Exploring indirect vehicle-bridge interaction for bridge SHM

Bridge structures are subject to continuous degradation due to the environment, ageing and excess loading. Monitoring of bridges is a key part of any maintenance strategy as it can give early warning if a bridge is becoming unsafe. This paper will theoretically assess the ability of a vehicle fitted with accelerometers on its axles to detect changes in damping of bridges, which may be the result of damage. Two vehicle models are used in this investigation. The first is a two degree-of-freedom quarter-car and the second is a four degree-of-freedom halfcar. The bridge is modelled as a simply supported beam and the interaction between the vehicle and the bridge is a coupled dynamic interaction algorithm. Both smooth and rough road profiles are used in the simulation and results indicate that changes in bridge damping can be detected by the vehicle models for a range of vehicle velocities and bridge spans.

2014

Many bridges in the world's transport infrastructure are old and have deteriorated over time. The solution to this problem is to either repair or replace a bridge or to establish its safety and maintain it in service. It is generally very costly to repair or replace a bridge. With reduced maintenance budgets there is an increasing interest in maintaining these old bridges in service by using probabilistic methods to prove that they are safe. Bridge safety is assessed based on (i) the loading which it will experience in service and (ii) the resistance of the structure. Improved knowledge of loading and resistance allows a more accurate assessment of whether a bridge is safe to remain in service without the requirement for expensive repair or replacement strategies. BridgeMon is an EU-FP7 funded project which aims to improve current monitoring techniques for road and rail bridges. This will be done by developing improved methods of evaluating traffic loading on bridges and carrying out Structural Health Monitoring (SHM) to identify damage and assess their remaining resistance. Bridge Weigh-in-Motion (B-WIM) refers to the technique of using the measured response of a bridge to calculate the vehicle loads crossing it and is a useful tool in monitoring traffic loading on bridges. BridgeMon will improve the accuracy of current B-WIM technologies and develop the first B-WIM system for railways. It is also developing the concept of virtual monitoring, whereby sensors are used to calculate vehicle weights which are then used to calculate stress histories throughout the bridge. Results of testing of a rail B-WIM system on a bridge in Poland are presented. Results show that the system is capable of accurately calculating train weights.

Civil Engineering Research Journal, 2017

Recently in the area of bridge health monitoring, there is a shift towards the use of indirect measurements of a passing vehicle to assess the structural integrity of bridge structures, which is known as "Drive-by Bridge inspection." This approach is based on determining the dynamic characteristics of the bridge using the vehicle responses, such as bridge frequencies, bridge mode shapes, and even bridge stiffness and damping. The change in these characteristics over a period of time reflects the level of deterioration of the bridge's health condition. This article introduces a brief discussion on the development of this field of research since it was revealed. The article addresses the prominent studies in this domain, while some other work is not included for the sake of brevity in the paper. This article is a good starting point for those interested in researching this topic.

Recent catastrophic bridge failures clearly indicate the urgent need for improving interval-based bridge inspection procedures that are qualitative and subjective in nature. Structural Health Monitoring (SHM) can mitigate the deficiencies of interval-based inspection techniques and provide real-time diagnostic information regarding the bridge structural health. SHM is not flawless however; the variability in the vehicle characteristics and traffic operational conditions makes it prone to false diagnosis. Recent advancements in the integration of SHM with intelligent transportation systems (ITS) demonstrate the successful use of ITS devices (e.g., traffic cameras, traffic detectors) in the analysis of bridge responses to multimodal traffic with varying loads or during the critical events that cause excess vibration beyond the normal limit. In an ITS-informed SHM system, the ITS device collected data can be integrated with SHM to increase the reliability and accuracy of the SHM system. This integration would reduce the possibility of false diagnosis of damages detected by the SHM system (e.g., vibrations caused by heavy vehicles on a bridge could be read by a SHM sensor as a structural health problem of the bridge), which would eventually decrease the bridge maintenance costs. Similarly, in SHM-informed ITS system, SHM sensors can provide data on bridge health condition for ITS applications, where ITS uses this bridge health condition information for real-time traffic management. In this paper, literature related to both ITS-informed SHM and SHM-informed ITS is reviewed. Based on the literature review, potential challenges and future research directions associated with ITS-SHM integration are also discussed.

