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O'Brien, Eugene J.
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O'Brien, Eugene J.
Official Name
O'Brien, Eugene J.
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Now showing 1 - 10 of 22
- PublicationDetermination of longitudinal profile of railway track using vehicle-based inertial readingsThe longitudinal profile of a railway track excites a dynamic response in a train which can potentially be used to determine that profile. A method is proposed in this paper for the determination of the longitudinal profile through an analysis of bogie vertical accelerations and angular velocities resulting from the train/track dynamic interaction. The Cross Entropy optimisation technique is applied to determine the railway track profile elevations that generate a vehicle response which best fits the measured dynamic response of a railway carriage bogie. Numerical validation of the concept is achieved by using a 2-dimensional quarter-car dynamic model, representing a railway carriage and bogie, traversing an infinitely stiff profile. The concept is further tested by the introduction of a 2-dimensional car dynamic vehicle model and a 3 layer track model to infer the track profile in the longitudinal direction. Both interaction models are implemented in Matlab. Various grades of track irregularity are generated which excite the vehicle inducing a dynamic response. Ten vertical elevations are found at a time which give a least squares fit of theoretical to measured accelerations and angular velocity. In each time step, half of these elevations are retained and a new optimisation is used to determine the next ten elevations along the length of the track. The optimised elevations are collated to determine the overall longitudinal profile over a finite length of railway track.
1237Scopus© Citations 28 - PublicationApplication of Laser Measurement to the Drive-by Inspection of Bridges(National Technical University of Athens (NTUA), 2015-05-27)
; This paper introduces the application of laser vibrometer measurements to the drive-by inspection of bridges. Drive-by methods usually process the acceleration response measured from an accelerometer installed on a vehicle passing over a bridge. In this paper, two laser vibrometers and two accelerometers are installed on the vehicle to measure a rela-tive velocity between the bridge and vehicle and the vehicle acceleration. The vehicle velocity is removed from the relative velocity by subtracting the time integration of the vehicle accel-eration. It is shown by subtracting two following bridge spatial velocities at moving coordi-nates, that the spatial velocity of the road roughness can be removed. As a result, the bridge velocity at the moving coordinate is obtained. By applying the FFT to the bridge velocity, the fundamental frequency of the bridge is visible in the spectrum.498 - PublicationDetermination of Vertical Alignment of Track using Accelerometer Readings(2015-04-23)
; ; Railway track vertical alignment is an important indicator of serviceability condition. Through comparisons with past history, track alignment also informs maintenance planning. The vertical alignment of a railway track excites a dynamic response in a train which can potentially be used to determine that alignment. A method is proposed in this paper for the detection of the alignment through an analysis of vehicle accelerations resulting from the train/track dynamic interaction. The Cross Entropy optimisation technique is applied to determine the railway track profile heights that best fit the measured accelerations at and above a railway carriage bogie. Such an approach, using relatively low-cost accelerometers fixed to trains in regular service, would provide inexpensive daily 'drive-by' track monitoring to complement and compare data collected by the Track Recording Vehicle (TRV). The use of a TRV is the current preferred method used to determine railway track profiles using laser based methods. Numerical validation of the concept is achieved by using a 2-dimensional quarter-car dynamic model for the railway carriage and bogie to infer the track profiles in the longitudinal direction. The interaction model is implemented in MATLAB. The track is modelled as an infinitely stiff beam featuring various grades of rail irregularity which excite the vehicle inducing a dynamic response. Ten vertical elevations are found at a time which give a least squares fit of theoretical to measured accelerations. In each time step, half of these elevations are retained and a new optimisation is used to determine the next ten elevations along the length of the track. The optimised displacements are collated to determine the overall rail track profile over a finite length of railway track. This paper reports the results of the numerical simulations and the plans that are underway to further develop the model and test the concept in field trials.580 - PublicationAllowing for a rocking datum in the analysis of drive-by bridge inspections(2014-08-29)
; 'Drive-By' damage detection is the concept of using sensors on a passing vehicle to detect damage in a bridge. At highway speeds, the vehicle spends a short amount of time on the bridge: it may not even go through a full cycle of vibration, resulting in only a partial signal of the bridge motion being detected. Given that the spectral resolution of standard signal processing techniques depends on the length of data in the signal, they cannot be used to identify the bridge frequency accurately. In addition, the nonlinear and non-stationary nature of the vehicle-bridge interaction system poses challenges. The aim of this study is to model a 'drive-by' bridge inspection approach using a beam in free vibration. An optimisation approach is proposed in numerical simulations as an alternative to standard signal processing techniques to overcome the challenges of short signals and the nonlinear nature of the drive-by system.190 - PublicationIndirect Monitoring of Railway Bridges by Direct IntegrationRailway bridges are of importance as critical elements in transportation networks. Unfortunately, many railway bridges are old and these structures are subject to degradation over time. To monitor bridge structures, many methods are introduced. In recent years, indirect bridge monitoring methods have become more popular. These methods use passing vehicles to measure dynamic responses such as accelerations. In this paper, a new direct integration approach is introduced to directly calculate the apparent railway track profile (AP) that is consistent with the measured accelerations. An adaptation of the Newmark Beta numerical method is used for this purpose. Using AP, bridge displacement profile difference (BDPD) is calculated to monitor bridges. The BDPD is the difference between the baseline (healthy) profile and the apparent profile after damage and environmental effects. BDPD is sensitive to temperature change and bridge damage. It has its own frequency which is close to the bridge frequency.
