Rebuilding America's Infrastructure

Researching the Future
From smart materials to sustainable standards
By Solomon Lieberman

A specimen of bendable concrete, produced by the materials research lab at the University of Michigan, Ann Arbor. a force of five percent tensile strain is being applied. regular concrete would fail at 0.01 percent tensile strain. this specimen also includes a self-healing ability, wherein bending creates hairline “microcracks” that, after cycles of wetting and drying, form thin, white scars of calcium carbonate. Nicole Casal Moore, University of Michigan

The reality of infrastructure, whether it’s the Pantheon or County Road 73, is the inevitable decline of the blocks used in the building. It is this reality that makes engineering such a precarious privilege. With each new bridge or road, the engineers’ promise of stability is sacrosanct, yet entirely limited by the expiration of the materials, the whimsy of the elements, and all the intangibles in between.

Road-tested and approved products and approaches will always get specified before more speculative options, as they probably should, but it is also the responsibility of the engineer to consider what’s new, because without innovation our conventions will remain, if nothing else, conventional.

During the last few months, the editors of Rebuilding America’s Infrastructure surveyed the nation’s premier research programs, reached out to firms and manufacturers, and contacted individuals who are researching and developing the future. The result is a look at some of the new materials, technologies, and methods that could greatly influence the bridge and road industry

Illinois Structural Health Monitoring Project University of Illinois at Urbana-Champaign Prof. B.F. Spencer Jr.	Trip-Generation at Mixed-Use Developments Fehr & Peers, Jerry Walters, T.E., chief technical officer
What are the details and goals of the project?
To improve structural health monitoring (SHM) practices by employing Wireless Smart Sensors Networks (WSSN) to measure structural response and perform in-network data processing. WSSN technology offers the opportunity to transform infrastructure monitoring and maintenance by improving on traditional approaches. This research has developed the key hardware and software components to make this technology accessible to a broad audience of researchers and engineers.	To improve methods used to account for all factors that affect traffic generation at mixed-use development sites. The research studied the generation of vehicle trips, transit trips, walk trips and vehicle miles traveled (VMT) at 239 mixed-use sites throughout the U.S., and it built statistical models that predict site-specific travel generation as a function of development density, mix, design, scale, regional location, transit access, and demographics. It validated the models through traffic counts at 16 sites in various parts of the U.S.
Why is the project important?
WSSN can provide useful information about the condition of a structure at a lower cost and higher density than traditional monitoring systems. Ultimately, such systems will improve the life-cycle costs of structures, and most importantly, improve public safety.	Improves transportation engineers’ ability to size infrastructure, determine energy impacts and climate impacts of newer forms of development, by providing more reliable methods for predicting the traffic trip generation of suburban and urban mixed-use projects.
Timeline
Initial hardware and software development began in 2003, and full-scale deployment began in 2009. The research will be ongoing, as both the hardware and software are being validated through a 70-node sensor network deployed on a full-scale cable-stayed bridge in South Korea. Spencer expects the industry to benefit from the findings in anywhere from a few months to a few years.	The project began in April 2007, and it was completed in April 2009. The results are currently undergoing review by the Institute of Transportation Engineers for possible inclusion in the “Trip Generation Handbook.” The industry is expected to benefit from the findings in 2010, and beyond, as Fehr & Peers continues its research on trip generation.
Editor’s word
Just because some are slower than others to incorporate SHM technology, doesn’t mean the evolution of SHM should slow down, too. To learn more visit shm.cs.uiuc.edu.	A holistic approach to trip generation; it considers the increasingly common variations in development sites, and the economic and environmental impacts. To learn more visit fehrandpeers.com.

