Vibration control of suspension bridge due to vertical ground motions

2020 ◽  
Vol 23 (12) ◽  
pp. 2626-2641
Author(s):  
Seyed Hossein Hosseini Lavasani ◽  
Hamed Alizadeh ◽  
Rouzbeh Doroudi ◽  
Peyman Homami
Keyword(s):  
Active Control ◽  
Passive Control ◽  
Ground Motions ◽  
Tuned Mass Damper ◽  
Suspension Bridges ◽  
Control Force ◽  
Wide Range ◽  
Mass Damper

Suspension bridges due to their long span can experience large displacement response under dynamic loading like earthquakes. Unlike other structures, their vertical vibration may make remarkable difficulty that a control strategy seems to be essential. Tuned mass damper is a passive control system that can be changed to active one by adding an external source producing the active control force called active tuned mass damper. Unlike passive systems, active ones need a controller system affecting the performance of them considerably. In this study, the efficiency of tuned mass damper and active tuned mass damper are investigated in the bridges. Two controllers, fuzzy type 2 and fuzzy type 1, are used to estimate control force of active tuned mass damper. Tuned mass damper’s parameters are optimized under wide range of ground motions. Also, fuzzy type 2 and fuzzy type 1’s parameters are optimized under the influence of three different conditions containing far-field and near-field ground motions and also combination of them. In addition, Lion Pride Optimization Algorithm is selected for optimizing section. Numerical analysis indicates that active tuned mass damper is more effective than tuned mass damper, and also active tuned mass damper does not make any instability matter of concern in active control systems. Furthermore, performance of fuzzy type 2 is better than fuzzy type 1.

Semi-active seismic control of an 11-DOF building model with TMD+MR damper using type-1 and -2 fuzzy algorithms

2017 ◽  
Vol 24 (13) ◽  
pp. 2938-2953 ◽  
Author(s):  
Akbar Bathaei ◽  
Seyed Mehdi Zahrai ◽  
Meysam Ramezani
Keyword(s):  
Active Control ◽  
Structural Damage ◽  
Structural Control ◽  
Passive Control ◽  
Fuzzy Controller ◽  
Mr Damper ◽  
Control Force ◽  
Building Model

Nowadays, vibration control of structures is considered as a challenging field among scientists and engineers. Structural damage and financial losses due to recent earthquakes in different countries have more than ever before accentuated the importance of controlling earthquake-induced vibrations. In recent years, semi-active control has been introduced as an efficient and reliable type of structural control which provides the reliability of passive control and flexibility of active control systems at the same time. In this study, the performance of a semi-active tuned mass damper (TMD) with adaptive magnetorheological (MR) damper is investigated using type-1 and -2 fuzzy controllers for seismic vibration mitigation of an 11-degree of freedom building model. The TMD is installed on the roof and the MR damper is located on the 11th story. The MR damper has a capacity of producing a 1000 kN control force. The fuzzy system is designed based on the acceleration and velocity of the top floor determining the input voltage needed to produce the control force based on accelerating or decelerating movements of structure. The seismic performance of semi-active type-2 controller, which considers the uncertainties related to input variables, is higher than that of the type-1 fuzzy controller. The type-2 fuzzy controller is capable of reducing further the maximum displacement, acceleration, and base shear of the structure by 11.7, 14, and 11.2%, respectively, compared to the type-1 fuzzy controller.

Optimizing tuned mass damper parameters to mitigate the torsional vibration of a suspension bridge under pulse-type ground motion: A sensitivity analysis

2019 ◽  
Vol 26 (11-12) ◽  
pp. 1054-1067 ◽  
Author(s):  
Seyyed Hossein Hossein Lavassani ◽  
Hamed Alizadeh ◽  
Peyman Homami
Keyword(s):  
Sensitivity Analysis ◽  
Torsional Vibration ◽  
Passive Control ◽  
Suspension Bridge ◽  
Tuned Mass Damper ◽  
Gyration Radius ◽  
Suspension Bridges ◽  
Torsional Mode ◽  
Mass Damper ◽  
Pulse Type

Suspension bridges are structures that because of their long span and high flexibility can be prone to ambient vibrations such as ground motions. They can experience high amplitude vibrations in torsional mode during an earthquake, where a vibration control strategy seems necessary. Recently, control systems have been widely used to mitigate vibration of structures. Tuned mass damper is a passive control system. Its performance and effectiveness have been verified both theoretically and practically. In this study, a tuned mass damper system is used to mitigate the torsional vibration of a suspension bridge. The Vincent Thomas suspension bridge is selected as a case study, and its response is reduced by a tuned mass damper under ten pulse-type records from 10 major worldwide earthquakes. By using sensitivity analysis, a parametric study is carried out to optimize tuned mass damper parameters, namely, mass ratio, gyration radius, tuning frequency, and damping ratio according to the maximum reduction of the response maxima. Finally, the optimum range of each parameter that can give the best performance and provide both operational and economic justification for the implementation of the project is suggested. The numerical results indicate that the optimized tuned mass damper system can substantially reduce the maximum response and vibration time.