208 - PublicationA New Damage Indicator for Drive-by Monitoring using Instantaneous Curvature(Austroads, 2017-04-06)
; ; ; Drive-by monitoring has enhanced the possibilities for bridge damage detection, with the potential to deliver a bridge rating in the time it takes an instrumented vehicle to pass overhead. This paper outlines the importance of Instantaneous Curvature (IC) as an indicator of local damage. For the IC calculation, bridge deflections are measured from the vehicle before and after the occurrence of damage, so that a comparison between the two situations can be made. Differences in curvature are clearly visible in numerical simulations, especially at the damage location. A Finite Element model of a simply supported bridge subject to a crossing vehicle is modelled dynamically. In this paper, the Curvature Ratio (CR) is proposed as the damage indicator, defined as the ratio of IC in the current bridge to IC in the corresponding healthy bridge. Road profile and random noise in the simulated measurements are considered to represent realistic conditions. Simulations in MATLAB demonstrate that CR is an effective indicator in most of the analysis cases.292 - PublicationDrive-by structural health monitoring of railway bridges using train mounted accelerometers(2015-05-27)
; ; ; Bridge damage can be detected by observing changes in its spectral properties. In its infancy, bridge health monitoring involved monitoring physical properties via direct instrumentation, i.e. sensors attached to the bridge. In recent years many authors have investigated the ability of indirect methods to assess the structural health of bridges, i.e. the vehicles traversing the bridges are fitted with sensors. This has the potential of reducing monitoring costs as the vehicle may be used to monitor many bridges on the network. Most of the investigation in this relatively new field of study has been on road bridges and road vehicles. A method is proposed in this paper for the detection of the bridge damage through an analysis of vehicle accelerations resulting from the train/track/bridge dynamic interaction. In a train/track/bridge interaction there are additional complications which do not exist on road bridges. The signal generated by the train as it traverses the bridge is normally short in duration. Studies on railway bridges are complicated by the addition of rails, sleepers and sometimes ballast between the tracks and the bridge deck. However, the weight of the train relative to the bridge is considerably larger than previous studies using road vehicles and this will excite the bridge to a higher degree. Numerical validation of the drive-by concept is achieved by using a 2-dimensional dynamic vehicle model with 10 degrees of freedom. The finite element interaction model is implemented in MATLAB. The track is modelled as a continuous beam, supported at 0.545m centres on three layers of springs and masses representing sleepers, and ballast lying on a simply supported bridge beam. This paper reports the results of the numerical simulations and the plans that are underway to test the concept in field trials.752 - PublicationUsing Instrumented Quarter-Cars for 'Drive By' Bridge InspectionThis paper investigates the concept of ‘drive by’ bridge inspection, a low cost alternative to Structural Health Monitoring (SHM), involving no sensors on the bridge. The concept may be of particular value after an extreme event, such as an earthquake or a flood, where a rapid indication of bridge condition is needed. Vehicle/bridge dynamic interaction is modelled to test the effectiveness of the approach. Damage is simulated here as a change in the bridge damping ratio. Two quarter cars are simulated crossing the bridge with accelerometers on board. A frequency domain analysis then illustrates changes in the Power Spectral Density of the accelerations as the bridge becomes damaged. The time-lagged difference in the accelerations is found to be effective in detecting damage. Results are compared to those with sensors on the bridge and found to be similar.
323 - PublicationFleet Monitoring - Using Sensors in a Fleet of Passing Vehicles to Monitor the Health of Bridges(2021-09-17)
; ; ; ; This paper proposes the use of a fleet of instrumented vehicles to monitor the condition of infrastructure and bridges. It is anticipated that data from privately owned vehicles with low-cost accelerometer and GPS data, will be available for this purpose in the future. An inverse version of the well known Newmark-Beta method is proposed to determine road/rail surface profile from measured accelerations. Some results are reported from an instrumented train that made repeat runs on railway track over a period of a month. For bridge health monitoring, the concept of a moving reference influence line is proposed as a damage indicator. It is shown in simulation to give good indications of bearing damage in a simply supported bridge.153 - PublicationDrive-by inference of railway track longitudinal profile using accelerometer readings taken by in-service vehicles(Civil Engineering Research Association of Ireland, 2016-08-30)
; ; ; Accurate knowledge of the longitudinal profile of railway track is essential to support maintenance planning by track asset managers. The dynamic response of a train is largely dependent on the longitudinal profile of the railway track it crosses. This dynamic response can potentially be used to determine that profile. Cross Entropy optimisation is used to infer railway track longitudinal profile elevations through analysis of measured vehicle bogie accelerations with added uncertainty in vehicle and track properties. A numerical analysis is presented in this paper using a 2 dimensional half car vehicle and a finite element 3-layer track model implemented in Matlab. A population of track longitudinal profiles is generated through a random mechanism. A vehicle track interaction with randomly generated uncertainty in vehicle and track properties is carried out for each longitudinal profile in the population. The bogie acceleration signal produced for each profile is compared to the measured signal. The best fitting bogie accelerations are used to gather an elite set of rail longitudinal profiles. This elite set is used to generate an improved population of estimates for the next iteration. Once a convergence criterion is met the profile generating an acceleration signal that best fits the measured bogie acceleration signal is kept as the inferred longitudinal rail profile. This paper reports the results of the numerical simulations.139