Current Research Program

THEME 1 PROJECTS

Intelligent Sensing and Structural Health Monitoring

Director: Dr. J.J. Roger Cheng, University of Alberta

THEME 1 OVERVIEW

Fibre Optic and Other Sensing for SHM

The objective of this project is to develop an alternative to conventional damage detection techniques based on detecting changes in vibration model properties of a monitored structure. A novel fibre optic sensor system will be developed that is based on the state of polarization variations in optical fibres for continuous SHM of bridges. Advanced signal processing schemes will be developed for the novel fibre optic sensors. Also, new data processing techniques and pattern recognition algorithms will be developed for structural condition assessment and damage detection applications of the new sensor system. Both laboratory and field testing on operating bridges form part of the project.

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Wireless Sensing for SHM (F1.1.2)
Project Leader: Dr. Douglas Thomson, University of Manitoba

The objective of this project is threefold: to build on the completed ISIS research of a strain sensor and complete the development of a wireless sensor by creating an antenna that can be embedded into concrete through which the sensor can be interrogated; to conduct a field demonstration project; and thirdly, followed by the development of a field useable interrogation system.

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This project consists of developing the hardware and software for concrete crack and deformation detection with the distributed Brillouin sensor system. The project will deliver a signal processing and data-fitting program to complement recently developed distributed sensor system. In collaboration with Prof. Shi’s group, the new compact distributed sensor system will be demonstrated on bridges, tunnels and railways in China.

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Since fibre optic sensors are presently expensive and constitute a barrier to widespread use, the object of this project is to develop a low cost sensor based on electrically conducting fibre reinforced cementitious composites (ECFRC). When reinforced with highly conducting, high performance carbon fibre, ECFRCs are 1000 times more conducting than plain concrete and possess a greater fracture toughness, enhanced durability and strain tolerance. This three phase project consists of investigating the use of embedded ECFRC sensors as chemical sensors aimed at excessive chlorides and resulting corrosion, and determining the consistency and reliability of such sensors. It involves development, followed by laboratory analysis, and then field tests at two bridge sites.

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Structural Health Monitoring

Strait Crossing Bridge Limited and ISIS Canada will conduct a joint venture research program on this bridge to enhance the collection of long term information related to the performance of this structure. In the process, ISIS will install 22 fibre optic sensors in the main girder and drop section near pier 31. This collaborative project has three tasks: Bragg fibre optic sensor assessment; ice abrasion rate assessment; and data management services. Web-based monitoring and data processing techniques will be developed for the bridge.

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The objective of this project is to assemble all the relevant information that ISIS has gathered in the past nine years on SHM and create a blueprint for structural health monitoring of steel-free bridge decks. This will include the integration of the sensing and communication systems, data processing, structural modeling and damage detection. This project addresses the question of “How to apply SHM to steel-free bridge decks.”

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Despite the challenges associated with applying vibration-based damage detection (VBDD) methods to operating civil engineering structures, the development of reliable VBDD methods for innovative and conventional constructed facilities has the potential for great benefit to infrastructure owners. The project consists of field and laboratory-based testing and numerical studies aimed at developing VBDD methods to the point that they can be reliably applied to operating bridges. Considerations include multi-girder and multi-span continuous structures, the effect of environmental conditions, and quantification of measurement uncertainties caused by electromagnetic noise, calibration errors and different methods of excitation.

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The major goal of this research project is to investigate the established methods of damage detection and adapt and apply them to civil engineering applications. The research will primarily consider model-based methods, where a finite element model is updated after the occurrence of damage. The resulting reduction in stiffness is interpreted as damage.  Since the updating is an inverse problem, questions of sensitivity with respect to measurement errors, optimal placement of sensors, and stable solutions have to be addressed.  The aim is to develop methods that take these aspects into account and also to show the expected accuracy as well as the inherent limitations of damage detection based on dynamic properties.

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The objective of this project is the development of efficient and adaptive signal processing techniques capable of performing automated, real time, pre-processing, filtering and compression of SHM measurement data. Details of the research program address all the foregoing aspects of the consideration. A planned deliverable is to provide a guide for the use of the adaptive signal processing techniques and an outline for the establishment of data management centres.

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The objective of this project is to build on what has already been accomplished in structural health monitoring to transfer ISIS technologies to the user sector, especially the Quebec Ministry of Transportation. The research consists of developing or adapting software and hardware for acquisition and transfer of data, data-filtering techniques, and algorithms for intelligent data processing. The goal is to implement a decision making software and develop an interactive web-based monitoring system for use by authorized people.

