COMPARISON OF DIFFERENT METHODS FOR VISCOUS DAMPER PLACEMENT IN EXISTING FRAME BUILDINGS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Luca Landi ◽  
Filippo Conti ◽  
Pier Paolo Diotallevi
Keyword(s):  
Case Studies ◽  
Damping Ratio ◽  
Time History ◽  
Nonlinear Behavior ◽  
Concrete Frames ◽  
Viscous Dampers ◽  
Fluid Viscous Dampers ◽  
Rc Frames ◽  
Vertical Distributions ◽  
Nonlinear Dynamic Analyses

The main purpose of this research is to investigate the effects of different vertical distributions of the properties of nonlinear fluid-viscous dampers for the retrofit of existing multi-story reinforced concrete frames. In particular, the different distributions are defined on the basis of the same value of the supplemental damping ratio. Since the viscous dampers are used for the retrofit of existing buildings, they are dimensioned assuming that the structure can exceed the elastic limit, with the only condition to satisfy the prefixed performance limit. In the design phase the different vertical distributions of damper properties are compared in terms of the total sum of the damping coefficients. The effectiveness of the different distributions is then examined by performing time-history analysis of several case studies considering a nonlinear behavior both for the viscous dampers and for the structural members. The results of the nonlinear dynamic analyses are examined in terms of inter-story drifts and dampers forces. The considered case studies are five RC frames characterized by different number of stories (3, 6 and 9 stories) and also by different properties in terms of regularity in elevation. In this way it is also possible to investigate the effect of the vertical distribution of the damper properties for regular and irregular frames.

scholarly journals Improving the Dynamic Behavior of Adjacent Buildings with Fluid Viscous Dampers

2016 ◽  
Vol 10 (12) ◽  
pp. 245
Author(s):  
Solmaz Yaghobzadeh
Keyword(s):  
Control Systems ◽  
Dynamic Behavior ◽  
Time History ◽  
Tall Buildings ◽  
System Response ◽  
Response Analysis ◽  
Viscous Dampers ◽  
Fluid Viscous Dampers ◽  
Adjacent Buildings ◽  
The Impact

Explained ways to strengthen structures against lateral dynamic loads can be divided into two broad categories. The first part is the structural systems for controlling seismic displacement and second part is the use of applying systems of control forces. Response mechanism of structures using control systems are improved and greatly reduce the risks of damage caused by earthquakes.Today the use of these control systems in buildings have been increased and it’s important to reduce vibration of structures is felt more than ever. As well as to improve the dynamic behavior of nearby buildings, control systems can be installed between adjacent buildings as activated, semi-active and inactivated systems. The main purpose of this study is the use of control systems in two similar adjacent buildings to reduce the entire system response which will be the analytical study of the impact of viscous dampers to control system performance.In order to analysis of modeling to improve the dynamic behavior of different adjacent buildings connected with dampers, two models of the original sample will be examined in this article. All examples are different from each other and to elicit response analysis and time history software SAP 2000was used. According to the results the effect of fluid viscous dampers for tall buildings compared shorter building, is less. Also, these dampers for adjacent buildings with different heights than buildings with same height are more effective.

INFLUENCE OF ADDED VISCOUS DAMPERS ON THE PROBABILISTIC SEISMIC PERFORMANCE EVALUATION OF RC FRAMES

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Luca Landi ◽  
Cristina Vorabbi ◽  
Pier Paolo Diotallevi
Keyword(s):  
Nonlinear Dynamic ◽  
Ground Motions ◽  
Frame Structures ◽  
Rc Frame ◽  
Viscous Dampers ◽  
Fluid Viscous Dampers ◽  
Hazard Curve ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses ◽  
Rc Frame Structures

This paper deals with the parameters which influence the probability of reaching the near collapse limit state of RC frame structures equipped with nonlinear fluid viscous dampers. The study can be divided into two steps. The first aims to assess how the median and the dispersion of seismic demand can vary in the RC frame structures with and without dampers, considering a wide set of ground motions. The second step evaluates the expression in closed form, given by 2000 SAC/FEMA method, to assess the annual probability of failure of RC structures. This probability has been estimated considering a wide set of ground motions and different methods to approximate the hazard curve. The evaluations have been made on the basis of the results of a large number of nonlinear dynamic analyses; in particular, 180 nonlinear dynamic analyses have been made for the case studies with and without dampers. In conclusion, it has been noticed that the probabilistic assessment depends on the number of records considered and that the simplified formula provided by the 2000 SAC-FEMA method is strongly sensitive to the variation of the hazard curve and the dispersion.

scholarly journals Seismic and Time History Performance of RCC Framed Buildings with and without Passive Energy Dissipators

2020 ◽  
Vol 9 (3) ◽  
pp. 2230-2240
Keyword(s):  
Base Isolation ◽  
Lateral Displacement ◽  
Response Spectrum ◽  
Time History ◽  
Base Shear ◽  
Viscous Dampers ◽  
Fluid Viscous Dampers ◽  
Seismic Force ◽  
Energy Dissipators ◽  
Lateral Displacements

