Structural Health Monitoring of Streicker Bridge

Prof. Branko Glisic and his team have recently installed a SHM system on the Streicker Bridge at Princeton University.

The project involves instrumenting the bridge with various sensors, and to transform it into an on-site laboratory for various research and educational purposes. The main aims of the instrumentation are to face the following challenges related to SHM:

• Education gap. In spite of its importance, the culture on SHM is not yet widespread. It is often considered as an accessory activity that does not require specific skills and detailed planning, while the facts are rather the opposite.
• Real structural behavior data sets. The complete data sets collected over long-terms are needed to fully understand real structural behavior and its interaction with environment. The SHM was applied to various types of structures, but the results of monitoring are frequently only partially disclosed or incomplete, thus the knowledge basis is rather deficient.
• Change in strain patterns caused by unusual behaviors. The patterns of degradation in performance and damage in monitoring results are often “masked” by environmental influences (temperature, wind, humidity, etc.) and human-made actions (live load fluctuations) and consequently, cannot be reliably identified in controlled laboratory conditions. More real data with unusual behaviors are needed in order to develop reliable detection algorithms.
• Characterization of SHM contribution to sustainability of built environment. SHM has promising potential to contribute to the sustainability of built environment since it provides with objective information concerning the real structural performance, which can be used as an input to optimize maintenance, extend structure’s life, increase safety, decrease life-cycle costs, reduce the use of construction material, minimize adverse impact on society that may occur in case of structural deficiency, and help reducing greenhouse gas emissions.
• Besides addressing above listed challenges, the Streicker Bridge will be used for full scale testing of new SHM methods, and newly developed monitoring systems.

The SHM of Streicker Bridge is a long-term project and it will be realized in several phases. The initial phase consists of instrumentation of main span and south-east leg. The instrumentation of main span was completed on August 14, 2009 with two fiber-optic sensing technologies:

(1) Discrete Fiber Bragg-Grating (FBG) long-gage sensing technology (average strain and temperature measurements);

(2) Truly distributed sensing technology based on Brillouin Optical Time Domain Analysis (average strain and temperature measurements).

The sensors were embedded in concrete during the construction.

More information can be found on the project website.

[Prof Glisic, SHM Lab,Princeton University]

The Economist reports on Smart Bridges

The Economist reports about smart bridges and the SHM system that was installed by Roctest and SMARTEC on the I35W bidge in Minneapolis.

Here are some interesting parts:

When an eight-lane steel-truss-arch bridge across the Mississippi River in Minneapolis collapsed during the evening rush hour on August 1st 2007, 13 people were killed and 145 were injured. There had been no warning. The bridge was 40 years old but had a life expectancy of 50 years. The central span suddenly gave way after the gusset plates that connected the steel beams buckled and fractured, dropping the bridge into the river.

In the wake of the catastrophe, there were calls to harness technology to avoid similar mishaps. The St Anthony Falls bridge, which opened on September 18th 2008 and replaces the collapsed structure, should do just that. It has an embedded early-warning system made of hundreds of sensors. They include wire and fibre-optic strain and displacement gauges, accelerometers, potentiometers and corrosion sensors that have been built into the span to monitor it for structural weaknesses, such as corroded concrete and overly strained joints.

Some civil engineers are sceptical about whether such instrumentation is warranted. Emin Aktan, director of the Intelligent Infrastructure and Transport Safety Institute at Drexel University in Philadelphia, points out that although the sensors generate a huge amount of data, civil engineers simply do not know what happened in the weeks and days before a given bridge failed. It will take a couple of decades to arrive at a point when bridge operators can use such data intelligently.

The last part is quite pessimistic. While more research is certainly needed in the field of data analysis, there is a lot of useful information that can be obtained today from a monitoring system such as the one installed on the I35 Bridge.

[The Economist]

New Book: Structural health monitoring of civil infrastructure systems

Woodhead Publishing has released a new book on "Structural health monitoring of civil infrastructure systems", edited by V M Karbhari (University of Alabama at Huntsville) and F Ansari (University of Illinois at Chicago).

More details on the Woodhead Publishing website.

I have contributed a chapter on "Structural health monitoring of bridges: general issues and applications"

Abstract:

Structural health monitoring is an extremely important methodology in evaluating the ‘health’ of a structure by assessing the level of deterioration and remaining service life of civil infrastructure systems. This book reviews key developments in research, technologies and applications in this area of civil engineering. It discusses ways of obtaining and analysing data, sensor technologies and methods of sensing changes in structural performance characteristics. It also discusses data transmission and the application of both individual technologies and entire systems to bridges and buildings.

