New Minnesota laws on Bridge Inspection

Four DFL lawmakers stood before the press and proposed a 10-point package of bridge safety reforms that they say is a first step toward a bill they will introduce during next year’s legislative session.

The package has been in the works for weeks, and is in direct response to reports and recommendations contained in two independent studies on bridge safety that have been concluded in response to the I-35 bridge collapse last August — by the Office of the Legislative Auditor in February and the law firm of Gray Plant Mooty in May. But the harrowing incident over the weekend — in which a six-foot-by-nine-foot slab of concrete tore away from the underside of Maryland Avenue and fell into Highway 35E, damaging two vehicles and snarling traffic for eight hours — added urgency and gravitas to the legislators’ recommendations.

Among the more prominent recommendations set forth on Monday was the necessity for bridges to be inspected at least every 12 months, and the setting and followup of specific performance targets at MnDOT, including the stipulation that an analysis be done by the agency whenever any of their goals or forecasts aren’t met. The package also recommends that the state salary cap be lifted for MnDOT engineers in order to assist with recruitment and retain quality personnel, and that either the commissioner or deputy commissioner of MnDOT be a professional engineer.

Read more here. [minnesotaindependent.com]

US Sweeping bridge safety bill includes fiber optic

U.S. Rep. Steven C. LaTourette (R-Bainbridge Township) today announced that a sweeping bridge safety bill approved by the House includes a study of fiber optic sensors like those developed by companies with offices in Twinsburg and Mentor that can detect stresses on bridges before they collapse or fail.

The House of Representatives today approved H.R. 3999, the Highway Bridge Reconstruction and Inspection Act, by a vote of 367-55. LaTourette said the measure authorizes $2 billion over two years for bridge reconstruction nationwide and requires the Federal Highway Administration (FHWA) to update national bridge inspection standards. It also calls on the FHWA to improve training for highway bridge inspectors. The bill was introduced after the August 2007 bridge collapse in Minneapolis that killed 13 people.

LaTourette said the bill includes language he supported that will authorize the FHWA to study the effectiveness of fiber optic sensors and other sensors in detecting deficiencies in bridges, particularly those under construction or renovation. LaTourette said he believes fiber optic sensors marketed by companies in Twinsburg and Mentor might have detected extreme stresses on the 35W Bridge in Minneapolis before it collapsed. It was loaded with heavy equipment and traffic had been shifted to accommodate construction, he said.

LaTourette said two 14th District companies are marketing cutting edge products that might have been able to avert the tragedy in Minneapolis. Cleveland Electric Laboratories Co. in

Twinsburg is marketing fiber-optic sensors that are attached to bridges to detect and monitor stress loads, and its product is being used on a project in Albany, NY. Roctest Ltd. of Quebec, which has its U.S. office in Mentor, is also marketing a fiber optic sensor system to detect stresses on bridges, and it will be used as the 35W Bridge in Minneapolis is rebuilt.

“We’re lucky that inspectors almost always catch problems and avert tragedies, but there are situations where unusual stresses on a bridge can lead to catastrophe. I think this technology

certainly merits more study so we never experience another disaster like the one in Minneapolis. It’s exciting to have two Northeast Ohio companies right in the mix,” LaTourette said.

LaTourette said construction can place unusual stresses on a bridge, and the small fiber optic sensors can monitor and record the level of stress.

“Who hasn’t been on a bridge where all the traffic is shifted to one side while the other is filled with workers and heavy equipment?” LaTourette said. “If a tiny sensor can detect when stress becomes so great that it makes a bridge susceptible to collapse, that’s a tremendous safety benefit not only for motorists but the workers renovating the bridge.”

[latourette.house.gov]

Roctest Introduces New SensCore System

Roctest Ltd. announced the introduction of the new SensCore product line, dedicated to the monitoring of corrosion in reinforced concrete structures. The SensCore system is a wireless sensor network, designed to detect and predict the onset of steel corrosion in concrete. The system consists of sensors, dataloggers and a measurement hub that concentrates the data from several dataloggers and transmits it to a central database, where it can be accessed by the authorized users. The sensors are able to measure several parameters, which are critical to evaluate the present and future risk of rebar corrosion in concrete. In particular the corrosion current and the concrete humidity are measured at several depths between the concrete surface and the rebar depth, to analyze the progression of the corrosion front as well as evaluate the performance of hydrophobic coatings.

The sensors are extremely simple to deploy and can transmit their data wirelessly to the measurement hub, thus eliminating the need to install any wiring in the structure to be monitored. Because of its modular design, this system is adapted to structures of all sizes, from a small overpass to a long tunnel and can be installed in both new and existing structures. The SensCore system integrates seamlessly with all present Roctest, Télémac and SMARTEC product lines, based on electrical, vibrating wire or fiber optics technologies. It is therefore possible to combine several technologies in order to implement an optimal monitoring network for any type of structure, being it a bridge, a building, a tunnel, a dam or any other concrete structure. The SensCore System ties into Roctest’s SDB database system, providing a unified

display and interface to all monitoring data, regardless of the underlying sensing technologies.

The SensCore system has been developed in cooperation with a leading Swiss University and has already being deployed on tens of structures, including the I35 St. Antony Falls Bridge in Minneapolis recently instrumented by Roctest. “Corrosion is one of the leading concerns in reinforced concrete structures and often limits their durability” said Daniele Inaudi, Roctest’s CTO, “it is therefore advantageous to complement the current monitoring strategies with a direct measurement of the corrosion progression”.

“The SensCore system ideally expands our growing toolbox of sensing systems” added François Cordeau, Roctest’s CEO, “further positioning our Company as the leading provider of Structural Health Monitoring solutions”.

Roctest Press Release [Roctest]

Bridge Doctors Podcast

Structural engineer Michael Todd describes the state of bridge monitoring around the world in this podcast. Interview by Rima Chaddha. Edited by David Levin. 

[NOVA]

Roctest wins contract for Jinping 2 dam in China

Roctest Ltd.  and its Chinese agent, Earth Products China Ltd, have been awarded a major contract for the deliveries of numerous instruments for the second highest dam in the world, Jinping 2 HPP, located on the Yalong River in China. The project started in February 2007 and is scheduled to be completed by 2014. Roctest is the main supplier of geotechnical instrumentation for the project, which is part of a network of five dams along the Yalong River, including the Ertan Dam , which was also instrumented by the Roctest Group between 1995 and 2000.

“We are very proud to have won another prestigious contract in such a highly competitive market. This not only demonstrates our ability to meet stringent requirements but also to offer a complete solution to a very complex engineering structure,” said Francois Cordeau, President & Chief Executive Officer of Roctest. “Roctest is 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 Mr. Cordeau.

With a height of 305 meters, this concrete dam will be the second highest in the world, after the Rogun Dam, in Tajikistan at 335 meters high. The total capacity of Jinping 2 will be 4800 MW, with its eight generators at 600 MW each.

This project will require thousands of sensors, a magnitude rarely seen in the industry, and will measure different parameters such as pore pressure in the foundation of the dam, settlement, strain and other types of movement during construction and all along the lifespan of the structure.

Press Release Roctest [Roctest]

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]