scholarly journals Lyapunov-Based Control for Suppression of Wind-Induced Galloping in Suspension Bridges

2011 ◽  
Vol 2011 ◽  
pp. 1-23 ◽  
Author(s):  
Naif B. Almutairi ◽  
Mohamed Zribi ◽  
Mohamed Abdel-Rohman
Keyword(s):  
Bridge Deck ◽  
Suspension Bridge ◽  
High Amplitude ◽  
Tuned Mass Damper ◽  
Suspension Bridges ◽  
Control Force ◽  
Controlled System ◽  
Mass Damper ◽  
Suspended Cables ◽  
Simulation Results

This paper investigates the suppression of galloping in a suspension bridge due to wind loads. The galloping phenomenon can be destructive due to the high-amplitude oscillations of the structure. Two controllers are proposed to generate the control force needed to suppress the vertical galloping in the suspended cables and in the bridge deck. SIMULINK software is used to simulate the controlled system. The simulation results indicate that the proposed controllers work well. In addition, the performance of the system with the proposed controllers is compared to the performance of the system controlled with a tuned mass damper.

AGN1 vs AGN2 dichotomy as seen from the point of view of ionized outflows

2019 ◽  
Vol 15 (S356) ◽  
pp. 96-96
Author(s):  
Eleonora Sani
Keyword(s):  
Accretion Rate ◽  
Point Of View ◽  
Emission Lines ◽  
Black Hole Mass ◽  
X Ray ◽  
Bolometric Luminosity ◽  
Wide Range ◽  
Strong Contrast

AbstractI present a detailed study of ionized outflows in a large sample of 650 hard X-ray detected AGN. Taking advantage of the legacy value of the BAT AGN Spectroscopic Survey (BASS, DR1), we are able to reveal the faintest wings of the [OIII] emission lines associated with outflows. The sample allows us to derive the incidence of outflows covering a wide range of AGN bolometric luminosity and test how the outflow parameters are related with various AGN power tracers, such as black hole mass, Eddington ratio, luminosity. I’ll show how ionized outflows are more frequently found in type 1.9 and type 1 AGN (50% and 40%) with respect to the low fraction in type 2 AGN (20%). Within such a framework, I’ll demonstrate how type 2 AGN outflows are almost evenly balanced between blue- and red-shifted winds. This, in strong contrast with type 1 and type 1.9 AGN outflows which are almost exclusively blue-shifted. Finally, I’ll prove how the outflow occurrence is driven by the accretion rate, whereas the dependence of outflow properties with respect to the other AGN power tracers happens to be quite mild.

scholarly journals Seismic Performance Analysis of a Connected Multitower Structure with FPS and Viscous Damper

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Xiaohan Wu ◽  
Jun Wang ◽  
Jiangyong Zhou
Keyword(s):  
Seismic Behavior ◽  
Passive Control ◽  
Time History ◽  
Tuned Mass Damper ◽  
Seismic Excitations ◽  
History Analysis ◽  
Mass Damper ◽  
Tower Structure ◽  
Design Requirements ◽  
Friction Pendulum

A high four-tower structure is interconnected with a long sky corridor bridge on the top floor. To reduce the earthquake responses and member forces of the towers and sky corridor bridge, a passive control strategy with a friction pendulum tuned mass damper (FPTMD) was adopted. The sky corridor bridge was as the mass of FPTMD. The connection between the towers and the sky corridor bridge was designed as flexible links, where friction pendulum bearings (FPBs) and viscous dampers were installed. Elastoplastic time-history analysis was conducted by using Perform-3D model to look into its seismic behavior under intensive seismic excitation. The optimal design of the FPTMD with varying friction coefficients and radius of friction pendulum bearing (FPB) under seismic excitations was carried out, and the seismic behavior of the structure was also investigated at the same time.Results show that, for this four-tower connected structure, the friction pendulum tuned mass damper (FPTMD) has very well effect on seismic reduction. The structure can meet the seismic resistance design requirements.

scholarly journals LQR Control of Wind Excited Benchmark Building Using Variable Stiffness Tuned Mass Damper

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
S. N. Deshmukh ◽  
N. K. Chandiramani
Keyword(s):  
Linear Time ◽  
Variable Stiffness ◽  
Tuned Mass Damper ◽  
Nonlinear Static Analysis ◽  
Performance Criteria ◽  
Control Law ◽  
Control Force ◽  
Displacement Control ◽  
Lqr Control ◽  
Mass Damper