With its distinguished editors and international team of contributors, Structural health monitoring of civil infrastructure systems is a valuable reference for students in civil and structural engineering programs as well as those studying sensors, data analysis and transmission at universities. It will also be an important source for practicing civil engineers and designers, engineers and researchers developing sensors, network systems and methods of data transmission and analysis, policy makers, inspectors and those responsible for the safety and service life of civil infrastructure.

Contents:

Structural health monitoring: applications and data analysis

F N Catbas, University of Central Florida, USA

PART 1 STRUCTURAL HEALTH MONITORING TECHNOLOGIES

Piezoelectric impedence transducers for structural health monitoring of civil infrastructure systems, Y W Yang and C K Soh, Nanyang Technological University, Singapore

Wireless sensors and networks for structural health monitoring of civil infrastructure systems, R A Swartz and J P Lynch, University of Michigan, USA

Synthetic aperture radar and remote sensing technologies for structural health monitoring of civil infrastructure systems, M Shinozuka, University of California, USA and B Mansouri, International Institute of Earthquake Engineering and Seismology, Iran

Magnetoelastic stress sensors for structural health monitoring of civil infrastructure systems

M L Wang, Northeastern University, USA

Vibration-based damage detection techniques for structural health monitoring of civil infrastructure systems, V M Karbhari, University of Alabama in Huntsville and L S-W Lee, University of the Pacific, USA

Operational modal analysis for vibration-based structural health monitoring of civil structures, V M Karbhari, University of Alabama in Huntsville, H Guan HDR, USA and C Sikorsky, California Department of Transportation, USA

Fiber optic sensors for structural health monitoring of civil infrastructure systems, F Ansari, University of Illinois at Chicago, USA

Data management and signal processing for structural health monitoring of civil infrastructure systems, D K McNeill, University of Manitoba, Canada

Statistical pattern recognition and damage detection in structural health monitoring of civil infrastructure and other systems, K Worden, G Manson and S Rippengill, University of Sheffield, UK

PART 2 APPLICATIONS OF STRUCTURAL HEALTH MONITORING IN CIVIL INFRASTRUCTURE SYSTEMS

Structural health monitoring of bridges: general issues and applications, D Inaudi, SMARTEC SA, Switzerland

Structural health monitoring of cable-supported bridges in Hong Kong, K Y Wong, Highways Department and Y Q Ni, The Hong Kong Polytechnic University, Hong Kong

Structural health monitoring of historic buildings, A De Stefano, Turin Polytechnic and P Clemente, ENEA, Italy

Structural health monitoring research in Europe: trends and applications, W R Habel, BAM Federal Institute for Materials Research and Testing, Germany

Structural health monitoring research in China: trends and applications, J Ou, Dalian University of Technology and Harbin Institute of Technology and H Li, Harbin Institute of Technology, China

ISBN 1 84569 392 2

New Book: An Introduction to Optoelectronic Sensors

A recently published book on Optoelectronic Sensors contains several chapters of interest for SHM. The volume is edited by Giancarlo C. Righini, Antonella Tajani and Antonello Cutolo.

This book offers an overview of the technologies and applications of optoelectronic sensors. Based on the R&D experience of more than 70 engineers and scientists, mainly from the Italian academic and industrial community in this area, this book provides a broad description of the state-of-the-art optoelectronic technologies for sensing. The most innovative approaches, such as the use of photonic crystals, squeezed states of light and microresonators for sensing, are considered. Application areas range from environment to medicine and healthcare, from aeronautics, space, and defence to food and agriculture.

There are chapters on Fiber Bragg Gratings, Distributed sensing and one chapter dedicated to the application of fiber optic sensors for Strucutral HEalth Monitoirng.

A few chapters can be previewed on Google Books and on Amazon.

Call for papers: NDE/NDT for Highways and Bridges

NDE/NDT for Highways and Bridges: Structural Materials Technology (SMT) 2010

16–20 August 2010, New York LaGuardia Airport Marriott, New York, NY, USA

The conference promotes the exchange of information among national and international researchers, practitioners and infrastructure stakeholders on the application of nondestructive evaluation (NDE) and nondestructive testing (NDT) technologies for condition assessment of highway infrastructure. Contributions focused on field applications, case studies, technology implementation, applied research, and practical experience are invited to submit abstracts. Through technical presentations and exhibits, infrastructure stakeholders, transportation officials, researchers, consultants, and contractors will be exposed to the state-of-the-practice in NDE methods. In addition, participants will have opportunities to discuss urgent problems faced by civil infrastructure stakeholders and the potential solutions utilizing available and emerging NDE technologies.

