New installation scheme for viscoelastic dampers using cables

2010 ◽  
Vol 37 (9) ◽  
pp. 1201-1211 ◽  
Author(s):  
Hyunhoon Choi ◽  
Jinkoo Kim
Keyword(s):  
Nonlinear Dynamic Analysis ◽  
Relative Displacement ◽  
Damping Force ◽  
Viscoelastic Dampers ◽  
Passive Energy Dissipation ◽  
Passive Dampers ◽  
Energy Dissipation Devices ◽  
Configuration Scheme ◽  
Model Structures ◽  
Installation Cost

Passive energy dissipation devices, such as, viscous, viscoelastic, and friction devices are generally installed in buildings using diagonal or chevron braces. To increase the effective damping force and to reduce the damper volume, various magnifying system of the damper displacement, such as, toggle brace system and scissor-jack-damper configuration have been developed with increase in installation cost. In this study, new installation scheme for passive dampers was proposed using cables installed in such a way that relative displacement equal to storey displacement occurs between the cable and the structure when the structure is subjected to lateral load. The cables can be installed continuously or discretely between base and top storey of the structure. To verify the validity of the proposed method nonlinear dynamic analysis of model structures with viscoelastic dampers installed using the proposed configuration scheme was carried out using three earthquake records and two sinusoidal forces. According to the analysis, the proposed method resulted in significant reduction in the size of dampers compared with the conventional installation methods.

scholarly journals Distribution of Seismic Damage in Steel Buildings Component Equipped by Viscoelastic Dampers against Far-Field Earthquake

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yaser Parvin Darabad ◽  
Alireza Hassanpour Yasaghi ◽  
Beniamin Khodaei ◽  
Reza Zarei
Keyword(s):  
Nonlinear Dynamic Analysis ◽  
Relative Displacement ◽  
Inelastic Behavior ◽  
Steel Buildings ◽  
Base Shear ◽  
Viscoelastic Dampers ◽  
International Regulations ◽  
The Face ◽  
Frame System ◽  
Distant Field

Damage to structures with the concept of inelastic behavior and consequently hysteresis energy is very close. Therefore, it can be said that hysteresis energy at these levels can be a significant criterion for designing or controlling the structure. In this research, the first three steel frames of 4, 8, and 12 floors with the medium bending frame system have been designed with the statically equivalent method according to valid international regulations; then, all frames have been subjected to nonlinear dynamic analysis by seven accelerometers. The purpose of this study is to investigate the distribution of damage, energy, relative displacement, roof displacement, and base shear in the studied frames. In the following, the necessity of using the retrofitting method to reduce the relative displacement is described based on the regulations. Then, viscoelastic dampers are used to strengthen and reduce damage in the studied frames in the face of distant field records. The obtained results indicate that despite the uniform distribution of resistance in the height of the floors, the hysteresis energy distribution and damage diagrams do not follow this distribution and other parameters such as hysteresis energy, which play a major role in structural members’ damage, should be included in the design process. In this research, viscoelastic dampers have been used for retrofitting. The results show that this type of damper shows good performance in reducing damage under earthquakes in the remote area.

scholarly journals Optimal Placement of Passive Energy Dissipation Devices by Genetic Algorithms

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Ji-ting Qu ◽  
Hong-nan Li
Keyword(s):  
Mathematical Model ◽  
Optimal Placement ◽  
Passive Energy Dissipation ◽  
Building Models ◽  
Best Response ◽  
Combination Modes ◽  
Structural Responses ◽  
Passive Dampers ◽  
Energy Dissipation Devices ◽  
Combination Mode

A mathematical model is proposed in this paper for locating optimal positions for passive energy dissipative dampers. Three control indices of structural responses with the storey-drift angle, storey displacement, and acceleration are taken in this model. Firstly, six combination modes of these indices are presented. On the premise that the number of dampers is fixed, this paper deals with the optimal placement of two types of passive dampers for several building models with different number of storeys and seismic ground motions at four types of sites using genetic algorithm. Secondly, two estimating indices are presented to assess the reasonable combination mode of coefficients under different conditions, which can generally express the best response control. Numerical examples are illustrated to verify the effectiveness and feasibility of the proposed mathematical model. At last, several significant conclusions are given based on numerical results.

scholarly journals Seismic Performance of the Inerter and Negative Stiffness–Based Dampers for Vibration Control of Structures

2021 ◽  
Vol 7 ◽  
Author(s):  
Naqeeb Ul Islam ◽  
R. S. Jangid
Keyword(s):  
Energy Dissipation ◽  
Mathematical Formulation ◽  
Negative Stiffness ◽  
Optimization Approach ◽  
Comparative Performance ◽  
Viscoelastic Dampers ◽  
Passive Energy Dissipation ◽  
Recent Developments ◽  
Energy Dissipation Devices ◽  
Shear Building

Passive energy dissipation devices or supplemental damping devices have been successfully implemented into structures for controlling the excessive vibrations under wind and seismic excitation. Recent developments in the form of negative stiffness dampers (NSDs) and inerter-based vibration absorbers (IVAs) as potential energy dissipation devices are of considerable interest to researchers. The present study evaluates the performance of the combined NSD and IVA as a possible alternative to the traditional energy dissipation devices such as viscous dampers (VDs) and viscoelastic dampers (VEDs). The mathematical formulation and optimal design of the combined NSD and IVA mechanism are presented. A 20-storey benchmark building is modeled as a multi-degree-of-freedom (MDOF) shear building. The dynamic equations for the MDOF building are written in the state-space form, and a simple optimization approach based on effective modal damping is prescribed. Comparative performance between traditionally applied and novel IVA and NSD is investigated. The design considerations to analyze structures employing combined NSDs and IVAs are developed. It is demonstrated that NSDs and IVA-based passive energy dissipation devices are the most efficient devices in reducing inter-storey drifts and floor accelerations compared with VDs and VEDs using the same damping coefficient.

