Paul Fidler

Long-Term Wireless Structural Health Monitoring of the Ferriby Road Bridge

As part of an effective bridge management system, sensor networks can provide data to support both inspection and assessment. Wireless sensor networks (WSNs) have the potential to offer significant advantages over traditional wired monitoring systems in terms of sensor, cabling, and installation costs as well as expandability. However, there are drawbacks with WSNs relating to power, data bandwidth, and robustness. To evaluate the potential of WSNs for use in bridge management, a network of seven sensor nodes was installed on the Ferriby Road Bridge, a three-span reinforced concrete bridge. Three displacement transducer nodes were placed across cracks on the soffit of the bridge to measure the change in crack width. Three inclinometer sensor nodes were mounted on two of the elastomeric bearing pads to measure the change in inclination of the bearing pads while a final node monitored temperature in the box that contained the gateway. The installation of the WSN is discussed and data from this network is analyzed. Finally, the use of sensor networks to support inspection and assessment is discussed.

Analysis of Structural Health Monitoring Data from Hammersmith Flyover

AbstractThere has recently been considerable research published on the applicability of monitoring systems for improving civil infrastructure management decisions. Less research has been published on the challenges in interpreting the collected data to provide useful information for engineering decision makers. This paper describes some installed monitoring systems on the Hammersmith Flyover, a major bridge located in central London (United Kingdom). The original goals of the deployments were to evaluate the performance of systems for monitoring prestressing tendon wire breaks and to assess the performance of the bearings supporting the bridge piers because visual inspections had indicated evidence of deterioration in both. This paper aims to show that value can be derived from detailed analysis of measurements from a number of different sensors, including acoustic emission monitors, strain, temperature and displacement gauges. Two structural monitoring systems are described, a wired system installed by a...

A vibration powered wireless mote on the Forth Road Bridge

The conventional resonant-approaches to scavenge kinetic energy are typically confined to narrow and single-band frequencies. The vibration energy harvester device reported here combines both direct resonance and parametric resonance in order to enhance the power responsiveness towards more efficient harnessing of real-world ambient vibration. A packaged electromagnetic harvester designed to operate in both of these resonant regimes was tested in situ on the Forth Road Bridge. In the field-site, the harvester, with an operational volume of ~126 cm3, was capable of recovering in excess of 1 mW average raw AC power from the traffic-induced vibrations in the lateral bracing structures underneath the bridge deck. The harvester was integrated off-board with a power conditioning circuit and a wireless mote. Duty- cycled wireless transmissions from the vibration-powered mote was successfully sustained by the recovered ambient energy. This limited duration field test provides the initial validation for realising vibration-powered wireless structural health monitoring systems in real world infrastructure, where the vibration profile is both broadband and intermittent.

A handheld diagnostic system for 6LoWPAN networks

The successful deployment of low-power wireless sensor networks (WSNs) in real application environments is a much broader exercise than just the simple instrumentation of the intended monitoring site. Many problems, from node malfunctions to connectivity issues, may arise during commissioning of these networks. These need to be corrected on the spot, often within limited time, to avoid undesired delays in commissioning and yet a fully functional system does not guarantee that no new problems will occur after leaving the site. In this paper we present the first ever (to our knowledge) implementation of a handheld diagnostic system for fast on-site commissioning of low-power IPv6 (6LoWPAN) WSNs as well as troubleshooting of network problems during and after deployment. This system can be used where traditional solutions are insufficient to ascertain the root causes of any problems encountered at no additional complexity in the implementation of the WSN. The embedded diagnosis capability in our system is based on a lightweight decision tree that distills the functioning of communication protocols in use by the network, with a major focus on interoperable IPv6 standards and protocols for low-power WSNs. To show the applicability of our system, we present a set of experiments based on results from a real deployment in a large construction site. Through these experiments, important performance insights are gained that can be used as guidelines for improvement of operation and maintenance of 6LoWPAN networks.

