Roctest Wins Contract for the St. Anthony Falls Bridge (I-35W)

Roctest Ltd. has been awarded a major contract from Flatiron Constructors/Manson Construction Company of Minneapolis (Flatiron-Manson JV), principal contractors for the I-35W Minnesota Bridge construction. The contract includes instrumenting the I-35W Bridge with conventional vibratingwire products and fiber optic instruments. This bridge project is a world-first for Group Roctest for this type of combined applications as it also combines Roctest newly introduced SensCore concrete corrosion monitoring system.

The new I-35W Bridge project, designed by FIGG Engineering Group, was started in October 2007 following the tragic collapse of the original bridge on August 1, 2007. Group Roctest worked in close relationship with Minnesota DOT and the University of Minnesota in finalizing the optimal instrumentation solution for the bridge.

The monitoring instruments on the I-35W Bridge will measure dynamic and static parameter points to enable close behavioural monitoring for the bridge’s life span. This bridge will be considered one of the first Smart Bridges to be constructed in the United States.

”Roctest has instrumented hundreds of structures with fiber optic sensors and many customers have also combined our traditional vibrating wire technology with our fiber optic sensors in geotechnical applications. In this contract, fiber optic has been selected as a complementary solution for monitoring I-35W Bridge, clearly proving the maturity of our solution

and it will certainly lead to more opportunities in bridge and other structural applications” said François Cordeau, President and Chief Executive Officer of Roctest. “Roctest is really the only instrumentation company offering a complete toolbox of solutions, providing world-class traditional vibrating-wire instruments, leading edge fiber optic sensors, the unique

SensCore concrete corrosion monitoring system and the application software to monitor complex structures.” added François Cordeau.

Roctest Press Release [Roctest]

Popular Mechnics Special Report on Rebuilding Aamerica

Popular Mechanics published a series of interesting articles on rebuilding America's Infrastructure.

http://www.popularmechanics.com/rebuildingamerica/

Stories include:

5 Engineering Lessons From the New, Reopened Minnesota Bridge
Bridge's Sensors Scan Tragedy Before It Strikes
Green Tech Plans Hide Obama-McCain Disparity on Infrastructure
How to Fix American Infrastructure
4 Big Reasons the D.C. Area's New Super Bridge Took One of America's Top Engineering Honors
For Hard-Charging Innovators, Rebuilding America Means Making Deals With the Government 
10 Expert Solutions for a Smarter, Cleaner U.S. Electric Grid
10 Expert Solutions for a Better American Water Supply
New Minnesota Bridge’s Super Sensors Scan Tragedy Before It Strikes: First Look New Minnesota Bridge Is America's Smartest Yet
6 Questions for Intelligent Bridge Geek Jerome Lynch
Engineers Go Gonzo to Bombproof U.S. Bridges
Building the Earthquake-Proof Bay Bridge
10 Expert Solutions for Harder, Better, Faster and Stronger Buildings and Bridges
5 Questions for Geologist Jeff Mount on California’s Crumbling Delta Levees
Sacramento Delta Tops Experts List of 5 to Fix
The Lessons of Hurricane Katrina
6 Questions for Port of Los Angeles Chief Geraldine Knatz
5 Questions for Lillian C. Borrone on Boosting Efficiency in America's Ports
The 10 Pieces of U.S. Infrastructure We Must Fix Now
5 Disasters Coming Soon If We Don't Rebuild U.S. Infrastructure
Report Sees Dire Future for Warming's Impact on U.S. Transport
First Look: New Minnesota Bridge Plans Arise as Bad Plates Fingered in Collapse
Minn. Bridge Collapse Reveals Brittle America
Will Longest U.S. Underground Expressway See the Light?
SPECIAL REPORT: Highway of the Future
Mega Engineering: Building the World's Toughest, Strongest, Biggest Projects
Special Report: The Lessons of Hurricane Katrina
3 Ways to Re-Engineer the Gulf and Stop Katrina 2.0

An SHM system for the new Minnesota Bridge

The St. Anthony Falls Bridge is already under the microscope as construction continues at breakneck speed to replace the collapsed I-35W bridge—and it’s already pushing new boundaries in intelligent design. But by turning the lens on itself, America’s smartest bridge could have an even bigger impact. 

A new high-tech structural health monitoring system equipped with 240 sensors should inform how we monitor other bridges and, eventually, determine how we build them. For all the details and an exclusive animation of the accelerometer-laden fiber-optic rig, we sat down with Figg Engineer Group CEO Linda Figg, who’s heading up St. Anthony Falls' design, before she appeared at the PM-NSF Bridge to the Future summit today. 

