scholarly journals Determining Time Variation of Cable Tension Forces in Suspended Bridges Using Time-Frequency Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Gannon Stromquist-LeVoir ◽  
Kevin F. McMullen ◽  
Arash E. Zaghi ◽  
Richard Christenson
Keyword(s):  
Frequency Analysis ◽  
Ambient Vibration ◽  
Vibration Measurements ◽  
Cable Tension ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Tensile Forces ◽  
Motion Studies ◽  
Ambient Vibration Measurements ◽  
Cable Forces

A feasibility study was conducted to develop a novel method to determine the temporal changes of tensile forces in bridge suspender cables using time-frequency analysis of ambient vibration measurements. An analytical model of the suspender cables was developed to evaluate the power spectral density (PSD) function of a cable with consideration of cable flexural stiffness. Discrete-time, short-time Fourier transform (STFT) was utilized to analyze the recorded acceleration histories in both time and frequency domains. A mathematical convolution of the analytical PSD function and time-frequency data was completed to evaluate changes in cable tension force over time. The method was implemented using acceleration measurements collected from an in-service steel arch bridge with a suspended deck to calculate the temporal variation in cable forces from the vibration measurements. The observations served as proof of concept that the proposed method may be used for cable fatigue life calculations and bridge weigh-in-motion studies.

scholarly journals Estimation of Modal Properties of Low-Rise Buildings Using Ambient Excitation Measurements

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
K. K. Wijesundara ◽  
C. Negulescu ◽  
E. Foerster
Keyword(s):  
Damping Ratio ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Accurate Estimation ◽  
Vibration Measurements ◽  
Time Frequency ◽  
Modal Properties ◽  
Step Procedure ◽  
Ambient Vibration Measurements ◽  
Ambient Excitation

Continuous wavelet transform (CWT) has recently emerged as a promising tool for identification of modal properties through ambient excitation measurements of structures. However, it is difficult to obtain an accurate estimation of damping ratio directly from time-frequency decomposition of ambient vibration measurements using CWT. The main objective of this study is to introduce a new method called two-step procedure in the estimation of damping ratios using ambient vibration measurements. The two-step procedure involves the development of random decrement (RD) signature from the ambient vibration measurements, which is equivalent to the damped free vibration response of a structure under a given initial displacement and subsequently decomposition of time domain RD signature into time-frequency domain using CWT. The secondary objective of the study is to show that CWT is capable of identifying the natural periods and mode shapes of low-rise buildings using ambient vibration measurements. Furthermore, the two-step procedure is validated with two practical applications in a five-storey reinforced concrete structure with masonry infill walls and a three-storey masonry structure. Finally, a conclusion can be drawn that the two-step procedure yields a reasonably good estimation of damping ratio.

scholarly journals Bridge Dynamic Cable-Tension Estimation with Interferometric Radar and APES-Based Time-Frequency Analysis

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 501
Author(s):  
Jian Wang ◽  
Xiang Wang ◽  
Chongyi Fan ◽  
Yueli Li ◽  
Xiaotao Huang
Keyword(s):  
Frequency Analysis ◽  
Field Experiments ◽  
Displacement Vector ◽  
Frequency Resolution ◽  
Cable Tension ◽  
Time Frequency Analysis ◽  
Vibration Equation ◽  
Time Frequency ◽  
String Vibration ◽  
Analysis Technique

Dynamic cable-tension is an important bridge-health indicator. However, it is difficult to be measured precisely and efficiently. A remote bridge dynamic cable-tension measurement method is proposed. It uses an interferometric radar sensor, a time-frequency analysis technique, and a tension estimation approach based on a string-vibration-equation. One radar can measure the displacements of multiple cables aligned on one side of a bridge, at the same time. By solving the string vibration equation, each cable-tension is calculated from its fundamental frequency, which is obtained by time-frequency analyzing a short section of the cable’s whole displacement vector in an overlapped-piecewise manner. An adaptive amplitude and phase estimation (APES) algorithm is used to solve the frequency resolution deterioration problem due to the short duration. Simulations and field experiments with a K band interferometric radar validate that the proposed method is superior to traditional cable-tension measurements in terms of precision, robustness, and efficiency. The proposed method is of great application value in measuring and monitoring large cable-stayed bridges and cable-suspended bridges.

Time-Frequency Analysis of Partial Discharge Phenomena in SF6 gas using Wavelet Transform

1997 ◽  
Vol 117 (3) ◽  
pp. 338-345 ◽  
Author(s):  
Masatake Kawada ◽  
Masakazu Wada ◽  
Zen-Ichiro Kawasaki ◽  
Kenji Matsu-ura ◽  
Makoto Kawasaki
Keyword(s):  
Wavelet Transform ◽  
Frequency Analysis ◽  
Partial Discharge ◽  
Time Frequency Analysis ◽  
Time Frequency
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