Experimental study on seismic control of towers in cable-supported bridges by incorporating fluid viscous dampers between sub-towers

2020 ◽  
Vol 23 (10) ◽  
pp. 2086-2096
Author(s):  
Peng Zhou ◽  
Min Liu ◽  
Suchao Li ◽  
Hui Li ◽  
Gangbing Song
Keyword(s):  
Control Strategies ◽  
Experimental Tests ◽  
Shaking Table ◽  
Viscous Dampers ◽  
Damping Force ◽  
Alternative Scheme ◽  
Seismic Control ◽  
Fluid Viscous Dampers ◽  
Seismic Loadings ◽  
Energy Dissipation Devices

In this article, the seismic control of towers incorporated with fluid viscous dampers between sub-towers is investigated experimentally. To replace one entire tower, an alternative scheme consisting of four separate sub-towers is first proposed. Fluid viscous dampers are utilized as energy dissipation devices to be installed between sub-towers. Experimental tests are conducted to study the damping force characteristics. Three control strategies with various distributions of these dampers between sub-towers are developed. Then, a series of shaking table tests are carried out to evaluate the control performance of the proposed control strategies. Different earthquake records are adopted as seismic loadings. Experimental results clearly show a remarkable reduction in the towers seismic responses, including the accelerations, relative displacements, and strains. Rather than attaching dampers in concentrated ways, the strategy of distributing dampers uniformly behaves better.

Design and Analysis of a Magnetorheological Fluid Mount Featuring Uni-Directional Squeeze Mode

2015 ◽  
Author(s):  
Xian-Xu Bai ◽  
Peng Chen ◽  
Li-Jun Qian ◽  
Ping Kan
Keyword(s):  
Dynamic Stiffness ◽  
Magnetorheological Fluid ◽  
Relative Displacement ◽  
Bottom Surface ◽  
Damping Properties ◽  
Damping Force ◽  
Equivalent Damping ◽  
Engine Vibration ◽  
Coil Winding ◽  
Stiffness And Damping

A magnetorheological fluid (MRF) mount featuring unidirectional squeeze mode for vehicle engine mounting system is proposed and designed to attenuate the engine vibration with characteristics of broadband and small amplitude. The MRF mount is comprised of upper and lower bases for installation, a main rubber for static load, a bobbin for electromagnetic coil winding and a squeeze plate. The bottom surface of the bobbin and the top surface of the squeeze plate form the polar plates, between which the MRF is squeezed during the rebound of the MRF mount. Combining dynamic stiffness property of passive hydraulic mounts without fluid and adjustable damping force of MRF at squeeze mode, the MRF mount could provide a unique variable dynamic stiffness and damping properties, by adjusting the exciting current. To evaluate the performance of the MRF mount, a mathematical model considering the behavior of MRF at squeeze mode is derived to theoretically analyze and numerically simulate the dynamic stiffness and equivalent damping properties of the MRF mount. Further, the MRF mount based quarter vehicle mounting system model considering suspension system is constructed to analyze the force transmissibility of engine mounting system in frequency domain and simulate the relative displacement response in time domain.

On The Dynamics of Intermittent-Motion Mechanisms. Part 1: Dynamic Model and Response

1983 ◽  
Vol 105 (3) ◽  
pp. 534-540 ◽  
Author(s):  
Ting W. Lee ◽  
A. C. Wang
Keyword(s):  
Dynamic Models ◽  
Damping Ratio ◽  
Relative Displacement ◽  
Dynamical Response ◽  
Damping Force ◽  
Damping Material ◽  
Proposed Model ◽  
Maximum Relative Displacement ◽  
Motion Characteristics ◽  
Intermittent Motion

This paper deals with a basic problem regarding intermittent-motion mechanisms, namely, how to formulate a predicative model for the study of the dynamics of these mechanisms. A mathematical model is developed in this investigation. The model, which includes clearance, damping, material compliance, and mechanism elasticity, is basic to the determination of the dynamical response such as force amplification and motion characteristics of mechanisms with intermittent motion. A new approach in the modeling of system damping is presented. Instead of using damping ratio, which is difficult to estimate accurately, a new damping function is introduced, which characterizes the speed and load dependent nature of damping. Two types of damping functions are proposed and both of their corresponding damping forces satisfy the expected hysteresis boundary conditions, i.e., zero damping force at zero and maximum relative displacement of contact. A comparative study of the present model with conventional dynamic models is performed. It demonstrates the characteristics and the usefulness of the proposed model for the study of the dynamics of intermittent-motion mechanisms.

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