scholarly journals ATC-55 Based Friction Damper Design Procedure for Controlling Inelastic Seismic Responses

2005 ◽  
Vol 9 (1) ◽  
pp. 9-16 ◽  
Keyword(s):  
Design Procedure ◽  
Friction Damper ◽  
Seismic Responses ◽  
Damper Design

An Integrated Approach for Friction Damper Design

1990 ◽  
Vol 112 (2) ◽  
pp. 175-182 ◽  
Author(s):  
T. M. Cameron ◽  
J. H. Griffin ◽  
R. E. Kielb ◽  
T. M. Hoosac
Keyword(s):  
Optimal Design ◽  
High Speed ◽  
Design Procedure ◽  
Single Mode ◽  
Design Parameters ◽  
Bench Test ◽  
Friction Damper ◽  
Friction Dampers ◽  
Damper Design ◽  
Blade Model

A procedure is outlined for determining the optimal design of friction dampers for high-speed turbomachinery blading. The procedure includes: An integration of bench test results with finite-element analysis and a single-mode blade model to ensure accuracy of the analytical model and improve reliability of the friction damper design; an extension of the single-mode blade model to predict the engine behavior of friction dampers; and a new way of viewing analytical and experimental results in terms of a damper performance curve to determine optimal design parameters, when the levels of excitation and damping in the system are unknown. Unique experiments are performed on a test disk in order to demonstrate and verify the accuracy of the design procedure.

Seismic retrofit of structures using rotational friction dampers with restoring force

2020 ◽  
Vol 23 (16) ◽  
pp. 3525-3540
Author(s):  
Asad Naeem ◽  
Jinkoo Kim
Keyword(s):  
Ground Motions ◽  
Design Procedure ◽  
Steel Structures ◽  
Friction Damper ◽  
Heavy Duty ◽  
Limit States ◽  
Restoring Force ◽  
Friction Dampers ◽  
Torsional Spring ◽  
Capacity Spectrum

In this study, the seismic performance of a rotational friction damper with restoring force is presented. The torsional spring friction damper consists of rotational friction pads with the heavy duty torsional springs attached on both sides of the friction damper. An analytical model and a design procedure for the damper are developed using capacity spectrum method. A parametric study is carried out to investigate the influence of the torsional spring in the response of the structure when subjected to ground motions. The seismic performances of steel structures retrofitted with the torsional spring friction damper and conventional rotational friction dampers are evaluated using fragility analysis, which shows that the structure retrofitted with the torsional spring friction damper has the smallest probability of reaching the specific limit states.

scholarly journals Optimization of Friction Damper Weight, Simulation and Experiments

1997 ◽  
Author(s):  
Gabor Csaba ◽  
Magnus Andersson
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Friction Damper ◽  
High Pressure Turbine ◽  
Coupled Modes ◽  
Modes Of Vibration ◽  
Damper Design ◽  
The Right

A new friction damper has been designed by Volvo Aero Corporation. It is used in the high pressure turbine stage of a turbojet engine. The objective of this paper was to find the optimal weight of the new damper that minimizes the blade response amplitude for six and nine engine order excitation and to compare the new damper design with that currently used. Another objective was to compare how well simulation results agree with experimental results from spin pit tests. Simulations were made with a damper model that incorporates the possibility of both micro- and macro-slip in the blade-damper contact interface. Turbine blades were modeled using finite element beam elements. Experimental data were provided from spin pit tests with a completely bladed high pressure turbine rotor. Results show that the simulation model can be used to give qualitative results but has to be further developed to incorporate mistuning effects and coupled modes of vibration for the blade. The spin pit test shows that the new damper design is more efficient in reducing resonance stresses than the old design. It was not possible to see if simulations predict the right optimal damper weight by comparing with experimental data because the rotor could not be excited up to the design point.

DESIGN OF ISOLATED BRIDGES USING POLYNOMIAL FRICTION PENDULUM ISOLATOR

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
T. Y. Lee ◽  
L. Y. Lu ◽  
K. J. Chung
Keyword(s):  
Ground Motions ◽  
Near Field ◽  
Design Procedure ◽  
Design Parameters ◽  
Seismic Responses ◽  
Nonlinear Responses ◽  
Seismic Design Code ◽  
Friction Pendulum ◽  
Isolated Bridges ◽  
Restoring Stiffness

This paper is aimed to develop a design procedure of Polynomial Friction Pendulum Isolator (PFPI), a various-frequency sliding isolator, for decreasing the seismic responses of isolated bridges. Although sliding isolators have been widely used to mitigate seismic hazard, it may be not effective in decreasing the seismic responses of isolated structures subjected to near-field ground motions. The sliding surface of the PFPI is defined by a sixth-order polynomial function to avoid resonance under near-field ground motions. The restoring stiffness of the PFPI possesses softening section as well as hardening section. The structural acceleration response can be decreased by decreasing the restoring stiffness in softening section while the structural displacement response can be decreased by increasing the restoring stiffness in hardening section. However, it is difficult to determine the design parameters of PFPI in practical implementations. This study proposes a design procedure for the PFPI based on the bridge seismic design code in Taiwan. Designers can follow this procedure to easily design the bridge with PFPIs which satisfies the requirements of the code. The bridge with PFPIs designed by using this procedure is analyzed to realize the dynamic nonlinear responses of the bridge under artificial strong earthquake. The results show that the PFPIs effectively decrease the seismic responses of isolated bridges as compared with non-isolated bridges.