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FOS Condition Monitoring and Modeling of Water Mains (F1.2.7)
Project Leader: Dr. Catalin Gheorghiu, University of Manitoba

Many water distribution systems are gradually deteriorating due to aging, operational stresses and interior and exterior environmental conditions. This deterioration results in increased operation and maintenance costs and a reduction in the quality of both service and water supply. To ensure that municipalities can manage their water distribution systems to provide an adequate supply of safe water in a cost-effective, reliable and sustainable manner, it is essential that a clear understanding be developed of the water main's condition. This project will study an innovative way to continuously monitor water main conditions using fibre optic sensors to enable early detection of any potential problem that may lead to structural failure. This project is the first ISIS application of FOS monitoring of lifelines such as water mains, a field that is in great need of innovative monitoring techniques.

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Demonstration Field Assessments

Life Cycle Costing and SHM to Reduce Freight Costs (F1.3.1)
Project Leader: Dr. Gordon Sparks, University of Saskatchewan

The Hudson Bay bridge in Saskatchewan supports an important timber haul connecting local mills to forested areas. Currently, however, concerns regarding the strength of the bridge have limited permitted truck loads. Efforts that successfully support higher truck loads will therefore lower the trucking costs incurred by industry - leading to a more cost-competitive forestry sector in the province.

To strengthen the bridge, Saskatchewan Department of Highways and Transportation SDHT) has opted for CFRP wraps installed under centre span beams. To ensure the added strength obtained is sufficient to support higher truck loads and to ameliorate concerns regarding long-term durability, SDHT and Weyerhauser agreed to participate in a structural health monitoring (SHM) research program designed to monitor and analyze the behaviour of the bridge under live load before, during and after the installation of the CFRP wraps. The results of this research will help determine whether or not bridge engineers within SDHT permit higher loads over the bridge.

From the standpoint of life cycle costing (LCC), any haul weight decisions reached should balance the cost-savings enjoyed by industry and the infrastructure-related costs incurred by SDHT. While higher haul weights certainly suit industry, concomitant implications for bridge- and road-related efforts and costs must be taken into account to ensure total life cycle costs are indeed minimized. Broadly speaking, the purpose of project 1.3.16 is to establish a haul weight policy that is likely to minimize the total life cycle costs of infrastructure use and management in this regards.

Employing the life cycle engineering and costing (LCE&C) method developed under project 4.1.1, participants in this research program will iteratively model and analyze the life cycle costs associated with the use and management of Hudson Bay bridge to help determine an optimal haul weight policy. Ultimately, the insights reached through this investigation will be embodied in a computer-based LCE&C model linking condition assessment (supported by SHM) to life cycle performance prediction and, finally, to life cycle costs.

See Field Demo

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Instrumented Loading Dock at ChemBioE Building (UBC) with Three Types of Embedded Sensors (F1.3.2)
Project Leader: Dr. Nemkumar Banthia, University of British Columbia

Long-term structural health monitoring of the loading dock at the newly built ChemBioE Building at the University of British Columbia is being undertaken. The outdoor dock is heavily leaded and will witness a chloride-rich environment. Three types of sensors will be installed in the dock for long term remote monitoring. These will include traditional electrical resistance gauges, fibre optic sensors and the newly developed ECFRC (cement-based) sensors. The latter are capable of monitoring the chemical environment in concrete and detect onset of rebar corrosion. Data from the above sensors will be further supported by non-destructive tests (NDT) including Ultrasonic Pulse Velocity (UPV) measurements (using Raleigh Waves) and Electrical Impedance (EM) measurements (using Wenner Probe Protocol). In addition, the corrosion activity will be monitored at select locations in the loading dock by using a sitemounted Potentiostat/ Galvanostat/ EIS System. Along with sensing, the dock will be divided into five parts to investigate the following novel concepts in concrete technology: joint-free floor technology; fibre reinforced concrete; high volume fly-ash concrete; and concrete with shrinkage reducing admixture (SRA).

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SHM of South Perimeter Red River Bridge in Winnipeg (F1.3.3)
Project Leader: Dr. Aftab Mufti, University of Manitoba

The South Perimeter Red River Bridge is located on the South Perimeter Highway that encircles the city of Winnipeg.  It is a 250 meter long, 7-span bridge, consisting of three simply supported spans and one continuous span.  Over a period of two years, the entire bridge deck will be replaced with a second generation steel-free GFRP hybrid bridge deck consisting of steel straps and GFRP reinforcement bars.

