The use of a dynamic truck-trailer drive-by system to monitor bridge damping

Bridge structures are continuously subject to degradation due to the environment, ageing and excess loading. Periodic monitoring of bridges is therefore a key part of any maintenance strategy as it can give early warning if a bridge becomes unsafe. This article investigates an alternative method for the monitoring of bridge dynamic behaviour: a truck-trailer vehicle system, with accelerometers fitted to the axles of the trailer. The method aims to detect changes in the damping of a bridge, which may indicate the existence of damage. A simplified vehicle-bridge interaction model is used in theoretical simulations to assess the effectiveness of the method in detecting those changes. The influence of road profile roughness on the vehicle vibration is overcome by recording accelerations from both axles of a trailer and then analysing the spectra of the difference in the accelerations between the two axles. The effectiveness of the approach in detecting damage simulated as a loss in stiffness is also investigated. In addition, the sensitivity of the approach to the vehicle speed, road roughness class, bridge span length, changes in the equal axle properties and noise is investigated

Portable Bridge WIM Data Collection Strategy for Secondary Roads

A common method of collecting traffic loading data across a large road network is to use a network of permanent pavement-based WIM systems. An alternative is to use one or more portable Bridge Weigh-In-Motion systems which are moved periodically between bridges on the network. To make optimum use of such a system, a suitable data collection strategy is needed to choose locations for the system. This paper describes a number of possible strategies which the authors have investigated for the National Roads Authority in Ireland. The different strategies are examined and their advantages and disadvantages compared. Their effectiveness at detecting a heavy loading event is also investigated and the preferred approach is identified

Drive-by damage detection in bridges using the apparent profile

The concept of using sensors on a passing vehicle, rather than on the bridge, is known as 'Drive-by' damage detection. The newly developed traffic speed deflectometer (TSD) is a device used for pavement deflection measurements and is investigated here in numerical simulations as a means of bridge damage detection. A TSD vehicle model containing two displacement sensors is simulated crossing a simply supported finite element beam containing damage simulated as a loss in stiffness of one of the elements. An adapted Cross Entropy optimisation algorithm procedure is proposed to determine the apparent profile, where the displacements recorded by the sensors are used as the inputs. The time-shifted difference in the apparent profile is used as the damage indicator. Results show that this can be reliably used as a damage indicator in the presence of noise and changes in the transverse position of the vehicle on the bridge.Science Foundation Irelan

Using Instrumented Quarter-Cars for 'Drive By' Bridge Inspection

The 2013 International Association for Bridge and Structural Engineering Conference (IABSE 2013), Rotterdam, The Netherlands, 6-8 May 2013This 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

Using Instrumented Quarter-Cars for \u27Drive By\u27 Bridge Inspection

The 2013 International Association for Bridge and Structural Engineering Conference (IABSE 2013), Rotterdam, The Netherlands, 6-8 May 2013This 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

The analysis of short signal segments and its application to Drive-by bridge inspection

‘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 oscillation, 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. An optimisation approach is proposed here as an alternative to standard signal processing techniques to overcome the challenges of short signals and the nonlinear nature of the drive-by system. Signal pollution due to the road profile is overcome using time-shifted bridge curvatures, a novel damage indicator.Science Foundation Irelan

Using an Instrumented Tractor-Trailer to Detect Damage in Bridges

The 31st IMAC Conference on Structural Dynamics, California, United States of America, 11-14 February 2013This paper investigates an alternative to Structural Health Monitoring (SHM) which involves no sensors on the bridge itself. It uses a vehicle fitted with accelerometers on its axles as a method of monitoring the dynamic behavior of the bridge, which in turn gives an indication of the bridge's structural condition. The concept, known as 'drive by' bridge inspection, 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. In the paper, a two dimensional numerical model is described of a 3-axle truck towing a half-car trailer. The vehicle-bridge dynamic interaction is modeled to test the effectiveness of the approach in identifying the structural damping of the bridge. The damping of the bridge is used here as an indicator of damage. The accelerations in the two axles of the trailer are subtracted to remove the effect of the road profile. Results indicate that the algorithm works well and is not sensitive to transverse position of the vehicle on the bridge.Science Foundation IrelandUS-Ireland Research Partnership Schem

Allowing for a rocking datum in the analysis of drive-by bridge inspections

Civil Engineering Research in Ireland, Belfast, UK, 28 - 29 August, 2014'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.Science Foundation Irelan

Drive-by damage detection with a TSD and time-shifted curvature

‘Drive-by’ damage detection is the concept of using sensors on a passing vehicle to detect damage in a bridge. The newly developed traffic speed deflectometer (TSD) is a device used for pavement velocity/deflection measurements and is investigated here in numerical simulations as a means of bridge damage detection. A TSD vehicle model containing five displacement sensors is simulated crossing a simply supported finite element beam containing damage simulated as a loss in stiffness of one of the elements. Time-shifted curvature is derived from the displacements and is proposed as a novel damage indicator, which removes the influence of the road profile and all vehicle motions except for pitch. Results show that the time-shifted curvature can be reliably used as a damage indicator in the presence of noise and changes in transverse position of the vehicle on the bridge.Science Foundation Irelan

Drive-by damage detection in bridges using the apparent profile

The concept of using sensors on a passing vehicle, rather than on the bridge, is known as \u27Drive-by\u27 damage detection. The newly developed traffic speed deflectometer (TSD) is a device used for pavement deflection measurements and is investigated here in numerical simulations as a means of bridge damage detection. A TSD vehicle model containing two displacement sensors is simulated crossing a simply supported finite element beam containing damage simulated as a loss in stiffness of one of the elements. An adapted Cross Entropy optimisation algorithm procedure is proposed to determine the apparent profile, where the displacements recorded by the sensors are used as the inputs. The time-shifted difference in the apparent profile is used as the damage indicator. Results show that this can be reliably used as a damage indicator in the presence of noise and changes in the transverse position of the vehicle on the bridge.Science Foundation Irelan