A parametric study on reliability-based tuned-mass damper design against bridge flutter

2015 ◽  
Vol 23 (9) ◽  
pp. 1518-1534 ◽  
Author(s):  
Filippo Ubertini ◽  
Gabriele Comanducci ◽  
Simon Laflamme
Keyword(s):  
Design Procedure ◽  
Tuned Mass Damper ◽  
Computationally Efficient ◽  
Long Span Bridges ◽  
Long Span ◽  
Mass Damper ◽  
Supplemental Damping ◽  
Damper Design ◽  
Reducing Costs ◽  
First Order Method

We present a probabilistic methodology for designing tuned mass dampers for flutter suppression in long-span bridges. The procedure is computationally efficient and computes the probability of flutter occurrence based on a modified first-order method of reliability analysis, a reduced-order representation of the structure and a time domain formulation of aeroelastic loads. Results of a parametric investigation show that the proposed methodology is preferable to a deterministic design procedure, which relies on nominal values of mechanical and aerodynamic parameters and does not guarantee the maximum safety. Furthermore, the reliability-based approach can be effectively used in the design of multiple tuned mass damper configurations by enhancing robustness against frequency mistuning and by reducing costs associated with supplemental damping for a given safety performance level.

Simplified seismic code design procedure for friction-damped steel frames

1999 ◽  
Vol 26 (1) ◽  
pp. 55-71 ◽  
Author(s):  
Yaomin Fu ◽  
Sheldon Cherry
Keyword(s):  
Design Procedure ◽  
Steel Structures ◽  
Lateral Force ◽  
Building Codes ◽  
Degree Of Freedom ◽  
Friction Damper ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Damped System ◽  
Seismic Force

This paper describes the development of a proposed seismic design procedure for friction-damped steel structures, which employs the lateral force provisions used in many modern building codes. Closed-form expressions are first derived that relate the normalized response of a single degree of freedom friction-damped system with the system parameters, such as bracing stiffness ratio, damper slip ratio, and frame member ductility. A parametric analysis is then used to reveal that the seismic displacement of a friction-damped frame can be controlled by combining the frame stiffness with the bracing stiffness of the friction damper component, while the seismic force can be controlled by the damper slip force. A force modification factor (equivalent to the code R-factor) and displacement estimate for a friction-damped system are next determined. The single degree of freedom results are subsequently used to develop expressions for dealing with the multi degree of freedom situation, which permits the seismic lateral force design procedure adopted by many current building codes to be applied to friction-damped systems. The proposed procedure allows the frame response to be controlled so that the displacement can be limited to small magnitudes and the overall structural shape to an essentially straight-line deformation. Design examples illustrate that friction-damped frame systems are economical and offer a better overall response performance than that provided by conventional systems under the design earthquake.Key words: passive energy dissipation system, friction damper, steel frame, design procedure, static analysis.

A Simple Design Procedure of Seismic Reinforcement Structure with Mild Steel Dampers

2014 ◽  
Vol 1065-1069 ◽  
pp. 1397-1401
Author(s):  
Zhen Huang ◽  
Zuo Wei Qin ◽  
Peng Wu
Keyword(s):  
Energy Dissipation ◽  
Mild Steel ◽  
Design Process ◽  
Design Procedure ◽  
Time History ◽  
Simple Design ◽  
Seismic Responses ◽  
Reinforcement Structure ◽  
Rare Earthquake ◽  
Reinforcement Design

This paper presents a reinforcement design of five-story R/C structure with mild steel dampers in high seismic fortification intensity site. The details of the design process are listed in the paper, and the time history analyses under frequent and rare earthquake are performed on structure models with and without dampers. Through the comparison, the peak of maximum story drifts angles with damper-added structural is reduced by 38% and the distribution is more uniformly. The results show that energy-dissipation design with mild steel dampers can be a reliable and effective method in reducing seismic responses of reinforcement structure.

Estimation of Contact Stiffness and its Role in the Design of a Friction Damper

2001 ◽  
Author(s):  
J. Szwedowicz ◽  
M. Kissel ◽  
B. Ravindra ◽  
R. Kellerer
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Contact Stiffness ◽  
Contact Problems ◽  
Analytical Models ◽  
Rational Approach ◽  
Friction Damper ◽  
Friction Dampers ◽  
Performance Curves ◽  
Damper Design

The use of under-platform friction dampers is a common practice for the elimination of high cycle fatigue failures of turbomachinery blading. Damper performance curves and damper optimization curves are used for the design of friction dampers. It is establishedAAfrom the previous work that apart from damper mass, the contact stiffness between damper and the blade platform is an important parameter in achieving a good damper design. Several methods for the estimation of damper stiffness have been proposed in the literature. Some of them include: 1. Curve fitting approach to a measured frequency response function, 2. Compliance measurement, 3. Measurement of hysteresis loop etc. However, it is not possible to carry out extensive sets of experiments to observe the influence of various parameters on the contact stiffness. Numerical and/or analytical models for contact stiffness evaluation are the present needs for a damper designer. This paper addresses a detailed investigation of the contact stiffness computation. Finite element modeling of the damper and the platform is carried out to study the effect of various parameters such as friction coefficient, centrifugal load, material properties etc. on the contact stiffness. The role of surface roughness and wear are neglected in the present analysis. The reliability of the applied finite element meshes is verified by simulating Hertz’s contact problems. The parametric study indicates that the contact stiffness builds up with increase in friction coefficient, centrifugal force and elastic modulus of the damper material. The results received from a pilot experiment are also presented for further evaluation of the computed results. Finally, a very good agreement between the numerical and experimental performance curves (resonance response amplitude of the blade versus excitation amplitude for the constant damper mass; Cameron et. al, 1987) of the blade with the damper is found for the tangential contact stiffness obtained from the finite element calculation. The present work extends the quest for a rational approach to damper design.

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