scholarly journals On the Estimation of the Moving Mass of a TMD Installed on a Lively Structure

2021 ◽  
Vol 11 (10) ◽  
pp. 4712
Author(s):  
Alvaro Magdaleno ◽  
Cesar Pelaez ◽  
Alvaro Iglesias-Pordomingo ◽  
Antolin Lorenzana
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Structural Response ◽  
Degree Of Freedom ◽  
Moving Mass ◽  
Tuned Mass Dampers ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Modification Technique ◽  
One Step

Tuned Mass Dampers are devices which can be assimilated to single-degree-of-freedom systems with a certain amount of moving mass, a natural frequency and a damping ratio intended to be installed on lively structures to reduce the contribution of a certain mode to their response. Once placed on the structure, the movement of the mass damper couples to the structural response and determines its properties as an isolated system becomes challenging. The authors have previously presented a methodology to estimate the natural frequency and damping ratio of an SDOF system installed on a structure and not necessarily tuned to a certain mode. It was based on a transmissibility function and, thus, the moving mass could not be estimated. With this work, the authors go one step further and present a novel procedure to estimate the moving mass value by means of the same transmissibility function and two well selected frequency response functions. The methodology is applied to estimate the properties of a real single-degree-of-freedom system placed on a lively timber platform. The results are compared with the mass modification technique to show that the proposed methodology provides better estimations in a more efficient way.

Single-Degree-of-Freedom Based Pressure-Impulse Diagrams for Blast Damage Assessment

2014 ◽  
Vol 567 ◽  
pp. 499-504 ◽  
Author(s):  
Zubair Imam Syed ◽  
Mohd Shahir Liew ◽  
Muhammad Hasibul Hasan ◽  
Srikanth Venkatesan
Keyword(s):  
Damage Assessment ◽  
Structural Response ◽  
Blast Loading ◽  
Computational Effort ◽  
Degree Of Freedom ◽  
Negative Phase ◽  
Single Degree Of Freedom ◽  
Pressure Impulse ◽  
Single Degree ◽  
Structural Resistance

Pressure-impulse (P-I) diagrams, which relates damage with both impulse and pressure, are widely used in the design and damage assessment of structural elements under blast loading. Among many methods of deriving P-I diagrams, single degree of freedom (SDOF) models are widely used to develop P-I diagrams for damage assessment of structural members exposed to blast loading. The popularity of the SDOF method in structural response calculation in its simplicity and cost-effective approach that requires limited input data and less computational effort. The SDOF model gives reasonably good results if the response mode shape is representative of the real behaviour. Pressure-impulse diagrams based on SDOF models are derived based on idealised structural resistance functions and the effect of few of the parameters related to structural response and blast loading are ignored. Effects of idealisation of resistance function, inclusion of damping and load rise time on P-I diagrams constructed from SDOF models have been investigated in this study. In idealisation of load, the negative phase of the blast pressure pulse is ignored in SDOF analysis. The effect of this simplification has also been explored. Matrix Laboratory (MATLAB) codes were developed for response calculation of the SDOF system and for repeated analyses of the SDOF models to construct the P-I diagrams. Resistance functions were found to have significant effect on the P-I diagrams were observed. Inclusion of negative phase was found to have notable impact of the shape of P-I diagrams in the dynamic zone.

scholarly journals An approach to quantify the influence of ground motion uncertainty on elastoplastic system acceleration in incremental dynamic analysis

2017 ◽  
Vol 20 (11) ◽  
pp. 1744-1756 ◽  
Author(s):  
Peng Deng ◽  
Shiling Pei ◽  
John W. van de Lindt ◽  
Hongyan Liu ◽  
Chao Zhang
Keyword(s):  
Dynamic Analysis ◽  
Ground Motion ◽  
Earthquake Engineering ◽  
Structural Response ◽  
Incremental Dynamic Analysis ◽  
Degree Of Freedom ◽  
Maximum Acceleration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Performance Based Earthquake Engineering

Inclusion of ground motion–induced uncertainty in structural response evaluation is an essential component for performance-based earthquake engineering. In current practice, ground motion uncertainty is often represented in performance-based earthquake engineering analysis empirically through the use of one or more ground motion suites. How to quantitatively characterize ground motion–induced structural response uncertainty propagation at different seismic hazard levels has not been thoroughly studied to date. In this study, a procedure to quantify the influence of ground motion uncertainty on elastoplastic single-degree-of-freedom acceleration responses in an incremental dynamic analysis is proposed. By modeling the shape of the incremental dynamic analysis curves, the formula to calculate uncertainty in maximum acceleration responses of linear systems and elastoplastic single-degree-of-freedom systems is constructed. This closed-form calculation provided a quantitative way to establish statistical equivalency for different ground motion suites with regard to acceleration response in these simple systems. This equivalence was validated through a numerical experiment, in which an equivalent ground motion suite for an existing ground motion suite was constructed and shown to yield statistically similar acceleration responses to that of the existing ground motion suite at all intensity levels.

