Monitoring oscillations of slender structures with GPS and accelerometers (original) (raw)
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Structural monitoring with GPS and accelerometers: the chimney of the power plant in Piacenza, Italy
3rd IAG Symposium on …, 2006
The construction industry is increasingly involved in the safety assessment and survey of existing structures, often following refurbishment and structural modification works. The increasing difficulty in selecting building areas and getting funding for new constructions, jointly to the not negligible costs related to the demolition of the old ones as well as to the costs for the following site clearance, has led to a greater environmental awareness and to a cultural desire to maintain ancient and historic structures. The Italian Centre for Experimental Electric Science (CESI) and Politecnico di Milano set up a monitoring system aimed at the detection of structural modification of slender structure in near real time. The system, installed on a 120 m high chimney of the Piacenza (Italy) power plant, acquires data at a frequency of 10 Hz from 3 GPS (one rover on the chimney, connected to the acquisition and processing unit by a WI-FI system, and two masters) and, at a frequency of 125 Hz, from 4 accelerometers. The paper reports on the acquisition system, explains the data analysis procedure as well as the results of the measurement campaign, three months long.
International Journal of Architectural Heritage, 2014
Modern monitoring techniques contribute to accurately describing the structural health conditions of historical buildings and to optimising the plan of maintenance as well as the restoring intervention. Particularly, dynamic testing gives knowledge about global structural behaviour and can be used to calibrate numerical models and to predict the response to dynamic and earthquake loading. In some circumstances, vibration-based monitoring can also help in evaluating safety conditions. The present paper proposes a discussion about the methodological multidisciplinary approach to modal testing when applied to architectural heritage buildings and structures, along with the description of selected case studies. These examples were chosen to cover the various issues connected to test design and interpretation.
Monitoring of Vibrations for the Protection of Architectural Heritage
A peculiar aspect in Structural Health Monitoring is concerning the monitoring of vibrations in urban environments that may affect the integrity and conservation of architectural heritage buildings. The paper reviews the main issues on the subject and takes into consideration the problem of measuring and interpreting vibrations in buildings. The use of numerical models is also discussed and a practical case study is finally presented.
Computer-Aided Civil and Infrastructure Engineering, 2008
A computer-based algorithm computing the mean amplitude of small-scale, high frequency oscillations of civil engineering structures using GPS and Robotic Theodolites (RTS) is presented. This algorithm is based on a peak-picking filter derived from supervised learning through independent experiments. This filter is a function of the oscillation frequency, computed even from noisy, apparent displacement records. The algorithm minimizes the noise of high-frequency GPS and RTS recordings and calculates the mean amplitude of the oscillations with millimeter accuracy.
Journal of Sound and Vibration, 2008
Global Positioning System (GPS) has been successfully used to measure displacements of oscillating flexible civil engineering structures such as long suspension bridges and high-rise buildings, and to derive their modal frequencies, usually up to 1 Hz, but there is evidence that these limits can be exceeded using high frequency GPS receivers. Based on systematic experiments in computer controlled oscillations with one- and three-degrees of freedom we investigated the potential of GPS, first to record higher oscillation frequencies, at least up to 4 Hz at the minimum resolution level of this instrument for kinematic applications (⩾5 mm), and second, to identify more than one dominant frequency. Data were processed using least squares-based spectral analysis and wavelet techniques which permit to analyze entire time series, even those of too short duration or those characterized by gaps, in both the frequency and the time domain.The ability of GPS to accurately measure frequencies of oscillations of relatively rigid (modal frequencies 1–4 Hz) civil engineering structures is demonstrated in the cases of two bridges.The outcome of this study is that GPS is suitable for the identification of dynamic characteristics of even relatively rigid (modal frequencies up to 4 Hz) civil engineering structures excited by various loads (wind, traffic, earthquakes, etc.) if displacements are above the uncertainty level of the method (⩾5 mm). Structural health monitoring of a wide range of structures appears therefore a promising field of application of GPS.
Optimized procedures and strategies for the dynamic monitoring of historical structures
Journal of Civil Structural Health Monitoring, 2016
Compared with other diagnostic techniques, which are limited to the local investigation, the structural dynamic monitoring allows to obtain information about seismic response and vulnerability of structures, in their whole. The experimental modal analysis evaluates the dynamic parameters such as frequencies, vibration modes and damping coefficients. For historic buildings, due to their heterogeneity and complexity, these data are not yet readily available. The possibility of applying the simplified procedures for the dynamic identification of the different historic structural typologies is, therefore, strategic to obtain useful information to apply the design criteria and the structural verifications in the seismic field. Besides the simplified procedures allow an optimization both on the execution time and on the costs. The paper provides some hypothesis of simplified dynamic monitoring procedures through the reduction/optimization of the accelerometric sensors used for three case studies, which differ in structural typology such as Churches, Towers and Palaces.
2005
The Global Positioning System is becoming a leading technology for monitoring dynamic displacements of structures, notably large bridges and tall buildings. These structures have been monitored in the past by geotechnical instruments such as accelerometers and displacement transducers. In this paper we compare the precision and accuracy of displacements from GPS data with values from a displacement transducer and an accelerometer. In order to compare GPS with a displacement transducer, an experiment was conducted on a footbridge to measure the amplitude and frequency of displacements induced by pedestrians. For comparing the performance of GPS with values from an accelerometer, an electro-mechanical oscillator (EMO) was used to apply the same periodic vertical displacements to both instruments. In this paper, we present a brief summary of the methodology used and the test results. The Phase Residual Method (PRM) was used to determine the displacements as sensed by the GPS antenna. A...
GPS in Pioneering Dynamic Monitoring of Long-Period Structures
Earthquake Spectra, 2002
Global Positioning System (GPS) technology with 10–20-Hz sampling rates allows scientifically justified dynamic measurements of relative displacements of long-period structures. The displacement response of a simulated tall building in real time and permanent deployment of GPS units at the roof of a building are described. To the authors’ best knowledge, this is the first permanent deployment of GPS units (in the world) for continuous dynamic monitoring of a tall building. Data recorded from the building during a windy day is analyzed to determine the structural characteristics. When recorded during extreme motions caused by earthquakes and strong winds, such measurements can be used to compute average drift ratios and changes in dynamic characteristics, and therefore can be used by engineers and building owners or managers to assess the structural integrity and performance by establishing pre-established thresholds. Such information can be used to secure public safety and/or take s...
Türkiye RECENT DEVELOPMENTS ON DYNAMIC MONITORING OF STRUCTURES
2008
In this paper, a cursory summary of current seismic instrumentation objectives and methods are discussed. Such instrumentation evolved over 3-4 decades aims to obtain response data to facilitate studies to improve design and analyses procedures. However, with recent advances in electronic hardware and transmission of data, the objectives of applying dynamic monitoring of structures are shifting from its former objectives to real-time assessments of health of structures. As an example, use of Global Positioning System (GPS) to dynamically monitor long-period structures such as tall buildings and long-span bridges is now a reality. Such developments can be used to make decisions to assess the safety of structures and the public using them. Özet: Bu tebliğde, güncel olarak kullanılan sismik aletsel ölçmenin amaç ve yöntemleri özetlenmektedir. Son 30-40 yıl içerisinde uygulamalar, genellikle, yapıların deprem esnasındaki tepkilerinin kaydedilerek davranışları hakkında incelemeleri ve di...