of control- structure interaction. In this study, magnetorheological (MR) fluid dampers, which belong to the class of controllable fluid dampers, are proposed as the supplemental damping devices, and a clipped-optimal control algorithm, shown to perform well in previous studies involving MR fluid dampers, is employed. The dynamic model for MR fluid dampers is considered as a modified Bouc-Wen model, which is obtained from data based on experimental results for large-scale dampers. Numerical results show that the performance of the proposed semi-active control strategy using MR fluid dampers is quite effective.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.662-665
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• 2004

In this paper, based on shaking table test results on a seismically isolated bridge model, an inelastic numerical model is refined by using Bouc-Wen model representing the hysteretic behavior of isolators. Seismic responses of isolated bridges are numerically investigated varying with relative stiffness ratios, which is a ratio of the effective stiffness of isolator to the lateral stiffness of bridge pier. From the results, it is found that an adequate range of relative stiffness ratio could be defined for seismic design of isolated bridges without considering the flexibility of piers.

• Steel and Composite Structures
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• 제33권2호
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• pp.277-298
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• 2019

Concrete filled steel tubular (CFST) column joints with composite beams have been widely used as lateral loading resisting elements in civil infrastructure. To better utilize these innovative joints for the application of structural seismic design and analysis, it is of great importance to investigate the dynamic behavior of the joint under cyclic loading. With this aim in mind, a novel phenomenal model has been put forward in this paper, in which a Bouc-Wen hysteresis component is employed to portray the strength and stiffness deterioration phenomenon caused by increment of loading cycle. Then, a modified chicken swarm optimization algorithm was used to estimate the optimal model parameters via solving a global minimum optimization problem. Finally, the experimental data tested from five specimens subjected to cyclic loadings were used to validate the performance of the proposed model. The results effectively demonstrate that the proposed model is an easy and more realistic tool that can be used for the pre-design of CFST column joints with reduced beam section (RBS) composite beams.

• Earthquakes and Structures
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• 제22권2호
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• pp.147-155
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• 2022

Regarding the importance of seismic pounding, the available standards and guidelines specify minimum separation distance between adjacent buildings. However, the rules in this field are generally based on some simple assumptions, and the level of confidence is uncertain. This is attributed to the fact that the relative response of adjacent structures is strongly dependent on the frequency content of the applied records and the Eigen frequencies of the adjacent structures as well. Therefore, this research aims at investigating the separation distance of the buildings through a probabilistic-based algorithm. In order to empower the algorithm, the record-to-record uncertainties, are considered by probabilistic approaches; besides, a wide extent of material nonlinear behaviors can be introduced into the structural model by the implementation of the hysteresis Bouc-Wen model. The algorithm is then simplified by the application of the linearization concept and using the response acceleration spectrum. By implementing the proposed algorithm, the separation distance in a specific probability level can be evaluated without the essential need of performing time-consuming dynamic analyses. Accuracy of the proposed method is evaluated using nonlinear dynamic analyses of adjacent structures.

• Steel and Composite Structures
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• 제43권2호
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• pp.153-164
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• 2022

In this study, a series of cyclic loading tests were performed on viscoelastic dampers (VED) composed of viscoelastic polymer composite material and thin steel plates to observe the variation of the mechanical properties under different loading conditions. A mathematical model was developed based on the Kelvin-Voigt and Bouc-Wen models to formulate the nonlinear force-displacement relationship of the viscoelastic damper. The accuracy of the proposed mathematical model was verified using the data obtained from the tests. The mathematical model was applied to analyze a reinforced concrete framed structure retrofitted with viscoelastic dampers. Nonlinear dynamic analysis results showed that the average maximum inter-story drift ratios of the retrofitted structure met the target limit state after installing the VED. In addition, both the maximum and residual displacements were significantly reduced after the installation of the VED.

• Steel and Composite Structures
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• 제47권5호
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• pp.587-599
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• 2023

The establishment of a hysteretic model which can accurately predict the hysteretic characteristics of the stud connection is of utmost importance for the seismic assessment of composite structures. In this paper, the Bouc-Wen-Baber-Noori(BWBN) model was adopted to describe the typical hysteretic characteristics of stud connections. Meanwhile, the Newton-Raphson iterative procedure and the Backward Euler method were used to determine the restoring force, and the Genetic Algorithm was employed to identify the parameters of the BWBN model based on the experimental data consisting of eight specimens. The accuracy of the identified parameters was demonstrated by comparison with the experimental data. Finally, prediction equations for the BWBN model parameters were developed in terms of the physical parameters of stud connections, which provides an approach to get the hysteretic response of stud connections conveniently.

• Smart Structures and Systems
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• 제33권2호
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• pp.133-143
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• 2024

Piezoelectric (PZT) actuators have been widely used in precision positioning fields for their excellent displacement resolution. However, due to the inherent characteristics of piezoelectric actuators, hysteresis has been proven to greatly reduce positioning performance. In this paper, five mathematical hysteretic models based on activation function are proposed to characterize the nonlinear hysteresis characteristics of piezoelectric actuators. Then the performance of the proposed models is verified by particle swarm optimization (PSO) algorithm and the experiment data. Thirdly, the fitting performance of the proposed models is compared with the classical Bouc-Wen model. Finally, the performance of the five proposed models in modelling hysteresis nonlinearity of piezoelectric drivers is compared, in terms of RMSE, MAPE, SAPE and operation efficiency, and relevant suggestions are given.

• Earthquakes and Structures
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• 제7권2호
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• pp.119-139
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• 2014

A new method is proposed for random vibration anaylsis of hysteretic systems subjected to non-stationary random excitations. With the Bouc-Wen model, motion equations of hysteretic systems are first transformed into quasi-linear equations by applying the concept of equivalent excitations and decoupling of the real and hysteretic displacements, and the derived equation system can be solved by either the precise time integration or the Newmark-${\beta}$ integration method. Combining the numerical solution of the auxiliary differential equation for hysteretic displacements, an explicit iteration algorithm is then developed for the dynamic response analysis of hysteretic systems. Because the computational cost for a large number of deterministic analyses of hysteretic systems can be significantly reduced, Monte-Carlo simulation using the explicit iteration algorithm is now viable, and statistical characteristics of the non-stationary random responses of a hysteretic system can be obtained. Numerical examples are presented to show the accuracy and efficiency of the present approach.

• Earthquakes and Structures
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• 제12권3호
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• pp.285-296
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• 2017

Base isolation is a quite practical control strategy for enhancing the response of structural systems induced by strong ground motions. Due to the dynamic effects of base isolation systems, reduction in the interstory drifts of the superstructure is often achieved at the expense of high base displacement level, which may lead to instability of the structure or non-practical designs for the base isolators. To reduce the base displacement, several hybrid structural control strategies have been studied over the past decades. This study investigates a particular strategy that employs Tuned Mass Dampers (TMDs) for improving the performance of base-isolated structures and unlike previous studies, specifically focuses on the effectiveness of this hybrid control strategy in structures that are equipped with nonlinear base isolation systems. To consider the nonlinearities of base isolation systems, a Bouc-Wen model is selected and nonlinear dynamic OpenSees models are used to perform several time-history simulations in time and frequency domains. Through these numerical simulations, the effects of several parameters such as the fundamental period of the structure, dynamic properties of the TMD and isolation systems and properties of the input ground motion on the behaviour of TMD-structure-base isolation systems are examined. The results of this study provide a better insight into the performance of linear shear-story structures with nonlinear base isolators and show that there are many scenarios in which TMDs can still improve the performance of these systems.