The Response of Nonlinear Systems to Modulated High-Frequency Input

1993 ◽  
Author(s):  
S. A. Nayfeh ◽  
A. H. Nayfeh
Keyword(s):  
Nonlinear Systems ◽  
Natural Frequency ◽  
Amplitude Modulation ◽  
Carrier Frequency ◽  
High Frequency ◽  
Degree Of Freedom ◽  
Resonant Excitation ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Different Types

Abstract We study the response of a single-degree-of-freedom system with cubic nonlinearities to an amplitude-modulated excitation whose carrier frequency is much higher than the natural frequency of the system. The only restriction on the amplitude modulation is that it contain frequencies much lower than the carrier frequency of the excitation. We apply the theory to different types of amplitude modulation and find that resonant excitation of the system may occur under some conditions.

Demonstrator to show the effects of negative stiffness on the natural frequency of a simple oscillator

2008 ◽  
Vol 222 (7) ◽  
pp. 1189-1192 ◽  
Author(s):  
A Carrella ◽  
M J Brennan ◽  
T P Waters
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Degree Of Freedom ◽  
Negative Stiffness ◽  
Test Rig ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Horizontal Beam ◽  
Additional Correction

This article describes a demonstrator to show the effects of negative stiffness on the free vibration of a simple oscillator. The test rig consists of a horizontal beam that is hinged at one end and is supported by two coil springs to form a single-degree-of-freedom system. Additional correction springs, which provide negative stiffness, can be attached to lower the natural frequency of the system. The effect of the change in natural frequency can be easily seen visually, and it is shown that for one of the configurations of correction springs, the natural frequency can be reduced by a factor of about 4.

Effectiveness of neoprene pad vibration isolators at high frequencies

2021 ◽  
Vol 263 (4) ◽  
pp. 2172-2183
Author(s):  
Jerry Lilly
Keyword(s):  
Natural Frequency ◽  
Insertion Loss ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Frequency Wave ◽  
Single Degree Of Freedom ◽  
High Frequencies ◽  
Vibration Isolators ◽  
Single Degree ◽  
Wide Range

The natural frequency, dynamic stiffness, and insertion loss of commercially available neoprene pad vibration isolators have been measured in a simple, single degree of freedom system over a wide range of pad loadings out to a maximum frequency of 10 kHz. The results reveal that dynamic stiffness can vary significantly with pad loading as well as the durometer of the material. It will also be shown that insertion loss follows the theoretical single degree of freedom curve only out to a frequency that is about 5 to 10 times the natural frequency, depending upon the pad durometer rating. Above that frequency wave resonances in the material cause the insertion loss to deteriorate significantly out to a frequency near 1 kHz, above which the insertion loss maintains a relatively constant value, again depending upon the pad durometer rating. In some instances the insertion loss values can approach 0 dB or even become negative at specific frequencies in the frequency region that is 10 to 20 times the natural frequency of the system.

scholarly journals Development of equivalent linear systems for single-degree-of-freedom structures with magneto-rheological dampers for seismic design application

2017 ◽  
Vol 28 (19) ◽  
pp. 2675-2687 ◽  
Author(s):  
Yunbyeong Chae ◽  
James M Ricles ◽  
Richard Sause
Keyword(s):  
Response Spectrum ◽  
Damping Ratio ◽  
Time History ◽  
Analysis Procedure ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Design Response Spectrum ◽  
Simplified Analysis ◽  
Magneto Rheological

Numerous studies have been conducted for magneto-rheological dampers, but the application of magneto-rheological dampers in seismic design is limited due to the lack of a systematical design procedure. In this article, a simplified analysis procedure is proposed to estimate the response of a single-degree-of-freedom structure with diagonal bracing and a magneto-rheological damper without performing the time history analysis. The proposed simplified analysis procedure is based on the equivalent linear system of a magneto-rheological damper. The equivalent damping ratio and the effective period of the single-degree-of-freedom system are determined from the loss factor and the effective stiffness of the magneto-rheological damper based on the quasi-static model. Design response spectrum is utilized to calculate the displacement of the single-degree-of-freedom system. The equivalent damping ratio and the effective stiffness of the single-degree-of-freedom system are dependent on the displacement of the system; thus, the proposed procedure is iterated until the displacement from the design response spectrum converges. The accuracy of the simplified analysis procedure is evaluated by comparing the estimated response from this procedure with the response from the time history analysis. The results show a good agreement between two methods, demonstrating the robustness of the proposed simplified analysis procedure.

