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Rapid Construction of Pre-Fabricated Substructure Systems for Durable and Sustainable Bridges

I. Research Problem Statement
A significant number of bridges in the US require rehabilitation or replacement. As a result, increased emphasis is being placed on improving work zone safety and minimizing traffic disruption, while maintaining construction quality and reducing the life cycle costs and environmental impact. The use of innovative prefabricated systems away from the work zone can be an efficient solution, which would address many of the challenges in bridge construction, rehabilitation and replacement, in terms of the systems design effort, on-site construction time, minimum lane closure time, and minimum environmental impact.

Simultaneously with the FHWAs drive for rapid construction (Get in, Get out, Stay out! policy), the bridge community has explored a variety of design and construction options to prevent rapid deterioration of bridge substructures in harsh aggressive environments, such as in coastal areas and splash zones where the support columns would be alternately submerged and exposed. Similarly, problems have persisted in cold climate with the effect of deicing salt. Corrosion protection measures such as epoxy coating of re-bars, have not been successful over long periods of time in aggressive environments such as the Florida Keys. Rehabilitation or replacement of bridge substructure is often costly, and results in traffic disruption, work zone safety issues, and environmental impact. In the early 1990s, few states including Oregon and Florida initiated very expensive plans for galvanizing the corroded epoxy-coated re-bars for substructures of several bridges along their coastlines.
Emergence of fiber reinforced polymers (FRP) as potential solution to these problems has been related to their resistance to electro-chemical corrosion and high strength-to-weight ratio. FRP shells can provide environmental protection, construction form, and structural reinforcement for concrete support columns in a bridge. The possibility of using cathodic protection with the FRP shell adds another valuable opportunity to explore. The proposed column supports could be combined with the bent cap as segmental prefabricated substructure system, thus eliminating the need for individual substructure elements. This could enhance the speed of construction tremendously.

Despite great promise, the use of FRP for prefabricated segmental construction of bridge substructure systems has been limited to few demonstration projects due to lack of appropriate design guidelines, an initiative and a systematic approach by the AASHTO and the bridge community.

II. Research Proposed

The objective of the proposed study is to produce innovative systems, design guidelines, design specifications and recommended construction specifications for pre-fabricated substructure systems made of concrete and FRP, whereby the FRP shell acts as form work, structural reinforcement, and environmental protective jacket for concrete. It may also provide additional cathodic protection for internal reinforcement.
The performing agency will be required to review literature and gather published and unpublished experiences from engineers on these types of systems. The agency needs to further develop design concepts that are suitable for different applications. The agency needs to explore combining the column bents with the bent cap as segmental construction. Examples of such systems exist with traditional piles and bent caps. However, the technology has not yet been transported to the new materials. The agency will then study and determine the behavior of each system analytically and experimentally, and develop limitations and practical applications for each system. Cost-effectiveness of the system needs to be studied as well. The agency will then develop design guidelines and specifications, and recommend field procedures for the construction of these types of system.

III. Estimate of Problem Funding and Research Period
Recommended Funding: $600,000

Research Period: 30 Months

IV. Urgency, Payoff Potential, Implementation and Support for Business Needs

Premature and rapid deterioration of bridge substructure has been one of the major reasons for the current status of the nations infrastructure, where over 40% of the bridges are classified as structurally deficient or functionally obsolete. Even newer bridges have shown a growing rate of premature decay. A major effort is now underway to rebuild the nation's infrastructure. In order to simply maintain the current conditions (with no improvement), an average annual cost of $5.2 billion is needed through the year 2011. Hence, it is vital to the U.S. economy and for the state departments of transportation to explore cost-effective structural systems and materials in order to extend service life, and to improve performance of bridge substructures.

The long-term benefits of this research include lower maintenance costs and longer service lives for bridge substructures particularly in harsh environments. Durability is significantly greater than that of traditional systems. This will reduce the annual backlog for bridge replacement, resulting in lower costs to maintain or improve the transportation system. The results of this research will be used by bridge designers, bridge construction, contractors, and FRP manufacturers. Another advantage of the use of proposed system for bridge substructure is the efficient use of innovative prefabricated technology, which is a advocated by the FHWA in recent years. The proposed research will produce design guidelines and specifications and recommended field procedures for the construction of structurally integrated and environmentally protective stay-in-place forms for concrete bridge substructures particularly in harsh environments.

The proposed research will address AASHTOs identified business need (See NCHRP 20-7, Task 121) to develop and apply sustainable materials, products, structural systems, and technologies that reduce life-cycle costs, extend useful life, and improve the constructability of bridges. Specifically, it addresses the objective of developing policies, procedures, and methodologies that enable the acceptance and adoption of new technologies. The results of the study would also help develop the Technologies building block by providing the means to advance bridge construction.

V. Person Developing the Problem

Dr. Sami Rizkalla
Distinguished Professor of Civil Engineering and Construction, and Director of the Constructed Facilities Laboratory
Department of Civil, Construction, and Environmental Engineering
North Carolina State University
Raleigh, NC 27695-7908
E-mail: sami_rizkalla@ncsu.edu

VI. Date and Submitted by

Issam Harik
E-Mail: iharik@engr.uky.edu

Sponsoring Committee:AKB10, Innovative Highway Structures and Appurtenances
Date Posted:12/28/2006
Date Modified:07/18/2011
Index Terms:Rapid construction, Prefabricated structures, Prefabricated bridges, Sustainable maintenance, Bridges, Bridge construction, Rehabilitation (Maintenance), Bridge substructures, Key West (Florida), Coastal engineering, Work zone safety, Epoxy coatings, Reinforcing bars, Environmental protection, Bridge columns, Bents,
Cosponsoring Committees: 
Bridges and other structures

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