Zenodo (CERN European Organization for Nuclear Research), 2023

The dynamics of bridges and (traversing) vehicles are coupled through the contact forces at the interface between the two subsystems. This study proposes the concept of virtual sensing (response reconstruction) in bridges using information from on-board sensors installed on an instrumented vehicle with known dynamic characteristics. The premise of the proposed approach is that contact force estimation requires knowing solely the properties of the vehicle model and information from on-board sensors, and, subsequently, using the Augmented Kalman Filter (AKF) technique. Interestingly, the proposed contact force estimation scheme does not necessitate knowledge of the rail profile irregularities characteristics, even though the contact forces depend on them. The estimated contact forces become then input to a finite element model of the traversed bridge, which enables the reconstruction of bridge response (acceleration, displacement, strains, stresses, etc). The estimated strain/stress time histories on the bridge can provide valuable information on the health status of the bridge. The proposed approach is verified with the aid of simulated data from railway bridge-vehicle interaction analyses, examining a 10-degree-of-freedom vehicle model that is representative of realistic train vehicles. The railway bridge considered is a simply supported Euler-Bernoulli beam model. The results offer valuable insights into the effects of different factors (measurement and model errors, vehicle speed, and rail irregularities) on the accuracy of contact force estimation and bridge response reconstruction, and suggest an optimal sensor configuration based on the minimum number of sensors required and their location on the vehicle.

Laboratory model tests were conducted to examine the feasibility of detecting structural deterioration in highway bridges by vibrational signature analysis. The model is a two-span aluminum plate-girder bridge that permits vibrations to be induced using vehicular excitation. The ambient vibration method was used to obtain vibrational signature elements. Data was processed both by curve fitting and by using a more automatable analytical approach. Using low-mass vehicular excitation, ambient vibration results compare well with conventional modal analyses for resonant frequencies and mode shapes, but damping is overestimated. Roadway roughness and vehicle velocity do not influence resonant frequencies or mode shapes, although variable mass can have a significant impact on resonant frequencies. Vehicular mass influences on mode shapes appear to be minimal. Major structural degradation can cause significant changes to both resonant frequencies and mode shapes. Degradation is detectable using a readily automatable analytical approach. Preliminary full-scale tests suggest that vibrational signatures are obtainable in the field using the same methodology employed in the laboratory.

Highway structures such as bridges are subject to continuous degradation primarily due to ageing, loading and environmental factors. A rational transport policy must monitor and provide adequate maintenance to this infrastructure to guarantee the required levels of transport service and safety. Increasingly in recent years, bridges are being instrumented and monitored on an ongoing basis due to the implementation of Bridge Management Systems. This is very effective and provides a high level of protection to the public and early warning if the bridge becomes unsafe. However, the process can be expensive and time consuming, requiring the installation of sensors and data acquisition electronics on the bridge. This paper investigates the use of an instrumented 2-axle vehicle fitted with accelerometers to monitor the dynamic behaviour of a bridge network in a simple and cost-effective manner. A simplified half car-beam interaction model is used to simulate the passage of a vehicle over a bridge. This investigation involves the frequency domain analysis of the axle accelerations as the vehicle crosses the bridge. The spectrum of the acceleration record contains noise, vehicle, bridge and road frequency components. Therefore, the bridge dynamic behaviour is monitored in simulations for both smooth and rough road surfaces. The vehicle mass and axle spacing are varied in simulations along with bridge structural damping in order to analyse the sensitivity of the vehicle accelerations to a change in bridge properties. These vehicle accelerations can be obtained for different periods of time and serve as a useful tool to monitor the variation of bridge frequency and damping with time.

Applied Sciences

The issue of monitoring the structural condition of bridges is becoming a top priority worldwide. As is well known, any infrastructure undergoes a progressive deterioration of its structural conditions due to aging by normal service loads and environmental conditions. At the same time, it may suffer serious damages or collapse due to natural phenomena such as earthquakes or strong winds. For this reason, it is essential to rely on efficient and widespread monitoring techniques applied throughout the entire road network. This paper aims to introduce an integrated procedure for structural and material monitoring. With regard to structural monitoring, an innovative approach for monitoring based on Vehicle by Bridge Interaction (VBI) will be proposed. Furthermore, with regard to material monitoring, to evaluate concrete degradation, a non-invasive method based on the continuous monitoring of the pH, as well as chloride and sulfate ions concentration in the concrete, is presented.

IABSE Symposium Report, 2013