Topics of interest for the conference include NDE technologies for bridge superstructures, substructure and decks, pavement NDE and structural health monitoring. Quality control/quality assurance (QC/QA) practices, bridge inspection methods and the integration of inspection findings in bridge evaluation and management programs are also of interest.

Suggested Topics Include:

• Condition assessments of existing highway infrastructure

• Implementation of NDE technologies

• Quality control (QC) and forensic investigation of in-service structures

• Quality assurance (QA) during construction

• Inspections at the fabrication yards

• Bridge inspection challenges faced by State DOT’s

• Structural health monitoring (SHM) and load rating

• Foundation integrity and unknown depth

• Pavement integrity evaluations

• Bridge cable inspection

• Underwater inspection technologies

• Scour evaluation

• Long-term bridge monitoring

• Innovative sensors for civil infrastructure

• Embeddable sensors

• Tunnel and culvert inspection

• Inspection and evaluation of fiber reinforced polymer (FRP) material and FRP structures

• Inspection of light poles and sign supports

• Quantification of bridge deterioration

• Training and certification of inspection personnel

Deadlines

Abstracts submission: 1 February 2010

Acceptance notification: 15 March 2010

Final paper submission: 14 May 2010

More information: http://www.asnt.org/events/conferences/smt10/smt10.htm

SHMLive Presentation

This video introduces SHMLive:

National Instruments intruduces SHM Kit

National Instruments has introduced an SHM system:

The NI Wi-Fi Structural Health Monitoring (SHM) System is based on NI Wi-Fi data acquisition (DAQ) devices, which combine IEEE 802.11 wireless or Ethernet communication, direct sensor connectivity, and the flexibility of NI LabVIEW software for remote monitoring of electrical, physical, mechanical, and acoustical signals. With built-in signal conditioning and the highest commercially available network security, NI Wi-Fi DAQ devices stream data in real time for easy-to-use, high-performance remote measurements.

The NI Wi-Fi SHM System features four accelerometer and four strain input channels; however, the system is expandable for additional measurements. The accelerometer channels offer software-selectable IEPE signal conditioning, 24-bit resolution, 102 dB dynamic range, 51.2 kS/s maximum simultaneous sampling, and antialiasing filters. The strain channels provide 24-bit resolution, 50 kS/s maximum simultaneous sampling, programmable half- and full-bridge completion, 1000 Vrms transient isolation, and transducer electronic data sheet (TEDS) smart sensor compatibility. The system also offers mixed-measurement capability for temperature, voltage, and other variables.

[National Instruments]

It appears to be a combination of wireless data acquisiton system, a few accellerometers and

Labview. So it is missing several key components for a true SHM system. It is probably aiming more the industrial sector and not the civil engineering Strucutral Health Monitoring segment that usually requires more sofisticated multi-sensor, multi-parameter solutions, along with data analysis and remote data trasmission.

New ISHMII Fellows

During the SHMII-4 conference in Zurich, six new ISHMII society fellows have been elected:

Prof. J. Brownjohn (first left)
Dr. S. Alampalli (second left)
Prof. Z. Wu (second right)
Dr. D. Inaudi (first right)
Prof. H. Koh
Prof. D. Frangopol

The awards were presented by the newly applinted ISHMII President, Prof. Farhad Ansari (in the center) and the SHMII-4 conference organizer, prof. Urs Maier.

Roctest launches SHMLive

Roctest launches SHMLive structural health monitoring solution to improve the safety of major public and private infrastructure. Real-time monitoring service will alert owners of structural risks and enable them to deploy resources where they are most needed.

Roctest Ltd (“Roctest”) (TSX: RTT), a leading designer and manufacturer of high-precision sensors for the civil engineering market, today announced the launch of SHMLive, a new and innovative web-based solution to monitor the health and status of infrastructure projects. Offered as a complete turnkey solution for a fixed monthly fee, SHMLive can save both up front capital costs and ongoing maintenance and repair costs for the owners of bridges, tunnels, high rise buildings and other infrastructure.

“SHMLive offers a choice that has not previously been available in the marketplace,” said François Cordeau, President and CEO, Roctest. “Traditionally, infrastructure owners have had to pay the full cost of a monitoring system at the outset, and then concern themselves with managing and interpreting the endless flow of data generated. With SHMLive, they can achieve superior monitoring capability and ease of adoption, with more predictable impact on their budgets."