Some details of the sensing system have been ironed out, but most are being determined as the bridge goes up—much like its entire design and construction, which occurred almost simultaneously. The importance of the sensors, Figg insisted, is that all the information they collect will funnel into a database, eventually helping other engineers determine how best to design and build a bridge. 

To round up that data, the system—a collaboration between the University of Minnesota and the Minnesota Department of Transportation—will employ at least four different kinds of sensors: accelerometers (red), chloride penetration sensors (magenta), linear potentiometers (blue) and wire strain gauges (green). "The accelerometers will measure vertical deflections [or deformation] with traffic loads," Figg said. The chloride penetrating sensors will evaluate the condition of surface wear and tear by measuring whether or not salt is penetrating the pavement on the bridge deck. Repair and replacement are pricey, so early monitoring should make up for the initial cost of the sensors. 

Meanwhile, linear potentiometers will measure pressure to keep track of St. Anthony Falls’ expansion joints and bearings; Figg said UMinn and Mn/DOT would correlate that data with design codes to analyze how the bridge performs over its lifespan. Finally, the wire strain gauges will measure temperature as well as the amount of force per sq. in. placed on the concrete—all important in assessing a bridge's condition. 

The four sensors will be hardwired using fiber optics through the bridge, then wirelessly transmitted for analysis. They will account for about 100 of the sensors on the bridge; the University of Minnesota will outfit 140 more for research purposes. 

[Erin McCarthy via Popular Mechanics.com]

German Institute to Develop SHM

Several Fraunhofer institutes and various industrial partners are currently working on an SHM system that will use ultrasound to detect any damage to the technical structures of aircraft, pipelines or wind turbines. The core of the sensors used is made up of ceramic piezo fibers that convert mechanical energy into electrical impulses and vice-versa. Any piezo element can be used as either a transmitter or a receiver. It can excite the structure to produce vibrations, and it can record vibrations in the structure.
The ultrasound waves spread out in certain patterns depending on the type of structure. Cracks and other flaws alter this wave pattern in the same way as a rock changes the pattern of waves in a lake. Even a group of four piezo elements is sufficient to locate flaws accurately to the nearest centimeter – flaws that are often no more than a few millimeters in size.
“Our system is intended to supplement the checks used up to now,” says Bernhard Brunner of the Fraunhofer Institute for Silicate Research ISC, Würzburg. But that is only the first step. If the SHM systems prove successful, the researchers can envisage a status-dependent maintenance and repair system: “to save inspections and therefore time,” adds Brunner’s project partner Bernd Frankenstein of the Fraunhofer Institute for Non-Destructive Testing IZFP in Dresden. He is in no doubt that SHM systems will eventually replace conventional test methods, at least in part. The task of the Fraunhofer Institute for Structural Durability and System Reliability LBF is to create deliberate flaws in structures, which can then be detected during tests.
There are even more reasons for teaching structures to ‘feel’. It helps to make better use of valuable resources, both materials and energy. This is particularly noticeable in the aviation industry, where each gram less in the weight of the aircraft increases its potential payload as well as reducing exhaust fumes.
Continuous monitoring by SHM systems is also expected to yield greater safety, particularly for equipment such as offshore wind farms that are not readily accessible. The artificial nervous system fulfills a dual task in such cases: It monitors the structure and at the same time delivers data about occurrences in the structure during day-to-day operation. Data of this kind, which hardly existed until now, will help to optimize the next generations of components.
[Fraunhofer-Gesellschaft via physorg.com]

Scientists use an old bridge for new tests

Scientists at Britain's National Physical Laboratory say they have saved a 46-year-old foot bridge from demolition and will use it to develop new technology.

Scientists at the facility -- the national measurement standards laboratory for the United Kingdom -- said the 14-ton, 66-foot-long and 16-foot-high bridge had been used to allow access from one side of the NPL site to the other.

With redevelopment of the NPL site the bridge had become redundant. But rather than demolish the bridge, researchers will use it as a demonstrator to try different techniques for maximizing a structure's lifetime while minimizing maintenance costs.

During the three-year project the bridge will be loaded until it cracks, repaired using new composite repair methods and then retested.

NPL officials said the opportunity to have a large scale structure that can be abused while being monitored is a once-in-a-lifetime event and will provide evidence for the cost saving benefits of structural health monitoring.

