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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... more
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.
Many bridges across the world have very extensive structural health monitoring (SHM) systems that generate vast quantities of data. There are many engineers and researchers who envisage a brave new world of smart bridges with ubiquitous... more
Many bridges across the world have very extensive structural health monitoring (SHM) systems that generate vast quantities of data. There are many engineers and researchers who envisage a brave new world of smart bridges with ubiquitous sensors providing real time information on all aspects of bridge performance. How realistic is this aspiration? How do we currently utilise the data generated in existing bridge SHM systems? How are such SHM systems designed in the first place? A major research programme at the Centre for Smart Infrastructure and Construction (CSIC) at Cambridge University in the UK has been at the forefront of some of these smart technology developments, specifically in fibre optics, wireless sensor networks, MEMS sensors, computer vision techniques and data interpretation tools. A recent PhD study by Webb [10] in which he investigated the manner in which such monitoring systems are currently designed, deployed and utilised for bridges has led to a re-evaluation of their effectiveness. A new framework which provides guidance for bridge engineers on how to design such SHM systems has been developed and will be presented in this paper.
This paper presents a study of the constraints and challenges faced by the authors when invited to study the feasibility of developing a monitoring system to provide specific information sought by the designer and contractor during the... more
This paper presents a study of the constraints and challenges faced by the authors when invited to study the feasibility of developing a monitoring system to provide specific information sought by the designer and contractor during the construction of the new 225m high, 48 storey steel-framed Leadenhall Building, located at 122 Leadenhall Street in London. The original goal of the study was to develop a system to assist with the active alignment of the building during construction, a key aim being to determine if the diagonal bracing members were in tension or compression. Installing strain gauges directly onto the steel bracing members was not permitted due to concerns regarding the integrity of the intumescent paint coating. A laboratory study to investigate the ability to measure strain directly from the paint surface was undertaken. Aesthetic concerns also imposed further restrictions on what could be attached to the structure. This feasibility study did result in the development of a new wireless sensor to measure temperature and optionally strain. In order to allow the sensors to be unobtrusive they were designed to fit within holes already present in the steel sections, originally used for attaching lifting equipment during erection of the steel frame. This exploratory study demonstrates that such collaborations can yield outcomes which, while not originally envisaged, nevertheless have the potential to benefit the research organisation, the designer and the contractor. This paper demonstrates how a bespoke wireless sensor platform can be rapidly developed using existing technologies to fit the needs of an individual project. The potential for use on future construction projects of a similar nature is also highlighted and future research directions discussed.
This paper presents data from fiber-optic strain monitoring of the Nine Wells Bridge, which is a three-span, pretensioned, pre-stressed concrete beam-and-slab bridge located in Cambridgeshire in the United Kingdom. The original deployment... more
This paper presents data from fiber-optic strain monitoring of the Nine Wells Bridge, which is a three-span, pretensioned, pre-stressed 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.
Vardanega, P.J., Webb, G.T., Fidler, P.R.A., Middleton, C.R. & Collins, J. (2017). Discussion: Assessing the potential value of bridge monitoring systems. Proceedings of the Institution of Civil Engineers – Bridge Engineering, 170(1):... more
Vardanega, P.J., Webb, G.T., Fidler, P.R.A., Middleton, C.R. & Collins, J. (2017). Discussion: Assessing the potential value of bridge monitoring systems. Proceedings of the Institution of Civil Engineers – Bridge Engineering, 170(1): 87-88 https://doi.org/10.1680/jbren.16.00027
There 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... more
There 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 pre-stressing 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 commercial contractor on behalf of the client and a research wireless deployment installed by the University of Cambridge. Careful interpretation of the displacement and temperature gauge data enabled bearings that were not functioning as designed to be identified. The acoustic emission monitoring indicated locations at which rapid deterioration was likely to be occurring; however , it was not possible to verify these results using any of the other sensors installed and hence the only method for confirming these results was by visual inspection. Recommendations for future bridge monitoring projects are made in light of the lessons learned from this monitoring case study.
The findings of an extensive literature survey focusing on bridge structural health monitoring (SHM) deployments are presented. Conventional, maturing, and emerging technologies are reviewed as well as deployment considerations for new... more
The findings of an extensive literature survey focusing on bridge structural health monitoring (SHM) deployments are presented. Conventional, maturing, and emerging technologies are reviewed as well as deployment considerations for new SHM endeavors. The lack of published calibration studies (and quantification of uncertainty studies) for new sensors is highlighted as a major concern and area for future research. There are currently very few examples of SHM systems that have clearly provided significant value to the owners of monitored structures. The results of the literature survey are used to propose a categorization system to better assess the potential outcomes of bridge SHM deployments. It is shown that SHM studies can be categorized as one (or a combination) of the following: (1) anomaly detection, (2) sensor deployment studies, (3) model validation, (4) threshold check, and (5) damage detection. The new framework aids engineers specifying monitoring systems to determine what should be measured and why, hence allowing them to better evaluate what value may be delivered to the relevant stakeholders for the monitoring investments.
Ongoing developments in smart technologies such as wireless sensor networks, micro-electro-mechanical systems (MEMS), computer vision, fibre optics and advanced data interpretation techniques may revolutionise structural health monitoring... more
Ongoing developments in smart technologies such as wireless sensor networks, micro-electro-mechanical systems (MEMS), computer vision, fibre optics and advanced data interpretation techniques may revolutionise structural health monitoring (SHM). Dedicated SHM of bridge assets has the potential to produce valuable data-sets and provide owners and managers with information to aid with key questions such as: current performance, margins of safety, actual loading, stress history and risk of fatigue, extent of deterioration and residual life. However, the parameters measured and value of the data obtained will differ when viewed from the perspectives of different stakeholders such as asset owners, designers, contractors and researchers. In this paper the purposes of monitoring are reviewed. A methodology is proposed to facilitate formal discussions between the key stakeholders before any deployment is specified and to ensure that scarce resources are not wasted in the pursuit of data as opposed to information. This approach can be used to determine if there is a prima facie case for the specification of SHM on a project and assess the potential value of any information that may be obtained. The developed methodology has been trialled with five historical monitoring case studies on bridges with which the authors are familiar.
ABSTRACT A variety of monitoring equipment has been installed on the Hammersmith Flyover in London in an attempt to provide more information about the state of deterioration of this key piece of infrastructure. This paper presents an... more
ABSTRACT A variety of monitoring equipment has been installed on the Hammersmith Flyover in London in an attempt to provide more information about the state of deterioration of this key piece of infrastructure. This paper presents an analysis of some of the data obtained, to determine whether useful conclusions about the structural condition of the bridge can be drawn and to evaluate the effectiveness of these monitoring systems.While some useful conclusions about the condition of the bridge can be drawn there is much data which is of very limited use. Theoretical predictions can be used to demonstrate why some sensors will not provide useful information. Lessons learnt from this project can be applied to the design of future monitoring systems to prevent unnecessary sensors being installed.