SHMLive deployments will make use of the full range of available monitoring technologies. With more than 60 years of experience instrumenting complex structures worldwide, Roctest is the only company that can seamlessly integrate traditional vibrating wire instruments, fiber optic based sensors using five different technologies, concrete corrosion sensors, and any type of electrical sensors into a fully automated data acquisition system and integrated database while displaying the data in real-time anywhere in the world through its secure web site www.shmlive.com .

SHMLive Description

SHMLive deployments will begin with Roctest working with the infrastructure owner to identify specific objectives and design a customized monitoring system. Roctest will then install, operate and maintain the system providing a guaranteed service level. All data will be automatically transferred to Roctest’s secure online database where the data will be displayed in real-time on the SHMLive secure web site. With the support of selected local engineering partners, warning and alert limits can then be used to trigger the agreed upon protocol. All the instruments and sensors currently offered by Roctest and its subsidiaries integrate seamlessly in the SHMLive solution, as do third party traditional electrical sensors.

SHMLive Benefits

A 2008 U.S. Department of Transportation report found that 24% of the nearly 600,000 U.S. bridges were structurally deficient or functionally obsolete. This classification is based on visual inspection only and cannot fully capture hidden structural defects or capacity reserves. To monitor these assets becomes an enormous task for any organization if one only considers the amount of data generated by the monitoring sensors. SHMLive will behave the same way as a regular house security system, providing an alert whenever unusual behaviour is detected. Being an exceptionbased system, SHMLive does not require an army of engineers to continuously monitor the data, allowing smaller organizations with less resource to finally provide surveillance of critical structures. The same benefits will apply in Europe and Asia where aging infrastructures are a fact of life. Roctest is partnering with certified engineering firms worldwide to provide value-added services; however, the owner can also select its preferred engineering firm to analyze its data and recommend actions.

By understanding the static and dynamic behaviour of a structure, the owner can set priorities for maintenance and repairs, resulting in improved safety for its users and, in many cases, safely extending the life of the infrastructure with limited or no interventions. For large organizations like Departments of Transportation (D.O.T.) in the U.S. responsible for thousands of structures, the ability to assess and extend the useful remaining life of a structure will result in positive Return on Investment (R.O.I.) by prioritising rehabilitation efforts and optimizing the associated maintenance budget.

In the case of a high-rise building, SHMLive will provide instantaneous feedback on its health following an earthquake. For aging underground infrastructures like parking lots and tunnels, SHMLive will detect, in real-time, minuscule movements indicative of more serious issues. For geotechnical applications, SHMLive will provide a simple and cost-effective means of distributing measurements and alerts to all stakeholders involved in a construction project.

By offering this service based for a monthly fixed fee, Roctest provides infrastructure owners an affordable way to monitor these assets compared with the large capital expenditure that has historically been required, resulting in additional flexibility for owners to monitor more structures.

“Roctest will also continue to offer its complete portfolio of products in the same way we have for the last 60 years, targeting the large civil engineering projects and the continued surveillance of infrastructures by providing custom solutions using standard products. SHMLive will complement our offering by providing a value-added option to our customers who prefer a turnkey solution. The new service will be offered by all Roctest Group companies, including Roctest, Smartec and Telemac,” concluded Francois Cordeau.

For more information on SHMLive, please visit www.shmlive.com .

The Polytect European project, with SMARTEC as one of the partners, was featured in a 8 minuets video on Euronews recently.

The video can be watched here.

Here are some highlights:

Structural engineer for D’Appolonia SpA, Thomas B.Messervey said: “The idea is simply to make architectural structures more like the human body, and to build a skin for those structures. So by combining the information that we can obtain from sensors, we can build a relationship with the architectural structure overtime.

And we can ideally conduct what we call ‘;structural health modelling’ which hopes to answer four questions: Is the damage present? Where is that damage on the structure? How severe is that damage? And finally what does this damage mean? What is the life of the structure after this damage has occurred?”

And they are already well advanced with some prototypes.

Messervey went on: “There is a product for a masonry structure. The glass fibres go in many different directions, because the stresses and the loads in the architectural structure go also in many different directions. And inside we have sensors, fibre-optic cables in this case, that we can send light through to assess the health and the state of the structure. For geotechnical products, to protect against landslides, we will put these textiles underground in the earth. We can use filter-type products or we can use a grid-like material to both stregthen the soil or to filter water, and still be able to pass light and information throughout our sensors to interrogate whether or not the soil is moving.

[Euronews]