International Concrete Abstracts Portal

A Sustainable built-environment requires a comprehensive process from material selection through to reliable management. Although traditional materials and methods still dominate the design and construction of our civil infrastructure, nonconventional reinforcing and strengthening methods for concrete bridges and structures can address the functional and economic challenges facing modern society. The use of advanced materials, such as fiber reinforced polymer (FRP) and ultra-high performance concrete (UHPC), alleviates the unfavorable aspects of every-day practices, offers many new opportunities, and promotes strategies that will be cost-effective, durable, and readily maintainable. Field demonstration is imperative to validate the innovative concepts and findings of laboratory research. Furthermore, documented case studies add value to the evaluation of emerging and maturing technologies, identify successful applications or aspects needing refinement, and ultimately inspire future endeavors. This Special Publication (SP) contains nine papers selected from three technical sessions held during the virtual ACI Fall Convention of October 2020. The first and second series of papers discuss retrofit and strengthening of super- and substructure members with a variety of techniques; and the remaining papers address new construction of bridges with internal FRP reinforcing and prestressing in beam, slabs, decks and retaining walls. All manuscripts were reviewed by at least two experts in accordance with the ACI publication policy. The Editors wish to thank all contributing authors and anonymous reviewers for their rigorous efforts. The Editors also gratefully acknowledge Ms. Barbara Coleman at ACI for her knowledgeable guidance.

Many aging concrete bridges across the United States have exhibited severe deteriorations and in urgent need of rehabilitation, retrofitting or replacement. The deterioration is caused by a combination of factors including corrosion of reinforcing steel, freeze-thaw damage and chloride/water ingress. Fiber-Reinforced Polymer (FRP) composite fibers, laminates, reinforcing bars and prestressed tendons have been successfully employed in civil infrastructure applications in the past three decades. The State of West Virginia has one of the highest percentages of structurally deficient bridges in the United States and this study covers a few case studies of the use of FRP composites for rehabilitating the State’s deficient bridges. Non-destructive ultrasonic pulse-echo testing is employed to map reinforcing rebars and detect delaminations of reinforced concrete slabs. A software, that employs the modified synthetic aperture focusing technique (SAFT) image reconstruction algorithm and signal processing, is developed to effectively visualize the reinforcing rebars and delaminations.

The design principle of fiber-reinforced polymer (FRP) reinforcing composite bars for concrete structures has been well established through extensive research and field practices. Provisions governing certification testing and evaluation as well as quality control/assessment and FRP design provisions, are now in place to regulate materials specifications and design aspects and guide FRP manufacturers and end-users. The Canadian Standards Association (CSA) group addressing the state-of-the-art FRP material specifications and design requirement recently issued two updated provisions. The new edition of CSA S807 includes several additions and modifications in terms of quality and qualification requirements, material properties, testing procedures, and material mechanical and durability limitations. Additionally, the updated Section 16 of CSA S6 for the design of fiber-reinforced structures and highway bridges aimed at providing more rational design algorithms and allowing practitioners to take full advantage of the efficiency and economic appeal of FRP bars. This paper presents a summary of these recent modifications in Canadian codes and standards, introducing the underlying rationale. Additionally, the paper highlights the recent field applications of FRP bars in different types of concrete civil-engineering infrastructure.

This case study highlights the use of Fiber Reinforced Polymer (FRP) materials on the US 41 Highway Bridge over North Creek in Sarasota County near the Florida Gulf Coast. Design and construction involved the use of Glass-FRP (GFRP) reinforcement on the cast-in-place (CIP) concrete flat slab superstructure, Carbon-FRP (CFRP) prestressing strands on the concrete piles, and GFRP reinforced precast panels for the substructure combining a bridge bearing abutment and retaining wall system. The application of FRP prestressing and reinforcing is promoted by the Florida Department of Transportation (FDOT) under their Transportation Innovation Challenge initiative. Soldier-pile retaining walls are a commonly used system in southeastern US coastal states, but the incorporation of innovative materials such as CFRP-prestressing for piles and GFRP-reinforcing for concrete panels is not yet widespread. Comparison of lateral stability results of this wall system during construction and in the final condition is discussed. In addition, to describing the preferred FRP-PC/RC solution adopted for this project, a comparison is provided to a recently completed adjacent bridge that utilized a conventional carbon-steel PC soldier-pile and RC precast panel wall system. A further comparison is presented for the design and cost of the wall system based on the project design criteria (ACI 440.1R, ACI 440.4R, and 2009 AASHTO LRFD Bridge Design Guide Specifications for GFRPReinforced Concrete, 1st Edition) with the refinements and savings possible under the newer editions. Finally, the life-cycle cost, durability and environmental benefits from the use of the innovative CFRP and GFRP reinforcing systems in this type of traditional wall system, are identified for typical urban coastal areas with extremely aggressive conditions, congested access, and challenging environmental constraints.

The intent of this paper is to provide an illustrative example of a municipal bridge replacement design project utilizing fiber reinforced polymer materials approved for use by the Florida Department of Transportation. Specifically this paper describes the design of the Nathaniel J. Upham (40th Avenue NE) Bridge replacement project and illustrates the application of carbon fiber reinforced polymer (CFRP) prestressing tendons and glass fiber reinforced polymer (GFRP) reinforcing bars in both precast and cast-in-place concrete elements. Due to the structure’s high level of exposure in the extremely aggressive environment, the design for the replacement bridge focused on concrete elements that were durable and resilient to the effects of corrosion in those conditions. Prestressed and castin- place concrete elements with GFRP and CFRP reinforcement and prestressing tendons were utilized for the primary structural elements with direct exposure to salt water. In addition, link slabs with GFRP reinforcing were utilized at each intermediate bent to improve the bridge’s performance. The design of the bridge elements followed the Florida Department of Transportation’s design guidelines and requirements. The bridge replacement project is currently at the completion of the design phase and is scheduled to be advertised in the early summer of 2020 with the start of construction anticipated in the fall of 2020.