Base isolation is an effective way to protect large structures from earthquake damage. It is a costly approach, as the entire structure must be supported on elastomeric or sliding bearings. Viscous dampers distributed throughout an otherwise conventional structure can achieve the same result at a significantly lower cost. Dampers are used to resist lateral forces coming on the structure. Dampers are the energy dissipating devices which also resist displacement of Reinforced Concrete (RC) buildings during an earthquake. These dampers help the structure to reduce buckling of columns thereby increasing the stiffness of the structure. During earthquakes, multi-storeyed buildings get damaged and as a result, large deformation occurs. Dampers reduce vibration and deformation of structural elements during an earthquake. Retrofitting buildings with fluid viscous dampers (FVDs) can improve Interstorey drifts and floor accelerations. In the present study, an RC framed building is modelled and analysed under Southern Sumatra and Chile earthquakes to evaluate the performance of the structure and its elements with and without energy dissipators. For the study, a model (G+19) with and without energy dissipators is modelled in ETABS. The seismic force is applied based on the time history data of the models pertaining to Southern Sumatra and Chile Earthquake. Response Spectrum analysis has been carried out to find the lateral displacements, storey shear and Base shear for the model with and without dampers. The lateral displacement, storey drift, storey shear and Base shear are found to less for the model with Linear FVDs when compared to the model with Non-Linear FVDs and without FVDs.

scholarly journals Performance of Fluid Viscous Dampers on Seismic Response of RCC Structures

2019 ◽  
Vol 8 (12) ◽  
pp. 3685-3691
Keyword(s):  
Seismic Response ◽  
Structural Response ◽  
Time History ◽  
Seismic Energy ◽  
Seismic Zone ◽  
Viscous Dampers ◽  
Modeling And Analysis ◽  
Fluid Viscous Dampers ◽  
Live Loads ◽  
Storey Building

Structures are mainly subjected to various types of loading conditions such as dead loads, live loads and dynamic loads such as earthquake and wind loads etc. The earthquake creates vibration at the base of the structure. In modern seismic design, the damping devices are used to reduce the seismic energy and enable the control of the structural response of the structure. In the present study, the seismic behavior of a structure connected with and without Fluid Viscous Dampers (FVD) has been describes. The software ETABS 2016 is used to perform the modeling and analysis of G +10 storey building by considering seismic zone IV. For analysis IS codes have been referred. The response of the RCC building is evaluated using Push-over and Time history analyses. Fluid Viscous Dampers are suggested to the structure, to control the seismic response and increase the stiffness of the structure.

Implementation of Structural Control with Viscous Damper

2011 ◽  
Vol 94-96 ◽  
pp. 771-781 ◽  
Author(s):  
Deh Shiu Hsu ◽  
Yung Feng Lee ◽  
Ping Cheng Huang ◽  
Yu Ching Wu
Keyword(s):  
Dynamic Analysis ◽  
Case Studies ◽  
Software Package ◽  
Structural Control ◽  
Time History ◽  
Nonlinear Behavior ◽  
Viscous Damper ◽  
Key Points ◽  
Highly Nonlinear ◽  
Behavior Systems

For the sake of safety of structures subjected to abnormal loadings, damper could be one of the effective devices to reduce the responses by the energy dispassion functions. Key points in the process of development and application of damper and aseismatic engineering are narrated. Due to the highly nonlinear behavior properties, most of the case studies aim on these kind of dynamic analysis only working on structures with elastic linearly behavior systems. In addition to the nonlinearly behavior of damper devices, structures behave into nonlinearly as well when subjected by abnormal excitation, for instance, severe earthquakes. Materials respond into nonlinearly beyond yielding or plastic hinges occurred somewhere in the controlled structures. Proper software package is used to calculate the responses of simple portal frames which are controlled with dampers allocated. Both of structures and damper devices are considered and behaved according to its nonlinearly properties. Responses beyond yielding of material are rationally analyzed and revealed in time history expressions.

Introducing Dynamic Nonlinear Soil-Foundation-Structure Interaction Effects in Displacement-Based Seismic Design

2013 ◽  
Vol 29 (2) ◽  
pp. 475-496 ◽  
Author(s):  
Roberto Paolucci ◽  
Raffaele Figini ◽  
Lorenza Petrini
Keyword(s):  
Seismic Design ◽  
Damping Ratio ◽  
Time History ◽  
Nonlinear Behavior ◽  
Interaction Effects ◽  
Structure Interaction ◽  
Soil Foundation ◽  
Displacement Based ◽  
Dynamic Time ◽  
Displacement Based Seismic Design

An iterative linear-equivalent procedure to take into account nonlinear soil-structure interaction effects in the displacement-based seismic design is presented for the case of shallow foundations. The procedure is based on the use of empirical curves to evaluate the stiffness degradation and the increase of damping ratio as a function of foundation rotation. Iterations are performed to ensure that admissible values of foundation rotations are complied with, in addition to the standard checks on structural displacements and drifts. Some examples of application of the approach to the design of bridge piers are provided. Design results are checked by means of nonlinear dynamic time-history analyses performed by a macro-element-based numerical tool, assuming nonlinear behavior of both structure and soil-foundation system.

