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.

The Sunshine Skyway Bridge is recognized as the State of Florida’s “flagship bridge.” The goal of the Florida Department of Transportation (FDOT) and specifically its entity that maintains the Skyway Bridge, the District 1 & 7 Structures Maintenance Office (DSMO), is to extend the life of this bridge to 100 years. Beam cracking on the trestle spans have been noted since the 1990s. In 2005 the DSMO initiated an in-depth study to determine the cause of cracking and to recommend a repair procedure. Upon completion, a committee of FDOT staff from various key offices in the State, along with consultant experts, determined criteria to address these cracks. The repairs included epoxy crack injection, penetrant sealer, and carbon fiber reinforced polymer (CFRP) wrap installation. FDOT addressed the repairs in three phases. The first repair project was in 2009, the second in 2013, and the third and final began in 2019.

A reinforced concrete bridge built in 1940 and located in Dallas, Texas, exhibited moderate to severe corrosion-related deterioration in the concrete bent caps. The damaged bent caps were repaired with epoxy mortar and externally strengthened with carbon fiber reinforced polymer (CFRP) laminates. Three-dimensional numerical models of the bent caps were created to better understand the cap behavior in bending and during various stages of the repair. The models were calibrated using data obtained from full-scale live load bridge testing. . The models were loaded until failure (rapid crack opening or CFRP debonding) to show the crack patterns, strain distributions and the bent cap capacities. The bent cap moment capacity increased by about 30% after repair/strengthening, because the original bent caps had extensive damage at the flexure-critical areas. The dowel-connected newer bent caps from the 1970 widened bridge contributed to the load sharing with the older bent caps.

Conventional reinforcing and strengthening methods and material for bridges and structures has several limitations including include the increased weight of structure, the limited service life of the repair, short periods between repairs, uncertain strength of the reinforcement, extended time of repair and typically a heavy carbon footprint based on the materials used. Application of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) solutions have shown the potential to replace traditional methods over the coming decade because the superior mechanical and durability properties reduce the required thickness of a repairing layer and extend the service life. Based on the overall cost of a given rehabilitation project, UHPFRC based solutions can already compete today but require certain specialized equipment and trained workforce creating real or perceived barriers. In this paper, a new type of nano-engineered UHPFRC based on carbon-nanofibers (CNFs) was introduced, named UHPC 2.0TM. The test results show that UHPC 2.0TM possesses ultra-high mechanical properties, improved direct tension performance and durability. In addition, an analytical procedure is provided for case studies to show the performance and economic benefits of usage of UHPC 2.0TM compared to traditional UHPFRC.

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.