Towards Green Bridges Scott Snelling, P.E. Senior engineer with Hardesty & Hanover, LLP, New York City	Application of Smart Materials in Seismic Retrofit of Bridges Georgia Institute of Technology Prof. Reginald DesRoches, Ph.D.,
What are the details and goals of the project?
Snelling drafted a green standard for the bridge industry because none exists. Green standards have been implemented successfully in other infrastructure sectors, such as buildings and roads, and provide a means to recognize projects that are constructed according to environmental best practices. Snelling’s proposed standard has a total of six prerequisites and 39 points grouped into seven categories. The categories are: materials & resources, alternative transportation, project delivery process, construction activity, maintenance & access, environment & water, and energy.	A defining image after an earthquake is often a bridge deck that dropped from its supports and crashed to the earth. Researchers have been searching for innovative ways to keep decks in place so that bridges can ride-out earthquakes with minimal damage. One innovation is the use of “smart” cables that can stretch during the earthquake, and pull decks back into place when the earthquake is over. This research is pursuing the anchoring of bridge decks or highway overpasses with restraining cables made from “smart” shape memory alloys, rather than traditional steel cables.
Why is the project important?
In line with the global climate change mitigation strategies, the proposed Greenbridges standard aims to reduce life-cycle costs, energy use, greenhouse gas emissions, pollution emissions, waste, and the use of non-renewable resources to sustainable levels. This will be accomplished by encouraging practices such as: waste management, alternative transportation, life-cycle analysis, and others.	Given the significant damages to bridges observed in past earthquakes and hurricanes, this technology has the ability to revolutionize the design and rehab of bridges and seeks to dramatically improve the performance of bridges subjected to extreme loads.
Timeline
The research began in November 2006. The project will be ongoing until there is an organization on-board to publish and administer the standard. Snelling is currently presenting it to organizations such as TRB, USGBC, ASCE, Greenroads, and DOTs.	The research began in 2006 and ended in 2008. DesRoches expects the industry to benefit from the research in two to three years.
Editor’s word
The acceptance of such a standard seems inevitable, and applause should go to Snelling for his in-depth approach and dedication to Greenbridges. To learn more, contact Snelling at ssnelling@hardesty-hanover.com.	As DesRoches noted, the indelible images that remain after a natural disaster are often of collapsed pieces of critical infrastructure. And since we can’t yet prevent an earthquake, we should do everything in our power to help a bridge survive it. To learn more visit people.ce.gatech.edu/~rd72.

Effects of Ambient Temperature Changes on Integral Bridges Kansas State University Dunja Peric, Ph.D., associate professor	Engineered Cementious Composites University of Michigan Professor Victor C. Li, Ph.D., FASCE, FASME, FWIF
What are the details and goals of the project?
To advance the knowledge-base about integral bridges, specifically: the influence of level of compactness of the soil adjacent to the abutment on the stresses in the continuous deck and piles, and the magnitude of the temperature change on the stresses in the deck and piles. Computational modeling was used to simulate a response of an actual integral bridge to a combined thermal and gravity loading. A powerful 3-D live graphics rendering provided visualizations of a deforming bridge with superimposed color-coded displacements and stresses.	The project aims at creating a better concrete for civil infrastructure, for extended service life with lower maintenance requirements, and for enhancing environmental sustainability. The result is Engineered Cementitious Composites (ECC) — nicknamed Bendable Concrete — which is hundreds of times more ductile compared with normal concrete. Laboratory tests under various environments confirm enhanced structural durability.
Why is the project important?
Advancing the knowledge-base about integral bridges will enable wider acceptance of better performing, less expensive, and better looking bridges. Multiple benefits arise from the continuity, including: increased resilience and longevity; decreased construction and whole-life maintenance costs; improved vehicular ride safety and quality; and pleasing aesthetics.	Many infrastructure owners often find it difficult to keep up with maintenance demands, especially in today’s tight budget situation. Public motorists would prefer to see less traffic jams due to repair or reconstruction events. We all need both a well-built environment and a stable natural environment. Better concrete is not the only means to get there, but it can play a very important role.
Timeline
The research began in September 2000 and ended in December 2007. Peric said the industry began benefiting from the research in January 2008, as thermally induced displacement and stresses in integral bridges can now be computed more accurately.	ECC research began about 15 years ago. Li said it will continue thanks to sponsorships, as the team looks to learn from full-scale applications, and to add further smart functionality, including self-healing and self-sensing.
Editor’s word
As Peric noted, there are around 600,000 bridges in the U.S., so improving the industry’s understanding of these integral structures can only bolster the collective foundation. To learn more visit ce.ksu.edu/facultystaff/peric/research.html.	Built into the ECC project is a commitment to constant improvement and collaboration, and the more support it gets, the better it will get. Recent iterations of the self-healing variety are particularly compelling. To learn more visit www.ace-mrl.engin.umich.edu

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