Innovative Bridge Design Handbook

Structural health monitoring (SHM) has the potential to transform the bridge engineering industry by providing stakeholders with additional information to inform decisions about the design, operation, and management of bridges throughout the structures’ lifespans. This chapter gives guidance on SHM for engineers who design, build, operate, and maintain bridges. There remain numerous technical challenges to overcome when deploying SHM systems; however the most important issues to consider are how to decide what information is required, and then how to develop a strategy to deliver this information in a form that is easy to interpret and can inform decision making. This chapter gives an introduction to the uses and current capabilities of SHM. Directions for future research and management of bridge SHM systems are also discussed.

Monitoring A Large Construction Site Using Wireless Sensor Networks

Despite the significant advances made by wireless sensor network research, deployments of such networks in real application environments are fraught with significant difficulties and challenges that include robust topology design, network diagnostics and maintenance. Based on our experience of a six-month-long wireless sensor network deployment in a large construction site, we highlight these challenges and argue the need for new tools and enhancements to current protocols to address these challenges.

Real World Assessment of an Auto-parametric Electromagnetic Vibration Energy Harvester

The convention within the field of vibration energy harvesting has revolved around designing resonators with natural frequencies that match single fixed frequency sinusoidal input. However, real world vibrations can be random, multi-frequency, broadband and time-varying in nature. Building upon previous work on auto-parametric resonance, this fundamentally different resonant approach can harness vibration from multiple axes and has the potential to achieve higher power density as well as wider frequency bandwidth. This article presents the power response of a packaged auto-parametric VEH prototype (practical operational volume of ∼126 cm−3) towards various real world vibration sources including vibration of a bridge, a compressor motor as well as an automobile. At auto-parametric resonance (driven at 23.5 Hz and 1 g rms ), the prototype can output a peak of 78.9 mW and 4.5 Hz of −3dB bandwidth. Furthermore, up to ∼1 mW of average power output was observed from the harvester on the Forth Road Bridge. The harvested electrical energy from various real world sources were used to power up a power conditioning circuit, a wireless sensor mote, a micro-electromechanical system accelerometer and other low-power sensors. This demonstrates the concept of self-sustaining vibration powered wireless sensor systems in real world scenarios, to potentially realise maintenance-free autonomous structural health and condition monitoring.

Analysis of fiber-optic strain-monitoring data from a prestressed concrete bridge

© 2017, American Society of Civil Engineers (ASCE). All rights reserved. This paper presents data from fiber-optic strain monitoring of the Nine Wells Bridge, which is a three-span, pretensioned, prestressed concrete beam-and-slab bridge located in Cambridgeshire in the United Kingdom. The original deployment at the site and the challenges associated with collecting distributed strain data using the Brillouin optical time domain reflectometry (BOTDR) technique are described. In particular, construction and deployment issues of fiber robustness and temperature effects are highlighted. The challenges of interpreting the collected data as well as the potential value of information that may be obtained are discussed. Challenges involved with relating measurements to the expected levels of prestress, including the effects due to debonding, creep, and shrinkage, are discussed and analyzed. This paper provides an opportunity to study whether two commonly used models for creep and shrinkage, adequately model data collected in field conditions.

Project VIMTO: A new system for the vibration and impact monitoring of tram operations

This work was funded by the EPSRC Impact Acceleration Account (Grant No. EP/K503757/1) and by the Cambridge Centre for Smart Infrastructure and Construction (EP/I019308/1).

Research Data supporting "Analysis of Fiber-Optic Strain-Monitoring Data from a PrestressedConcrete Bridge"

This dataset contains fibre-optic strain and temperature readings taken from two pre-stressed concrete beams on the Nine Wells road-over-rail bridge, located to the south of Cambridge. Each of these beams was instrumented with three fibre-optic cables prior to pouring of the concrete. One of the cables is used to measure strains caused by temperature, while the other two are sensitive to both mechanical strain and temperature strain. Readings were taken on various dates in July and August 2008.