Structural health monitoring will be performed on the bridge, with the following objectives:

• To determine live load stress ranges
• To determine transverse load distribution pattern for establishing the position of a truck
• To determine live load stress ranges over an intermediate support
• To study transverse load distribution in negative moment regions
• To monitor live load stresses in straps
• To measure wheel loads
• To study the effect of time on live load stresses in crack-control grid
• To study participation in longitudinal GFRP bars in negative moments over intermediate support
• To study the effectiveness of FRP bars to control crack widths in deck slab over intermediate supports

The SHM system consists of both conventional electrical strain gauges and fibre optic Bragg grating sensors.

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Continuously Reinforced Concrete Pavement with GFRP Bars on Hwy. 40 in Quebec (F1.3.4)
Project Leader: Dr. Brahim Benmokrane, Université de Sherbrooke

This research project is designed to investigate the behaviour of continuously reinforced concrete pavement (CRCP) with GFRP reinforcing bars under environmental and wheel load conditions. In Quebec and North America, there is a persistent problem of deterioration of steel-reinforced concrete pavements, frequently due to the harsh environment that causes the steel to rapidly corrode.  In an attempt to avoid contraction joints and reduce crack widths, and hence make it difficult for moisture and de-icing salts to penetrate the pavement through the cracks and attack the steel, CRCP has been introduced as an alternative to the joint concrete pavement.  The Ministère des tranports du Québec is currently undertaking reconstruction of a part of Highway 40 East in Montreal using CRCP with galvanized steel bars.  GFRP reinforcement bars have been incorporated into this project and will be monitored over a period of three years.  The objective is to determine the optimal design parameters and to provide design and construction recommendations of the CRCP reinforced with GFRP bars.

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SHM of Continuous RC Pavement with GFRP Bars on Hwy. 40, Quebec (F1.3.5)
Project Leader: Dr. Xiaoyi Bao, University of Ottawa

As part of foregoing Project F1.3.5, the objective of this project is to perform field tests with distributed Brillouin fiber sensors (DBFS) and provide strain and temperature information through different seasons for determining the optimal design parameters. The advantage of DBFS is that strain and temperature information can be collected at any point along the optical fiber that can be installed on the structure for ten kilometers. Optical fibers have been installed to monitor the strain and potential cracks and deformation of the pavements.

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CFRP Post-Tensioned Girders for the Baden Bridge (F1.3.6)
Project Leader: Dr. Khaled Soudki, University of Waterloo

Recently, a novel anchor system for a carbon fibre reinforced polymer (CFRP) tendon has been developed at the University of Waterloo. This project advances the UW anchor into field use and to employ CFRP tendons for the post-tensioning of girders in the Baden bridge in the Region of Waterloo. The research comprises: 1) design of CFRP post-tensioned beams for the Baden bridge, 2) laboratory verification of the performance of prototype CFRP post-tensioned beams under load, 3) fabrication of the bridge beams in the Hanson precast facility, 4) instrumentation of the CFRP tendons, 4) post-tensioning of the beams using CFRP tendons gripped with the UW anchor, 5) deployment of the beams for installation in the field, 6) monitoring the long-term (creep) performance of the post-tensioned beams. The monitoring will be performed using conventional strain gauges and possibly fibre optic sensors.  The data collected will be useful for long-term and creep performance of CFRP post-tensioned beams under field conditions. This project is the first field application for using advanced materials to post-tension concrete flexural members in Ontario.

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Field Repair of Post-Tensioned Concrete Slabs Using CFRP Strands (F1.3.7)
Project Leader: Dr. Mark Green, Queen's University

This field application investigates the feasibility of using CFRP strands to replace corroded steel strands in unbonded, post-tensioned concrete buildings. Unbonded post-tensioning is an advanced form of concrete construction used in thousands of parking garages and high-rise buildings in North America. The concrete slabs in these buildings are reinforced internally using 7-wire strands that are tensioned to high stress during construction. Corrosion damage is significant in many of these structures and replacement of the corroded strands is often necessary. CFRP tendons provide a more durable alternative to steel strand. CFRP is lighter than steel strand, which facilitates repair. CFRP is also stronger than steel, so that a smaller diameter CFRP strand can be used to provide an equivalent prestressing force. A smaller diameter CFRP strand can be more easily inserted into an existing duct or sheath in a concrete slab.

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