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.

For protective construction applications involving high-velocity projectile impacts, design engineers rely on properly designed reinforced concrete barriers to provide the necessary resistance to penetration. Typically dynamic testing, analytical, semi-empirical and/or computational approaches are called upon to properly handle this highly complex physical problem. The presented research evaluates the use of Applied Element Method (AEM), implemented in Extreme Loading for Structures (ELS) software, to predict the localized damage and penetration of concrete slabs due to high-velocity normal impacts of rigid projectiles. Two validation cases were considered involving different concrete and reinforcing rebar material properties and projectile impact velocities. The applicability of AEM simulations was validated by comparing predicted damage and projectile penetrations to corresponding observations and measurements obtained during impact testing. A limited parametric study including seven analytical cases was performed to investigate the effects of varying concrete strengths, reinforcement arrangements and concrete thickness on the penetration resistance of concrete targets. To achieve this, three concrete classes; Normal Strength Concrete (NSC), Medium Strength Concrete (MSC) and High Strength Concrete (HSC), three reinforcement configurations (unreinforced, single-layer/ larger bar, double-layers) and larger thickness were considered. The application of the engineering-oriented AEM/ ELS software was found to provide impact response predictions that are in good agreement with physical test results. The results of the parametric study confirmed the advantages of using higher concrete strengths and higher reinforcement ratios in improving the penetration resistance and reducing the scabbing damage of reinforced concrete barriers.

Carbon Reinforced Concrete (CRC) can be used for new structures and to strengthen existing components. Carbon fibre rods and fabrics are used as reinforcement for new components. Besides CFRP-lamellas, grid-like carbon reinforcements and shotcrete are very suitable for strengthening. Due to the low concrete cover, thin strengthening layers can be realised, which minimise the additional dead load. Depending on the chosen fibre material and impregnation, different failure mechanisms can be observed. The fibre strand should preferably be able to reach the maximum stress under load, but at this stage, the bond behaviour has to be thoroughly considered to prevent failure due to pull-out or delamination. Two carbon reinforcement fabrics are currently being investigated in the research programme C³ - Carbon Concrete Composite.This paper presents the results of large-scale tests on reinforced concrete slabs strengthened with CRC. In addition to the strengthening procedure and the large-scale component tests that have been carried out, this paper deals mainly with the recalculation of the test results and the positional accuracy of the carbon reinforcement and its influence on the flexural strength.

Textile-reinforced concrete (TRC) combines high-performance fabrics made of impregnated carbon yarns with state-of-the-art high strength concrete. Due to the corrosion resistance of non-metallic reinforcement, the application of TRC for external components especially with freeze-thaw and de-icing salt exposure is promising. This allows for reduction of concrete cover, to create slender structural elements and to execute thin slabs without additional waterproofing or protective decking. Different existing theoretical models and experience from various research projects were used in design of several pedestrian- and road bridges in Germany. The pedestrian bridges in Rems Valley and Ottenhöfen use TRC slabs without shear reinforcement as transversal loadbearing component. For the road bridges in Gaggenau, skew slabs made of TRC with shear reinforcement were chosen as principal structural system. Prior and during construction, experimental investigations on shear capacity were performed at the Institute of Structural Concrete (IMB) of RWTH Aachen. A comprehensive characterization of the material properties of the non-metallic reinforcement is a prerequisite for transfer and adaption of existing design rules, e.g. the determination of tensile strength of the bent portion of pre-formed shear reinforcement. This paper highlights the application potential and further challenges for the use of textilereinforced concrete in new engineering constructions.

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.