Semi-Active Fluid Viscous Dampers for Seismic Mitigation of RC Elevated Liquid Storage Tanks

2019 ◽  
Vol 19 (03) ◽  
pp. 1950020 ◽  
Author(s):  
Manisha V. Waghmare ◽  
Suhasini N. Madhekar ◽  
Vasant A. Matsagar
Keyword(s):  
Active Control ◽  
Time History ◽  
Control Algorithms ◽  
Storage Tanks ◽  
Base Shear ◽  
Viscous Dampers ◽  
Mass Model ◽  
Fluid Viscous Dampers ◽  
Liquid Storage ◽  
Seismic Mitigation

The effectiveness of the semi-active control strategies using fluid viscous dampers (SAFVDs) for seismic mitigation of reinforced concrete (RC) elevated liquid storage tanks is investigated. Three control algorithms are employed for regulating the damping coefficient of the SAFVDs: (1) Passive-OFF, (2) Passive-ON, and (3) Clipped Optimal Control (COC). The uncontrolled response of the tank is compared with those installed with SAFVD of different control algorithms. Focus is also placed on various positions of the dampers, viz., dampers installed at alternate levels (Configurations I, II, IV, and V) and at all levels (Configurations III and VI) of the staging. A discrete two-mass model for the liquid and multi-degree-of-freedom system for the staging, installed with the dampers, is developed for the RC elevated liquid storage tanks. The response of the broad and slender tanks is studied, for which the ratios of the height of the liquid to the radius of the container are 0.5 and 2.0, respectively. The time-history response of the elevated tank is evaluated for eight different earthquake ground motions, including near- and far-field earthquakes. A MATLAB code was developed to solve the coupled differential equations of motion of the system using the state-space approach. Key parameters, viz., convective displacement, rigid mass displacement, base shear, overturning moment, and damper force, are evaluated. The results show that all the control systems considered herein are beneficial in reducing the seismic responses. The frequency response function for the uncontrolled and semi-actively controlled liquid storage tank in frequency domain exhibits significant response reduction, highlighting the effectiveness of the SAFVDs. The structural response is effectively controlled using the SAFVDs with Passive-OFF (valve closed) and COC algorithms. The COC algorithm employed in this study is a promising candidate for the seismic mitigation of RC elevated liquid storage tanks using the semi-active control.

Seismic Vulnerability Analysis of Reinforced Concrete Frames with Mild Steel Dampers

2011 ◽  
Vol 368-373 ◽  
pp. 1526-1530 ◽  
Author(s):  
Jian Zhu ◽  
Ping Tan
Keyword(s):  
Reinforced Concrete ◽  
Mild Steel ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Response Spectrum ◽  
Time History ◽  
Concrete Frames ◽  
Rc Frames ◽  
History Analysis ◽  
Reduction Effect

This study focus on derivation of such fragility curves using conventional old reinforced concrete (RC) frames with Mild Steel Damper (MSD) of flexural energy dissipation braces. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. Weak position was be pointed out, The result reveal that excellent reduction effect for structure of MSD is favorable and obvious under major earthquake.

scholarly journals Seismic Design and Performances of Frame Structures Connected to a Strongback System and Equipped with Different Configurations of Supplemental Viscous Dampers

2021 ◽  
Vol 7 ◽  
Author(s):  
Michele Palermo ◽  
Vittoria Laghi ◽  
Giada Gasparini ◽  
Stefano Silvestri ◽  
Tomaso Trombetti
Keyword(s):  
Time History ◽  
Elastic Field ◽  
Frame Structure ◽  
Viscous Dampers ◽  
Single Degree Of Freedom ◽  
Fluid Viscous Dampers ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Supplemental Dampers ◽  
Dynamic Time

The paper investigates the dynamic behavior of structural systems obtained by connecting a moment-resisting frame structure with a vertical rigid truss pinned at the base, known in literature as “strongback,” and equipped with added fluid-viscous dampers. The strongback, designed in order to remain in the elastic field under strong seismic ground motion, acts as a mast by imposing to the structure a linear lateral deformed shape. By regularizing the lateral drift profile of the structure, the strongback limits undesired effects such as weak-storey mechanisms, damage concentration and residual drifts. In addition, when supplemental dampers are inserted in the structure, a considerable amount of energy can be dissipated, thus reducing the peak seismic response. The aim of the work is twofold: i) to provide analytical formulations for the preliminary design of added dampers based on the Generalized Single Degree Of Freedom (GSDOF) concept, and ii) to evaluate the increase in energy dissipation capabilities for selected dampers configurations thanks to the presence of the strongback. The formulas are developed for different configurations of added viscous dampers: dampers inserted within the frame between all or selected consecutive storeys (inter-storey placement) and dampers located at the base of the strongback to realize a rigid “dissipative tower.” The effectiveness of the dampers configurations is evaluated through dynamic time-history analyses.

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