[United Press International]

SHM on Government Technology

An article on SHM of bridges appeared in "Government Technology "

http://www.govtech.com/gt/261440?topic=117693

Entitled "Wireless Sensors May Help Governments Monitor Health of Aging Infrastructure" it describes the consequences of the 35W bridge collapse and some of the technologies that might prevent similar accidents in the future.
In particular, the article introduces a wireless technology perfected at Clarkson University by the team of prof. Kerop Janoyan:

New York is one of many states re-evaluating bridge inspection methods after the Minneapolis bridge collapse by turning to SHM technologies. The state department of transportation's pilot program uses wireless sensors placed on bridges to transmit data on stress and vibration, and should warn if a bridge is weak or needs repairs. The system, designed by Clarkson University associate professor Kerop Janoyan, is expected to help engineers monitor the state's 17,000 bridges.
"Providing more information is the first step to a feedback system," Janoyan said. "Without information, you can't have any feedback when ultimately you're trying to control potential damage."
A New York bridge between Canton and Potsdam is serving as a test site - 40 wireless channel sensors affixed to the bridge log in real-time data to a base station. Each sensor is about the size of a few decks of playing cards, and cost about $200. The battery-powered sensors are connected to a computer that aggregates sensor data and determines whether to alert inspectors.

The article than describes the work of prof. Farhad Ansari at the University of Chicago on optical fiber sensors:
The Department of Civil and Materials Engineering at the University of Illinois at Chicago is developing a similar bridge monitoring approach, using fiber-optic wires instead of wireless sensors. A research program at the university called - Smart Sensors and NDT Laboratory - develops fiber-optic sensors for monitoring structures during construction and throughout their service lives.
The Illinois Department of Transportation awarded a $55,000 contract in September 2007 to the laboratory - to devise a system that can detect bridge scour - when sediment is washed from the bottom of the river and weakens a bridge's support. The project involves embedding a fiber-optic sensor in a rod and driving the rod into a river base near the piers.
Fiber-optic sensors assess a bridge's overall health by measuring microfractures and vibration frequency. Fiber optics promise many innovations for bridge monitoring since they are smaller and more flexible than electrical wires, are immune to interference from wireless devices, and aren't prone to fires or explosions, said Farhad Ansari, professor and head of the Civil Engineering and Materials Department at the University of Illinois at Chicago.

The article also describes projects at the University of Michigan on "sensing paint" at at Sandia National labs on remote sensing.

35W bridge collapse pictures

In this interesting document, it is possible to observe a large number of pictures of the 35W bridge that collapsed into the Mississippi river.

http://www.ntsb.gov/dockets/Highway/HWY07MH024/387406.pdf

In particular it is interesting to notice that some of the gusset plates appear to be buckled as early as 2003 and the fractured plate show signs of corrosion.

Other related documets and reports can be found here:

http://www.ntsb.gov/dockets/Highway/HWY07MH024/default.htm

SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring

I am currently at the
SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring conference in San Diego.

Several interesting trends emerged in this edition:

• The seems to be a growing interest in aerospace applications, SHM and smart structures for active control.


• The civil engineering and structural monitoring parts are attracting less presentations and little new work. Probably more specific conferences such as SHMII and IABMAS are becoming more relevant in this field.


• A lot of papers as usual on Fiber Optic sensing and a growing number on wireless sensing. This technology is maturing and appears now adapted for field use, but mostly limited to short- and medium-term applications.


• Besides the usual bridges, other structures were also monitored, including aircraft, oil platforms and buildings.

Norhwestern University pubblications

Here is a list of interesting papers and presentations on "Improved Condition Monitoring for Bridge Management / Non-Destructive Evaluation" published by the insfrastructure Technology Institute at northwestern University.

2nd Asia-Pacific Workshop on Structural Health Monitoring

Conference Announcement:

Organiser: Materials Australia
Location: Melbourne, Australia
Date: December 02-04, 2008

This is the second in a series of biennial Asia-Pacific workshops that focuses on the field of Structural Health Monitoring (SHM). This is a particularly promising area that has attracted significant attention in recent years for its wide potential of applications, particularly for civil infrastructures, and maritime and aircraft structures. The purpose of the workshop is to allow a forum where key and emerging technical issues that are critical and unique in structural health monitoring can be discussed and identified, as well as allow current state-of-the-art technologies and R&D activities in the field to be presented. The workshop is also intended to promote exchanges and cross-fertilisation among many disciplines.

The workshop shall focus on, but is not limited to, the following topics:

- Sensor and Actuator Development
- Reliability of Structural Health Monitoring Methodologies
- Bio-inspired sensors
- Damage Identification and Properties/ Integrity Characterisation and Assessment: Intelligent Processing of Materials and Structures
- System Integration
- Applications (particularly in the field of aircraft, automotive, rail and maritime structures, civil and petroleum infrastructure, textiles etc)
- Homeland Security

Website: http://www.materialsaustralia.com.au/SHM2008/