LQR control of wind induced motion of a benchmark building is considered. The building is fitted with a semiactive variable stiffness tuned mass damper adapted from the literature. The nominal stiffness of the device corresponds to the fundamental frequency of the building and is included in the system matrix. This results in a linear time-invariant system, for which the desired control force is computed using LQR control. The control force thus computed is then realized by varying the device stiffness around its nominal value by using a simple control law. A nonlinear static analysis is performed in order to establish the range of linearity, in terms of the device (configuration) angle, for which the control law is valid. Results are obtained for the cases of zero and nonzero structural stiffness variation. The performance criteria evaluated show that the present method provides displacement control that is comparable with that of two existing controllers. The acceleration control, while not as good as that obtained with the existing active controller, is comparable or better than that obtained with the existing semiactive controller. By using substantially less power as well as control force, the present control yields comparable displacement control and reasonable acceleration control.

scholarly journals Web-Based Benefit-Finding Writing for Adults with Type 1 or Type 2 Diabetes: Preliminary Randomized Controlled Trial (Preprint)

2019 ◽  
Author(s):  
Joanna Crawford ◽  
Kay Wilhelm ◽  
Judy Proudfoot
Keyword(s):  
Mental Health ◽  
Type 2 Diabetes ◽  
Positive Affect ◽  
Active Control ◽  
Benefit Finding ◽  
Diabetes Distress ◽  
Web Based ◽  
To Receive

BACKGROUND The high prevalence of diabetes distress and subclinical depression in adults with type 1 and type 2 diabetes mellitus (T1DM and T2DM, respectively) indicates the need for low-intensity self-help interventions that can be used in a stepped care approach to address some of their psychological needs. However, people with diabetes can be reluctant to engage in mental health care. Benefit-finding writing (BFW) is a brief intervention that involves writing about any positive thoughts and feelings concerning a stressful experience such as an illness, avoiding potential mental health stigma. It has been associated with increases in positive affect and positive growth and has demonstrated promising results in trials in other clinical populations. However, BFW has not been examined in people with diabetes. OBJECTIVE This study aimed to evaluate the efficacy of a Web-based BFW intervention for reducing diabetes distress and increasing benefit finding in diabetic adults with T1DM or T2DM compared to a control writing condition. METHODS Adults with T1DM or T2DM and diabetes distress were recruited online through the open access Writing for Health program. After completing baseline questionnaires, they were randomly allocated to receive online BFW or an active control condition of online writing about the use of time (CW). Both groups completed 15-minute online writing sessions, once per day, for 3 consecutive days. Online measures were administered at baseline, 1 month, and 3 months postintervention. Participants were also asked to rate their current mood immediately prior to and following each writing session. RESULTS Seventy-two adults with T1DM or T2DM were recruited and randomly allocated to receive BFW (n=24) or CW (n=48). Participants adhered to the BFW regimen. Greater increases in positive affect immediately postwriting were found in the BFW group than in the CW group. However, there were no significant group-by-time interactions (indicating intervention effects) for benefit finding or diabetes distress at either the 1-month or 3-month follow-up. Both the BFW and CW groups demonstrated small, significant decreases in diabetes distress over time. CONCLUSIONS BFW was well tolerated by adults with diabetes in this study but did not demonstrate efficacy in improving diabetes distress or benefit finding compared to an active control writing condition. However, due to recruitment difficulties, the study was underpowered and the sample was skewed to individuals with minimal diabetes distress and none to minimal depression and anxiety at baseline. Future research should continue to investigate the efficacy of variants of therapeutic writing for adults with T1DM or T2DM, using larger samples of participants with elevated diabetes distress. CLINICALTRIAL Australiand New Zealand Clinical Trials Registry ACTRN12615000241538; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=368146

Analytical analysis for the design of nonlinear tuned mass damper

2020 ◽  
Vol 26 (9-10) ◽  
pp. 646-658
Author(s):  
Lu-yu Li ◽  
Tianjiao Zhang
Keyword(s):  
Passive Control ◽  
Design Method ◽  
Tuned Mass Damper ◽  
Control Device ◽  
Control Performance ◽  
Tuned Mass Dampers ◽  
Mass Damper ◽  
Practical Engineering ◽  
Optimum Formula ◽  
Nonlinear Tuned Mass Damper

A tuned mass damper is a passive control device that has been widely used in aerospace, mechanical, and civil engineering as well as many other fields. Tuned mass dampers have been studied and improved over the course of many years. In practical engineering applications, a tuned mass damper inevitably produces some nonlinear characteristics due to the large displacement and the use of the limiting devices, but this nonlinearity is often neglected. The simulation results in this study confirm that neglecting the nonlinearity in the design process can produce adverse effects on the control performance. This paper takes into account the nonlinearity of the tuned mass damper produced in the process of vibration and deduces an optimum formula for the frequency of a tuned mass damper by the complexification averaging method and multiscale method. Based on this formula, a modified design method for the frequency of a tuned mass damper is presented. The numerical results show that the nonlinear tuned mass damper after modification is better than a linear tuned mass damper in terms of control performance.

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