Ambient vibration and seismic evaluation of a cantilever truss bridge

Shama, Ayman A.; Mander, John B.; Chen, Stuart S.; Aref, Amjad J.

doi:10.1016/s0141-0296(01)00027-x

Cited by 21 publications

(7 citation statements)

References 7 publications

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“…The longitudinal motion documented by accelerometer measurements can be attributed to vertical bending of the bridge deck or generally interaction between vertical and longitudinal modes of the bridge deck [54,55], an explanation supported by the similarity of oscillation frequency in the longitudinal and vertical axes and to the presence of isolators increasing the ability of the deck to move in the longitudinal direction. It must also be noticed that longitudinal deflections have been measured in the past during modal tests including excitation of bridges in the longitudinal direction or ambient vibration testing [56][57][58], but to the best of the authors' knowledge, the Kifissos bridge seems to provide some evidence of longitudinal deflections as a result of vertical excitation, especially because of the similarities of their modal frequencies (Figure 4). The significance of this result is double because (i) it supports previous experimental results showing that vertical loading can cause horizontal forces [59] and significant horizontal response of the bridge deck.…”

Section: Discussionmentioning

confidence: 99%

Three-dimensional dynamic deflections and natural frequencies of a stiff footbridge based on measurements of collocated sensors

Moschas

Stiros

2013

Struct. Control Health Monit.

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SUMMARYA redundant system of collocated geodetic sensors and an accelerometer were used to measure the displacements of a stiff, 40-m-long footbridge excited by essentially vertical synchronized jumps. A main output of the measurements was that excitations produced vertical deflections (of the order of several mm), lateral deflections with an amplitude about half that of the vertical, an effect known for various bridges, and also smaller-scale longitudinal deflections, probably induced by the vertical ones. This combination of deflections in three axes is not an artifact of measuring errors, or of limitations of specific instruments, and do not reflect random effects, for they have been observed in different experiments by different sensors (Global Navigation Satellite System-GNSS, i.e., Global Positioning System-GPS plus the Russian Global Navigation Satellite System-GLONASS), robotic total stations-RTS (or robotic theodolite), and an accelerometer, and were tested through control of the measurement errors from time series reflecting no bridge oscillations. In all cases, sensors provided similar estimates of deflections and of deflection-derived dominant frequencies, which were found equal to those derived from the accelerometer. The proposed instrumentation and methodology seem suitable to control deflections of bridges in cases that visibility of satellites is poor or is disrupted by vehicle circulation. Measurement-based modeling of bridges described might be useful for understanding the structural behavior of bridges under several types of dynamic loads and can contribute to the displacement-based design of structures.

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Section: Discussionmentioning

confidence: 99%

Three-dimensional dynamic deflections and natural frequencies of a stiff footbridge based on measurements of collocated sensors

Moschas

Stiros

2013

Struct. Control Health Monit.

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“…5 contrasting several nonlinear designs to the linear case must be carefully assessed when comparing systems excited by the same noise level. Consider a bridge having lowest natural frequency near 0.8 Hz [2]. For our "essentially nonlinear" test system with natural frequency 4.141 Hz, this represents a bandwidth r % 0.19, while for the linear counterpart having natural frequency 23.38 Hz, this is a bandwidth of r % 0.03.…”

Section: Resultsmentioning

confidence: 99%

“…For example, vibration energy harvesting in an urban environment may pose less cost-benefit attraction than achieving successful electrical power generation on a wireless weather station buoy far at sea or a health-monitoring sensor on a truss bridge span over a gorge. The ambient vibration sources to harness in these remote environments are often characterized by stochastic oscillations with peak amplitudes in the range of a few Hz or less [1][2][3][4]. Above the frequencies associated with peak acceleration amplitudes, the power spectra roll off at a rate of 20-40 dB/decade, which is characteristic of exponentiallycorrelated (colored) or quasi-monochromatic noise sources [5].…”

Section: Introductionmentioning

confidence: 99%

Prospects for Nonlinear Energy Harvesting Systems Designed Near the Elastic Stability Limit When Driven by Colored Noise

Harne

Wang

2013

Journal of Vibration and Acoustics

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Ambient vibration sources in many prime energy harvesting applications are characterized as having stochastic response with spectra concentrated at low frequencies and steadily reduced power density as frequency increases (colored noise). To overcome challenges in designing linear resonant systems for such inputs, nonlinear restoring potential shaping has become a popular means of extending a harvester's bandwidth downward towards the highest concentration of excitation energy available. Due to recent works which have individually probed by analysis, simulation, or experiment the opportunity for harvester restoring potential shaping near the elastic stability limit (buckling transition) to improve power generation in stochastic environments-in most cases focusing on postbuckled designs and in some cases arriving at conflicting conclusionswe seek to provide a consolidated and insightful investigation for energy harvester performance employing designs in this critical regime. Practical aspects drive the study and encourage evaluation of the role of asymmetries in restoring potential forms. New analytical, numerical, and experimental investigations are conducted and compared to rigorously assess the opportunities and reach well-informed conclusions. Weakly bistable systems are shown to potentially provide minor performance benefits but necessitate a priori knowledge of the excitation environment and careful avoidance of asymmetries. It is found that a system designed as close to the elastic stability limit as possible, without passing the buckling transition, may be the wiser solution to energy harvesting in colored noise environments.

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“…In bridge monitoring projects, for example, a well-known example is the WASHMS system which has mounted more than 800 sensors to monitor and identify the operational condition of three landmark bridges in Hong Kong [1]. Also, Shama et al [2] conducted ambient vibration tests on North Grand Island Bridge in West New York for the FE model validation. Brown john et al [3] acquired the OMA data of the Humber Bridge in 2008 and studied the modal parameter variation from an old dataset obtained decades ago.…”

Section: Introductionmentioning

confidence: 99%

Statistically Filtering Data for Operational Modal Analysis under Ambient Vibration in Structural Health Monitoring Systems

Wang

Song

et al. 2016

MATEC Web Conf.

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Abstract. Operational modal analysis (OMA) is prevalent in large structure modal identification for that it asks for output measurements only. To guarantee identification accuracy, theoretically, OMA data need to be a random process of Gaussian white noise (GWN). Although numerous OMA applications are found in practice, few have particularly discussed the data distribution and to what extent it would blur the modal judgement. This paper presents a method to sieve segments mostly obeying the GWN distribution out of a recording. With a windowing technique, the data segments are evaluated by the modified Kurtosis value. The process has been demonstrated on the monitoring data of two case study structures: one is a laboratory truss bridge excited by artificial forces, the other is a real cable-stayed bridge subject to environmental loads. The results show that weak randomness data may result in false peaks that would possibly mislead the non-parametric modal identification, such as using the Frequency Domain Decomposition method. To overcome, cares on selecting the optimal segment shall be exercised. The proposed method is verified effective to find the most suitable data for modal identification of structural health monitoring systems.

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Ambient vibration and seismic evaluation of a cantilever truss bridge

Cited by 21 publications

References 7 publications

Three-dimensional dynamic deflections and natural frequencies of a stiff footbridge based on measurements of collocated sensors

Three-dimensional dynamic deflections and natural frequencies of a stiff footbridge based on measurements of collocated sensors

Prospects for Nonlinear Energy Harvesting Systems Designed Near the Elastic Stability Limit When Driven by Colored Noise

Statistically Filtering Data for Operational Modal Analysis under Ambient Vibration in Structural Health Monitoring Systems

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