The Random Response of a Single Degree of Freedom Generalized Maxwell Damping Structure

2015 ◽  
Vol 744-746 ◽  
pp. 1648-1653
Author(s):  
Wan Jie Zou ◽  
Chuan Gao Li ◽  
Yun Xia Zhang
Keyword(s):  
Laplace Transform ◽  
Structural Response ◽  
Second Order ◽  
Degree Of Freedom ◽  
Inverse Laplace Transform ◽  
Maximum Response ◽  
Random Response ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Response Variance

Using the model of stationary white noise excitation, defining the exact analytic method of random response and nearer value of earthquake action about single degree of freedom generalized Maxwell damping, firstly transform the motion equation into standard form, with the Laplace transform and Inverse Laplace transform method, obtained the exact analytical formula of structural response, calculate the response variance by the complex modal method and frequency domain decomposition and make comparisons, The response variance decomposition for the first standard vibrator and second order of the standard vibrator, According to the corresponding relationship between maximum response of the second order vibrator and The design response spectrum, calculated the maximum response by it, base on the maximum response proportion of the first standard vibrator and second, obtained the design of the structural response values and its corresponding earthquake force.

Inelastic Structural Response to Cascadia Subduction Zone Earthquakes

1995 ◽  
Vol 11 (1) ◽  
pp. 63-89 ◽  
Author(s):  
M. Lee Marsh ◽  
Christopher M. Gianotti
Keyword(s):  
Subduction Zone ◽  
Structural Response ◽  
Degree Of Freedom ◽  
Cascadia Subduction Zone ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Energy Demands ◽  
Cyclic Displacement ◽  
Energy Dissipated ◽  
Subduction Zone Earthquakes

The effects of postulated Cascadia subduction zone earthquakes on inelastic structural response are examined. The earthquakes considered ranged in size from those previously recorded to the largest plausible event, a magnitude 9.5 earthquake. Artificial acceleration records were generated and used as input for inelastic response history analyses of single-degree-of-freedom systems with bilinear or degrading stiffness hysteretic relationships. The results indicate that the maximum displacements are not significantly greater than those produced by previously recorded events. The inelastic energy dissipated and the numbers of displacement cycles are somewhat greater for the largest events, although the energy demands and the cyclic displacement demands are similar to those from the recorded events for magnitudes up to 8.5.

Spectral Variability and Its Relationship to Structural Response Estimated from Scaled and Spectrum-Matched Ground Motions

2016 ◽  
Vol 32 (4) ◽  
pp. 2191-2205 ◽  
Author(s):  
A. E. Seifried ◽  
J. W. Baker
Keyword(s):  
Response Spectrum ◽  
Ground Motions ◽  
Structural Response ◽  
Degree Of Freedom ◽  
Structural Systems ◽  
Spectral Variability ◽  
Single Degree Of Freedom ◽  
Inelastic Response ◽  
Single Degree ◽  
Spectral Dispersion

Conditional spectral dispersion ( CSD) is a measure of response spectrum variability that implicitly characterizes the variety of spectral shapes within a suite of ground motions. It is used here to explain the discrepancy between median structural demands estimated from different suites of scaled and spectrum-matched ground motions. Performing response history analyses with spectrum-matched ground motions is known to result in unconservatively biased median demand estimates in some cases. Herein, several suites of scaled ground motions with equivalent median intensities and varying levels of CSD are selected. A single suite of spectrum-matched ground motions is also created. These records are used to analyze the responses of inelastic single-degree-of-freedom and first-mode-dominated multiple-degree-of-freedom structural systems. Collapse capacities are also examined. A consistent trend between CSD and resulting median responses indicates that the bias phenomenon can be fully explained by an asymmetric relationship between conditional spectral ordinates at periods affecting inelastic response.

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