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Vibration Surveys (vibration + survey)

Distribution by Scientific Domains
Engineering100%

Selected Abstracts

Dynamic performance of twin curved cable-stayed bridges

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 1 2004
C. Gentile
Abstract The dynamic behaviour of two curved cable-stayed bridges, recently constructed in northern Italy, has been investigated by full-scale testing and theoretical models. Two different excitation techniques were employed in the dynamic tests: traffic-induced ambient vibrations and free vibrations. Since the modal behaviour identified from the two types of test are very well correlated and a greater number of normal modes was detected during ambient vibration tests, the validity of the ambient vibration survey is assessed in view of future monitoring. For both bridges, 11 vibration modes were identified in the frequency range of 0ndash;10Hz, being a one-to-one correspondence between the observed modes of the two bridges. Successively, the information obtained from the field tests was used to validate and improve 3D finite elements so that the dynamic performance of the two systems were assessed and compared based on both the experimental results and the updated theoretical models. Copyright © 2003 John Wiley & Sons, Ltd. [source]

On the influence of trigger level in distribution vibration surveys

PACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2009
Vincent Rouillard
Abstract This paper follows on from recently published research that examined the effects of recording parameters on the outcomes of distribution vibration surveys. Whereas the previous research focused on the effects of the sampling period at which sub-records of the process are captured, this paper deals with another often-used recording parameter, namely, the vibration level trigger. The paper describes the development of a software tool that was designed specifically to study the influence of various sampling parameters on continuously recorded vibration data. This software tool was used to undertake a thorough statistical analysis on a vibration record set consisting of continuously sampled data measured from a wide variety of vehicle types and routes. The paper shows that the outcomes of vibration surveys are very sensitive to the trigger level and can produce highly distorted results by introducing a bias that nearly always overestimates the overall vibration levels. This is reflected in estimates of common descriptors of random vibration processes such as the average power spectral density (PSD), the peak-hold PSD and the overall root-mean-square values. The main outcome of this analysis is the formulation of a correction method based on relationships between the true mean and peak-hold PSDs and estimates from sampled data. The effect and significance of the proposed correction procedure is demonstrated, especially in the context of laboratory simulation of distribution vibrations. The paper concludes by making specific recommendations for configuring high-capacity field data recorders and applying correction strategies to ensure that vibration surveys yield statistically sound results. Copyright © 2009 John Wiley & Sons, Ltd. [source]

On the effects of sampling parameters when surveying distribution vibrations

PACKAGING TECHNOLOGY AND SCIENCE, Issue 8 2008
Vincent Rouillard
Abstract This paper presents the initial outcomes of a study aimed at better understanding the effects of recording parameters on the outcomes of distribution surveys. With the advent of vibration recorders with increasing capacity, there has been a corresponding increase in the number of studies aimed at evaluating and characterizing the random vibrations generated by transport vehicles across a wide variety of distribution environments. Oftentimes, the sampling and recording parameters used in these studies are not given adequate attention, resulting in statistical estimates that are open to interpretation. The paper shows how the selection of the sampling and recording parameters can have significant effects on much used descriptors of random vibration processes such as the average power spectral density (PSD), the peak-hold PSD and the root mean square distribution. The paper shows that the results of vibration surveys are most sensitive to the sampling period, especially when the vibrations are highly non-stationary. The paper concludes by making specific recommendations for configuring high-capacity vibration recorders to ensure that vibration surveys yield statistically sound results. Copyright © 2008 John Wiley & Sons, Ltd. [source]